Patent Publication Number: US-2021179995-A1

Title: Filter Systems for Separating Microcarriers from Cell Culture Solutions

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 16/389,688, filed Apr. 19, 2019, which is a divisional of U.S. application Ser. No. 15/193,962, filed Jun. 27, 2016, now U.S. Pat. No. 10,301,585, which is a continuation of U.S. application Ser. No. 13/449,101, filed Apr. 17, 2012, now U.S. Pat. No. 9,376,655, which application claims the benefit of U.S. Provisional Application No. 61/540,967, filed Sep. 29, 2011, which are incorporated herein by specific reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. The Field of the Invention 
     The present invention relates to filter systems and assemblies for separating microcarriers from cell culture solutions and related methods. 
     2. The Relevant Technology 
     The use of microcarriers in the biopharmaceutical industry is well known. Microcarriers can support the growth of anchorage-dependent cells thereon. Because of this, microcarriers are regularly used during cell culturing to optimize growth of various anchorage-dependent cell lines, such as protein-producing or virus-generating adherent cell populations, which are commonly used in the production of biologics (proteins) and vaccines. 
     Microcarriers have a surface chemistry that allows for attachment and growth of the anchorage dependent cells in cell culture procedures. Microcarriers can be made from a number of different materials and typically have a density that allows them to be maintained in suspension with gentle stirring. 
     Microcarrier cell culturing is typically carried out in a bioreactor. During culturing, the cells grow on the surface of the microcarriers. Once the cell culturing process is completed, the cultured cells are detached from the microcarriers through a chemical process carried out in the solution. The cultured solution containing the cells is then separated from the microcarriers for use or further processing. The gathered microcarriers can be cleaned, sterilized, and re-used, or can be discarded. 
     Separation of the microcarriers from the cultured solution that includes the detached cells is typically achieved by passing the solution through a rigid container having a horizontal screen that extends across the rigid container. The screen is a rigid mesh that allows the cultured fluid to pass through but prevents the microcarriers from doing so. However, as the microcarriers build up on the screen, they begin to clog the screen and prevent the fluid from passing therethrough. Once the screen is clogged, the process stops until the screen is unclogged. Furthermore, once the process is completed, the rigid container and related screen must be cleaned and sterilized before it can be reused. These process steps can be expensive and time consuming. 
     Accordingly, what is needed in the art are methods and/or systems that can alleviate one or more of the above problems. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various embodiments of the present invention will now be discussed with reference to the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. In the drawings, like numerals designate like elements. Furthermore, multiple instances of an element may each include separate letters appended to the element number. For example, two instances of a particular element “ 20 ” may be labeled as “ 20   a ” and “ 20   b ”. In that case, the element label may be used without an appended letter (e.g., “ 20 ”) to generally refer to every instance of the element; while the element label will include an appended letter (e.g., “ 20   a ”) to refer to a specific instance of the element. 
         FIG. 1  is a block diagram of a cell culturing system that uses a filter system according to one embodiment; 
         FIG. 2  is a perspective view of a filter system according to one embodiment; 
         FIG. 3  is a cross sectional side view of the filter assembly of the filter system shown in  FIG. 2 ; 
         FIG. 4  is a cross sectional side view of the filter port and filter shown in  FIG. 3 ; 
         FIG. 5  is a perspective view of the support housing of the filter system shown in  FIG. 2 ; 
         FIG. 6  is a cross sectional side view of the support housing of the filter system shown in  FIG. 2 ; 
         FIG. 7  is a cross sectional view of the filter system shown in  FIG. 2  taken along section line  7 - 7  of  FIG. 2 ; 
         FIGS. 8A-8C  are cross sectional side views of the filter and a portion of the filter port of the filter system shown in  FIG. 2 , showing fluid flow through the filter during various stages of use; 
         FIG. 9  is a cross sectional side view of a portion of a filter system showing one embodiment of a filter port that can be directly attached to the support housing; 
         FIG. 10A  is a cross sectional side view of a portion of a filter system showing another embodiment of a filter port directly attached to the support housing; 
         FIG. 10B  is a perspective view of the clamp assembly of the filter system shown in  FIG. 10A ; 
         FIG. 11  is a cross sectional side view of a filter system in which an alternative embodiment of a filter assembly is disposed within the support housing; 
         FIGS. 12A-12C  are cross sectional side views of the filter assembly shown in  FIG. 11 , showing fluid flow through the filter during various stages of use; 
         FIG. 13  is a cross sectional side view of a filter system in which another alternative embodiment of a filter assembly is disposed within the support housing; 
         FIG. 14  is a cross sectional side view of the filter and outlet port of the filter assembly shown in  FIG. 13 ; 
         FIGS. 15A-15C  are cross sectional side views of the filter assembly shown in  FIG. 13 , showing fluid flow through the filter during various stages of use; 
         FIG. 16  is a cross sectional side view of an alternative embodiment of a filter/outlet port combination; 
         FIG. 17A  is a perspective view of a hanger attached to the support housing; 
         FIG. 17B  is a cross sectional side view of a portion of a filter system showing another embodiment of an inlet port directly attached to the support housing using the hanger shown in  FIG. 17A ; 
         FIG. 17C  is a perspective view of the clamp assembly shown in  FIG. 17B ; 
         FIG. 18  is an exploded perspective view of a retention ring having hangers formed thereon and a related support housing; 
         FIG. 19  is a cross sectional side view of a filter system in which another alternative embodiment of a filter assembly is disposed within the support housing; 
         FIG. 20  is a cross sectional side view of the filter shown in  FIG. 19 ; 
         FIG. 21  is an exploded perspective view of a portion of the filter shown in  FIG. 20 ; 
         FIGS. 22A-22C  are cross sectional side views of the filter assembly shown in  FIG. 19 , showing fluid flow through the filter during various stages of use; 
         FIG. 23A  is an exploded perspective view of an alternative filter sheet configuration that can be used in the filter assembly shown in  FIG. 19 ; 
         FIG. 23B  is a cross sectional side view of a filter that incorporates the filter sheet configuration shown in  FIG. 22A ; 
         FIG. 23C  is a cross sectional side view of a filter that incorporates another alternative filter sheet configuration; 
         FIG. 24A  is an exploded perspective view of another alternative filter sheet configuration that can be used in the filter assembly shown in  FIG. 19 ; and 
         FIG. 24B  is a cross sectional side view of a filter that incorporates the filter sheet configuration shown in  FIG. 23A . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     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 in viewing the drawings and are not intended to limit the scope of the claims in any way. 
     The present invention relates to various apparatuses and methods for effectively filtering microcarriers or other particulates out of a cell culture solution without clogging or otherwise impeding the flow of the solution away from the microcarriers. 
       FIG. 1  depicts a cell culturing system  100  that incorporates embodiments of the present invention. In cell culturing system  100 , cells are grown within a biological container, such as bioreactor  102 . Bioreactor  102  can be a microgravity bioreactor, internally-stirred bioreactor, fluidized bed bioreactor, rocker bag bioreactor or any other type of bioreactor known in the art. Bioreactor  102  can also be a rigid tank reactor that needs to be sterilized between uses or a single use bioreactor that includes a disposable bag. Other types of bioreactors or other biological containers can alternatively be used, such as, e.g., a spinner flask. The cells are grown in a nutrient growth medium that can include a variety of different components. The components are typically dependent on the cell type and processing conditions. Growth mediums and related components are known in the art and are not discussed herein. 
     Microcarriers are added to the growth medium within the bioreactor so that anchorage-dependent cells can grow thereon. The microcarriers can be spherically shaped beads ranging between about 130 microns to about 300 microns in diameter. Other sizes can also be used. It is also appreciated that the microcarriers can have alternative shapes but typically have a maximum diameter in a range between about 130 microns to about 300 microns. The microcarriers have a density that allows them to be maintained in suspension with gentle stirring. For example, the microcarriers can also have a density of about 1.02 g/cm 3  to about 1.10 g/cm 3 . Other densities are also possible. The microcarriers can be made from a number of different materials including DEAE-dextran, glass, polystyrene plastic, acrylamide, and collagen. The different types of microcarriers can differ in their porosity, specific gravity, optical properties, presence of animal components, and surface chemistries. Surface chemistries can include extracellular matrix proteins, recombinant proteins, peptides, and positively or negatively charged molecules. The microcarrier materials, along with the different surface chemistries, can influence cellular behavior, including morphology, proliferation and adhesion. 
     During culturing, the cells grow on the surface of the microcarriers disposed within the mixture. Once the cell culturing process is completed, a chemical reagent, such as an enzyme, is added to the mixture, which includes the medium and the microcarriers suspended within the medium. The chemical reagent causes the cells to detach from the microcarriers so that the cells are freely suspended within the growth medium. The mixture is then removed from the bioreactor  102  and passed through a filter system  104 . Filter system  104  includes a filter assembly  106  that can be housed in an optional support housing  108 . The filter assembly  106  comprises a filter  170  disposed within a container  112 . Filter  170  separates the microcarriers from the cultured solution, which includes the growth medium and the detached cells, by allowing the cultured solution to pass therethrough while preventing the microcarriers from doing so. Container  112  can be substantially rigid or flexible and can be disposable, if desired. 
       FIG. 2  shows a perspective view of filter system  104  including support housing  108  and filter assembly  106 . Depicted in  FIG. 3  is a cross sectional side view of filter assembly  106 . In part, filter assembly  106  includes container  112 , a filter port  151  coupled to container  112  and filter  170  coupled to filter port  151 . Filter assembly  106  can also include one or more inlet ports and an outlet ports through which fluid can flow into and out of container  112 , respectively, as described in more detail below. In one embodiment, container  112  comprises a flexible and collapsible body  120 , such as a flexible bag, having an interior surface  122  and an opposing exterior surface  124 . Interior surface  122  bounds a compartment  126 . More specifically, body  120  comprises a sidewall  128  that, when body  120  is unfolded, has a substantially circular or polygonal transverse cross section that extends between a first end  130  and an opposing second end  132 . First end  130  terminates at a top end wall  134  while second end  132  terminates at a bottom end wall  136 . 
     Body  120  is comprised of a flexible, water impermeable material such as polyethylene or other polymeric sheets having a thickness in a range between about 0.1 mm to about 5 mm with about 0.2 mm to about 2 mm being more common. Other thicknesses can also be used. The material can be comprised of a single ply material or can comprise two or more layers which are either sealed together or separated to form a double 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. 
     The extruded material comprises a single integral sheet that comprises two or more layers of different material that can be separated by a contact layer. All of the layers are simultaneously co-extruded. One example of an extruded material that can be used in the present invention 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. The outer layer is a polyester elastomer coextruded with an ultra-low density polyethylene product contact layer. Another example of an extruded material that can be used in the present invention is the Thermo Scientific CX5-14 cast film also available from Thermo Fisher Scientific. The Thermo Scientific CX5-14 cast film comprises a polyester elastomer outer layer, an ultra-low density polyethylene contact layer, and an EVOH barrier layer disposed therebetween. In still another example, a multi-web film produced from three independent webs of blown film can be used. The two inner webs are each a 4 mil monolayer polyethylene film (which is referred to as the Thermo Scientific BM1 film) while the outer barrier web is a 5.5 mil thick 6-layer coextrusion film (which is referred to as the Thermo Scientific BX6 film). 
     The material is approved for direct contact with living cells and is capable of maintaining a solution sterile. In one embodiment, the material can be sterilizable such as by ionizing radiation or other conventional techniques. Other 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. 
     In one embodiment, body  120  comprises a two-dimensional pillow style bag wherein two sheets of material are placed in overlapping relation and the two sheets are bounded together at their peripheries to form internal compartment  126 . Alternatively, a single sheet of material can be folded over and seamed around the periphery to form internal compartment  126 . In another embodiment, body  120  can be formed from a continuous tubular extrusion of polymeric material that is cut to length and is seamed closed at the ends. In still other embodiments, such as in the depicted embodiment, body  120  comprises a three-dimensional bag that not only has an annular sidewall  128  but also a two-dimensional top end wall  134  and a two-dimensional bottom end wall  136 . Three dimensional containers can comprise a plurality of discrete panels, typically three or more, and more commonly four or six. Each panel can be substantially identical and can comprise a portion of the sidewall, top end wall, and bottom end wall of the container. Corresponding perimeter edges of each panel can be seamed. The seams are typically formed using methods known in the art such as heat energies, RF energies, sonics, or other sealing energies. 
     In alternative embodiments, the panels can be formed in a variety of different patterns. Further disclosure with regard to one method of manufacturing three-dimensional bags is disclosed in United States Patent Publication No. US 2002-0131654 A1 that was published Sep. 19, 2002 of which the drawings and Detailed Description are hereby incorporated by reference. 
     Although in the above discussed embodiment body  120  is in the form of a flexible bag, in alternative embodiments it is appreciated that body  120  can also comprise any form of collapsible container or semi-rigid container. Body  120  can also be transparent or opaque and can have ultraviolet light inhibitors incorporated therein. 
     It is appreciated that body  120  can be manufactured to have virtually any desired size, shape, and configuration. For example, body  120  can be formed having compartment  126  that is sized to hold in a range from about 10 liters to about 2,000 liters, with about 20 liters to about 250 liters and about 20 liters to about 100 liters being more common. Other volume sizes can also be used. Although body  120  can be any shape, in one embodiment body  120  is specifically configured to be substantially complementary to a first chamber  232  ( FIG. 6 ) of support housing  108 , as discussed below. 
     Continuing with  FIG. 3 , one or more hanging tabs  140  can be mounted on top end wall  134  or the upper end of sidewall  128  to support the upper end of body  120  within support housing  108 , if used. For example, in the depicted embodiment a plurality of radially spaced apart hanging tabs  140  are positioned on top end wall  134  at or near the outer perimeter thereof. Each hanging tab  140  includes a first end  142  secured to body  120  and an opposing second end  144  through which an opening  146  is formed. As shown in  FIG. 2 , when filter assembly  106  is positioned within support housing  108 , a hanger  238  can be received within a corresponding opening  146  of each hanging tab  140  to support container  112  within support housing  108 . 
     Hanging tabs  140  can be attached to body  120  or integrally formed therewith. Hanging tabs  140  can be made of the same material as body  120 , if desired. In embodiments in which body  120  is comprised of panels, hanging tabs  140  can be attached to body  120  by being welded between the panels. In other embodiments, hanging tabs  140  can be mounted on the outside of body  120  such as by welding or adhesion. 
     As shown in  FIG. 3 , one or more inlet ports can be mounted on top end wall  134  of body  120 . In the depicted embodiment, an inlet port  150  is shown. Inlet port  150  comprises a barbed tubular stem  152  having a flange  154  radially encircling and outwardly projecting therefrom. Inlet port  150  bounds a fluid passageway  155  that extends therethrough. During assembly, a hole is made through top end wall  134  for the port. The stem  152  of port  150  is then passed through the hole until flange  154  rests against top end wall  134 . Conventional welding or other sealing techniques are then used to seal each flange  154  to top end wall  134 . During use, stem  152  can be selectively coupled with a tube or container for delivering material into and/or out of compartment  126 . 
     Mounted on bottom end wall  136  of body  120  is an outlet port  156 . Similar to inlet port  150 , outlet port  156  comprises a barbed tubular stem  158  having a flange  160  radially encircling and outwardly projecting therefrom. Outlet port bounds a fluid passageway  162  that extends therethrough. As with inlet ports  150 , during assembly a hole is formed in bottom end wall  136 . Outlet port  156  is seated within the hole so that flange  160  rests against bottom end wall  136 . Again, conventional welding or other sealing technique is then used to seal flange  160  to bottom end wall  136 . During use, stem  158  is selectively coupled with an outlet tube for delivering material out of compartment  126 . 
     It is appreciated that any number of inlet ports  150  or outlet ports  156  can be formed on body  120  and that a variety of different types and sizes of ports can be used depending on the type of material to be dispensed into compartment  126  and how the material is to be dispensed therefrom. The ports  150  and  156  can also be located at different locations on body  120  such as sidewall  128 . 
     Filter port  151  also functions as an inlet port. Specifically filter port  151  includes a flange  157  mounted to top end wall  134 . A tubular first stem  153  upwardly projects from one side of flange  157  and has an annular barb formed on the end thereof. A tubular second stem  172  projects from an opposing side of flange  157  so as to extend downward into compartment  126 . A support flange  180  encircles and radially outwardly projects from the end of second stem  172 . Turning to  FIG. 4 , filter port  151  has an inside surface  176  that bounds a fluid passageway  179  extending therethrough, i.e., fluid passageway  179  extends through first stem  153 , flange  157 , second stem  172  and support flange  180 . Filter port  151  can be integrally formed as a single unitary structure or can comprise two or more parts secured together. Support flange  180  has a lower face  182  and an opposing upper face  184  that both radially extend to an outside face  186 . An annular groove  188  can be recessed on outside face  186  for mounting filter  170  thereto, as discussed below. 
     Filter  170  comprises a body  190  having an interior surface  192  that bounds a compartment  193  and an opposing exterior surface  194 . A mouth  196  is formed on body  190  so as to communicate with compartment  193 . In one embodiment, filter  170  is flexible and can be in the form of a porous bag or sock. Filter  170  is attached to filter port  151  by inserting support flange  180  within mouth  196 . A connector  202  such as a clamp, cable tie crimp ring, strap, or the like is then positioned over filter  170  and tightened so as to secure filter  170  within groove  188 . In alternative embodiments, it is appreciated that other conventional methods can be used to secure filter  170  to filter port  151 . For example, filter  170  can be secured to filter port  151  by welding, adhesive or the like. In other embodiments, support flange  180  can be eliminated and filter  170  can be attached directly to second stem  172 . In still other embodiments, support flange  180  and second stem  172  can both be eliminated and filter  170  can be attached to an extended version of flange  157 . 
     Lower face  182  of support flange  180  and interior surface  192  of filter  170  together bound an inlet chamber  204  that is fluidly coupled with fluid passageway  179 . As discussed below in greater detail, during use a mixture of cultured solution and associated microcarriers can be delivered to inlet chamber  204  through filter port  151 . Filter  170  comprises a material that will allow the cultured solution to pass therethrough while preventing the microcarriers from passing therethrough. As such, the microcarrier are collected within inlet chamber  204  of body  190 . Filter  170  can be comprised of a porous material, such as a mesh, netting, perforated sheets, lattice type of material, or any other material that will allow the cultured solution to pass therethrough while preventing the associated microcarriers from passing therethrough. To enable the cells to pass therethrough but prevent the microcarriers from passing therethrough, filter  170  is typically made of a material, having pores in the size of about 15 microns to about 100 microns, with about 30 microns to about 100 microns being common. If desired, filter  170  can be expandable and/or resiliently stretchable. Examples of materials that can be used for filter  170  include polyester (PET), polyamide (PA), polypropylene (PP), and polyetheretherketone (PEEK). Other materials can also be used. 
     In alternative embodiments, it is appreciated that part or all of filter  170  can be rigid or semi-rigid. For example, filter  170  can comprise body  190  formed from a porous flexible material while a rigid ring is mounted to body  190  and encircles mouth  196 . The rigid ring could then be used to secure filter  170  to filter port  151  such as by threaded connection, bayonet connection, snap fit connection, press fit engagement, crimped engagement or the like. In other embodiments, filter  170  can be comprised of a rigid material. For example, filter  170  can be molded from a plastic, metal, or composite material, that has holes formed therethrough through which the cultured fluid can pass but the microcarriers cannot. 
     Returning to  FIG. 3 , as a result of filter  170  being coupled with filter port  151  which is attached to top end wall  134 , filter  170  is suspended down into compartment  126 . When disposed within compartment  126 , filter  170  essentially divides compartment  126  into two chambers—inlet chamber  204  of filter  170 , and an outlet chamber  206 . Outlet chamber  206  is the portion of compartment  126  external to inlet chamber  204  and fluid passageway  178 . As such, fluid flows from inlet chamber  204  to outlet chamber  206  through filter  170 . 
     In one embodiment, filter  170  is sized and positioned so as to be suspended above bottom end wall  136  of container  112  and away from sidewall  128 , as shown in  FIG. 3 . In some embodiments it can be desirable to keep filter  170  away from bottom end wall  136  and sidewall  128  since contacting filter  170  against a structure can cause blocking of that portion of filter  170  which can decrease fluid flow through filter  170 . In some embodiments, filter  170  remains above bottom end wall  136  during use so as to not contact bottom end wall  136 . In other embodiments, filter  170  may contact bottom end wall  136  and/or sidewall  128  such as after a portion of the microcarriers have been collected. 
     If an expandable material is used for filter  170 , the weight of the microcarriers may cause filter  170  to expand downward and outward as more microcarriers are received, as discussed below. However, by being suspended from top end wall  134 , filter  170  can in some embodiments be configured to remain above bottom end wall  136  even when expanded, as discussed in more detail below. 
     Support housing  108  can be used to support filter assembly  106  or any of the filter assemblies discussed herein. This can be especially helpful if container  112  is flexible, as support housing  108  can provide rigid support for container  112 . Returning to  FIG. 2 , support housing  108  generally includes a substantially rigid receptacle  210  seated on a dolly  212 . As depicted, receptacle  210  is configured to receive and support filter assembly  106 . 
     Turning to  FIGS. 5 and 6 , receptacle  210  comprises a substantially cylindrical sidewall  214  that extends from an upper end  216  to an opposing lower end  218 . As depicted in  FIG. 6 , receptacle  210  includes a floor  220  formed inside of receptacle  210  at a position between upper end  216  and lower end  218 . Floor  220  has a substantially frustoconical configuration. More specifically, floor  220  has a frustoconical portion  221  with a top surface  222  that extends between an inner edge  224  and an opposing outer edge  226 . Floor  220  also includes a flat base portion  223  inwardly extending from frustoconical portion  221 . Base portion  223  bounds a central opening  228  extending through floor  220 . Outer edge  226  is integrally formed with or is otherwise connected to sidewall  214 . The slope of floor  220  functions in part as a funnel to direct all material toward central opening  228 . In alternative embodiments, floor  220  can be flat, cupped, irregular, or other desired configurations. 
     Sidewall  214  of receptacle  210  has an interior surface  230  disposed above floor  220 . Interior surface  230  and floor  220  bound first chamber  232  formed in upper end  216  of receptacle  210 . First chamber  232  is sized to receive container  112  and can thus have a corresponding size. Depicted in  FIG. 5 , upper end  216  of receptacle  210  terminates at an upper edge  234  that bounds an opening  236  to first chamber  232 . 
     As shown in  FIG. 5 , an optional annular lid  250  can be removably disposed over upper edge  234  so as to selectively close opening  236 . Clamps  252  can be used to selectively secure lid  250  to receptacle  210 . Lid  250  can include one or more holes  253  extending therethrough. Holes  253  can be configured to align with ports  150  and  151  of container  112  so that inlet tubes can extend therethrough to attach to ports  150  and  151  and pass fluid into filter assembly  106 . 
     As previously mentioned, one or more hangers  238  can be secured to lid  250  or sidewall  214  of receptacle  210  at or near upper edge  234  to receive the corresponding hanging tabs  140  of filter assembly  106 . For example, as shown in  FIG. 6 , hangers  238  can be in the form of hooks positioned on interior surface  230  to receive hanging tabs  140  positioned on container  112 , as shown in  FIG. 2 . As shown in  FIG. 2 , each hanger  238  is positioned on interior surface  230  so as to correspond to the position of one of the hanging tabs  140  when filter assembly  106  is positioned within first chamber  232 . Hangers  238  can be attached to receptacle  210  by using screws, adhesive, welding or other known attachment methods. 
     When it is desired to remove filter assembly  106  from support housing  108 , hanging tabs  140  can simply be disconnected from hangers  238  to allow filter assembly  106  to be removed. It is appreciated that hangers  238  can come in a variety of different forms. For example, hangers  238  can comprise hook that connect to hanging tabs  140  and then catches directly onto edge  234  of receptacle  210  for supporting filter assembly  106 . In this embodiment, hangers are not fixed to receptacle  210 . In still other embodiments, hangers  238  can comprise hooks or other types of projections or fasteners that are mounted on the exterior surface of sidewall  214 . In this embodiment, hanging tabs  240  can pass over edge  234  and then connect to hangers  238 . 
     Depicted in  FIG. 18  is another alternative embodiment for the hangers. Specifically, a retention ring  540  is used for supporting container  112  within first chamber  232  of receptacle  210 . Retention ring  540  comprises a substantially C-shaped ring body  542  that terminates at opposing ends having flanges  544 A and  544 B formed thereat. A fastener  546  extends through flanges  544 A and B and can be used for selectively drawing and securing flanges  544 A and B together. In one embodiment, fastener  546  can comprise a bolt and nut assembly. In alternative embodiments, fastener  546  can comprise a clamp, latch, or any other conventional fastener that achieves the desired objective. 
     Ring body  542  is typically in the form of a narrow band having an inside face  548  and an opposing outside face  550 . A plurality of spaced apart hangers  552  are mounted on inside face  548  of ring body  542 . In one embodiment, each hanger  552  comprises an elongated pin having a first end  554  that is secured, such as by welding, at a central location on inside face  548 . Each pin also comprises an opposing second end  556  that projects up above ring body  542 . If desired, second end  556  of each pin can be rounded. Although not required, in one embodiment a plurality of spaced apart notches  558  are recessed on the bottom edge of ring body  542  such that the top of each notch  558  is disposed adjacent to first end  554  of a corresponding hanger  552 . 
     During use, fastener  546  is loosened so as to expand the size of ring body  542 . Ring body  542  is then positioned on upper end  476  of receptacle  210  so that ring body  542  encircles the exterior surface of sidewall  214  at upper end  216 . In this configuration, first end  554  of each hanger  552  rests on top of upper edge  234  of sidewall  214  so that retention ring  540  is properly positioned. If desired, a flange can be formed at first end  554  of each hanger  552  for receiving upper edge  234 . Notches  558  permit a visual inspection to ensure that ring body  542  is properly seated. Fastener  546  is then used to clamp retention ring  540  on sidewall  214 . As container  112  ( FIG. 3 ) is inserted within first chamber  232 , second end  556  of each hanger  552  is passed through opening  146  of a corresponding hanging tab  140  ( FIG. 3 ) so that container  112  is supported within first chamber  232 . 
     In still other embodiments hangers  238  can be in the form of microhook and loop systems (commonly known as VELCRO), threaded connections, clamps, or the like that connect hanging tabs  140  to receptacle  210 . 
     As shown in  FIG. 6 , sidewall  214  also has an interior surface  254  formed below floor  220 . Interior surface  254  and floor  220  bound a second chamber  256  disposed at lower end  218  of receptacle  210 . An access port  260  extends through sidewall  214  at lower end  218  of receptacle  210  so as to provide side access to second chamber  256 . In alternative embodiments, the portion of sidewall  214  extending below floor  220  can be replaced with one or more spaced-apart legs or other supports that elevate floor  220  off of the ground, dolly  212 , or other surface on which receptacle  210  rests. 
     In the embodiment depicted, receptacle  210  comprises a barrel molded from a polymeric material. In alternative embodiments, receptacle  210  can be comprised of metal, fiberglass, composites, or any other desired material. Furthermore, although receptacle  210  is shown as having a substantially cylindrical configuration, receptacle  210  can be substantially boxed shaped or have a transverse configuration that is polygonal, elliptical, irregular, or any other desired configuration. 
     As depicted in  FIG. 5 , dolly  212  comprises a frame  262  having a plurality of wheels  264  mounted thereon. Dolly  212  enables easy movement of receptacle  210 . In alternative embodiments where it is not necessary or desired to move receptacle  210 , wheels  264  and/or frame  262  can be eliminated. In this regard, receptacle  210  can sit on a ground surface or any other desired structure. As shown in  FIG. 6 , lower end  218  of receptacle  210  is received on dolly  212  so as to be stably supported thereby. 
     Before use, filter assembly  106  can be positioned within first chamber  232  of receptacle  210  so that outlet port  156  can be received within central opening  228  extending through floor  220  of receptacle  210 , as depicted in  FIG. 7 . 
     It is typically desirable that when filter assembly  106  is received within first chamber  232 , container  112  is at least generally uniformly supported by floor  220  and sidewall  214  of receptacle  210  when container  112  is at least partially filled with a fluid. Having at least general uniform support of container  112  by receptacle  210  helps to preclude failure of container  112  by hydraulic forces applied to container  112  when filled with a solution. 
     Hanging tabs  140  disposed on top end wall  134  are looped over hangers  238  disposed on interior surface  230  of receptacle  210  to suspend container  112  within first chamber  232 . As such, container  112  may not extend all the way down to floor  220  until fluid is introduced into container  112 . Before container  112  is disposed within first chamber  232 , an outlet tube  270  can be connected to outlet port  156 . Outlet tube  270  extends through central opening  228  and can extend out from support housing  108  through access port  260 . 
     As noted above, filter  170  is suspended from top end wall  134  of container  112  by virtue of its coupling with filter port  151 . Because filter  170  is indirectly attached to top end wall  134 , filter  170  is generally suspended above bottom end wall  136  of container, as shown in  FIG. 7 . 
     An inlet tube  272  is coupled with first stem  153  of filter port  151 . Either before or after filter assembly  106  has been positioned within first chamber  232 , inlet tube  272  can be coupled in a sterile fashion with bioreactor  102  ( FIG. 1 ). During use, a mixture of the cultured solution and the associated microcarriers from bioreactor  102  is introduced into inlet chamber  204  of filter assembly  106  through inlet tube  272 . The cultured solution of the mixture, including the detached cells, passes through filter  170  and into outlet chamber  206 . 
     More specifically, the mixture passes through fluid passageway  179  in filter port  151  and is received by inlet chamber  204  of filter  170 , as depicted in  FIGS. 8A-8C . As shown in  FIG. 8A , as the mixture is first received within inlet chamber  204 , as denoted by arrow  280 , inlet chamber  204  is completely or mostly devoid of microcarriers and the cultured solution can freely pass through filter  170  through the sides and bottom thereof, as indicated by arrows  282 . As shown in  FIGS. 8B and 8C , as more mixture flows into inlet chamber  204 , the microcarriers (shown as a group of beads  284 ) within the mixture are retained and begin to accumulate at the bottom of inlet chamber  204 . The cultured solution continues to pass through filter  170 . However, the majority of the fluid passes out through the side portion of filter  170  that is above the accumulated microcarriers, as shown by arrows  286  and  288  in  FIGS. 8B and 8C . This is because the accumulated microcarriers at least partially block the flow of fluid through the portion of filter  170  that they rest against. Thus, the configuration of filter  170  permits an efficient collection of microcarriers while still permitting a free flow of cultured solution through filter  170 . 
     Filter  170  is typically sized so that all of the microcarriers from bioreactor  102  can be collected within inlet chamber  204  while still allowing a portion of filter  170  to be unobstructed by microcarriers so that the cultured solution can freely pass therethrough. Alternatively, a filter assembly  106  can be used until inlet chamber  204  is sufficiently filled with microcarriers that the cultured fluid can no longer pass through filter  170  as a desired processing rate. Filter assembly  106  can then be replaced with a new filter assembly  106  and the process continued. 
     If an expandable material is used for filter  170 , the weight of the microcarriers can cause filter  170  to expand downward and outward, as depicted in  FIGS. 8B and 8C . This expansion can cause filter  170  to become more elongate, thereby increasing the surface area of filter  170  and allowing more cultured solution to flow through the sides of filter  170  as to enable more microcarriers to be retained within inlet chamber  204 . 
     After the cultured solution passes through filter  170 , the cultured solution can either be retained within outlet chamber  206  or can pass directly out of container  112  through outlet port  156  and outlet tube  270 . Once all of the cultured solution has been processed through filter assembly  106 , filter assembly  106  can be removed from support housing  108  and discarded with the microcarriers contained therein. Alternatively, filter assembly  106  can be cut open and the microcarriers removed and recycled for further use. By forming filter assembly  106  from a disposable container and filter, the inventive system eliminates the need for cleaning or sterilizing the filtering system between different batches of culturing solution. 
     In some systems, the weight of the microcarriers combined with the force caused by the downward motion of the incoming mixture can cause a strain on container  112  where filter port  151  attaches to top end wall  134 . To alleviate this strain between filter port  151  and top end wall  134 , filter port  151  can also be directly attached to receptacle  210  instead of or in conjunction with the hanging tabs and hangers, discussed above. For example, in the embodiment shown in  FIG. 9 , a hanging flange  292  is attached to or is integrally formed with stem  153  of filter port  151 . Hanging flange  292  outwardly projects from stem  153  above flange  157  so that hanging flange  292  will be positioned outside of compartment  126  when filter port  151  has been attached to top end wall  134 . Hanging flange  292  has a top surface  294  and an opposing bottom surface  296  and bounds an opening  298  extending therethrough. Similar to hanging tabs  140 , discussed previously, opening  298  of hanging flange  292  can be looped over one of hangers  238  disposed on receptacle  210  to suspend filter port  151  and filter  170  from the top end of receptacle  210 . To position opening  298  of hanging flange  292  adjacent to a hanger  238 , filter port  151  can be positioned adjacent to the perimeter edge of top end wall  134 , as shown in the depicted embodiment. 
     All or portions of hanging flange  292  can be flexible or substantially rigid. If hanging flange  292  is substantially rigid, the portion of hanging flange  292  that includes opening  298  can be shaped to form an angle with respect to the rest of second flange  292 , as shown in the depicted embodiment, to more easily facilitate the attachment of hanging flange  292  to hanger  238  and to help keep filter  170  vertical. It is appreciated that all of the other methods as discussed above for securing hanging tabs  140  to receptacle  210  can also be used to secure hanging flange  292  to receptacle  210 . 
     In one embodiment, the hanging flange  292  is replaced by an attachment device that is removable and reusable. For example, as shown in  FIGS. 10A and 10B , the hanging flange  292  can be replaced by a clamp assembly  300  that removably attaches to stem  153 . Clamp assembly  300  includes a pair of mating arms  302  and  304  that rotate about a hinge  306  positioned at one end  308  of the pair of arms. Hinge  306  includes a tubular hinge pin  307  that bounds an opening  314 . At the other end  310  of arms  302 / 304  is a securing mechanism, such as a screw assembly  312 , to tighten arms  302  and  304  together around stem  153 . During use, opening  314  is advanced over hanger  316  so that hanger  316  supports filter port  151  and attached container  112 . If desired, hanger  316  can have substantially hard (i.e., about 90 degree) angles to facilitate keeping inlet port  151  and filter  170  in a generally vertical orientation. It is appreciated that opening  314  need not be located within hinge pin  307  but and otherwise be formed on clamp assembly  300 . 
     In another embodiment, a removable attachment device can be used with a modified hanging flange and hanger. For example, as shown in  FIG. 17A , hanger  316  can be replaced by a hanger  500  that is also secured to interior surface  230  of sidewall  214  at upper end  216  of receptacle  210 . Hanger  500  includes a flange  502  attached to and projecting from sidewall  214  and a substantially C-shaped retainer  504  disposed at the end thereof. Retainer  504  includes a stem  506  and a flange  508  radially outwardly projecting therefrom. Both stem  506  and flange  508  have a substantially C-shaped configuration. 
     Turning to  FIG. 17B , a hanging flange  510  is integrally formed with stem  153  of inlet port  151 . Hanging flange  510  is similar to hanging flange  292 , discussed above, except that hanging flange  510  may omit openings extending therethrough, if desired, and is typically flat. Hanging flange  510  radially encircles and outwardly projects from stem  153  above flange  157 . Hanging flange  510  has a top surface  512  and an opposing bottom surface  514 . For receptacle  210  to support filter port  151 , filter port  151  can be positioned so that stem  153  extends through stem  506  of support hanger  500  and the bottom surface  514  of hanging flange  510  rests upon flange  508  of hanger  500 . In this position, hanger  500  can provide the desired support for container  112 . 
     To secure filter port  151  to hanger  500 , a clamp assembly  516  can be used. Clamp assembly  516  can be similar to clamp assembly  300 , discussed above, with a few differences. As shown in  FIG. 17C , clamp assembly  516  includes a pair of mating arms  518  and  520  that rotate about a hinge  522  positioned at one end  524  of the pair of arms. At the other end  526  of the arms is a securing mechanism, such as a screw assembly  528 , to tighten arms  518  and  520  together. An annular channel  530  is formed on the inside surface of arms  518  and  520 . 
     Returning to  FIG. 17B , to secure filter port  151  to support  500 , arms  518  and  520  (collectively denoted as  519 ) are positioned around flange  508  and hanging flange  510  so that when clamp assembly  516  is closed and tightened, these structures are received within annular channel  530  and securely held together. A gasket or the like can also be positioned within annular channel  530 , if desired, to form a more secure connection between clamp assembly  516  and flange  508  and hanging flange  510 . Other types of securing methods and devices can alternatively be used to secure filter to receptacle  210 . 
       FIG. 19  depicts another embodiment of a filter assembly  600 . Like elements between filter assembly  600  and filter assembly  106  are identified by like reference characters. Similar to filter assembly  106 , filter assembly  600  comprises a filter  602  disposed within container  112  and attached thereto using a filter port  604 . However, instead of being directly attached to filter port  604 , filter  602  includes an inlet port  606  that is attached to filter port  604  using a dip tube line  608 . 
     Similar to filter port  151 , filter port  604  includes barbed first stem  153  upwardly projecting from a top side of flange  157 . A barbed second stem  610  projects from the bottom side of flange  157  so as to extend downward into compartment  126 . Second stem  610  is generally similar to first stem  153  except that second stem  610  extends in the opposite direction from flange  157 . Filter port  604  has an inside surface  612  that bounds a fluid passageway  614  extending therethrough, i.e., fluid passageway  614  extends through first stem  153 , flange  157 , and second stem  610 . Filter port  604  can be integrally formed as a single unitary structure or can comprise two or more parts secured together. 
     Turning to  FIG. 20 , filter  602  comprises a two-dimensional pillow style bag  616  wherein two sheets  618  and  620  of material are placed in overlapping relation and the two sheets are bounded together at their peripheries to form an inlet chamber  622 . 
     Turning to  FIG. 21  in conjunction with  FIG. 20 , sheet  618  has an interior surface  624  and an opposing exterior surface  626  extending to a perimeter edge  628 . Sheet  618  is comprised of a flexible material such as polyethylene or other polymeric sheets, similar to body  120  of container  112 . The material can be comprised of a single ply material or can comprise two or more layers which are either sealed together or separated to form a double 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. Sheet  618  can be comprised of the same type of materials as discussed above with regard to body  120  of container  112 . In one embodiment, sheet  618  is comprised of the same material as body  120 . Although shown in the depicted embodiment as being substantially circular, it is appreciated that sheet  618  can have virtually any desired shape. Similarly, it is appreciated that sheet  618  can have virtually any desired size. 
     A hole  630  is formed in sheet  618  so as to extend therethrough between interior and exterior surfaces  624  and  626 . Hole  630  is sized so as to be able to receive inlet port  606 . Although hole  630  is shown in the depicted embodiment as being substantially centered on sheet  618 , this is not required. Hole  630  can be positioned anywhere on sheet  618  and can be any size that will accommodate inlet port  606 . 
     Sheet  620  has an interior surface  632  and an opposing exterior surface  634  extending to a perimeter edge  636 . Sheet  620  is comprised of a flexible porous material that allows the cultured solution to pass through, yet prevents microcarriers from passing through. For example, sheet  620  can be comprised of a mesh material made of a polymeric material, such as those materials discussed above with respect to filter  170 . Other polymeric and non-polymeric materials can also be used. Furthermore, pore size ranges of the mesh can be similar to those discussed above with respect to filter  170 . Sheet  620  can be expandable and/or resiliently stretchable, if desired. Sheet  620  is generally sized and shaped to match the size and shape of sheet  618 , although this is not required. 
     Inlet port  606  is similar to inlet ports  150  positioned on body  120  (see  FIG. 19 ). As such, as shown in  FIG. 20 , inlet port  606  comprises a barbed tubular stem  152  having a flange  154  radially encircling and outwardly projecting therefrom. Inlet port  606  bounds a fluid passageway  155  that extends therethrough. During assembly, hole  630  is made through sheet  618  for the port. Stem  152  of inlet port  606  is then passed up through hole  630  until flange  154  rests against interior surface  624  of sheet  618 . Conventional welding or other sealing techniques are then used to seal flange  154  to sheet  618 . 
     After inlet port  606  has been secured to sheet  618 , interior surfaces  624  and  632  of sheets  618  and  620  are positioned against each other, as shown in  FIG. 20 , and corresponding perimeter edges  628  and  636  are attached or secured together using heat energies, RF energies, sonics, or other sealing energies. Adhesives or other types of securing or attaching devices or methods can also be used. Dashed lines  638  of  FIG. 21  depicts the perimeter portions of sheets  618  and  620  that are secured together during assembly. When secured, inside surfaces  624  and  632  together bound inlet chamber  622 , with material being deliverable thereinto via inlet port  606 . 
     Returning to  FIG. 19 , once filter  602  has been assembled, filter  602  can be positioned within container  112 . That is, during assembly of filter assembly  600 , stem  152  of filter  602  can be fluidly coupled with second stem  610  of filter port  604  using dip tube line  608 . Container  112  can then be sealed closed. 
     Similar to filter assembly  106 , filter assembly  600  can be positioned before use within first chamber  232  of receptacle  210 , and the top of container  112  can be attached to receptacle  210  using hanging tabs or other hanging elements. Also similar to filter assembly  106 , outlet tube  270  can be connected to outlet port  156  and extended through central opening  228  and out from support housing  108  through access port  260 . 
     During use, inlet tube  272  is coupled with bioreactor  102  ( FIG. 1 ) so that a mixture of cultured solution and associated microcarriers can be introduced into inlet chamber  622 . The cultured solution portion of the mixture passes through filter  602  and into outlet chamber  206 , where the fluid can collect or exit container  112  through outlet port  156  and outlet tube  270 . Filter  602  causes the microcarriers to be retained within inlet chamber  622  to be discarded or recycled for further use. 
     More specifically, the mixture passes through filter port  604  and dip tube line  608  to arrive at filter  602 . The mixture passes through inlet port  606  and is received by inlet chamber  622  through fluid passageway  155 , as depicted in  FIGS. 22A-22C . As shown in  FIG. 22A , as the mixture is first received within inlet chamber  622  as denoted by arrow  640 , inlet chamber  622  is completely or mostly devoid of microcarriers and the cultured fluid can pass through porous sheet  620  through the bottom thereof, as indicated by arrows  642 . Filter  602  can be substantially flat, as there is no weight to push it downward. 
     As shown in  FIG. 22B , as more mixture flows into inlet chamber  622 , the microcarriers  284  within the mixture are retained and begin to accumulate at the bottom of inlet chamber  622 . The weight of the microcarriers  284  can cause filter  602  to elongate and extend further downward. The cultured solution continues to pass through porous sheet  620 . However, the majority of the fluid passes out through the side portions of porous sheet  620  that is above the accumulated microcarriers, as shown by arrows  644 . 
     As shown in  FIG. 22C , as more microcarriers  284  continue to accumulate at the bottom portion of filter  602 , the weight of the microcarriers may cause filter  602  to further elongate and fluid can continue to flow through the upper portion of sheet  620  not covered by microcarriers, as denoted by arrows  646 . If an expandable material is used for porous sheet  620 , the weight of the microcarriers can cause porous sheet  620  to expand further downward. This expansion can increase the surface area of porous sheet  620  which can allow for more cultured solution to flow through the sides of porous sheet  620  and more microcarriers can be retained. 
       FIGS. 23A and 23B  depict another embodiment of a filter  650  based on filter  602  but using an alternative filter sheet configuration. The sheets of filter  650  are depicted as being rectangular. However, as discussed above, this is exemplary only and the sheets can be of any size and shape. Similar to filter  602 , filter  650  also includes flexible sheet  618  and porous sheet  620 . However, filter  650  also includes a picture-frame sheet  652  positioned against exterior surface  634  of porous sheet  620  so as to sandwich the edges of porous sheet  620  between sheets  618  and  652 , as particularly shown in  FIG. 23B . Sheet  652  has an interior surface  656  and an opposing exterior surface  658 . Sheet  652  bounds an opening  660  extending through sheet  652  between interior and exterior surfaces  656  and  658 . Sheet  652  can be comprised of similar materials as sheet  618  and can be used to aid in securing porous sheet  620  to sheet  618 . That is, sheet  652  may be useful if the porous material does not form a secure attachment to sheet  618 . Sheet  652  can provide a better attachment to sheet  618  and the edges of sheet  620  can be better attached due to its being sandwiched between sheets  618  and  652 . 
     In an alternative embodiment, shown in  FIG. 23C , sheet  652  can be omitted and sheet  618  can be sized to be larger than sheet  620 . The portion of perimeter edge  628  of sheet  618  that extends beyond perimeter edge  636  of sheet  620  can be folded over perimeter edge  636  so as to rest against exterior surface  634  of porous sheet  620  and form the picture-frame. 
       FIGS. 24A and 24B  depict another embodiment of a filter  670  based on filter  602  but using another alternative filter sheet configuration. Filter  670  is similar to filter  650 , except that sheet  618  is replaced with a sheet  672  that bounds an opening  674  extending therethrough. To prevent microcarriers from passing through opening  674 , another porous sheet  676  is also included to go along with porous sheet  620 . Sheet  676  is sized similar to opening  674  and is secured to the interior surface of sheet  672 . Porous sheet  676  does not cover hole  630  so that the cultured solution can pass through hole  630  and into inlet chamber  622 , which is now bounded by porous sheet  676  as well as sheets  672  and  620 , as particularly shown in  FIG. 24B . This embodiment provides more surface area for the solution to pass through than filters  602  or  650 , as solution can also pass through porous sheet  676  covering opening  674  on top sheet  672 . As shown in the depicted embodiment, hole  630  can be positioned near the perimeter edge of sheet  672  to allow opening  674  to have a larger surface area, if desired. 
     As with filter  650 , picture frame sheet  652  can alternatively be omitted and sheet  672  can be sized to be larger than sheets  620  and  676 . The portion of the perimeter edge of sheet  672  that extends beyond perimeter edge  636  of sheet  620  can be folded over perimeter edge  636  so as to rest against exterior surface  634  of porous sheet  620  and form the picture-frame in a manner similar to that discussed above with regard to filter  650 . 
     As with filter port  151 , filter port  604  can also be directly attached to receptacle  210  instead of or in conjunction with the hanging tabs and hangers, as discussed above with reference to  FIGS. 9-10B and 17A-17C . It is appreciated that the filter embodiments shown in  FIGS. 20-24B  are exemplary only and that other two-dimensional pillow style bags can also be used. It is also appreciated that instead of using a dip tube line  608  to attach filter port  604  to inlet port  606 , a single port can be used to directly attach top sheet  618  or  672  to body  120  of container  112 . 
       FIG. 11  depicts another embodiment of a filter assembly  320 . Like elements between filter assembly  320  and filter assembly  106  are identified by like reference characters. Filter assembly  320  includes a filter  322  that attaches directly or indirectly to the body  120  of container  112  to divide compartment  126  into an inlet chamber  324  and an outlet chamber  326 . Filter  322  comprises a sheet of a porous material that will allow the cultured solution to pass therethrough but will prevent the microcarriers from passing therethrough. Filter  322  can be comprised of a sheet of the same materials as discussed above with regard to filter  170 . Furthermore, filter  322  can be expandable and/or resilient, if desired. Filter  322  can be attached to or integrally formed with container  112 . 
     In embodiments in which body  120  is comprised of two or more panels, filter  322  can be attached to body  120  by placing filter  322  between the panels so that as the panels are welded together, filter  322  is concurrently welded therebetween. For example, if container  112  is a pillow style bag which is comprised of two overlying panels, filter  322  can be placed between the overlying panels. As the perimeter edges of the panels are welded together to form the bag, filter  322  is concurrently secured to or welded into the weld matrix so that filter  322  bisects the compartment of the pillow bag. This method is particularly useful where filter  322  is comprised of a perforated sheet of a polymeric material but can also be used with netting and other materials. In an alternative method, a perimeter edge of filter  322  can be secured on a face of a first panel by welding, adhesive, or the like. A second panel can then overlay the first panel and the second panel welded to the first panel either over top of or adjacent to filter  322 . In embodiments where container  112  is comprised of three or more panels, portions of filter  322  can be welded between different panels. Likewise, where container  112  comprises an extruded tube and opposing end panels, filter  322  can be welded or otherwise secured between the tube and one of the end panels or can be secured to one of the tube or the end panels and then the tube and end panel secured together. 
     Continuing with  FIG. 11 , filter  322  has an inlet surface  328  and an opposing outlet surface  330  that extend from a first end  332  at top end wall  134  of container  112  to a second end  334  at bottom end wall  136  or sidewall  128  of container  112 . Inlet chamber  324  is bounded by the interior surface  122  of a portion of container  112  and inlet surface  328  of filter  322 , and outlet chamber  326  is bounded by the interior surface  122  of the remaining portion of container  112  and outlet surface  330  of filter  322 . Inlet port  150  is positioned on top end wall  134  so as to fluidly communicate with inlet chamber  324  and outlet port  156  is positioned on bottom end wall  136  so as to fluidly communicate with outlet chamber  326 . As such, fluid passes through filter  322  as it moves between inlet and outlet ports  150  and  156 . 
     Similar to filter assembly  106 , filter assembly  320  also incorporates receptacle  210  into which container  112  is received. As such, similar to filter assembly  106 , filter assembly  320  can also be configured in different shapes, as discussed above and can include hanging tabs and hangers, as discussed above with respect to filter assembly  106 . In this embodiment, however, inlet port  150  would function as filter port  151  with regard to being modified or otherwise connected to receptacle  210  as discussed above with respect to filter port  151 . 
     Filter  322  is typically comprised of a sheet of flexible material but could be comprised of a sheet of rigid or semi-rigid material. As such, filter  322  can be substantially planar or have one or more curves between first and second ends  332  and  334 . Furthermore, filter  322  can be substantially taut or substantially loose. In the depicted embodiment, first end  332  of filter  322  is positioned at about the middle of top end wall  134  and second end  334  is positioned at bottom end wall  136  adjacent sidewall  128 . Other configurations are also possible. For example, first end  332  of filter  322  can be positioned on top end wall  134  nearer sidewall  128 , if desired. Also, first end  332  or second end  334  or both can be positioned on sidewall  128  instead of top and bottom end walls  134  and  136 . Regardless of the positioning of first and second ends  332  and  334  of filter  322 , however, filter  322  is positioned such that inlet port  150  directly fluidly communicates with inlet chamber  324  and outlet port  156  directly fluidly communicates with outlet chamber  326 . 
     Similar to filter assembly  106 , filter assembly  320  can be positioned before use within first chamber  232  of receptacle  210 , and the top of container  112  can be attached to receptacle  210  using hanging tabs or other hanging elements. Also similar to filter assembly  106 , outlet tube  270  can be connected to outlet port  156  and extended through central opening  228  and out from support housing  108  through access port  260 , as shown in  FIG. 11 . 
     During use, inlet tube  272  is coupled with bioreactor  102  ( FIG. 1 ) so that a mixture of cultured solution and associated microcarriers can be introduced into inlet chamber  324  therethrough. The cultured solution portion of the mixture passes through filter  322  and into outlet chamber  326 , where the fluid can collect or exit container  112  through outlet port  156  and outlet tube  270 . Filter  322  causes the microcarriers to be retained within inlet chamber  324  to be discarded or recycled for further used. 
     More specifically, the mixture passes through inlet port  150  and is received by inlet chamber  324  through fluid passageway  155 , as depicted in  FIGS. 12A-12C . As shown in  FIG. 12A , as the mixture is first received within inlet chamber  324 , as denoted by arrow  340 , inlet chamber  324  is completely or mostly devoid of microcarriers and the cultured fluid can pass through filter  322  along its entire length into outlet chamber  326 , as indicated by arrows  342 . The cultured fluid can then pass out of outlet chamber  326  through outlet port  156 , as denoted by arrow  344 . 
     As more mixture flows into inlet chamber  324 , the microcarriers  284  begin to accumulate at the bottom of inlet chamber  324  as the cultured fluid continues to pass through filter  322 , as shown by arrows  346  and  348  in  FIGS. 12B and 12C . As can be seen, because second end  334  of filter  322  extends to and is supported by top end wall  134  of container  112 , fluid can continue to flow through the upper portion of filter  322  not covered by microcarriers, as denoted by arrows  348 , even as more microcarriers may accumulate at the bottom portion of filter  322 . If an expandable material is used for filter  322 , the weight of the microcarriers can cause filter  322  to expand downward and outward, as depicted in  FIGS. 12B and 12C . This expansion increases the surface area of side surfaces  328  and  330  ( FIG. 11 ) of filter  322  which allows for more cultured solution to flow through the sides of filter  322  and more microcarriers to be retained. 
       FIG. 13  depicts another embodiment of a filter assembly  350  incorporating features of the present invention. Again, like elements between different embodiments are identified by like reference characters. Filter assembly  350  includes container  112  and a filter  352  coupled with an outlet port  388  so as to extend upward into compartment  126 . Turning to  FIG. 14 , outlet port  388  is similar to outlet port  156  but has an additional stem  390  extending upward from flange  160  (i.e., in the opposite direction from flange  160  as stem  158 ). Stem  390  is generally collinear with stem  158 , although this is not required. 
     Filter  352  includes a sidewall  356  having an inside surface  358  and an opposing outside surface  360  extending from an open first end  392  to a spaced apart closed second end  394 . Inside surface  358  of sidewall  356  bounds a fluid passageway  362  extending therethrough. The open first end  392  of filter  352  couples with stem  390  so that fluid passageways  162  and  362  fluidly couple with each other and combine to form fluid passageway  364 . Stem  158 ,  390 , and filter  352  can be substantially collinear, although that is not required. Filter  352  can attach to stem  390  by adhesive, welding, threaded connection, press fit, crimping or other known connecting method. In addition, if desired, a channel  396  can be formed on the inside surface  358  at first end  392  of filter  352  to aid in attaching to stem  390 , as in the depicted embodiment. 
     A plurality of openings  366  extend through sidewall  356  of filter  352  that are large enough to allow the cultured solution to flow through, but small enough to prevent the microcarriers from flowing through. The openings  366  can encircle and extend all along filter  352  or any portion thereof. In one embodiment, filter  352  comprises a stem that is substantially rigid so as to prevent filter  352  from collapsing as microcarriers build up around it. For example, filter  352  can be comprised of plastic, metal, composite, glass or the like. Openings  366  can be formed as part of a molding process or can subsequently be drilled or otherwise formed. Other methods for forming openings  366  can also be used. 
     As shown in  FIG. 13 , during assembly, a hole is formed in bottom end wall  136 . Outlet port  156  is seated within the hole so that filter  352  extends upward into compartment  126  and flange  160  rests against bottom end wall  136 . Similar to other outlet ports discussed herein, conventional welding or other sealing technique can then be used to seal flange  160  to bottom end wall  136 . 
     Similar to other embodiments discussed herein, filter  352  divides compartment  126  into two separate chambers—an inlet chamber  368  and an outlet chamber  370 . Fluid passageway  362  corresponds to outlet chamber  370 . Thus, outlet chamber  370  is fluidly coupled with fluid passageway  162  of outlet port  156 . Inlet chamber  368  is the portion of compartment  126  external to outlet chamber  370 . Fluid flows from inlet chamber  368  to outlet chamber  370  through filter  352 , as discussed below. 
     As noted above, when outlet port  156  is attached to container  112 , filter  352  extends upward into compartment  126 . Filter  352  can extend as far upward into compartment  126  as desired. In some embodiments, filter  352  has a length that allows it to contact and, if desired, attach to top end wall  134  of container  112 . Other lengths are also possible. Filter  352  can be attached to outlet port  156  by adhesive, threaded connection or other attachment method. Alternatively, filter  352  can be integrally formed with outlet port  156 . 
     Similar to the filter assemblies discussed above, filter assembly  350  can be positioned before use within first chamber  232  of receptacle  210 , and the top of container  112  can be attached to receptacle  210  using hanging tabs or other hanging elements. Also similar to the filter assemblies discussed above, outlet tube  270  can be connected to outlet port  156  and extended through central opening  228  and out from support housing  108  through access port  260 , as shown in  FIG. 13 . 
     Inlet tube  272  is also attached to inlet port  150  and extends to bioreactor  102  ( FIG. 2 ). During use a mixture of cultured solution and associated microcarriers are introduced into inlet chamber  368  through inlet port  150 . The cultured solution passes through the openings  366  ( FIG. 14 ) in the sidewall  356  of filter  352  and into outlet chamber  370 . The fluid flows down through fluid passageway  162  of outlet port  156  where the fluid can exit container  112  through outlet tube  270 . The microcarriers, which cannot pass through filter  352 , collect at the bottom of container  112 . 
     More specifically, the mixture passes through inlet port  150  and is received by inlet chamber  368  through fluid passageway  155 , as depicted in  FIGS. 15A-15C . As shown in  FIG. 15A , as the mixture is first received within inlet chamber  368 , as denoted by arrow  376 , inlet chamber  368  is completely or mostly devoid of microcarriers and the cultured fluid can pass through filter  352  along its entire length into outlet chamber  370 , as indicated by arrows  378 . The cultured fluid can then pass out of outlet chamber  370  through outlet port  156 , as denoted by arrow  380 . As more mixture flows into inlet chamber  368 , the microcarriers  284  begin to accumulate at the bottom of inlet chamber  368  as the cultured fluid continues to pass through the filter  352 , as shown by arrows  382  and  384  in  FIGS. 15B and 15C . As can be seen, however, as long as filter  352  extends upward beyond the retained microcarriers  284 , fluid can continue to flow through the upper portion of filter  352 , as denoted by arrows  384  even as more microcarriers may accumulate at the bottom portion of filter  352 . That is, because filter  352  extends vertically within container  112 , at least a portion of filter  352  remains openly exposed to receive the cultured solution even when a lower portion of filter  352  may be covered by microcarriers. 
     After use, filter assembly  350  can be discarded with the microcarriers. Alternatively, container  112  can be opened and the microcarriers recycled. 
       FIG. 16  depicts another embodiment of a filter  400  that can be used in place of filter  352  in filter assembly  350 . Similar to filter  352 , filter  400  also attaches to outlet port  156 . However, instead of being substantially vertical, filter  400  is substantially horizontal. To accommodate filter  400 , outlet port  156  includes a stem  402  that extends from a proximal end  403  at flange  160  to a spaced apart distal end  404 . The distal end  404  of stem  402  flairs out radially so as to be wider than at the proximal end  403  and has an opening  405  at distal end  404 . 
     A filtering element  407  is positioned over the opening  405  at the distal end  404  of stem  402 . Filtering element  407  has an outer surface  406  and an opposing inner surface  408  and can be made of any of the filtering materials discussed above. Thus, filtering element  407  permits cultured solution which includes the detached cells to pass through filtering element  407  but prevents microcarriers from passing therethrough. Stem  402  has an interior surface  410  that together with the inner surface  408  of filtering element  407  bounds a compartment  412  that is directly coupled with fluid passageway  162  of outlet port  156 . To accommodate for the weight of the microcarriers that may accumulate on the filtering material, a framework  414  can be positioned within compartment  412  to bolster filtering element  407  and prevent filtering element  407  from collapsing. Framework  414  can be comprised of intermingled struts and walls or can be a thick material through which fluid can pass. Regardless of its composition, framework  414  is configured to allow the cultured fluid to flow therethrough to outlet port  156 . To aid in the flow of the fluid, interior surface  410  can be angled to guide the fluid to the fluid passageway  162 . 
     The present invention 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. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.