Patent Publication Number: US-2020277559-A1

Title: Expressors and Expressor Systems for Separating Components of a Biological Suspension and Methods of Use

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. application Ser. No. 16/289,296, filed Feb. 28, 2019, which is incorporated herein by specific reference. 
    
    
     BACKGROUND 
     1. The Field of the Disclosure 
     The present disclosure relates to expressors, expressor systems, and related methods for driving a liquid supernatant out of a collapsible bag that also houses a pellet comprised of cells or microorganisms. 
     2. The Relevant Technology 
     Bioreactors and fermenters are used to grow a variety of different types of biological suspensions. Such suspensions are broadly defined as comprising cells or microorganisms and a liquid medium in which they are suspended. Once a suspension has been sufficiently grown, it is common to separate the biological suspension into components and then harvest the separate components for subsequent analysis or use. Centrifugation is a technique often employed during isolation or analysis of various cells, organelles, and biopolymers, including proteins, nucleic acids, lipids, and carbohydrates dissolved or dispersed in biological suspension. 
     In one approach to centrifugation, quantities of a suspension are dispensed from a bioreactor or fermenter into an open-top bottle. The bottle is then closed by manually applying a lid and then spun using a centrifuge rotor. The centrifugal force created by spinning of the rotor causes the solids within the suspension to sediment out of the solution to form a generally solid pellet towards the bottom of the bottle. A supernatant, which is a liquid that is less dense than the pellet, collects within the bottle above the pellet. The supernatant is then decanted from the bottle by removing the lid and then pouring and/or pumping out the supernatant. The pellet can then be separately removed from the bottle. 
     Although the above process is effective, it has a number of shortcomings. For example, the bottles that are used as open-top containers. Thus, both the suspension and the interior of the bottles are openly exposed to the surrounding environment as the suspension is initially dispensed into the bottles. In turn, the separated components are again openly exposed to the surrounding environment as the separated components are removed from the bottles. This open exposure to the environment increases the probability of the suspension and/or the separated components becoming contaminated. Subsequent purification steps can thus be required to remove any contaminates from one or both of the separated components. Conventional methods and systems thus have a high probability of contamination and can require added labor, time, and cost to run purification steps. 
     In addition to the above, it can be difficult in conventional systems to effectively separate the supernatant from the pellet. That is, it is typically desirable to maximize the quantity of cells or microorganism within the pellet and to minimize the quantity of cells or microorganism within the supernatant. However, in some applications the pellet can be easily disturbed causing the solids thereof to resuspend into the supernatant. As such, it can be a slow and labor intensive process to carefully decant the supernatant from the bottles without disturbing the pellet. It is often necessary to sacrifice some supernatant to avoid disturbing the pellet. 
     In one attempt to solve some of the above problems, a removable, open-top liner has been placed within a centrifuge container. The liner bounds the compartment of the container and receives the biological suspension. Following use, the liner is discarded and a new liner can be inserted within the centrifuge container without the need for cleaning or sterilization of the container. The liner, like the above discussed bottle, is open and exposed to the surrounding environment during dispensing of the biological suspension therein. As such, there remains an increased risk of the suspension and components being contaminated and the need for purification steps. Furthermore, the liner does not solve the difficulty of separating the supernatant from the pellet. Other shortcomings also exist. 
     Accordingly, what is needed in the art are improved system and methods that solve all or some of the above and other existing shortcomings. 
     SUMMARY OF THE DISCLOSURE 
     In a first independent aspect of the present disclosure, an expressor includes:
         a base;   a first platen having an inside face extending between an upper end and an opposing lower end, the lower end extending from the base;   a second platen having an inside face extending between an upper end and an opposing lower end, the second platen being movably mounted to the base so that the second platen can move between a collapsed position where the second platen is moved toward the first platen and a retracted position where the second platen is moved away from the first platen, at least a portion of the second platen being spaced apart from the first platen by a gap spacing when the second platen is in the collapsed position,   wherein either the first platen or the second platen is releasably attached to the base so that a width of the gap spacing when the second platen is in the collapsed position can be selectively adjusted.       

     In one embodiment, the lower end of the second platen is pivotably connected to the base so that the second platen can pivot between the collapsed position and the retracted position. 
     In another embodiment, the second platen moves laterally without pivoting as it moves between the collapsed position and the retracted position. 
     In another embodiment, either the first platen or the second platen is releasably attached to the base so that the width of the gap spacing can be selectively adjusted without pivoting of the first platen or the second platen. 
     In another embodiment, the first platen or the second platen can be moved laterally relative to the other platen to selectively adjust the width of the gap spacing. 
     In another embodiment, the first platen is releasably attached to the base so that the width of the gap spacing can be selectively adjusted. 
     In another embodiment, a releasable fastener releasably attaches the first platen to the base. 
     In another embodiment, a first opening passes through a portion of the first platen, the releasable fastener passing through the first opening. 
     In another embodiment, the inside face of the first platen is disposed in parallel alignment with the inside face of the second platen when the second platen is in the collapsed position. 
     In another embodiment, the first platen or the second platen is movably attached to the base so that the width of the gap spacing can be selectively adjusted by at least 0.25 cm, 0.5 cm, 1 cm, or 2 cm. 
     In another embodiment, the second platen is pivotably connected to the base by a hinge. 
     In another embodiment, means are provided for moving the second platen toward the first platen. 
     In another embodiment, the means for moving resiliently urges the second platen toward the first platen. 
     In another embodiment, the means for moving includes a spring, pneumatic piston or hydraulic piston. 
     In another embodiment, the first platen inwardly tapers at the lower end. 
     In another embodiment, the entire first platen is spaced apart from the second platen when the second platen is in the collapsed position. 
     In another embodiment, an expressor system includes:
         the expressor; and   a bag assembly including:
           a collapsible bag bounding a compartment that is adapted to hold a fluid, the bag being disposed between the first platen and the second platen; and   a tube projecting from the collapsible bag.   
               

     In another embodiment, a pellet comprised of cells or microorganisms is disposed within the compartment of the bag and a liquid supernatant is disposed within the compartment of the bag. 
     In another embodiment, the pellet includes cells that are free red blood cells and white blood cells. 
     In another embodiment, the liquid supernatant is free of plasma. 
     In another embodiment, an optical sensor and a pinch clamp are each disposed on or overlay the tube projecting from the collapsible bag. 
     In another embodiment, a method is provided for using the expressor for removing a supernatent from a compartment of a collapsible bag that houses the supernatant and a pellet comprised of cells or microorganisms, the method includes:
         moving the first platen or the second platen of the expressor relative to the base so as to adjust the width of the gap spacing between the first platen and the second platen based upon an amount of pellet within the compartment of the bag;   positioning the collapsible bag between the first platen and the second platen; and   moving the second platen toward the first platen so as to compress the bag between the first platen and the second platen and drive at least a portion of the supernatant out of the bag through a tube coupled with the bag.       

     In a second independent aspect of the present disclosure, an expressor includes:
         a base;   a first platen having an inside face and an opposing outside face extending between an upper end and an opposing lower end, the upper end having a perimeter edge with a first notch recessed into the perimeter edge so that the first notch passes between the inside face and the outside face, the lower end being connected to the base;   a second platen having an inside face extending between an upper end and an opposing lower end, the lower end of the second platen being movably mounted to the base so that the second platen can move between a collapsed position where the second platen is moved toward the first platen and a retracted position where the second platen is moved away from the first platen.       

     In another embodiment, the second platen is spaced apart from the first platen by a gap spacing when the second platen is in the collapsed position. 
     In another embodiment, the second platen is pivotably connected to the base so that the second platen can pivot between the collapsed position and the retracted position. 
     In another embodiment, the second platen is pivotably connected to the base by a hinge. 
     In another embodiment, the first notch has a width in a range between 0.5 cm and 3 cm. 
     In another embodiment, a second notch is recessed into the perimeter edge at the upper end of the first platen so that the second notch passes between the inside face and the outside face, the second notch being spaced apart from the first notch. 
     In another embodiment, means are provided for moving the second platen between the collapsed position and the retracted position. 
     In another embodiment, the first platen inwardly tapers at the lower end. 
     In another embodiment, an expressor system includes:
         the expressor; and   a bag assembly including:
           a collapsible bag bounding a compartment that is adapted to hold a fluid, the bag having a front face and an opposing back face, the bag being disposed between the first platen and the second platen;   a first port being disposed on the front face of the bag and communicating with the compartment, the first port being received within the first notch of the first platen;   a tube projecting from the first port.   
               

     In another embodiment, a pellet comprised of cells or microorganisms is disposed within the compartment of the bag and a liquid supernatant is disposed within the compartment of the bag. 
     In another embodiment, the pellet includes cells that are free red blood cells and white blood cells. 
     In another embodiment, the liquid supernatant is free of plasma. 
     In another embodiment, the expressor system further includes:
         the first platen further comprising a second notch recessed into the perimeter edge at the upper end of the first platen so that the second notch passes between the inside face and the outside face, the second notch being spaced apart from the first notch; and   the bag assembly further comprising a second port being disposed on the front face of the bag and communicating with the compartment, the second port being received within the second notch of the first platen.       

     In another embodiment, a method is provided for using the expressor for removing a supernatant from a compartment of a collapsible bag that houses the supernatant and a pellet comprised of cells or microorganisms, the method includes:
         positioning the collapsible bag between the first platen and the second platen of the expressor, a first port being disposed on the front face of the bag and communicating with the compartment, the first port being received within the first notch of the first platen; and   moving the second platen toward the first platen so as to compress the bag between the first platen and the second platen and drive at least a portion of the supernatant out of the bag through a tube coupled with the bag.       

     In a third independent aspect of the present disclosure, an expressor includes:
         a base;   a first platen having an inside face extending between an upper end and an opposing lower end, the lower end extending from the base;   a first arm and a spaced apart second arm movably mounted to the base;   a second platen having an inside face extending between an upper end and an opposing lower end, the second platen being pivotably connected to the first arm and the second arm so that the second platen can pivot toward and away from the first platen.       

     In another embodiment, the first arm and the second arm each have a first end and an opposing second end, the first end of each arm being pivotably connected to the base. 
     In another embodiment, the second platen is pivotably connected to the second end of each arm. 
     In another embodiment, the first arm and the second arm can each adjust in length. 
     In another embodiment, a spring resiliently urges the second platen toward the first platen. 
     In another embodiment, an expressor system includes:
         the expressor; and   a bag assembly including a collapsible bag bounding a compartment that is adapted to hold a liquid, the bag being disposed between the first platen and the second platen, the second platen being elevated by the first arm and the second arm so as to be spaced apart from the base.       

     In another embodiment, a pellet comprised of cells or microorganisms is disposed within the compart of the bag and a liquid supernatant is disposed within the compartment of the bag. 
     In another embodiment, the pellet includes cells that are free red blood cells or white blood cells. 
     In another embodiment, the liquid supernatant is free of plasma. 
     In another embodiment, the lower end of the second platen presses against the bag at a location above the pellet. 
     In another embodiment, a clamp is clamped across the bag at a location above the pellet. 
     In another embodiment, a method is provided for using the expressor for removing a supernatant from a compartment of a collapsible bag that houses the supernatant and a pellet comprised of cells or microorganisms, the method includes:
         positioning the collapsible bag between the first platen and the second platen of the expressor;   moving the first arm and the second arm so as to elevate the second platen;   urging a hinge connected to second platen against the bag at a location above the pellet; and   moving the second platen toward the first platen so as to compress the bag between the first platen and the second platen and drive at least a portion of the supernatant out of the bag through a tube coupled with the bag.       

     In a fourth independent aspect of the present disclosure, an expressor system includes:
         an expressor having:
           a base;   a first platen having an inside face extending between an upper end and an opposing lower end, the lower end extending from the base; and   a second platen having an inside face extending between an upper end and an opposing lower end, the second platen being movably mounted to the base so that the second platen can move between a collapsed position where the second platen is moved toward the first platen and a retracted position where the second platen is moved away from the first platen, at least a portion of the second platen being spaced apart from the first platen by a gap spacing when the second platen is in the collapsed position,   
           a collapsible bag bounding a compartment that is adapted to hold a fluid, the bag being disposed between the first platen and the second platen; and   a pellet and a liquid supernatant being disposed within the compartment of the bag, the pellet being comprised of cells or microorganisms and being free of red blood cells or white blood cells.       

     In one embodiment, the liquid supernatant is free of plasma. 
     In another embodiment, a method is provided for using the expressor system, the method including:
         moving the second platen toward the first platen so as to compress the bag between the first platen and the second platen and drive at least a portion of the supernatant out of the bag through a tube coupled with the bag; and   removing the bag from between the first platen and the second platen.       

     Each of the above independent aspects of the disclosure may include any of the features, options and possibilities set out in this document, including those under the other independent aspects, and may also include any combination of any of the features, options and possibilities set out in this document. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various embodiments of the present disclosure will now be discussed with reference to the appended drawings. It is appreciated that these drawings depict only typical embodiments of the disclosure and are therefore not to be considered limiting of its scope. 
         FIG. 1  is an elevated front view of a reactor that is fluid coupled with a bag assembly; 
         FIG. 2  is an elevated front view of the bag assembly shown in  FIG. 1 ; 
         FIG. 3  is an exploded view of the bag assembly shown in  FIG. 2 ; 
         FIG. 4  is an elevated front view of an alternative embodiment of the bag assembly shown in  FIG. 2 ; 
         FIG. 5  is an exploded view of the bag assembly shown in  FIG. 4 ; 
         FIG. 6  is an elevated front view of the bag assembly shown in  FIG. 1  including an inlet line and an outlet line; 
         FIG. 7  is a perspective view of one embodiment of a centrifuge (floor standing model) that can be used in the present disclosure; 
         FIG. 8  is an elevated front view of the bag assembly shown in  FIG. 6  after being removed from the centrifuge; 
         FIG. 9  is an elevated front view of the bag assembly shown in  FIG. 8  fluid coupled with a container in which the supernatant is to be disposed; 
         FIG. 10  is a front perspective view of an expressor in a retracted position; 
         FIG. 11  is a rear perspective view of the expressor shown in  FIG. 10 ; 
         FIG. 12  is an enlarged view of the section identified in  FIG. 11 ; 
         FIG. 13  is a rear perspective view of the expressor shown in  FIG. 10  in a collapsed position; 
         FIG. 14  a rear perspective view of the expressor shown in  FIG. 13  with the first platen thereof moved to a second position; 
         FIG. 15  is an enlarged perspective view of an alternative embodiment of an expressor having releasable cams; 
         FIG. 16  is a perspective view of the expressor shown in  FIG. 10  compressing the bag assembly shown in  FIG. 4  that is coupled to a container; 
         FIG. 17  is a perspective view of the assembly shown in  FIG. 16  being used with an optical sensor, an electronic pinch clamp and a processor; 
         FIG. 18  is a perspective view of an alternative embodiment of the expressor shown in  FIG. 10  being operated by a piston; 
         FIG. 19  is an elevated side view of an alternative embodiment of an expressor wherein the second platen moves laterally; 
         FIG. 20  is a front perspective view of an alternative embodiment of an expressor supporting the bag assembly of  FIG. 4 ; 
         FIG. 21  is a front perspective view of the expressor of  FIG. 20  compressing the bag assembly; 
         FIG. 22  is an elevated front view of the bag assembly with container shown in  FIG. 9  and having a clamp mounted on the bag assembly; and 
         FIG. 23  is a front perspective view of the expressor shown in  FIG. 20  having the clamp of  FIG. 22  mounted on the bag assembly. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Before describing the present disclosure in detail, it is to be understood that this disclosure is not limited to particularly exemplified apparatus, systems, methods, or process parameters that may, of course, vary. It is also to be understood that the terminology used herein is only for the purpose of describing particular embodiments of the present disclosure and is not intended to limit the scope of the disclosure in any manner. 
     All publications, patents, and patent applications cited herein, whether supra or infra, are hereby incorporated by reference in their entirety to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference. 
     The term “comprising” which is synonymous with “including,” “containing,” or “characterized by,” is inclusive or open-ended and does not exclude additional, unrecited elements or method steps. 
     It will be noted that, as used in this specification and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless the content clearly dictates otherwise. Thus, for example, reference to a “port” includes one, two, or more ports. 
     As used in the specification and appended claims, directional terms, such as “top,” “bottom,” “left,” “right,” “up,” “down,” “upper,” “lower,” “proximal,” “distal” and the like are used herein solely to indicate relative directions and are not otherwise intended to limit the scope of the disclosure or claims. 
     Where possible, like numbering of elements have been used in various figures. Furthermore, multiple instances of an element and or sub-elements of a parent element may each include separate letters appended to the element number. For example, two instances of a particular element “ 10 ” may be labeled as “ 10 A” and “ 10 B”. In that case, the element label may be used without an appended letter (e.g., “ 10 ”) to generally refer to all instances of the element or any one of the elements. Element labels including an appended letter (e.g., “ 10 A”) can be used to refer to a specific instance of the element or to distinguish or draw attention to multiple uses of the element. Furthermore, an element label with an appended letter can be used to designate an alternative design, structure, function, implementation, and/or embodiment of an element or feature without an appended letter. Likewise, an element label with an appended letter can be used to indicate a sub-element of a parent element. For instance, an element “ 12 ” can comprise sub-elements “ 12 A” and “ 12 B.” 
     Various aspects of the present devices and systems may be illustrated by describing components that are coupled, attached, and/or joined together. As used herein, the terms “coupled”, “attached”, and/or “joined” are used to indicate either a direct connection between two components or, where appropriate, an indirect connection to one another through intervening or intermediate components. In contrast, when a component is referred to as being “directly coupled”, “directly attached”, and/or “directly joined” to another component, there are no intervening elements present. Furthermore, as used herein, the terms “connection,” “connected,” and the like do not necessarily imply direct contact between the two or more elements. 
     Various aspects of the present devices, systems, and methods may be illustrated with reference to one or more exemplary embodiments. As used herein, the term “embodiment” means “serving as an example, instance, or illustration,” and should not necessarily be construed as preferred or advantageous over other embodiments disclosed herein. 
     Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present disclosure pertains. Although a number of methods and materials similar or equivalent to those described herein can be used in the practice of the present disclosure, the preferred materials and methods are described herein. 
     In general, present disclosure relates to expressors, expressor systems, and methods for driving a liquid supernatant out of a collapsible bag that also houses a pellet comprised of cells or microorganisms. The supernatant and pellet are typically derived from a biological suspension that is grown in a reactor. For example, with reference to  FIG. 1 , a reactor  10  is provided for growing a biological suspension  12 . Reactor  10  can comprise a bioreactor, fermenter, or any other device designed for growing or producing biological suspensions. The term “bioreactor” as used herein is broadly intended to cover multi-plate growth chambers such as the Cell Factory multi-plate growth chamber produced by Thermo Fisher Scientific. It is also appreciated that reactor  10  can comprise any conventional type of bioreactor or fermenter such as a stirred-tank reactor, rocker type reactor, paddle mixer reactor, or the like. Examples of reactor  10  are disclosed in pending U.S. application Ser. No. 16/289,296, filed Feb. 28, 2019 published as US Patent Publication No. ______ on ______, which is incorporated herein by specific reference in its entirety. 
     Biological suspension  12  includes cells or microorganisms and a growth medium in which the cells or microorganisms are suspended and grown. By way of example and not by limitation, reactor  10  can be used in culturing bacteria, fungi, algae, plant cells, animal cells, protozoans, nematodes, and the like. Examples of some common biologics that are grown include  E. coli , yeast,  bacillus , and CHO cells. In one embodiment, the biological suspension that is processed herein can be blood free, i.e., free of blood components such as plasma, red blood cells, white blood cells or platelets. Thus, the processed cells can be non-blood component cells. Reactor  10  can accommodate cells and microorganisms that are aerobic or anaerobic and are adherent or non-adherent. The composition for the medium is known in the art and changes based upon the cells or microorganisms being grown and the desired end product. In some uses, reactor  10  is used primarily only to grow and recover cells for subsequent use (e.g., preparing vaccine materials from the cells themselves). However, in many uses, the ultimate purpose of growing cells in reactor  10  is to produce and later recover biological products (such as recombinant proteins) that are exported from the cells into the growth medium. It is also common to use reactor  10  to grow cells in a master batch to prepare aliquots of cells for subsequent use as an inoculant for multiple subsequent batches of cells grown to recover biological products. 
     Although the disclosure herein is primarily designed for use with biological suspensions, the apparatus and methods of the present disclosure can also be used with non-biological suspensions where it is desired to separate solids from liquids. Such applications can be found in the production of chemicals, medicines, and other products. Accordingly, the discussions and examples set forth herein of separating a biological suspension and harvesting the separated components are also applicable to and should be considered as disclosure for separating non-biological suspensions and harvesting the separated components thereof. 
     Once suspension  12  has been sufficiently grown in reactor  10  or otherwise produced, suspension  12  is dispensed into a bag assembly  14  (such as  14 A or  14 B). Depicted in  FIG. 2  is one embodiment of a bag assembly  14 A that comprises a flexible, collapsible bag  54 A bounding a compartment  56 . Bag assembly  14 A further comprises a first port  58 A and a second port  58 B coupled to bag  54 A and communicating with compartment  56 . As depicted in  FIG. 3 , bag  54 A is comprised of a first sheet  60  overlying a second sheet  62 . Sheets  60  and  62  are bonded together (as shown in  FIG. 2 ) to form a seam line  64  that encircles compartment  56 . Seam line  64  can be produced by using conventional welding techniques such as heat welding, RF energy, ultrasonic, and the like. Other conventional techniques, such as by using an adhesive, can also be used to form seam line  64 . Ports  58 A and  58 B are bonded between sheets  60  and  62  so as to form a sealed engagement therebetween. Ports  58 A and  58 B can also be bonded to sheets  60  and  62  by welding, adhesive or other conventional techniques. Although two ports  58 A and  58 B are shown, other numbers of ports, such as one, three, four or more ports, could be secured between sheets  60  and  62  so as to communicate with compartment  56 . In other embodiments, as discussed below in more detail, ports  58 A and  58 B could be eliminated and one, two, three or more sections of tubing could be secured between sheets  60  and  62  so as to communicate with compartment  56 . 
     First sheet  60  and second sheet  62  can comprise a flexible, water impermeable polymeric film such as a low-density polyethylene. The polymeric film can have a thickness that is at least or less than 0.02 mm, 0.05 mm, 0.1 mm, 0.2 mm, 0.5 mm, 1 mm, 2 mm, 3 mm or in a range between any two of the foregoing. Other thicknesses can also be used. The film is sufficiently flexible that it can be rolled into a tube without plastic deformation and can be folded over an angle of at least 90°, 180°, 270°, or 360° without plastic deformation. 
     The film can be comprised of a single ply material or can comprise at least two, three, four or more layers that are either sealed together or separated to form a multi-wall container. Where the layers are sealed together, the material can comprise a laminated or extruded material. The laminated material comprises two or more separately formed layers that are subsequently secured together by an adhesive. One example of an extruded material that can be used in the present disclosure is the Thermo Scientific CX3-9 film available from Thermo Fisher Scientific. The Thermo Scientific CX3-9 film is a three-layer, 9 mil cast film produced in a cGMP facility. Although Sheets  60  and  62  can also be formed from a five-layer cast film CX5-14 available from Thermo Fisher Scientific, more favorable results have typically been obtained by forming bag  54 A from a three layer film. This is because bags  54 A formed from a three layer film are more flexible than bags  54 A formed from a five layer film and, as a result, produce fewer creases or folds during centrifugation. Such creases or folds in bags  54 A can have a negative influence during centrifugation because, in part, they can restrict movement of portions of suspension  12 . Accordingly, sheets  60  and  62  are commonly formed from extruded or laminated films having between 2-4 layers and, more commonly three layers and having a thickness between 7 mil and 11 mil and more commonly between 8 mil and 10 mil. 
     The material can be approved for direct contact with living cells and be capable of maintaining a solution sterile. In such an embodiment, the material can also be sterilizable such as by ionizing radiation. Examples of materials that can be used in different situations are disclosed in U.S. Pat. No. 6,083,587 which issued on Jul. 4, 2000 and United States Patent Publication No. US 2003-0077466 A1, published Apr. 24, 2003, which are hereby incorporated by specific reference. 
     Bags  54 A are commonly sized so that compartment  56 , when and if inflated, has a volume of at least or less than 0.5 liters, 1 liter, 1.5 liters, 2 liters, 2.5 liters, 3 liters, 5 liters, 6 liters, 10 liters, 13 liters, 15 liters or in a range between any two of the foregoing values. Other volumes can also be used. 
     Returning to  FIG. 2 , bag  54 A has a top end  66  where ports  58  are disposed and an opposing bottom end  68 . Seam line  64  comprises a top seam line section  70  disposed at top end  66  to which ports  58 A and  58 B are connected and which has an linear inner edge  70 A. Seam line  64  also includes opposing side seam line sections  72  and  74  that include linear inner edges  72 A and  74 A, respectively, that are perpendicular to inner edge  70 A. A corner seam line section  76  extends at an angle between top seam line section  70  and side seam line section  72  having a linear inner edge  76 A while a corner seam line section  77  extends between top seam line section  70  and side seam line section  74  having a linear inner edge  77 A. Inner edges  76 A and  77 A intersect with inner edge  70 A to each form an inside angle therebetween that is in a range between 110° and 170° with between 130° and 150° being more common. Other angles can also be used. In other embodiments corner seam line sections  76  and  77  can be configured to that inner edges  76 A and  77 A are curved. In yet other embodiments, corner seam line sections  76  and  77  can be eliminated and top seam line section  70  can intersect directly with side seam line sections  72  and  74 . 
     Finally, seam line  64  also includes a bottom seam line section  78  disposed at bottom end  68  that has an inner edge  78 A that arches away from top seam line section  70  and that extends as a smooth continuous curve between opposing side seam line sections  72  and  74 . The curve of bottom seam line section  78  can be an arc, U-shape, segment of an oval, segment of an ellipse, or have other configurations. In one embodiment, bottom seam section line  78  comprises at least 20%, 25%, 30%, 35%, or 40% of the entire length of seam line  64  that encircles compartment  56 . As depicted and in view of the foregoing, it is appreciated that top end  66  and bottom end  68  of bag  54 A, and particularly the seam lines thereat, have different configuration, i.e., they are not symmetrical about a lateral axis that extends between side seam line section  72  and  74 . 
     More specifically, with regard to a central longitudinal axis  79  that extends between top seam line section  70  and bottom seam line section  78 , compartment  56  is more constricted about central longitudinal axis  79 , i.e., compartment  56  is narrower, at bottom end  68  than at top end  66 . The constricting of compartment  56  at bottom end  68  functions to help consolidate the pellet produced during centrifugation, as discussed below, at a central location within compartment  56 . Consolidating the pellet in a constricted area makes the pellet thicker with more mass so that the pellet is more stable and less likely to break apart. Consolidating the pellet into a constricted area also assists with the removal of the supernatant and can assist with subsequent removal of the pellet that is located in a smaller area. Although inwardly tapering bottom end  68  of bag  54 A achieves the above discussed added benefits, in other embodiments bag  54 A could be formed so that bottom end  68  does not taper or does not taper more than top end  66 . That is, top end  66  and bottom end  68  of bag  54 A, and particularly the seam lines thereat, could be symmetrical about a lateral axis that extends between side seam line section  72  and  74 . 
     Bag  54 A further comprises a hanging tab  80  centrally formed at bottom end  68  with an opening  82  extended therethrough. Openings  84 A and  84 B also extend through sheets  60  and  62 , such as through seam line  64 , at opposing sides of bag  54 A at top end  66 . Openings  82  and  84  can be used for hanging or supporting each bag assembly  14  in a vertically up orientation or vertically down orientation. 
     It is appreciated that bag assembly  14  can also have a variety of other configurations. For example, depicted in  FIGS. 4 and 5  is a bag assembly  14 B. Bag assembly  14 B comprising a bag  54 B having ports  58 A 1  and  58 B 1  mounted thereon. Bag  54 B has substantially the same structural elements and substantially the same configuration as bag  54 A and can be made of the same material as bag  54 A. As such, like elements between bags  54 A and  54 B are identified by like reference characters and the prior discussion with regard to the elements of bag  54 A is also applicable to bag  54 B. Bag  54 B differs from bag  54 A in that corner seam lines sections  76  and  77  are curved. As such, corner seam line section  76  has an inner edge  76 A 1  that inwardly curves in an arc from inner edge  72 A to inner edge  70 A and corner seam line section  77  has an inner edge  77 A 1  that inwardly curves in an arc from inner edge  74 A to inner edge  70 A. In other embodiments, inner edges  76 A 1  and  77 A 1  could also be linear as in bag  54 A. Bag  54 B also has a hanging tab  400  formed at top end  66  and outwardly projecting from top seam line section  70 . Openings  84 A and  84 B extend through hanging tab  400  and are used for supporting bag  54 B in a vertical orientation. Hanging tabs  80  and  400  can simply comprise portions of the flexible film used to bound compartment  56  of bag  54 B. 
     Bag assembly  14 B differs from bag assembly  14 A in that bag assembly  14 B does not include ports  58 A and  58 B ( FIG. 2 ) projecting from top seam line section  70 . Rather, bag assembly  14 B includes ports  58 A 1  and  58 B 1  that are secured to and outwardly project from first sheet  60  at or toward top end  66  at locations spaced apart from seam line  64 . Specifically, first sheet  60  has an inside face  402  and an opposing outside face  404  having opening  406 A and  406 B extending therethrough at locations spaced apart from the perimeter edge of first sheet  60 . Each port  58 A 1  and  58 B 1  includes a tubular stem  408  having an annular flange  410  outwardly projecting from one end and an annular barb  412  outwardly projecting from an opposing end. Flange  410  has a top side  414  that faces toward stem  408  and an opposing bottom side  416 . One or more projections  418  can project from bottom side  416 . Projections  418  ensure that a spacing is formed between first sheet  60  and second sheet  62  at ports  58 A 1  and  58 B 1  so that fluid can freely flow from compartment  56  out through stems  408 . During assembly, stems  408  of ports  58 A 1  and  58 B 1  are passed though openings  406 A and  406 B, respectively, and flanges  410  are secured, such as by welded, adhesive or the like, to inside face  402  of first sheet  60 . Ports  58 A 1  and  58 B 1  can then be used in the same way as discussed herein with regard to ports  58 A and  58 B. 
     In the assembled configuration, ports  58 A 1  and  58 B 1  thus extend through first sheet  60  as opposed to simply being secured between sheets  60  and  62 . Furthermore, ports  58 A 1  and  58 B 1  are typically, though not required, equally spaced on opposing sides of central longitudinal axis  79  and are disposed at top end  66  at locations spaced apart from seam line  64 . With reference to bag assembly  14 B and longitudinal axis  79  being vertically orientated, as shown in  FIG. 4 , ports  58 A 1  and  58 B 1  are typically located within the upper ⅓, ¼, or ⅕ of the area of outside face  404  of first sheet  60  or within the upper ⅓, ¼, or ⅕ of the height/length of first sheet  60 /bag  54 B. Securing ports  58 A 1  and  58 B 1  on the face of first sheet  60 , as discussed above, results in less leaking, less integrity testing, and easier attachment than ports  58 A and  58 B welded between first sheet  60  and second sheet  62 . However, securing ports  58 A 1  and  58 B 1  on the face of first sheet  60  can make it more difficult to remove all of the fluid from bag  54 B relative to having ports  58 A and  58 B welded between sheets  60  and  62 . As such, the selected configuration for bag assemblies  14  can depend on the intended use. 
     In the above discussed embodiments, bags  54  (such as  54 A or  54 B) are disclosed as being two-dimensional, pillow type bags formed by seaming together two overlapping sheets of flexible film. In other embodiments, however, bags  54  can comprise three-dimensional bags that are typically formed by seaming together three, four or more sheets of flexible film. In yet another embodiment, bags  54  can be blown bags that are blown from a polymeric material and have no seam lines except at the opening through which they are blown. Because of the material that is used to form bags  54 , which includes bags  54 A and  54 B and the other alternatives discussed herein, bags  54  are collapsible in that they can be fully inflated and fully deflated flat without plastic deformation. Bags  54  can also be folded over or rolled into a tube without plastic deformation. 
     Returning to  FIG. 1 , an inlet line  90  fluid couples reactor  10  to bag  54 A. 
     Specifically, inlet line  90  is fluid coupled with port  58 A disposed on bag  54 A. A clamp  55  is mounted on inlet line  90 . Clamp  55  can be manually adjusted to regulate the flow of suspension  12  through inlet line  90  and can seal off inlet line  90  to prevent fluid flow therethrough. In addition, an outlet line  92  can be coupled with port  58 B disposed on bag  54 A. As depicted in  FIG. 6 , outlet line  92  has a terminal end with a fitting  94  disposed thereat. Fitting  94  can comprise a cap that seals outlet line  92  closed or it can comprise an aseptic connector that maintains outlet line  92  sealed closed but enables outlet line  92  to be selectively fluid coupled with another line under aseptic conditions. Other fittings can also be used. In yet other embodiments, fitting  94  can be eliminated and the terminal end of outlet line  92  can simply be sealed closed, such as by being welded closed. 
     Inlet line  90  and outlet line  92  can likewise be attached to ports  58 A 1  and  58 A 2  ( FIG. 4 ) of bag  54 B. It is noted that securing ports  58 A 1  and  58 B 1  on the face of first sheet  60  of bag  54 B, as opposed to welding ports  58 A and  58 B between first sheet  60  and second sheet  62  ( FIG. 3 ), makes it easier to store bag assembly  14 B with lines  90  and  92  within an insert, bucket, and/or rotor of a centrifuge with decreased risk of line  90  or  92  coming out of the insert, bucket, and/or rotor during centrifugation. That is, because lines  90  and  92  project horizontally off of ports  58 A 1  and  58 B 1  into the insert, bucket and/or rotor, as opposed to projecting vertically upward, lines  90  and  92  are more easily placed and retained within the insert, bucket and/or rotor. Further information with regard to using bag assemblies  14  within an insert, bucket, and/or rotor of a centrifuge is disclosed in U.S. application Ser. No. 16/289,296 (US Patent Publication No. ______), which was previously incorporated by reference. 
     Once bag  54 A has been filled with a desired amount of suspension  12 , a portion of inlet line  90  upstream of clamp  55  is sealed closed and then cut, thereby separating bag  54  (such as  54 A or  54 B) from reactor  10 . Accordingly, as depicted in  FIG. 6 , bag assembly  14 A can be further defined as comprising a portion of inlet line  90 , clamp  55 , outlet line  92  and, if used, fitting  94 . Each of the different elements of each bag assembly  14  can be modified, eliminated or replaced. For example, different numbers of ports  58 , such as 1, 3, 4 or more, can be coupled with bag  54  with a separate fluid line coupled with each port. In other embodiments, one or more of ports  58  can be eliminated and the corresponding fluid lines can be coupled directly to bag  54 . Likewise, although different embodiments have different advantages, bag assemblies  14 A,  14 B, and the other embodiments disclosed herein can typically be interchangeably used. Other shapes and volumes of bag assemblies  14  and bags  54  can also be used. Other examples of bag assemblies and bags and other systems and methods for filling the bags are disclosed in U.S. application Ser. No. 16/289,296 (US Patent Publication No.), which was previously incorporated by reference. For example, as discussed in detail in the &#39;296 application, multiple bag assemblies  14  can be concurrently coupled in parallel or series to reactor  10  through a manifold. Fluid flow to each bag assembly  14  can be controlled by regulating the fluid flow through the manifold. Once a bag assembly  14  is filled, it can be sealed and cut from the manifold and processed as described herein. 
     Compartment  56  of each bag assembly  14  is sterile as suspension  12  is first delivered therein and inlet line  90  provides a sterile fluid pathway through which suspension  12  can be delivered into compartment  56 . Reactor  10 , inlet line  90  and bag assemblies  14  combine to form a closed system in that the internal area they bound is not exposed to the open environment. As used in the specification and appended claims, the terms “sterile” and “sterilized” mean that the related item has been subjected to a sterilization process so that the sterility assurance level (SAL) is 10 −6  or lower. Sterility assurance level (SAL) is the probability that a single unit that has been subjected to sterilization nevertheless remains non-sterile, i.e., is not free from bacteria or other living microorganisms. As such, an SAL of 10 −6  means that there is a 1 in 1,000,000 chance that a unit subjected to the sterilization process remains non-sterile. 
     As noted above, after bag assemblies  14  are filled to their desired amount with suspension  12  and clamp  55  is closed, a section of inlet line  90  upstream of clamp  55  is welded closed. Inlet line  90  is then cut at a central location along the welded section so as to sever bag assembly  14  from reactor  10  as depicted in  FIG. 6 . By cutting inlet line  90  at a central location along the welded section, no leaking of suspension  12  occurs from inlet line  90 . In contrast to welding and cutting inlet line  90  upstream of clamp  55 , inlet line  90  could alternatively be welded at a location between clamp  55  and bag  54  and then cut through the welded section. This approach would eliminate clamp  55  as being retained as part of the bag assembly. 
     Suspension  12  can be dispensed into bag assembly  14  at different times during the growth cycle. For example, in one method, once suspension  12  has reached a desired growth stage, all of suspension  12  within reactor  10  can be dispensed into one or more bag assemblies  14  for further processing. Alternatively, portions of suspension  12  within reactor  10  can be dispensed into bag assemblies  14  at spaced apart intervals during the growth cycle, e.g., at days 14, 16, 18, etc. In this method, reactor  10  can be replenished with fresh medium to compensate, either exactly or approximately, for the volume of suspension  12  removed from reactor  10 . This method may be appropriate during bioproduction cell culture process development to determine any variability in cell performance or the production protein characteristics resulting from extended run time. 
     Next, separated bag assembly  14  is moved to a centrifuge for separation of suspension  12  therein. For example, depicted in  FIG. 7  is a centrifuge  112 . Centrifuge  112  is depicted as a floor standing centrifuge. However, centrifuge  112  can comprise any type, shape, or configuration of centrifuge. In general, centrifuge  112  has a body  114  that bounds a cavity  116  and has a spindle  117  disposed therein. Spindle  117  is rotated by a motor disposed within body  114 . A lid  118  can be hingedly mounted or removably secured to body  114  for selectively covering cavity  116  during operation. Cavity  116  is configured to receive a rotor that couples with spindle  117  and is rotated within cavity  116  by the rotation of spindle  117 . The rotor is configured to receive and support one or more bag assemblies. Floor standing centrifuges are commonly used because they have an enlarged cavity  116  that enables handling larger and/or more bag assemblies  14  during each run or operational cycle of the centrifuge. However, a table top centrifuge can also be used. 
     As bag assembly  14  is rotated within centrifuge  112 , the centrifugal force caused by spinning of the rotor of centrifuge  112  causes at least a portion of the solids within suspension  12 , e.g., the cells, microorganisms, and/or other solids, to sediment out of the solution and collect within bottom end  68  of bag assembly  14 A to form a pellet  214 , as shown in  FIG. 8 . The remaining fluid collects as a supernatant  216  above pellet  214  and can include some solids. Pellet  214  has a density that is greater than the density of supernatant  216 . Pellet  214  can also have a viscosity that is greater than the viscosity of supernatant  216 . For example, the density and viscosity of pellet  214  can be at least 2, 5, 7, 10, 15, 30 or 50 times that of supernatant  216 . In one application, pellet  214  can comprise a paste or a slurry while supernatant  216  typically comprises a free flowing liquid, like water. Methods, systems and alternatives for centrifugally rotating bag assemblies  14 /bags  54  so as to form pellet  214  and supernatant  216  are disclosed in U.S. application Ser. No. 16/289,296 (US Patent Publication No. ______), which was previously incorporated by reference. 
     As discussed in U.S. application Ser. No. 16/289,296 (US Patent Publication No. ______), there are benefits to having the bag assembly and centrifuge rotor configured so that pellets  214  form and consolidate at one location at (or near) bottom end  68  of bag assembly  14 . Some cells, microorganisms, and/or other solids of suspension  12  are found to make a generally firm and compact pellet  214  that is not easily disturbed and resuspended into supernatant  216 . In contrast, however, other cells such as mammalian cells, like Chinese hamster ovary (CHO) cells, can form a slurry or very loose pellet  214  and thus are easily resuspended into supernatant  216 . The time and speed at which bag assemblies  14  containing suspension  12  are rotated by centrifuge  112  is dependent in part on the composition and volume of suspension  12 . However, bag assemblies  14  are typically spun at a rate between 300 rpm and 5,000 rpm or between 300 rpm and 7,000 rpm with between 2,000 rpm and 5,000 rpm being more common. The time of rotation is typically between 5 minutes and 90 minutes with between 5 minutes and 30 minutes being more common. Other rates and times can also be used. 
     Once suspension  12  within bag assemblies  14  is separated into pellets  214  and supernatant  216 , the next step is to remove supernatant  216  from bag assemblies  14 . Where pellet  214  is firm and not easily resuspended, as discussed above, this step can be accomplished by fluid coupling outlet line  92  to a container  220  as depicted in  FIG. 9 . For example, where fitting  94  ( FIG. 6 ) is a cap, outlet line  92  can be cut, such as in a laminar flow hood, and then fluid coupled with container  220  using a sterile connection. In one method, outlet line  92  can be welded to an inlet line  222  extending from container  220  or can be directly coupled to container  220 . Alternatively, where fitting  94  ( FIG. 6 ) is an aseptic connector, fitting  94  can simply be coupled to a corresponding aseptic connector on inlet line  222  of container  220  to form a sterile fluid coupling. Other methods of fluid coupling can also be used. 
     In one method of separating supernatant  216  from pellet  214 , an expressor can be used to drive supernatant  216  from bag assembly  14  and into container  220  so that pellet  214  remains within bag  54 . As used in the specification and appended claims, the term “expressor” is broadly intended to comprise any type of device that can mechanically compress bag assembly  14  for driving supernatant  216  therefrom. For example, depicted in  FIG. 10  is one embodiment of an expressor  430 A incorporate features of the present disclosure. In general, expressor  430 A comprises a base  432  having a first platen  434  coupled thereto. A second platen  436  is coupled to base  432  so that second platen  436  can selectively move toward and away from first platen  434 . In the depicted embodiment, base  432  has a top surface  456  extending between a first end  458  and an opposing second end  460 . 
     First platen  434  is depicted as comprising a plate having an inside face  438  and an opposing outside face  440  that both extend between an upper end  442  and an opposing lower end  444 . First platen  434  has a perimeter edge  446  having a tapered configuration similar to the tapered configuration of bag assemblies  14 . More specifically, perimeter edge  446  has an upper edge portion  448  having two spaced apart notches  450 A and  450 B centrally recessed thereon. More specifically, notches  450 A and  450 B are recessed into perimeter edge  446  at upper edge portion  448  so as to extend toward lower end  444  and pass through first platen  434  between inside face  438  and opposing outside face  440 . 
     In one embodiment, first platen  434  has a central longitudinal axis  445  extending between upper end  442  and an opposing lower end  444  that is centrally disposed between notches  450 A and  450 B. Each notches  450 A and  450 B typically has a width W of at least 0.5 cm, 0.75 cm. 1 cm, 1.5 cm or 2 cm or is in a range between any two of the foregoing values. Notch  450 A and  450 B are sized so that when bag assembly  14 B ( FIG. 4 ) is used with expressor  430 A, first sheet  60  can be disposed against inside face  438  of first platen  434  with ports  58 A 1  and  58 B 1  being received within notches  450 A and  450 B, respectively. This configuration enables all or substantially all of bag  54 B to be uniformly compressed between platens  434  and  436 , as discussed further below. The number and location of notches  450  can vary based upon the number and location of ports  58  disposed on first sheet  60 . For example, if one, three or more ports  58  are used, then one, three or more notches  450  can be formed. Furthermore, is no ports  58  on disposed on first sheet  60 , such as when bag assembly  14 A ( FIG. 2 ) is used, notches  450  can be eliminated. 
     Perimeter edge  446  of first platen  434  also includes opposing side edge portions  452  and  454  that extend between upper end  442  and opposing lower end  444 . Side edge portions inwardly taper at lower end  444  relative to upper end  442  or, expressed in other terms, side edge portions outwardly taper at upper end  442  relative to lower end  444 . As a result, first platen  434  has a wider width at upper end  442  than at lower end  444 . In one embodiment, the width of first platen  434  at upper end  442  can be greater than the width of base  432 . The opposing side edge portions  452  and  454  of first platen  434  are tapered so that first platen  434  has a configuration complementary to tapered bag  54 , as discussed above. As a result, first platen  434  uniformly supports all of one side of bag  54  so that bag  54  can be uniformly compressed between platens  434  and  436 , as discussed below. In other embodiments, first platen  434  need not be tapered but could have a substantially constant width along the length. However, were bags  54  are tapered, forming platens with a complementary tapers reduces material cost and maximizes uniform compression. 
     First platen  434  is secured to base  432  at or toward second end  460 . In one embodiment, first platen  434  is secured so that when base  432  and/or top surface  456  thereof are horizontally disposed, inside face  438  is vertically disposed, i.e., is orthogonal to base  432  and/or top surface  456 . In other embodiments, first platen  434  can be angled so that an angle is formed between top surface  456  of base  432  and inside face  438  of first platen  434  that is at least or less than 110°, 120°, 130°, 140°, 150° or 160° or is in a range between any two of the foregoing angles. 
     Second platen  436  has substantially the same configuration as first platen  434 . As such, like elements between platens  436  and  434  are identified by like reference characters except that the reference characters for second platen  436  include the suffix “B.” For example, second platen  436  comprises a plate having an inside face  438 B and an opposing outside face  440 B that both extend between an upper end  442 B and an opposing lower end  444 B. Second platen  436  has a perimeter edge  446 B having a tapered configuration similar to the tapered configuration first platen  434 , i.e., similar to the tapering of bag assemblies  14 /bags  54 . More specifically, perimeter edge  446 B has an upper edge portion  448 B and two opposing side edge portions  452 B and  454 B. Side edge portions  452 B and  454 B inwardly taper at lower end  444 B relative to upper end  442 B or outwardly taper at upper end  442 B relative to lower end  444 B. 
     Second platen  436  distinguishes from first platen  434  in that second platen  436  does not include notches  450 A and  450 B. However, in an alternative embodiment, the one or more notches  450 A and  450 B could be formed on second platen  436  and not on first platen  434 . In this design, bag assembly  54 B ( FIG. 4 ) would be positioned so that first sheet  60  is disposed against second platen  436  and ports  58 A 1  and  58 B 1  are again received within notches  450 A and  450 B, respectively. 
     To enable visual inspection of bag assemblies  14  during operation of expressor  430 A, as discussed below, second platen  436  is commonly formed from a transparent polymer such as acrylic or polyethylene terephthalate glycol. Although first platen  434  could also be made from a transparent polymer, it is commonly less useful. As such, first platen  434  is commonly made from an opaque material, such as an opaque plastic or a metal. 
     Second platen  436  is movably mounted to base  432  so that second platen  436  can selectively move toward and away from first platen  434 . More specifically, second platen  436  is movable between a retracted position, as shown in  FIG. 10 , where second platen  436  is moved away from first platen  434 , and a collapsed position, as shown in  FIG. 13 , where second platen  436  is moved toward first platen  434 . Returning to  FIG. 10 , in one embodiment a hinge  462  is mounted on base  432 , such as by being secured to top surface  456 . Lower end  444 B of second platen  436  is secured to hinge  462  so that second platen  436  can hingedly pivot relative to base  432  between the retracted position and the collapsed position. It is appreciated that hinge  462  can have a variety of different configurations and can comprise two or more separate hinges the hingedly secure second platen  436  to base  432 . 
     As shown in  FIG. 10 , base  432  includes a platform  550  having a top surface  552  that extends between opposing ends  458  and  460 . A riser  554  is disposed on top of platform  550  at second end  460  with first platen  434  being disposed on top of riser  554 . Riser  554  has a height that corresponds to the height of hinge  462 . As such, when second platen  436  is in the collapsed position ( FIG. 13 ), platens  434  and  436  are disposed at substantially the same elevation, i.e., platens  434  and  436  are aligned horizontally. This alignment helps to ensure that bag assembles  14  are uniformly compressed between platens  434  and  436 . It is appreciated that the alignment of platens  434  and  436  can be achieved in a variety of other ways. For example, riser  554  could be eliminated and hinge  464  could be recessed within a slot formed on platform  550 . It is also noted that riser  554  and platform  550  can be formed as a single, unitary, integral structure as opposed to two parts connected together. 
     In one embodiment of the present disclosure, means are provided for mechanically moving second platen  436  toward first platen  343 , i.e., for mechanically moving second platen  436  from the retracted position to the collapsed position. By way of example, a spring  464  is coupled with hinge  462  so as to resiliently urge or bias second platen  436  toward the collapsed position, i.e., toward first platen  434 . In alternative embodiments, the means can comprise other convention drive mechanism such as a pneumatic or hydraulic piston, a gear assembly, screw drive, worm drive or linkage driven by a motor or compressor. Other spring or elastic band configurations could also be used. For example, one or more elastic bands could extend between platens  434  and  436  to resiliently urge second platen  436  toward the collapsed position. 
     As discussed below in more detail, the use of spring  464  has the advantage that it is inexpensive and does not require the use of a motor or controller. Other embodiments, such as the use of a piston or motor driven driver can have the advantage that they can be more precisely controlled. For example, the amount, rate and time that a force is applied to second platen  436  can be precisely controlled through a controller. 
     An elongated handle  466  projects from outside face  440 B of second platen  436  at lower end  444 B. A catch  468  is disposed on base  432  at or toward first end  458 . Handle  466  is used to manually pivot second platen  436  to the retracted position. Catch  468  can then engage handle  466  to hold second platen  436  in the retracted position. When handle  466  is released from catch  468 , second platen  436  resiliently rebounds under the force of spring  464  toward the collapsed position. 
     In one embodiment, first platen  434  can be permanently secured to or integrally formed with base  432 . However, in the present embodiment, first platen  434  is adjustably mounted to base  432  so that a gap spacing formed between first platen  434  and second platen  436  can be adjusted. For example, as shown in  FIG. 11 , a foot  470  outwardly projects from first platen  434  at lower end  444  so as to extend away from second platen  436 . In one embodiment, foot  470  can extend orthogonal to first platen  434 . Extending through foot  470  are two spaced rows  472 A and  472 B of a plurality of holes  474 . Rows  472 A and  472 B are in parallel alignment and extend orthogonal to first platen  434 . As better shown in  FIG. 12 , each row  472 A and  472 B is shown as comprising aligned holes  474 A,  474 B,  474 C and  474 D. Other numbers of holes  474 , such as at least 2, 3, 4, or 5, can also be used. In the depicted embodiment, each hole  474  is round. However, other configurations can also be used. 
     Upwardly projecting from base  432  at second end  458  are a pair of spaced apart mounting shafts  476 A and  476 B that are threaded. Mounting shafts  476  are configured to pass through holes  474 . For example, as depicted in  FIG. 12 , mounting shafts  476 A and  476 B are received within holes  474 A of rows  472 A and  472 B, respectively. In turn, nuts  478 A and  478 B, as shown in  FIG. 13 , can be threaded onto mounting shafts  476 A and  476 B, respectively, so as to bias against foot  470 , thereby securely fixing first platen  434  to base  432 . With first platen  434  so positioned and second platen  436  moved to the collapsed position, as shown in  FIG. 13 , a gap spacing  480  is formed between first platen  434  and second platen  436 . 
     More specifically, hinge  462  is configured so that second platen  436  can only rotate to a fixed orientation before it is mechanically stopped at the collapsed position. The fixed orientation for stopping second platen  436  is typically when inside faces  438  and  438 B of platens  434  and  436  are disposed in parallel alignment. Thus, by spacing apart first platen  434  and second platen  436 , gap spacing  480  is formed between inside face  438  of first platen  434  and inside face  438 B of second platen  436  when second platen is in the collapsed position. When the fixed orientation for stopping second platen  436  is set so that platens  434  and  436  are disposed in parallel alignment, the gap spacing  480  can be uniform along the lengths of platens  434  and  436 . This has the benefit in that bag  54  is uniformly compressed between platens  434  and  436 . However, in other embodiments, the fixed orientation for stopping second platen  436  can be set so that platens  434  and  436  are slightly angled relative to each other. For example, inside faces  438  and  438 B of platens  434  and  436  can be disposed in converging planes having an inside angle in a range between 1° and 15° with between 1° and 10° and between 1° and 5° being more common. In these embodiments, the gap spacing  480  can vary along the lengths of platens  434  and  436  when second platen  436  is in the collapsed position. Thus, gap spacing  480  referenced herein can refer to a minimum gap spacing or a maximum gap spacing. 
     Where it is desired to increase the width of gap spacing  480 , nuts  478  can be removed and first platen  434  raised vertically off of mounting shafts  476 . First platen  434  can then be repositioned so that mounting shafts  476  are positioned within one of the other holes  474 B- 474 D of foot  470  that are closer to first platen  434 . For example, as shown in  FIG. 14 , mounting shafts  476  are now placed within holes  474 D of rows  472 A and  472 B. Nuts  478  ( FIG. 13 ) can again be threaded onto mounting shafts  476  so as to bias against foot  470  and thereby securely fix first platen  434  to base  432 . In this second position of first platen  434 , gap spacing  480  when second platen  436  is in the collapsed position is now larger than when first platen  434  was in the first position shown in  FIG. 13 . Accordingly, by selectively moving mounting shafts  476  to different holes  474 , the width of gap spacing  480  can be selectively adjusted and set to a desired value. That is, gap spacing  480  is adjusted by laterally moving first platen  434  relative to base  432  and/or second platen  436 . Such movement of the first platen  434  does not require pivoting or rotating of first platen  434 . 
     In one embodiment, expressor  430 A can be configured so that gap spacing  480  can be selectively adjusted by an amount of at least 0.5 cm, 1 cm, 2 cm, 3 cm or 4 cm or in a range between any two of the foregoing values. Furthermore, gap spacing  480  is typically at least 0.5 cm, 1 cm, 2 cm, 3 cm or 4 cm or is a range between any two of the foregoing values when second platen  436  is in the collapsed position. The benefit of being able to adjust and/or set the width of gap spacing  480  will be discussed below in greater detail. 
     The use of mounting shafts  476 , holes  474  and nuts  478  is one example of means for selectively adjusting the width of gap spacing  480  between platens  434  and  436 . However, it is appreciated that a variety of other mechanism can likewise be used to selectively adjust the width of gap spacing  480  between platens  434  and  436 . By way of example and not by limitation, separate holes  474  of each row  472  could be replaced with elongated channels through which mounting shafts  476  can slide. Mounting shafts  476  and nuts  478  are also one example of fasteners that can be used to releasably secure first platen  434  to base  432 . In other embodiments, mounting shafts  476  and nuts  478  can be replaced with bolts, screws or other fasteners that passed down through select holes  474  or channels formed on foot  470  and secure into base  432  for adjusting gap spacing  480 . In yet other embodiments, mounting shafts  476  and nuts  478  can be replaced with one or more clamps, latches, catches, cams or other types of releasable fasteners for adjusting gap spacing  480 . 
       FIG. 15  depicts one alternative embodiment of the means for selectively adjusting the width of gap spacing  480  between platens  434  and  436 . In this embodiment, the rows of holes  474  have been replaced with elongated slots  500 A and  500 B through which shafts  476 A and  476 B pass, respectively. Cams  502 A and  502 B are rotatably mounted on shafts  476 A and  476 B, respectively. Cams  502 A and  502 B can be selectively rotated between a locked position (cam  502 A) where the cam presses foot  470  against base  432  so as to secure first platen  434  relative to base  432  and an unlocked position (cam  502 B) where foot  470  is released from base  432  so that first platen  434  can freely move relative to base  432 . That is, with cams  502 A and  502 B in the unlocked position, first platen  434  can freely move relative to base  432  by sliding shafts  476  within elongated slots  500 . 
     In the above discussed embodiments, gap spacing  480  is adjusted by moving first platen  434  relative to base  432 /second platen  436 . However, in an alternative embodiment, expressor  430 A can be configured so that gap spacing  480  is adjusted by moving second platen  436  relative to base  432 /first platen  434 . For example, a foot could project from hinge  462  having holes or slots formed thereon. Any of the above discussed fasteners used with first platen  434  could then be used to releasably secure second platen  436  to base  432  at spaced apart locations along the length of base  432  so as to adjust the width of gap spacing  480  when second platen  436  is in the collapsed position. Thus, gap spacing  480  can also be adjusted by laterally moving second platen  436  relative to base  432  and/or first platen  434  without pivoting or rotating of second platen  436 . 
     Expressor  430 A can be used to drive supernatant  216  from bag assemblies  14  into container  220 . For example, as depicted in  FIG. 16 , once suspension  12  within bag assembly  14 B is separated into pellets  214  and supernatant  216 , outlet line  92  of bag assembly  14 B is fluid coupled to inlet line  222  of container  220  or can be directly coupled to container  220  using any conventional method, such as those previously discussed. Either prior to or after fluid coupling bag assembly  14 B to container  220 , bag assembly  14 B is removed from the centrifuge or the bucket and/or insert thereof. With second platen  436  in the retracted position, bag assembly  14 B is then positioned between first platen  434  and second platen  436 . Although any of the bag assemblies  14  disclosed or envisioned herein can be used with expressor  430 A, bag assembly  14 B is shown in  FIG. 16 . In this assembly, ports  58 A 1  and  58 B 1  can be aligned with notches  450 A and  450 B so that inlet line  90  or outlet line  92  pass therethrough, respectively. Notches  450  function in part to prevent damage to port  58  and kinking of lines  90  and  92  during operation of expressor  430 A. If bag assembly  14 A is used ( FIG. 2 ), notches  450  are not needed. 
     Once bag assembly  14 B is properly positioned on expressor  430 A and fluid coupled with container  220 , second platen  436  can be moved toward first platen  434 , i.e., toward the collapsed position, so that bag assembly  14 B is compressed between platens  434  and  436 , thereby driving/forcing the supernatant  216  to flow out of bag assembly  14 B, through outlet line  92  and into container  220 . More specifically, once bag assembly  14 B is properly positioned on expressor  430 A and fluid coupled with container  220 , handle  466  ( FIG. 10 ) can be released from catch  468  which enables second platen  436  to move toward the collapsed position, i.e., toward the first platen  434 , under the force of spring  464  by pivoting about hinge  462 . The compressing of bag assembly  14 B between platens  434  and  436  under the force of spring  464  drives/forces the supernatant  216  to flow out of bag assembly  14 B, through outlet line  92  and into container  220 . 
     In one method of use, the width of gap spacing  480  ( FIG. 13 ) is selectively adjusted prior to use so that as second platen  436  moves to the final collapsed position, pellet  214  is pancaked so as to spread out within bag assembly  14 B by being compressed between platens  434  and  436  ( FIG. 13 ). The pancaking and spreading of pellet  214  further drives supernatant  216  out of bag assembly  14 B and into container  220 . However, gap spacing  480  is typically set so that no portion of pellet  214  flows out of bag assembly  14 B and into container  220 . That is, gap spacing  480  is set so that when second platen  436  reaches its collapsed position, i.e., second platen  436  is no longer advancing toward first platen  434 , the pancaked pellet  214  fills bag assembly  14 B up toward ports  58 A 1  and  58 B 1  but does not reach or pass out through ports  58 A 1  and  58 B 1 . As such, pellet  214  cannot flow into outlet line  92 . Rather, pancaked pellet  214  only extends up to a level below ports  58 A 1  and  58 B 1  so that some supernatant  216  remains within bag assembly  14 B and occupies the volume between the top of pancaked pellet  214  and ports  58 . 
     Typically, gap spacing  480  is set so that between 1 ml and 150 ml or between 25 ml and 150 ml and more commonly between 25 ml and 50 ml or between 50 ml and 100 ml of supernatant  216  remains within bag assembly  14  when second platen  436  has reached its final collapsed position. Commonly, the spacing between pancaked pellet  214  and ports  58 A 1  and  58 B 1  when second platen  436  is in the collapsed position is less than 4 cm and more commonly less than 3 cm, 2 cm, 1 cm, 0.5 cm, 0.2 cm or less. Other distances can also be used. It is typically preferred to minimize the amount of supernatant  216  that remains within bag  54  so as to optimize separation of supernatant  216  and pellet  214 . Adjusting the width of gap spacing  480  is used to help optimize separation of supernatant  216  and pellet  214  by ensuring that pancaked pellet  214  ends close to ports  58 A 1  and  58 B 1  when second platen  436  is in the collapsed position. The setting of gap spacing  480  can vary depending on the size/quantity of pellet  214  collected within bag  54 . For example, for a fixed sized bag  54 , gap spacing  480  can be to be increased as the size/quantity of pellet  214  increases and can be decreased as the size/quantity of pellet  214  decreases. 
     The amount of pellet  214  within a bag assembly  14  can vary dependent upon a number of different factors, including the volume percentage of cells in suspension  12  withdrawn from the reactor and fed into bag assembly  14 . As such, by using spring  464  ( FIG. 10 ) which requires no controller and by selectively adjusting gap spacing  480  dependent upon the quantity of pellet  214  within bag assembly  14 B, expressor  430 A can freely and independently operate to maximize the transfer supernatant  216  to container  220  with decreased risk of any of pellet  214  flowing into container  220 . Thus, expressor  430 A provides an inexpensive way to optimize separation pellet  214  and supernatant  216  with minimal monitoring. 
     Where it is desired to collect and further process and use supernatant  216 , it is desirable to prevent any of pellet  214  from flowing into container  220 . However, where supernatant  216  is not being used but rather pellet  214  is being collected for further use, it is less critical whether a portion of pellet  214  flows into container  220 . For example, it may be desirable to set gap spacing  480  so that a small portion of pellet  214  flows into container  220 , thereby helping to ensure that a maximum quantity of supernatant has been removed from bag assembly  14 . 
     Independent of or in combination with adjusting gap spacing  480  to prevent the unwanted removal of pellet  214  from bag assembly  14 , other mechanisms can also be used to prevent the flow of pellet  214  into container  220 . For example, as depicted in  FIG. 17 , outlet line  92  can have an optical sensor  482  overlaying outlet line  92  and an electric pinch clamp  484  overlying outlet line  92  down stream of optical sensor  482 . Optical sensor  482  and pinch clamp  484  can be electronically controlled by a processor  486 . During operation, while expressor  430 A is driving supernatant  216  from bag assembly  14  to container  220 , optical sensor  482  in combination with processor  486  monitors the clarity or density of the fluid flowing through outlet line  92 . 
     If processor  486  detects that the fluid flowing through outlet line  92  is starting to become less clear, i.e., more opaque, or has an increase in density, both of which can be signs that a portion of pellet  214  is starting to flow through outlet line  92 , processor  486  operates pinch clamp  484  to close outlet line  92 , thereby preventing any of pellet  214  from flowing into container  220 . Where second platen  436  is begin moved by a motor, as opposed to a resilient spring, processor  486  could also function to simply turn off the motor based on signals from optical sensor  482 , thereby again helping to ensure that no portion of pellet  214  reaches container  220 . Optical sensor  482  can be replaced with other sensors such as capacitance for conductivity or other sensors that detect the increase in cell content. 
     Depicted in  FIG. 18  is a modified version of expressor  430 A where handle  466  and spring  464  ( FIG. 10 ) have been removed and replaced with a piston  510 . Piston  510  can comprise a pneumatic or hydraulic piston and has a first end  512  hingedly coupled to second platen  436  and an opposing second end  514  hingedly coupled to base  432  at first end  458 . A compressor  516  is coupled to piston  510  and is used to selectively expand and contract a piston rod  518  of piston  510 . The expansion of piston rod  518  moves second platen  436  to the collapsed position and contraction of piston rod  518  moves second platen  436  to the retracted position. Processor  486  can be used to control the movement of piston  510  and thus the movement of second platen  436 . Processor  486  can be programmed to move piston  510  back and forth over a fixed distance or can be used with a sensor  520 , such as an optical sensor, that senses when second platen  436  has reached the collapsed position. Compressor  516  and piston  510  can also be used with optical sensor  482 , pinch clamp  484 , and processor  486 , as discussed above with regard to  FIG. 17 . Other methods for controlling the movement of piston  510  can also be used. 
     Depicted in  FIG. 19  is another alternative embodiment of an expressor  430 B that includes first platen  434  and second platen  436 . Expressor  430 B includes base  432  having first platen  434  upstanding therefrom. As discussed above, first platen  434  can be movably mounted on base  432  so as to adjust the gap spacing between platens  434  and  436 . Second platen  436  is movably positioned adjacent to first platen  434 . However, in contrast to the above embodiments where second platen  436  pivots as it moves between the retracted and collapsed positions, in expressor  430 B, second platen  436  moves laterally as it moves between the retracted and collapsed positions. More specifically, inside face  438 B of second platen  436  is typically disposed parallel to and remains parallel to inside face inside face  438  of first platen  434  as second platen  436  moves laterally between the retracted and collapsed positions. 
     In the depicted embodiment, second platen  436  is moved by piston  510  having a piston rod  518 . As discussed above, piston  510  can comprise a pneumatic or hydraulic piston and uses a compressor  510  to expand and contract piston rod  518 . First end  512  of piston  510  is secured to second platen  436  while second end  514  of piston  510  is secured to a brace  524  upstanding from base  432 . A support  526  also upstands from base  432  and supports piston rod  518  that passes therethrough. Processor  486  can be used to control the movement of piston  510  and thus the movement of second platen  436 . Processor  486  can be programmed to move piston  510  back and forth over a fixed distance or can be used with sensor  520 , such as an optical sensor, that senses when second platen  436  has reached the collapsed position. Compressor  516  and piston  510  can also be used with optical sensor  482 , pinch clamp  484 , and processor  486 , as discussed above with regard to  FIG. 17 . Other methods for controlling the movement of piston  510  and second platen  436  can also be used. 
     Expressor  430 B works in substantially the same way as expressor  430 A. 
     Specifically, with second platen  436  in the retracted position, bag assembly  14  is positioned between platens  434  and  436 . Bag assembly  14  can be supported on one of platens  434  or  436  or can simply be supported on base  432 . Second platen  436  is then moved laterally to the collapsed position through the use of compressor  516 . As bag  54  is compressed between platens  434  and  436 , the supernatant  216  is driven out of bag  54  and into container  220 . As discussed above, bag  54  is compressed until the desired amount of supernatant  216  has been removed. In contrast to using piston  510 , other types of drive mechanisms, such as a gear assembly, screw drive, worm drive or linkage driven by a motor can be used. In addition, one or more springs or elastic bands can be used to move second platen  436  from the retracted position to the collapsed position. 
     Where pellet  214  is fragile, further precautionary steps can be taken to prevent disturbing and resuspending portions of pellet  214  as supernatant  216  is removed from bag assembly  14 . For example, as shown in  FIG. 9 , outlet line  92  of bag assembly  14  is again coupled with container  220  through a sterile connection. As previously discussed with regard to  FIG. 9 , this can be through a direct coupling with container  220  or through inlet line  222  coupled with container  220 . This coupling can be accomplished either before or after removing bag assembly  14  from the centrifuge or the buck or insert thereof. 
     Once bag assembly  14  is fluid coupled within container  220 , bag assembly  14  is mounted on an expressor  430 C, as shown in  FIG. 20 . As discussed below in more detail, expressor  430 C functions to divide compartment  56  of bag assembly  14 B into an upper compartment  228  that houses supernatant  216  and a lower compartment  230  that houses pellet  214 . Again, pellet  214  has a higher density than supernatant  216  and can have a higher viscosity. Thus, expressor  430 C is applied so that upper compartment  228  holds a first component and lower compartment  230  holds a second component where the second component has a higher density and/or viscosity than the first component. It is appreciated that a small amount of supernatant  216  may be permitted to be retained within lower compartment  230  to minimize disruption of pellet  214  as expressor  430 C is attached. Expressor  430 C functions to seal upper compartment  228  from lower compartment  230  so that no portion of pellet  214  can pass into upper compartment  228 . 
     Except as noted below, expressors  430 A and  430 C operate in substantially the same way and like elements between expressors  430 A and  430 C are identified by like reference characters. Expressor  430 C includes base  432  having top surface  456 . Upstanding from base  432  is first platen  434 . Although first platen  434  could extend orthogonal to base  432 , in this embodiment first platen  434  is sloped to form an outside angle between first platen  434  and top surface  456  of base  432  that is greater than 90°. Expressor  430 C also includes second platen  436  having a lower end coupled to hinge  462 . Spring  464  is coupled to hinge  462  and is used to urge rotation of second platen  436  from the retracted position to the collapsed position. However, in contrast to expressor  430 A where hinge  462  is directly secured to base  432 , expressor  430 C includes a pair of elongated arms  490 A and  490 B each having a first end  492  and an opposing second end  494 . Second ends  494  of arms  490  are rotatably mounted on opposing sides of base  432  at or toward second end  460  of base  432 . Hinge  462  extends between first ends  492  of arms  490  so that second platen  436  hingedly rotates relative to arms  490 . 
     During operation, bag assembly  14  is supported against inside face  438  of first platen  434  by being suspended from a hanger  496  extending from first platen  434 . Next, arms  490  are rotated upward, as shown in  FIG. 21 , so that hinge  462  compresses bag assembly  14  against first platen  434  directly above pellet  214 , thereby dividing compartment  56  into upper compartment  228  that houses supernatant  216  and a lower compartment  230  that houses pellet  214 , as discussed above. Arms  490  are locked in place so as to secure the seal between compartment  228  and compartment  230 . 
     To assist in effectively using hinge  462  to divide compartment  56  into upper compartment  228  and lower compartment  230 , arms  490  can be adjustable in length and can lock at the desired length. For example, as shown in  FIG. 21 , each arm  490  can comprise a first portion  530 A and a second portion  530 B that slidably couple together, such as by telescoping. Portions  530 A and  530 B can be locked together in a desired length by a fastener  532 . Furthermore, each arm  490  can be rotated to a desired angle and locked in place. For example, as also shown in  FIG. 21 , a brace  534  can be mounted on base  432  adjacent to arm  490 A. An arched slot  536  extends through brace  534 . A fastener  538  is slidably received within slot  536  and is connected to arm  490 A. For example, fastener  538  can comprise a threaded bolt that passes through slot  536  and through an opening in arm  490 A with a nut mounted on the end of the bolt. Arm  490 A can be freely rotated relative to base  432  with fastener  538  sliding within slot  536 . Once arms  490  are in a desired orientation, fastener  538  can be tightened or otherwise locked in place so as to rigidly secure arm  490 A to brace  534 , thereby securing arms  490  at the desired angle. Accordingly, by selectively adjusting the length and angle of arms  490 , hinge  462  can be securely pressed against bag  54  to divide compartment  56  into compartments  228  and  230 . A soft sealing member  538  can also be disposed along the length of hinge  462  to bias against bag  54  for effecting a seal thereat. 
     Once hinge  462  has been positioned to form compartments  228  and  230 , second platen  436  is then permitted to freely rotate under the force of spring  464  so as to compress the portion of bag assembly  14  bounding compartment  228 , thereby driving supernatant  216  out of compartment  228 , through outlet line  92 , and into container  220  ( FIG. 9 ). Expressor  430 C thus limits the risk of any portion of pellet  214  flowing into container  220  because pellet  214  is sealed off from supernatant  216 . 
     To still further assist in helping to keep supernatant  216  separated from pellet  214 , a clamp  226  can be clamped over bag assembly  14  directly above pellet  214  as depicted in  FIG. 22 . Clamp  226  is typically applied prior to positioning bag assembly  14  on expressor  430 C. Clamp  226  functions to divide compartment  56  into upper compartment  228  that houses supernatant  216  and lower compartment  230  that houses pellet  214 . 
     Bag assembly  14 B with clamp  226  mounted thereon ( FIG. 23 ) can be suspended on first platen  434  using hanger  496  ( FIG. 20 ). Arms  490  can then be rotated upward, as discussed above, so that hinge  462  extends across bag assembly  14  just above clamp  226 . Second platen  436  can then be moved to the collapsed position that compresses upper compartment  228  and drives supernatant  216  into container  220 . 
     In alternative embodiments, other methods can be used to form and seal upper compartment  228  from lower compartment  230 . For example, bag assembly  14  could be temporarily pinched closed along the same line that clamp  226  is attached. This can be accomplished by pressing together structural members on opposing sides of bag assembly  14  along the clamp line so as to seal upper compartment  228  from lower compartment  230 . In another alternative, bag assembly  14  could be permanently welded closed along the clamp line so to seal upper compartment  228  from lower compartment  230 . Again, once upper compartment  228  is isolated from lower compartment  230 , supernatant  216  can be dispensed into container  220  without risk of resuspending pellet  214  into supernatant  216 . Other methods that seal upper compartment  228  from lower compartment  230  can also be used. 
     Once the supernatant  216  and pellet  214  separated and isolated, they can be used or discarded as desired. Uses and further processing steps for the separated supernatant  216  and pellet  214  are discussed in U.S. application Ser. No. 16/289,296 (US Patent Publication No.) ______, which was previously incorporated by reference. 
     The inventive systems disclosed herein have a number unique advantages over the prior art. For example, bag assemblies  14 , container  220  and other containers that may be fluid coupled with bag assemblies  14  can all be sterilized prior to use and all fluid couplings formed therewith or therebetween can be sterile connections. The transfer of suspension  12  from reactor  10  into bag assembly  14  and the transfer of the supernatant  216  and pellet  214  out of bag assembly  14  can thus be accomplished without exposing suspension  12  or its components to the open environment or other sources of contaminants. Thus, there is no risk, or at least minimal risk, of suspension  12  or its components being contaminated as they are processed, as set forth above. As a result, there is usually no need for post purification processing of the suspension components (other than, for example, filtering a small amount of residual cells from supernatant  216 ). The transfer of suspension  12  and separated components through closed lines also reduces the risk that product can be spilled. As such, there is lower risk of losing product by spilling. Delays and efforts in cleaning spilled product is also avoided. This closed processing in a sterile environment is in stark contrast to the prior art where both the original suspension and the formed supernatant are openly exposed to the environment as they are transferred into and out of the bottles or flasks that are used during centrifugation. 
     Furthermore, biological suspensions have traditionally not been separated by centrifugation within a closed bag to produce a supernatant and pellet. Using an expressor has been found to provide and easy and cost efficient method to remove the supernatant from the bag without removing the pellet while retaining the pellet and/or the supernatant sterile. 
     Although some of the expressors disclosed herein after have some components similar conventional plasma expressors, the disclosed expressors have unique features. For example, bag assemblies are  14 B are uniquely configured having ports  58 A 1  and  58 B 1  formed on the front face thereof ( FIG. 4 ). In part, as previously discussed herein, ports  58 A 1  and  58 B 1  are so positioned so as to help prevent damage or leakage during centrifugal rotation of bag assembly  14 B. In turn, notches  450  can be formed on first or section platens so receive ports  58 A 1  and  58 B 1 , thereby preventing blocking or kinking of the ports or lines extending therefrom during compression and better enabling uniform compression of bag assembly  14 . 
     In addition, bag assemblies  14  are tapered to help optimize the formation of a consolidated pellet within bag assemblies  14 . In turn, the platens of the disclosed expressors can be formed with a complementary taper to again help enable uniform compression of the bag assemblies while minimizing cost and limiting any obstructions to visualization of the bag assemblies. 
     Furthermore, blood bags used for separating plasma house blood which has a substantially constant concentration of plasma. As such, there is no need in plasma expressors to be able to adjust the gap spacing between adjacent platens. In contrast, the bag assemblies of the present disclosure can have wide fluctuations in the percent volumes of supernatant and pellet that are produced therein. Having the ability to adjust the spacing between platens based on the quantity of pellet within the bag assembly improves optimization of separating the supernatant from the pellet while minimizing risk that a portion of the pellet will outflow with the supernatant. 
     Furthermore, the use of expressor  430 C with or without clamp  226  or the other sealing mechanisms discussed herein provides an easy mechanism for isolating the supernatant from the pellet so that the pellet does not resuspend into the supernatant as the supernatant is removed from the bag assembly. This is particularly useful where the pellet is loose and easily resuspended. Accordingly, using expressor  430 C and the other sealing mechanisms both increases the quality of the supernatant that can be removed and shortens production time. 
     Various alterations and/or modifications of the inventive features illustrated herein, and additional applications of the principles illustrated herein, which would occur to one skilled in the relevant art and having possession of this disclosure, can be made to the illustrated embodiments without departing from the spirit and scope of the invention as defined by the claims, and are to be considered within the scope of this disclosure. Thus, while various aspects and embodiments have been disclosed herein, other aspects and embodiments are contemplated. While a number of methods and components similar or equivalent to those described herein can be used to practice embodiments of the present disclosure, only certain components and methods are described herein. 
     It will also be appreciated that systems, processes, and/or products according to certain embodiments of the present disclosure may include, incorporate, or otherwise comprise properties features (e.g., components, members, elements, parts, and/or portions) described in other embodiments disclosed and/or described herein. Accordingly, the various features of certain embodiments can be compatible with, combined with, included in, and/or incorporated into other embodiments of the present disclosure. Thus, disclosure of certain features relative to a specific embodiment of the present disclosure should not be construed as limiting application or inclusion of said features to the specific embodiment. Rather, it will be appreciated that other embodiments can also include said features without necessarily departing from the scope of the present disclosure. 
     Moreover, unless a feature is described as requiring another feature in combination therewith, any feature herein may be combined with any other feature of a same or different embodiment disclosed herein. Furthermore, various well-known aspects of illustrative systems, processes, products, and the like are not described herein in particular detail in order to avoid obscuring aspects of the example embodiments. Such aspects are, however, also contemplated herein. 
     The present disclosure may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. While certain embodiments and details have been included herein and in the attached disclosure for purposes of illustrating embodiments of the present disclosure, it will be apparent to those skilled in the art that various changes in the methods, products, devices, and apparatus disclosed herein may be made without departing from the scope of the disclosure or of the invention, which is defined in the appended claims. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.