Abstract:
The PRP separator-concentrator of this invention is suitable for office use or emergency use for trauma victims. The PRP separator comprises a motorized centrifugal separation assembly, and a concentrator assembly. The centrifugal separator assembly comprises a centrifugal drum separator that includes an erythrocyte capture module and a motor having a drive axis connected to the centrifugal drum separator. The concentrator assembly comprises a water-removal module for preparing PRP concentrate. The centrifugal drum separator has an erythrocyte trap. The water removal module can be a syringe device with water absorbing beads or it can be a pump-hollow fiber cartridge assembly. The hollow fibers are membranes with pores that allow the flow of water through the fiber membrane while excluding flow of clotting factors useful for sealing and adhering tissue and growth factors helpful for healing while avoiding activation of platelets and disruption of any trace erythrocytes present in the PRP.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a divisional of U.S. patent application Ser. No. 11/342,761 filed Jan. 30, 2006, which claims the benefit under 35 USC 120 of the filing dates of Provisional Application No. 60/651,050 filed Feb. 7, 2005, Provisional Application No. 60/654,718 filed Feb. 17, 2005 and Provisional Application No. 60/723,312 filed Oct. 4, 2005. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates to a device and method for preparing platelet-plasma concentrates with improved wound healing properties for use as a tissue sealant and adhesive. The product has a fully active (un-denatured) fibrinogen concentration that is several times greater than is found in blood and a platelet concentration that is many times greater than is found in blood. 
       BACKGROUND OF THE INVENTION 
       [0003]    Blood can be fractionated, and the different fractions of the blood can be used for different medical needs. Under the influence of gravity or centrifugal force, blood spontaneously sediments into three layers. At equilibrium, the top low-density layer is a straw-colored clear fluid called plasma. Plasma is a water solution of salts, metabolites, peptides, and many proteins ranging from small (insulin) to very large (complement components). 
         [0004]    The bottom, high-density layer is a deep red viscous fluid comprising anuclear red blood cells (erythrocytes) specialized for oxygen transport. The red color is imparted by a high concentration of chelated iron or heme that is responsible for the erythrocytes&#39; high specific gravity. The relative volume of whole blood that consists of erythrocytes is called the hematocrit, and in normal human beings this can range from about 37% to about 52% of whole blood. 
         [0005]    The intermediate layer is the smallest, appearing as a thin white band above the erythrocyte layer and below the plasma layer; this is called the buffy coat. The buffy coat itself has two major components, nucleated leukocytes (white blood cells) and anuclear smaller bodies called platelets (or thrombocytes). Leukocytes confer immunity and contribute to debris scavenging. Platelets seal ruptures in blood vessels to stop bleeding, and deliver growth and wound healing factors to a wound site. Slower speed or shorter duration centrifugation permits separation of erythrocytes and leucocytes from plasma, while the smaller platelets remain suspended in the plasma, resulting in PRP. 
         [0006]    A major improvement in making plasma concentrate from whole blood for use in wound healing and as a tissue sealant is described in U.S. Pat. No. 5,585,007; this patent is hereby incorporated by reference in its entirety. This device, designed for placement in a medical laboratory or surgical amphitheatre, used a disposable cartridge for preparing tissue sealant. The device was particularly applicable for stat preparations of autologous tissue sealants. Preparation in the operating room of 5 ml of sealant from 50 ml of patient blood required less than 15 minutes and only one simple operator step. There was no risk of tracking error because processing can be done in the operating room. Chemicals added could be limited to anticoagulant (e.g., citrate) and calcium chloride. The disposable cartridge could fit in the palm of the hand and was hermetically sealed to eliminate possible exposure to patient blood and ensure sterility. Adhesive and tensile strengths of the product were comparable or superior to pooled blood fibrin sealants made with precipitation methods. Use of antifibrinolytic agents (such as aprotinin) was not necessary because the tissue sealant contained high concentrations of natural inhibitors of fibrinolysis from the patient&#39;s blood. This new tissue sealant also optionally contained patient platelets and additional factors that promote wound healing, healing factors that are not present in commercially available fibrin sealants. 
         [0007]    This device used a new sterile disposable cartridge with the separation chambers for each run. Since the device was designed to be used in a normal medical setting with ample power, the permanent components, designed for long-term durability, safety and reliability, were relatively heavy, using conventional centrifuge motors and accessories. 
         [0008]    Small, self-contained centrifugal devices for obtaining platelet concentrates from blood are described in commonly assigned, copending application Ser. No. 10/394,828 filed Mar. 21, 2003, the entire contents of which are hereby incorporated by reference. This device separates blood into erythrocyte, plasma and platelet layers and selectively removes the platelet layer as a platelet concentrate, that is, platelets suspended in plasma. The plasma fraction, being in an unconcentrated form, is not effective as a hemostat or tissue adhesive. 
       SUMMARY OF THE INVENTION 
       [0009]    It is an objective of this invention to provide a compact, self-contained system for producing a concentrate of platelets suspended in concentrated fully active plasma, that is substantially unactivated platelets suspended in plasma concentrated by removing water, leaving the fibrinogen in a fully active form. 
         [0010]    The PRP separator-concentrator of the present invention is suitable for office use or emergency use for trauma victims. 
         [0011]    One embodiment is a disposable self-contained PRP separator and concentrator unit designed for use with a permanent motor assembly. 
         [0012]    Another embodiment is a self-contained disposable PRP separator and concentrator that includes an internal motor and power supply assembly. 
         [0013]    A still further embodiment comprises a motorized centrifugal separation unit for preparing PRP. 
         [0014]    The PRP separator comprises a motorized centrifugal separation assembly for and an optional concentrator assembly for concentrating the PRP. The centrifugal separator assembly comprises a centrifugal drum separator that includes an erythrocyte capture module and a motor with a drive axis connected to the centrifugal drum separator. The concentrator assembly comprises a water-removal system for preparing PRP concentrate. 
         [0015]    The centrifugal drum can have an inner wall surface with an upper edge and a lower edge, a drum bottom, and a central axis; the drum bottom can have a central depression and a floor sloping downward from the lower edge to the center of the central depression. 
         [0016]    In the portable, self-contained embodiment of the PRP separator-concentrator of this invention, the motorized centrifugal separation assembly includes a motor having a drive axis, the drive axis being coaxial with the central axis. The motor can have the capacity to rotate the centrifugal drum at a speed of at least 2,000 rpm for 120 seconds. The battery can be connected to the motor through an on/off switch or timer switch, the battery having the capacity to provide sufficient power to complete the separation process. The portable centrifugal separator can be fully enclosed within an outer container, the outer container having a top with a sterile syringe port aligned with the central depression, and an access tube connected to and extending downward from the syringe port. 
         [0017]    In one embodiment, the erythrocyte capture module is a depth filter lining the inner wall surface of the centrifugal separator unit, the depth filter having pores sized to capture erythrocytes moving into the pores during centrifugal separation of the erythrocytes from blood and to retain the erythrocytes in the depth filter when centrifugal separation is completed. The term “depth filter”, as used herein, is defined as a filter medium that retains contaminants primarily within tortuous passages. It can include an open-cell foam or other matrix made of a material such as a felt that does not significantly activate platelets contacting the surface thereof, whereby erythrocytes moving outward through the plasma during centrifugation move into and are captured by the depth filter leaving behind PRP substantially free from erythrocytes. 
         [0018]    In an alternative embodiment of the invention, the inner wall surface of the centrifugal drum can be sloped outwardly from the bottom at an angle of from 1° to 15° with respect to the central axis. The upper edge of the centrifugal drum can be surrounded by an outer, annular erythrocyte capture chamber, the erythrocyte capture chamber including, an outer wall and an inner wall, the outer wall having an upper edge with an elevation higher than the inner wall. The volume of the erythrocyte capture chamber below the top of the inner wall is sized to retain the total volume of separated erythrocytes in the blood while retaining a minimal volume of the PRP. In this embodiment, erythrocytes moving outward through the plasma during centrifugation are retained against the outer wall of the erythrocyte capture chamber and slide downward to substantially fill the lower volume of the erythrocyte capture chamber when centrifugation is ended. During centrifugation, platelets suspended in the liquid in the erythrocyte capture chamber are carried with the flow of plasma displaced by sedimenting erythrocytes so that they travel to the top and over the inner surface of the erythrocyte capture chamber and into the centrifugal drum. Optionally, at least the upper surface of the inner wall of the erythrocyte capture chamber has a slope forming an angle “a” of at least 25° with respect to the central axis for facilitating flow of platelets against the centrifugal force up and over the upper edge of the erythrocyte capture chamber during centrifugation. As the plasma flows from the erythrocyte capture chamber to the centrifugal chamber, the portal or cross-sectional area through which the plasma flows is reduced by the rising slope of the inner wall surface, causing an increase in the plasma flow velocity over the surface and increasing the portion of platelets successfully transported by the plasma. 
         [0019]    In one embodiment, the concentrator assembly of the PRP separator-concentrator includes a water-removing hollow fiber cartridge, a pump, and tubing connecting with the hollow fiber cartridge and the pump that circulates PRP in the centrifugal drum through the pump and hollow fiber cartridge and then returns it to the centrifugal drum. In the hollow fiber cartridge, the fibers are ultrafiltration membranes with pores that allow the flow of water through the fiber membrane while excluding the passage of growth factors helpful for healing. The pore structure and surfaces are selected to avoid activation of platelets and disruption of any erythrocytes remaining in the PRP. 
         [0020]    In another embodiment, the concentrator assembly includes a plasma concentrating syringe, the syringe having a Luer coupling for connection to the access tube to the center or central depression of the centrifugal drum. In this embodiment, the plasma concentrating syringe comprises a cylindrical barrel with an inner surface and an inlet/outlet port, and a cylindrical actuated piston having an outer surface engaging the inner surface of the barrel. Concentrating beads which can be desiccated hydrogel are positioned between the piston and the inlet/outlet port. A filter is positioned adjacent the inlet/outlet port to prevent escape of the concentrating beads through the inlet/out port. In the operation of the syringe concentrator, movement of the piston in a direction away from the inlet/outlet port draws PRP into the concentrating chamber. Water is removed from the PRP by the concentrating beads, thereby concentrating the PRP without activating the platelets or denaturing the fibrinogen in the plasma. Movement of the piston toward the inlet/outlet port expels concentrated PRP through the inlet/outlet port. 
         [0021]    Because the devices of this invention can be operated with standard batteries as their power source, they consume far less power than prior art centrifuge devices, leading to substantial power saving. 
         [0022]    A further PRP separator and concentrator embodiment of this invention has a central axis comprises a stationary housing and a rotary assembly mounted for rotation about the central axis with respect to the stationary housing. The rotatable assembly comprises a rotatable centrifugal separator and concentrator and a drive motor. A coupling connects the drive motor and the rotatable assembly, the motor and drive coupling being positioned to rotate the rotatable assembly about the central axis. 
         [0023]    The centrifugal separator has an inner separation chamber and an outer erythrocyte capture system. The concentrator comprises a concentration chamber containing desiccated beads. The concentration chamber comprises a floor and a plurality of upright screen supports, the upright screen supports having an inner surface and an outer surface. A cylindrical screen is supported on the outer surface of the upright screen supports. 
         [0024]    An axially concentric stationary tube is secured to the housing and extends through the concentration chamber. A stationary bead rake is secured to the tube and extends radially outward. The rake has a distal edge that is positioned adjacent the inner surface of the upright screen supports, 
         [0025]    With this assemblage, slow rotation of the rotary assembly with respect to the stationary housing pulls the beads past the stationary rake, reducing gel polarization and clumping of the beads. 
         [0026]    Each pair of adjacent upright screen supports can define a desiccating bead receptor for holding desiccated beads radially outward from the distal edge of the rake, whereby bead disruption by the rake during high speed rotational phases is substantially avoided. 
         [0027]    The separator and concentrator can include a motor controller, wherein the drive motor has a high rotational speed required for centrifugal separation and PRP collection phases and a slow rotational speed required for water removal by desiccated beads, the motor controller include a switch for initiating high and low rotational speeds of the rotary assembly. 
         [0028]    The switch initiates high rotational speed of the rotary assembly during centrifugal and PRP concentrate collection phases and initiates low slow rotational speed of the rotary assembly during the PRP concentrate collection phase. 
         [0029]    Another rotatable PRP concentrator of this invention has a stationary housing with a central axis, the concentrator including a drive motor and a coupling connecting the drive motor and the centrifugal separator for rotation about its central axis. The concentrator comprises a concentration chamber containing desiccated beads, the concentration chamber comprising a floor and a plurality of upright screen supports. The upright screen supports have an inner surface and an outer surface. A cylindrical screen is supported on the outer surface of the upright screen supports. An axially concentric stationary tube secured to the housing extends through the concentration chamber. A stationary bead rake is secured to the tube and extends radially outward to adjacent the inner surface of the upright screen supports. 
         [0030]    With this configuration, slow rotation of the rotary assembly with respect to the stationary housing pulls the beads past the stationary rake, reducing gel polarization and clumping of the beads. 
         [0031]    Each pair of adjacent upright screen supports and the screen segments extending therebetween defines a desiccating bead receptor for holding desiccated beads radially outward from the distal edge of the rake, whereby bead disruption by the rake during high speed rotational phases is substantially avoided. 
         [0032]    The separator and concentrator can include a motor controller, wherein the drive motor has a high rotational speed required for the PRP collection phase and a slow rotational speed required for water removal by desiccated beads. The motor controller includes a switch for initiating high and low rotational speeds of the rotary assembly. The switch initiates high rotational speed of the rotary assembly during the PRP concentrate collection phase and initiates low slow rotational speed of the rotary assembly during the PRP concentrate collection phase. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0033]    A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered with the accompanying drawings, wherein: 
           [0034]      FIG. 1  is a schematic cross-sectional drawing of a centrifugal separator of this invention with an annular erythrocyte trap. 
           [0035]      FIG. 2  is a fragmentary cross-sectional drawing of the centrifugal separator and annular erythrocyte trap portion of the centrifugal separator shown in  FIG. 1 . 
           [0036]      FIG. 2A  is a fragmentary cross-sectional drawing of an alternative erythrocyte trap. 
           [0037]      FIG. 2B  is a detailed fragmentary view of a vent system according to this invention that uses a sterile porous sheet to allow air movement into and from the outer container. 
           [0038]      FIG. 2C  is a detailed fragmentary view of a vent system according to this invention that uses a flexible balloon or diaphragm to allow air movement into and from the outer container. 
           [0039]      FIG. 3  is a schematic cross-sectional drawing of the separation separator of  FIG. 1  after being loaded with blood. 
           [0040]      FIG. 4  is a schematic cross-sectional drawing of the separation separator of  FIG. 1  during the spin separation phase. 
           [0041]      FIG. 5  is a schematic cross-sectional drawing of the separation separator of  FIG. 1  after centrifugation has ended. 
           [0042]      FIG. 6  is a cross-sectional drawing of a concentrator syringe. 
           [0043]      FIG. 7  a schematic cross-sectional drawing of the separation separator of  FIG. 1  after PRP has been drawn into a concentrator syringe. 
           [0044]      FIG. 8  shows a concentrator syringe containing PRP after the water removal phase with the PRP concentrate ready for use. 
           [0045]      FIG. 9  is a schematic cross-sectional drawing of a separation separator of this invention with a depth filter erythrocyte trap. 
           [0046]      FIG. 10  is a schematic cross-sectional drawing of the separation separator of  FIG. 9  after being loaded with blood. 
           [0047]      FIG. 11  is a schematic cross-sectional drawing of the separation separator of  FIG. 10  during the spin separation phase. 
           [0048]      FIG. 12  is a schematic cross-sectional drawing of the separation separator of  FIG. 10  after centrifugation has ended. 
           [0049]      FIG. 13  is a schematic cross-sectional drawing of the separation separator of  FIG. 9  after PRP has been drawn into a concentrator syringe. 
           [0050]      FIG. 14  is a schematic representation of a combination centrifugal separator and hollow fiber concentrator of this invention. 
           [0051]      FIG. 15  is a schematic cross-sectional view of a hollow fiber concentrator according to this invention. 
           [0052]      FIG. 16  is a cross-sectional view of the hollow fiber concentrator of  FIG. 15 , taken along the line  16 - 16 . 
           [0053]      FIG. 17  is a schematic cross-sectional view of the membrane valve in the hollow fiber concentrator of  FIG. 15 . 
           [0054]      FIG. 18  is a schematic cross-sectional drawing of an automated spring-clutch system for preparing PRP concentrate from a patient&#39;s blood. 
           [0055]      FIG. 19  is an isometric view of a plasma separator and concentrator embodiment of this invention. 
           [0056]      FIG. 20  is a top view of the plasma separator and concentrator shown in  FIG. 19 . 
           [0057]      FIG. 21  is a cross-sectional view of the plasma separator and concentrator of  FIG. 20 , taken along the line  21 - 21 , exploded along the vertical axis to show the motor drive and drive receptor relationship prior to placing the disposable separator-concentrator assembly on the drive base. 
           [0058]      FIG. 22  is a cross-sectional view of the plasma separator and concentrator of  FIG. 20 , taken along the line  22 - 22 . 
           [0059]      FIG. 23  is a fragmentary cross-sectional view of the separator-concentrator shown in  FIG. 22 . 
           [0060]      FIG. 24  is a cross-sectional drawing of the device of  FIGS. 19-23  after blood has been added. 
           [0061]      FIG. 25  is a cross-sectional drawing of the device of  FIGS. 19-23  during the centrifugal separation stage producing PRP. 
           [0062]      FIG. 26  is a cross-sectional drawing of the device of  FIGS. 19-23  during the slow rotation concentration stage. 
           [0063]      FIG. 27  is a cross-sectional drawing of the device of  FIGS. 19-23  during the centrifugal PRP concentrate separation stage. 
           [0064]      FIG. 28  is a cross-sectional view of a portable embodiment of this invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0065]    This device and method separates plasma-rich plasma from blood and removes water from the plasma-rich plasma without denaturing the fibrinogen or activating the platelets invention. One aspect of the invention is a portable, completely self-contained device that performs this method with a patient&#39;s blood to provide an autologous product that is useful as wound healing tissue sealant and adhesive that promotes and speeds healing. Another aspect of the invention is a portable disposable system that can be used with a permanent motorized unit to provide this method and product. A still further aspect is a portable disposable system for producing PRP from a patient&#39;s blood. 
         [0066]    The devices of this invention are small, portable, self-contained, disposable PRP separation systems. The centrifugal separation modules described with respect to  FIGS. 1-13  are one aspect of this invention. They are directed to disposable PRP separation systems that can be used by a medical assistant or doctor without extensive training to prepare PRP and a PRP concentrate from a patient&#39;s blood within minutes, with a high recovery of platelets and without significant activation of the platelets. The devices are completely automated and require no user intervention between, first, loading and actuating the device and, second, retrieving the PRP. The devices are able to process bloods of different hematocrits and different plasma densities. 
         [0067]    Another more highly automated separator-concentrator of this invention is the combination centrifugal separator and hollow fiber cartridge concentrator shown in  FIG. 14 . This system requires no user intervention between loading the blood and retrieving PRP concentrate. 
         [0068]      FIG. 1  is a schematic cross-sectional drawing of a centrifugal separator of this invention with an annular erythrocyte trap, and  FIG. 2  is a fragmentary cross-sectional drawing of the centrifugal separator and annular erythrocyte trap shown in  FIG. 1 . Referring to  FIGS. 1 and 2 , the separation system comprises a centrifugal separator unit or chamber  2  and a motor  4 . The centrifugal separator unit comprises a centrifugal drum  5  having an inner wall surface  6  with an upper edge  8  and a lower edge  10 , a drum bottom  12 , and a central axis (not shown). The drum bottom  12  has a central depression  14 , the bottom  12  constituting a floor sloping downward from the lower edge  10  to the central depression  14 . The motor  4  has a drive axis  16  that is coaxial with the central axis. The motor  4  has the capacity to rotate the centrifugal drum at a speed of at least 2,000 rpm for 120 seconds. 
         [0069]    The complete, self-contained unit includes a battery  18  connected to the motor  4  through conventional power connections, the battery  18  having sufficient capacity to complete the separation process. The battery  18  is connected to the motor through an on/off time switch  20  with a manual knob  22 . 
         [0070]    An outer container  24  encloses the centrifugal separation unit. The container  24  has a top  26  with a sterile syringe port  28  that can be a Luer fitting aligned with the central depression  14 . An access tube  29  connects to and extends downward from the syringe port  28  into the separation chamber  2 . Tube  29  is used for introducing blood into the separation chamber  2  and for removing PRP from the separation chamber  2  as is explained in greater detail with respect to  FIGS. 2-6  hereinafter. 
         [0071]    The inner wall surface  6  of the centrifugal drum  5  is sloped outwardly from the bottom  12  at an angle of from 75 to 89° from the central axis. The upper edge  8  of the centrifugal drum  5  is surrounded by an outer, annular erythrocyte capture chamber  31 . 
         [0072]    Preferably, the outer container  24  for the system is sealed to maintain sterility. To prevent pressure fluctuations from movement of liquid into and from the system, a vent system  30  is provided in a wall of the outer container that permits movement of air out of the container when liquid is introduced and movement of air into the container when liquid is removed. Details of suitable venting systems are described hereinafter with respect to  FIGS. 2B and 2C . 
         [0073]    Referring to  FIG. 2 , the erythrocyte capture chamber  31  includes an outer wall  32 , and an inner wall  34 , the outer wall  32  having a top edge  36  with an elevation higher than the top  8  of the inner wall  6 . The vertical distance between the top edge and the top of the inner wall is small, preferably less than 1 mm, but large enough to allow passage of cells, preferably greater than 50 microns. The narrow gap between the top of the inner wall and the top of the chamber serves to minimize the sweeping of erythrocytes from the erythrocyte capture chamber into the centrifugal drum by the swirling wave of PRP during deceleration after completion of the centrifugation step. To further minimize sweeping of erythrocytes back into the centrifuge drum during deceleration, the gap above the inner wall can be filled with a depth filter or screen. The volume of the erythrocyte capture chamber  31  is sized to retain the total volume of separated erythrocytes and leukocytes in the blood while retaining a minimal volume of PRP. An annular cap  38  is secured to the top of the centrifugal drum  5  and the erythrocyte capture chamber  31  in a sealing engagement that prevents escape of blood and blood products from the centrifugal chamber during the centrifugal separation step. 
         [0074]    The upper surface portion  42  of the inner wall  34  of the erythrocyte capture chamber  31  can optionally have a slope forming an angle “a” at least 25° with the central axis, facilitating flow of platelets in the PRP flowing inwardly over the upper edge  8  of the erythrocyte capture chamber  31  when the erythrocytes sediment to fill the erythrocyte capture chamber  31 . 
         [0075]      FIG. 1  shows the separation system coupled with a syringe  44  positioned to introduce blood into the separation chamber  2 . The syringe  44  is shown with the plunger or piston  46  in the extended, full position prior to the blood introduction. 
         [0076]      FIG. 2A  is a fragmentary cross-sectional drawing of an alternative erythrocyte trap configuration. In this alternative embodiment, the upper surface portion  42  of the erythrocyte capture chamber  31  shown in  FIG. 2  extends as surface  43  downward to the opposing wall  45 , providing a continuous sloped surface for movement of platelets to the centrifugal chamber  5  during centrifugation. Surface  43  forms the angle “a” with the central axis (not shown) of the erythrocyte capture chamber. 
         [0077]      FIG. 2B  is a detailed fragmentary view of a vent system  30   a  according to this invention that uses a sterile porous sheet to allow air movement into and from the outer container. In this embodiment, an air flow passageway  50  in a wall  52  of the outer container  24  ( FIGS. 1 and 2 ) is sealed with a conventional sterile porous sheet  54 . The sterile porous sheet  54  that has sufficient porosity to allow free movement of air through the sheet, but is an effective microorganism barrier that prevents movement of microorganisms from the outer environment into the container  24 . This prevents significant fluctuations of air pressure in the outer container  24  during liquid movement into and out of the system. 
         [0078]      FIG. 2C  is a detailed fragmentary view of a vent system  30   b  according to this invention that uses a flexible balloon or diaphragm to allow air movement into and out of the outer container  24 . In this embodiment, an air flow passageway  56  in the wall  52  of the outer container  24  ( FIGS. 1 and 2 ) is sealed with a balloon or flexible diaphragm  60 . The balloon or flexible diaphragm  60  should have sufficient flexibility and size to allow free movement of air through the air flow passageway  56  in a volume that can be at least equal to the total volume of blood that is introduced into the system during the separation process. This prevents significant fluctuations of air pressure in the outer container  24  during liquid movement into and out of the system. The balloon or flexible diaphragm  60  must have the integrity to be an effective microorganism barrier preventing movement of microorganisms from the outer environment into the container  24  during PRP removal. 
         [0079]      FIGS. 3-5  show successive stages in the preparation of PRP with the device of  FIG. 1 .  FIG. 3  is a schematic cross-sectional drawing of the centrifugal separator of  FIG. 1  after being loaded with blood  62  from syringe  44 . Syringe  44  is attached through the Luer port  28  and communicates with the access tube  29 , and the plunger  46  has been depressed to expel the blood contents of the syringe into the separation chamber  2 . 
         [0080]      FIG. 4  is a schematic cross-sectional drawing of the centrifugal separator of  FIG. 1  during the spin separation phase. During this phase, the syringe  44  can be removed as shown, to be replaced with a sterile cap or a fresh syringe to remove separated PRP product. Alternatively, the syringe  44  can be left in place during the separation phase (not shown) and reused to remove the PRP product. During the spin phase, the centrifugal force causes the more dense erythrocytes  64  to move outward through the plasma until they collect in the erythrocyte capture chamber, leaving PRP  66  in the centrifugal drum  5 . 
         [0081]      FIG. 5  is a schematic cross-sectional drawing of the centrifugal separator of  FIG. 1  after centrifugation has ended. When centrifugation is complete and the centrifugal forces are no longer present, the dense erythrocyte layer remains isolated in the erythrocyte capture chamber  31 , and the layer of PRP  66  in the centrifugal drum collects at the lowermost section of the centrifugal chamber. The PRP can then be removed through the access tube  29  from the centrifugal drum  5  with the original syringe  44  ( FIG. 3 ) or a fresh syringe positioned as shown in  FIG. 3 . 
         [0082]    If one desires to obtain a PRP concentrate according to this invention, one can use the concentrating syringe shown in  FIG. 6  wherein  FIG. 6  is a cross-sectional schematic view of a syringe embodiment for producing PRP concentrate from PRP. The syringe device  69  includes a process chamber  70  having an outer wall  72 . In the process chamber  70 , a plunger  74  is positioned above filter  76 , the plunger  74  and the filter  76  defining a concentrating portion or chamber  78  of the process chamber  70 . The concentrator chamber  78  contains concentrating desiccated hydrogel beads  80  and one or more agitators  82 . A concentrate chamber  84 , positioned below or downstream of filter  76 , includes an inlet/outlet port  86 . 
         [0083]    The concentrating desiccated hydrogel beads  80  can be insoluble beads or disks that will absorb a substantial volume of water and not introduce any undesirable contaminant into the plasma. They can be dextranomer or acrylamide beads that are commercially available (Debrisan from Pharmacia and BIO-GEL P™ from Bio-Rad Laboratories, respectively). Alternatively, other concentrators can be used, such as SEPHADEX™ moisture or water absorbents (available from Pharmacia), silica gel, zeolites, cross-linked agarose, etc., in the form of insoluble inert beads. 
         [0084]    The agitators  82  can be dense objects such as inert metal spheres. It will be readily apparent to a person skilled in the art that the shape, composition and density of the agitators  82  can vary widely without departing from the invention so long as the agitator has a density substantially greater than whole blood. It is advantageous that the agitator be a metal sphere such as a titanium or stainless steel sphere that will not react with blood components, or a dense sphere coated with an inert coating that will not react with blood components. 
         [0085]    The filter  76  can be any inert mesh or porous materials which will permit the passage of plasma and prevent passage of the hydrogel beads and agitator. The filter can be a metal wire or inert fiber frit of either woven or non-woven composition, or any other frit construction which, when the liquid in the concentration chamber is passed through the filter, will permit passage of the PRP and not the hydrogel beads and agitator, effectively separating the PRP from the hydrogel beads and agitators as will be described in greater detail hereinafter. 
         [0086]    It is important that the water removal procedure be carried out with minimal activation of the platelets and minimal denaturation of the fibrinogen. Prior art commercial procedures for preparing plasma concentrate use precipitation to separate fibrinogen from albumin and reconstitution to prepare the sealant. This deactivates a major portion of the fibrinogen and removes healing factors. As a result proportionally more of the reconstituted precipitate is required to achieve effective tissue sealing. With the device of this invention, denaturing of the fibrinogen is avoided by water removal and the healing factors in the plasma are retained with the fibrinogen during the concentration step, yielding a more effective tissue sealant and adhesive that also promotes healing. 
         [0087]      FIGS. 7 and 8  show the preparation of PRP concentrate using the syringe concentrator shown in  FIG. 6 .  FIG. 7  is a schematic cross-sectional drawing of the centrifugal separator of  FIG. 5  after PRP  66  has been drawn into a concentrator syringe, and  FIG. 8  shows a concentrator syringe containing PRP concentrate  90  after the water removal phase. Moving plunger or piston  74  draws PRP  66  from the centrifugal drum  5  into the syringe chamber. A volume of air is also drawn into the syringe to facilitate expulsion of PRP concentrate after concentration. 
         [0088]    The concentrator syringe is then withdrawn from the centrifugal separator and shaken by a reciprocal movement in the direction of the syringe axis. This movement causes relative agitating movement of the agitator balls  82  in the PRP  66 , stirring the hydrogel beads in the solution, and mixing the PRP to reduce localized concentrations and gel polarization of plasma proteins around the bead surfaces, thereby facilitating movement of water from the PRP into the beads  80 .  FIG. 8  shows the concentrator syringe with the PRP concentrate  90  after the water removal step is completed. Movement of the plunger  74  toward the inlet-outlet port  86  discharges PRP concentrate  90  through the applicator needle  92 , the filter  76  preventing movement of the hydrated beads  94  and agitator  82  with the PRP concentrate. Concentrated PRP retained within the interstitial space between beads is purged by air as the plunger is depressed further. 
         [0089]      FIG. 9  is a schematic cross-sectional drawing of a centrifugal separator of this invention with a depth filter erythrocyte trap. This embodiment also comprises a centrifugal separator unit  102  and a motor  104 . The centrifugal separator unit comprises a centrifugal drum  106  having an inner wall surface  108  with a bottom edge  110 , a drum bottom  112 , and a central axis (not shown). The drum bottom  112  has a central depression  114 , the bottom  112  constituting a floor sloping downward from the lower edge  110  to the central depression  114 . The motor  104  has a drive axis  116  coaxial with the central axis. The motor  104  has the capacity to rotate the centrifugal drum  102  at a speed of at least 2,000 rpm for 120 seconds with a total power consumption of less than 500 mAh, the power that is obtainable from a small battery such as a conventional 9 volt alkaline battery. 
         [0090]    The complete, self-contained unit includes a battery  118  connected to the motor  104  through conventional power connections. The battery  118  has the capacity to provide sufficient power to complete the separation process and being connected to the motor through an on/off toggle or timer switch  120  with a manual knob  122 . 
         [0091]    An outer container  124  encloses the centrifugal separation unit. The container  124  has a top  126  with a sterile syringe port  128  aligned with the central depression  114 , an access tube  130  connected to and extending downward from the syringe port  128  for introducing blood into the separation chamber  132  and for removing PRP from the separation chamber  132  as is explained in greater detail with respect to  FIGS. 10-13  hereinafter. 
         [0092]    The inner wall  108  of the centrifugal separator unit  102  is the surface of a depth filter  134  having pores sized to capture erythrocytes moving into the pores during centrifugal separation of the erythrocytes from blood and to retain the erythrocytes in the material of the depth filter when centrifugal separation is completed, the material of the depth filter being selected from a material that does not significantly activate platelets contacting the surface thereof. 
         [0093]    The depth filter  134  can be a honeycomb-like or woven fiber material that allows fluids and small particles to flow freely (e.g., felt or open cell polyurethane foam). Like a wetted sponge, the depth filter holds liquid against a certain head of pressure due to surface tension forces. Thus, blood cells or other suspended particulates remain entrapped within the foam when the centrifuge stops and separated platelet-rich plasma drains from the surface under the force of gravity. Foam can be either rigid or flexible and can be formed into the appropriate annular shape for the device by molding or die-cutting. The parts are sized so that the packed cell (e.g., erythrocyte and leukocyte) layer is fully contained within the outer depth filter chamber, which retains the cells when the centrifuge stops. 
         [0094]    With this device, erythrocytes moving outward through the plasma during centrifugation pass into and are captured by the depth filter  134 , and the PRP flowing downward when centrifugation is ended is substantially free from erythrocytes as is described hereinafter in greater detail with respect to  FIGS. 10-13 . 
         [0095]    Similar to the vent system provided in the system shown in  FIGS. 1 and 2 , a vent system  136  can be provided in the outer container  124 . This vent system can be the same as described hereinabove with respect to  FIGS. 2B and 2C . 
         [0096]      FIG. 10  is a schematic cross-sectional drawing of the centrifugal separator of  FIG. 9  after being loaded with blood  138  from syringe  140 , the syringe connecting through the sterile seal  128  and into the vertical tube  130 , and the plunger  142  having been depressed to expel the blood contents of the syringe into the separation chamber  132 . 
         [0097]      FIG. 11  is a schematic cross-sectional drawing of the centrifugal separator of  FIG. 10  during the spin separation phase. During this phase, the syringe  140  can be removed as shown to be replaced with a sterile cap or fresh syringe to remove the separated PRP product. Alternatively, the syringe  140  can be left in place (not shown) during the separation phase and used to remove the PRP product. During the spin phase, the centrifugal force causes the more dense erythrocytes to move outward through the plasma into the depth filter  134 , leaving PRP  148  substantially free from erythrocytes in the centrifugal drum  102 . 
         [0098]      FIG. 12  is a schematic cross-sectional drawing of the centrifugal separator of  FIG. 11  after centrifugation has ended. When centrifugation is complete and the centrifugal forces are no longer present, the erythrocyte-free PRP product  148  flows downward in the separator chamber  132 , the erythrocytes remaining trapped in the depth filter  134 . The PRP  148  that collects in the centrifugal drum  102  is substantially free from erythrocytes and leukocytes. The PRP  148  can then be removed from the centrifugal drum  102  with the original syringe  140  ( FIG. 10 ) or a fresh syringe as will be readily apparent to a person skilled in the art. 
         [0099]      FIG. 13  is a schematic cross-sectional drawing of the centrifugal separator of  FIG. 12  after PRP  148  has been drawn into a concentrator syringe  69 . Withdrawing the plunger or piston  74  draws PRP  148  from the centrifugal chamber  132  into the syringe barrel  150 . 
         [0100]    The water is removed from the PRP  148  to produce a PRP concentrate and expelled from the syringe as is described hereinabove with respect to  FIGS. 7 and 8 . 
         [0101]      FIG. 14  is a schematic representation of a combination centrifugal separator and hollow fiber concentrator of this invention. The entire separation and concentration components are enclosed in a housing  160 . The top of the housing has a sterile vent  162  to allow passage of air displaced during addition and removal of fluid from the device and a Luer fitting  164  to which a standard syringe  166  with a piston  168  and piston actuator  170  can be coupled. 
         [0102]    A centrifugal separator  172  can have the annular erythrocyte trapping system shown and described hereinabove with respect to  FIGS. 1-5  or it can have the depth filter erythrocyte trapping system shown and described hereinabove with respect to  FIGS. 9-13 . 
         [0103]    A drive motor  174  is positioned in the bottom section of the housing  160  below the centrifugal separator  172  in the basic configurations shown in  FIGS. 1 and 9 . 
         [0104]    Positioning the hollow fiber concentrator system  176  above the centrifugal separator  172  simplifies the liquid transfer components of the concentrator, although it will be readily apparent to a person skilled in the art that alternative configurations such as side-by-side placement or placing the centrifuge above the concentrator are also suitable, provided adequate space is provided to house the fluid transfer tubing. 
         [0105]    The concentrator system comprises a hollow fiber cartridge  178  and a pump  180 . 
         [0106]    A central tube  182  having outlet  184  extends from the Luer fitting  164  toward the depression  186  at the bottom of the centrifugal separator  172 . A inlet flow check valve  188  limiting liquid flow toward the centrifugal separator is placed in the central tube  182  at an intermediate level 
         [0107]    The tube outlet  184  is positioned to circulate PRP, preferably stopping short of the bottom  186 . 
         [0108]    A return tube  190  extends from the bottom depression  186  to a pump inlet check valve  192  communicating with the inlet of pump  180 . Check valve  192  directs liquid movement in the direction toward the pump, thus preventing backflow into line  190 . A second return tube, but also referred to as a line or conduit,  194  extends from pump outlet check valve  196  communicating with the outlet of pump  180 . Check valve  196  directs liquid movement in the direction leading away from the pump, thus preventing backflow from line  194  to the pump. Second return tube  194  extends to the inlet manifold  198  of the hollow fiber cartridge concentrator  178 . A third return tube  200  extends from the outlet manifold  202  of the hollow fiber cartridge  178  to a concentrator outlet check valve  204  leading to the central tube  182  at a position above (or upstream of) check valve  188 . Tube  200  is sized to restrict the flow of fluid, generating a backpressure upstream in the fluid circulation path to drive filtration through the hollow fiber membranes. Check valve  204  prevents backflow of liquid from the tube  182  to the hollow fiber cartridge  178 . 
         [0109]    The hollow fiber cartridge includes fiber membranes that efficiently remove water and salts from the plasma while leaving larger healing factors. Choice of the fiber materials and pore distributions is a critical factor because rapid water removal without significant platelet damage must be achieved. The large concentration of protein present in plasma presents another difficulty since it thickens along the membrane surface due to localized concentration and gel polarization. Therefore, the fiber membranes and their configuration must facilitate sweeping of the membrane surface by passing plasma, disrupting the polarization and redistributing the plasma constituents. Furthermore, because a preferred embodiment of this device is intended to be self-contained and highly portable, it is preferred that the hollow fiber cartridge provide its ultrafiltration function with minimal energy consumption so that complete separation and concentration can be achieved with a standard small (e.g., 9 volt transistor) battery. 
         [0110]    The pump  180  can be a conventional piston or diaphragm pump that provides the necessary circulation of plasma through the hollow fiber concentrator system  176  without use of excessive energy. Preferably, the pump  180  should have the capacity to complete concentration of the plasma with a power consumption of less than 500 mAh, that is, the power available from a small battery such as a standard 9 volt alkaline battery. 
         [0111]    Power to the motor  174  and pump  180  is provided by conventional wiring and a small battery (not shown) that has the capacity to provide sufficient power to complete the concentration process. A small (e.g., standard 9 V transistor radio) battery is acceptable. Alternatively, if the unit is to be used in a location with standard auxiliary power, a conventional power supply system using standard business and residential power can be used. 
         [0112]    The system shown in  FIG. 14  operates as follows: Blood is provided to separator Luer fitting by a blood-filled syringe, using syringe such as syringe  166 . Downward movement of the actuator  170  moves the piston  168  in a downward direction, expelling the contents of the syringe through the Luer fitting  164  and the tubing  182  through the inlet check valve  188  into the bottom of the centrifugal separator  172 . After its contents have been expelled, the syringe can be left in place or replaced with a fresh syringe or sealing cap to prevent fluid from escaping through the Luer port  164  during the concentrating step of the process. 
         [0113]    Operation of the centrifugal separator  172  removes erythrocytes and leukocytes from the blood, leaving PRP in the bottom of the centrifuge chamber after centrifugation is stopped. 
         [0114]    Operation of the pump  180  draws PRP from the lower depression  186  of the centrifugal separator upward through tube  190 , through the pump inlet check valve  192  into the pumping chamber (not shown) of the pump  180 . Then PRP flows through pump  180  and through pump outlet check valve  196 . From check valve  196 , the PRP passes through the tubing  194  into the inlet manifold  198  of the hollow fiber concentrator  178  and through the hollow fiber concentrator. 
         [0115]    PRP from which a portion of the water and salts have been removed then flows from the outlet manifold  202  of the hollow fiber concentrator  178  through flow restrictive tubing  200  and concentrator outlet check valve  204  to the inlet tubing  182 , and then through check valve  188  to the bottom of the centrifugal separator  172  where it mixes with the other PRP. This cycling process is continued, removing a portion of the water in each pass, until the desired concentration of PRP has been obtained. 
         [0116]    With the device of this invention PRP erythrocyte removal and concentration of the PRP to a platelet concentration of 3× can be automatically achieved within 5 minutes. If higher PRP concentration is needed for a particular application such as for sealing tissues to stop bleeding, the concentration cycle can be continued beyond 5 minutes, whereby concentration up to 5× and higher can be achieved. 
         [0117]      FIG. 15  is a schematic cross-sectional view of a hollow fiber concentrator shown in  FIG. 14 , and  FIG. 16  is a cross-sectional view of the hollow fiber concentrator of  FIG. 15 , taken along the line  16 - 16 . 
         [0118]    Referring to  FIG. 15 , the hollow fiber concentrator  178  is combined with an extracted liquid reservoir  206 . The concentrator  178  has an outer housing  208  that encloses the inlet manifold  198 , an outlet manifold  202 , a plurality of hollow ultrafiltration fibers  210  and an extracted liquid chamber  212 . Each of the hollow fibers  210  has a wall  214 , an axial passageway  216 , an inlet end  218  and an outlet end  220 . The inlet end  218  of each hollow fiber  210  is secured to a correspondingly sized hole in the inlet manifold plate  222  in a conventional manner that establishes communication between the hollow fiber passageway  216  and the inlet manifold  198  while preventing escape of the liquid contents thereof into the extracted liquid chamber  212 . The outlet end  220  of each hollow fiber  210  is secured to a correspondingly sized hole in the outlet manifold plate  226  in a conventional manner that establishes communication between the hollow fiber passageway  216  and the outlet manifold  202  while preventing escape of the liquid contents thereof into the extracted liquid chamber  212 . 
         [0119]    Referring to  FIGS. 15 and 16 , the extracted liquid chamber  212  is the space defined by the inner wall surface  213  of the housing  208 , the outer wall surface of the hollow fibers  210 , and the manifold plates  222  and  226 . The extracted liquid chamber  212  captures the liquid that passes through the hollow fibers  210  in the ultrafiltration process. 
         [0120]    The outlet end of conduit  194  shown in  FIG. 14  connects with the inlet manifold  232  through manifold inlet conduit  230 . The inlet end of conduit  200  shown in  FIG. 14  connects with the outlet manifold  202  through manifold outlet conduit  228 . 
         [0121]    During the water removal process, pressurized plasma passes from conduit  194  through the inlet manifold inlet conduit  230  into the inlet manifold  198 , and then through the hollow fibers  210 . In each pass a portion of the water and salts passes through the pores in the fiber walls into the extracted liquid chamber  212 . The concentrated plasma then passes into the outlet manifold  202 , through the outlet manifold outlet conduit  228  and then to the conduit  200 . 
         [0122]    The extracted liquid reservoir  206  has a reservoir housing  234  that connects with an overflow conduit  236 . The overflow reservoir  206  has an air vent  238 . 
         [0123]      FIG. 17  is a schematic cross-sectional view of the membrane valve air vent  238  in the hollow fiber concentrator of  FIG. 15 . The valve  238  comprises a porous lower hydrophilic membrane  240  communicating with the interior of the extracted liquid reservoir  206  and a porous upper hydrophobic membrane  242  that communicates with outer space surrounding the reservoir. The extracted liquid reservoir captures extracted liquid when the volume of the extracted liquid exceeds the volume of the extracted liquid chamber  213  and the excess liquid escapes through the extracted liquid conduit  236  into the extracted liquid chamber  206 . Air in the extracted liquid chamber displaced by the incoming liquid escapes through the porous membranes  240  and  242  until the liquid level reaches the membranes, saturating the hydrophilic membrane  140 . Escape of the extracted liquid from the extracted liquid chamber  206  is prevented by the hydrophobic membrane  242 . 
         [0124]    The valve prevents movement of air into the system when PRP concentrate is removed as follows. Movement of PRP concentrate from the centrifugal separator  172  ( FIG. 14 ) creates a partial vacuum in the system. Movement of air through the valve  238  in response to this partial vacuum is prevented by the liquid saturated hydrophilic membrane  240 . 
         [0125]      FIG. 18  is a schematic cross-sectional drawing of an automated spring-clutch system for preparing PRP concentrate from a patient&#39;s blood. Like other embodiments of this invention, the disposable, single-use system is enclosed in a compact portable device that can be smaller than a twelve ounce soft drink can. 
         [0126]    Referring to  FIG. 18 , the outer housing  252  is sealed except for the blood inlet port  254 , the PRP concentrate withdrawal port  256 , and sterile vent  258 . The PRP withdrawal port  256  is one end of a rigid PRP concentrate withdrawal tube  260  that is secured to the outer housing  252  and functions as a central axle around which the rotary separation components turn and also as a PRP concentrate withdrawal tube. The separation components comprise a upper rotary centrifugal separator housing  262  and a lower rotary water removal system housing  264 , these two housing being connected by an integral cylindrical waist element  266  into a unitary housing structure. The water removal system housing  264  includes a PRP concentrate reservoir  268  that communicates with the lower opening  270  of the PRP concentrate withdrawal tube  260 . 
         [0127]    The rotary components are supported on the drive axle  272  of the two direction, two speed motor  274 . The direction and speed of the motor  274  are controlled by the conventional motor controller  276  to which it is connected by electrical conduit  278 . Switch  280  activates the motor controller  276 . 
         [0128]    The relative position of the rotary components in the outer housing  252  is maintained by a roller bearing raceway structure. This structure that includes a plurality of roller bearings  282  positioned between an outer ring flange  284  secured to the outer housing  252  and an inner ring flange  286  secured to the upper rotary centrifugal separator housing  262 . 
         [0129]    The centrifugal blood separating components housed in the upper housing  262  of the rotary assemblage is similar in structure and function to other blood separators described hereinabove with respect to  FIGS. 9-13  in that the cylindrical rotary centrifugal separator  290  has the inner surface of its outer wall lined with a cylindrical depth filter  294 . A blood overflow reservoir  296 , defined by a floor  298  and an integral wall  300 , can function to control or limit the volume of blood that is subject to the separating operation. The overflow reservoir  296  can assist if the volume introduced exceeds the volume that can be effectively concentrated in the water removal operation, described in greater detail hereinafter. When the centrifugal separator spins during the separation phase, excess blood flows upwardly along the wall  300  and into the reservoir  296 . When the separation phase ends and the rotary speed slows, the wall  300  prevents escape of liquid as it settles on the floor  298 . 
         [0130]    Suitable depth filter materials have been described hereinabove with respect to  FIGS. 9-13 . Alternatively, the depth filter structure  294  and overflow reservoir structure  296  can be replaced with an erythrocyte trap and function such as is described with respect to  FIGS. 1-8  hereinabove in a manner that would be readily apparent to a person skilled in the art. 
         [0131]    During the centrifugal separation stage, erythrocytes separating from the plasma flow into the depth filter  294 , leaving a layer of PRP behind outside the depth filter. 
         [0132]    When the centrifugal separation is completed and centrifugal separation is ended, the PRP flows to the bottom of the centrifugal separator where it is held by the seal of the valve plate  302  against the floor  304  of the separation housing. 
         [0133]    The seal of the valve plate  302  against the floor  304  is opened by action of a spring clutch assembly. The valve plate  302  is a part of a valve assembly including a hollow upper valve stem  306  (a cylinder) integral with the plate  302  through which the rigid tube  260  extends. This stabilizes orientation of the valve assembly on the rigid tube  260 . The lower part of the valve assembly is outer cylinder  308  with internal threads  310 . 
         [0134]    The outer cylinder  308  further encloses an inner cylinder  312  that has external threads  314  engaging the internal threads  310  of the outer cylinder  308  in sliding engagement. The spring clutch  288  wraps around the rigid tube  260  and is positioned between the inner cylinder  312  to which it is secured and the rigid tube  260 . The spring clutch  288  functions as a slip bearing between the rotating internal threaded element  312  and the rigid tube  260  during the centrifugal separation phase because the direction of the movement of the spring around the rigid tube  260  tends to open the spring, reducing then sliding friction. 
         [0135]    After the centrifugal separation of the PRP is completed, the motor  274  is then activated to turn slowly in a reverse direction. The spring-clutch  288  rotates around the rigid tube  260  in a direction that tightens the spring, locking the spring to the rigid tube  260 . As the outer cylinder  308  turns around the locked stationary inner cylinder  312 , the outer cylinder  308  rises, lifting unseating the valve plate  306 , the movement continuing until the top surface  316  of the upper valve stem  306  abuts the collar  318  secured to the rigid tube  260 . 
         [0136]    When the valve plate  302  unseats, the PRP in the bottom of the centrifugal separator  290  flows downward through a channel  320  defined by the outer surface  322  of the lower cylinder and the inner surface  324  of the waist cylinder  266  into the lower rotary water removal system enclosed in the lower housing  264  where it contacts the desiccated gel beads  326 . Direct flow of liquid from the water removal system is prevented by O-ring seal  327 . 
         [0137]    The lower rotary water removal system  328  enclosed in lower housing  264  comprises a rotary cylindrical screen element  330  which has radially inwardly extending comb elements  332  and a rake system. The bottom of the lower housing  264  has a central opening with a downwardly extending cylindrical flange  333  to accommodate the rigid tube  260 . O-ring  327  is positioned between flange  333  and the rigid tube  260  to prevent liquid flow therebetween. The rake system comprises a rake cylinder  334  having radially outward extending rake elements  336  that mesh with the comb elements  332 . The rake cylinder  334  is separated from the rigid tube  260  by roller bearings  338  that reduce friction between the rake cylinder  334  and the tube  260  during the high speed rotation of the centrifugation step. The rake cylinder has a projecting spline  340  that engages a matching vertical recess grove (now shown) in the lower valve stem outer cylinder  308 . The spline  340  is positioned to move up and down in the matching grove to maintain engagement of the rake cylinder  334  and the lower valve stem outer cylinder  308  at all elevations of the valve stem. The spline system locks the rake cylinder  334  to the stationary tube  260  when the spring clutch engages, preventing rotation of the rake cylinder when the comb elements are rotated through the rakes. 
         [0138]    As water is removed from the PRP by the desiccated beads  326 , gel polarization occurs, slowing water absorption into the beads. To reverse this effect, the beads are slowly stirred during the dewatering process from slow rotation of the cylindrical screen and rake elements by the motor  274 . The relative movement of the rake  336  through the gel beads  326  and through the spaces of the comb  320  stirs the beads and breaks up bead clumps, increasing efficiency of the water removal process. This process is obtained as follows. 
         [0139]    When water removal is completed, the motor controller  276  can reverse rotational direction of the drive shaft  272 , causing disengagement of the spring clutch  288  from the rigid tube  260 , and permitting the separation assembly elements to rapidly spin as a unit. During this spin, the concentrated PRP is spun from the beads  270  through the cylindrical screen  330  where it is collected in the PRP concentrate reservoir  268 . PRP concentrate is then drawn from the PRP concentrate reservoir  268  though the rigid tube  260  and out through the PRP concentrate withdrawal port  256 . 
         [0140]      FIG. 19  is an isometric view of a plasma separator and concentrator embodiment of this invention; and  FIG. 20  is a top view of the plasma separator and concentrator shown in  FIG. 19 . This embodiment comprises a disposable separator/concentrator module  350  and a permanent base  352  with the motor and control system. The separator/concentrator module  350  has a housing  354  and a housing top  356 . The housing top  356  has a blood inlet port  358  and a plasma concentrate outlet port  360 . The base  352  has a base housing  362  with a control switch  364  and an external power connector  366  ( FIG. 20 ). This compact unit separates platelet rich plasma (PRP) from blood and removes water from the PRP to form an autologous platelet rich plasma concentrate from a patients blood within minutes. 
         [0141]      FIG. 21  is a cross-sectional view of the plasma separator and concentrator of  FIG. 20 , taken along the line  21 - 21 , separated along the vertical axis to show the motor drive and drive receptor relationship prior to placing the disposable separator-concentrator assembly on the drive base. The drive base  368  comprises a base housing  370  supported on a plurality of base feet  372 . The housing has a rotary assembly guide surface  374  that is shaped to match the shape of the base receptor  376  of the separator and concentrator assembly  350 . It has an annular support surface  380  that together with the top support surface  382  supports and aligns the separator and concentrator assembly  350  on the base  368 . In the base  368 , a motor  384  is mounted on a support plate  386  that is held in position by a plurality of support fixtures  388 . The motor  384  has a drive connector  390  that securely mates with the rotary assembly drive receptor  392 . The base has a conventional power connector  366  and a conventional motor control switch  364  that are electrically connected to the motor with conductors in a conventional manner (not shown). The motor control switch  364  includes a conventional timer that controls the motor speed at different phases of the separation and concentration process as is described in greater detail hereinafter. 
         [0142]    The rotary unit comprises the housing  354  with the housing top  356  supporting the PRP concentrate outlet port  360 . The housing  354  includes a base  394  with a base receptor  376  that is shaped and sized to mate with the top support surface  374  and assembly guide to support and align the separator and concentrator assembly  350  on the base  374 . Axially concentric bearing assembly  396  is positioned to support the separator and concentrator assembly  350  in position to permit mating of the drive connector  390  and the drive receptor  392 . The drive connector  390  and drive receptor  392  have matching shapes that require the two units to turn a single unit. They can have any cross-sectional shape that prevents the drive connector  390  from turning inside the drive receptor  392  such as the rectangular shape shown. It can also have any other polygonal or oval shape that provides this result. Circular cross-sections are also acceptable if they are keyed in a conventional manner fully within the skill of the art, and all functionally equivalent shapes are intended to be within the scope of this invention. 
         [0143]    The separation and concentration assembly  378  rotates about the vertical axes established by the stationary fixed tube  398 . Tube  398  also constitutes a PRP concentrate conduit. This communicates with the PRP concentrate outlet  360 . Tube  398  is rigidly secured against rotation about its central axis by its connection with the top  356  of the outer housing  354 . The lower end  398  of the tube  398  includes a PRP concentrate inlet  400  and a rake hub  402  that is rigidly connected to the tube so that it remains stationary when the rotary components are in motion as will be described in greater detail hereinafter. 
         [0144]    The separation and concentration assembly  378  includes a rotary housing  378 , the tapered bottom  404  of which includes the drive receptor  392 . The separation and concentration assembly  378  has a top plate  406  with a sterile vent  408  that is supported in its position on the tube  398  by sleeve bearing  410 . 
         [0145]    The desiccated gel beads used to removed water from the PRP are omitted from  FIGS. 21-23  to present more clearly the other components of the concentrating assembly. They are shown in  FIGS. 24-27 . 
         [0146]    The separation and concentration assembly  378  has an outer wall  412  that isolates the blood components during the separation and concentrating process. The upper portion of the housing  378  encloses a centrifugal plasma separator that comprises a cylindrical blood reservoir  416  with an outwardly tapering inner surface  418  and an inner wall  420  that surrounds the tube  398  and is configured to permit free rotation of the inner wall  420  around the tube  398 . This combination maintains axial orientation of the blood reservoir during centrifugal motion of the separation process. Surrounding the blood reservoir  416  is a cylindrical depth filter  424  above which is positioned an annular blood overflow reservoir  426 , details and functions of which are described in greater detail hereinbelow with respect to  FIG. 23 . 
         [0147]    A concentrator assembly  428  is positioned below the blood reservoir  416  and depth filter  424 . The concentration assembly comprises a concentrating basket  429  formed by an axially concentric rotary screen  430  and a concentrator base  432 . The screen has a cylindrical cross-section and is supported by a circular array of vertical supports  434 . Surrounding the screen  430  is a concentric PRP concentrate reservoir comprising a vertical side wall  438  and the tapered bottom  404 . The center of the tapered bottom  404  is positioned adjacent the inlet opening  400  of the tube  398 . 
         [0148]      FIG. 22  is a cross-sectional view of the plasma separator and concentrator of  FIG. 20 , taken along the line  22 - 22  and should be considered together with  FIGS. 21 and 23  to form a complete understanding of the structure of the invention. The view provided by this figure shows, in addition to features described above with respect to  FIG. 21 , a cross-sectional view of the blood inlet  358  supported by the housing top  356  and the rake elements  440  mounted on the rake hub  402 . 
         [0149]      FIG. 23  is a fragmentary cross-sectional view of the separator-concentrator shown in  FIG. 22 . A top plate  442  is secured to the top of the outer wall  412  to confine the blood to the separator during the centrifugal separation. The top plate  442  supports a blood distribution tube  444  that is positioned below and in alignment with the blood inlet port  358  at the first stage when blood is introduced into the separator. 
         [0150]    The annular blood overflow chamber  426  has a top plate  446  with a blood flow inlet opening  448  adjacent the top plate  442  and a second vent opening  450  that is radially inward from the blood inlet opening. This allows overflowing blood to enter the chamber during the centrifugal separation phase through the first inlet opening  448  and allows escape of air displaced by the blood through the second vent opening  450 . 
         [0151]    The tapered outer wall  418  of the blood reservoir has a tip edge  449 . 
         [0152]    A PRP flow passageway  451  leads from the outer separation chamber  453  to the concentrator basket  429 . 
         [0153]    The rakes  440  have a terminal tip edge  452  that are positioned adjacent the inner surfaces  454  of the upright screen supports  434  so they closely sweep the surfaces  454  during their rotation. The upright screen supports  434  have a thickness and openings  456  into which gel beads collect during the fast centrifuge phase, placing them beyond the tip edge of the rakes. 
         [0154]    The screen  430  has a mesh size that is sufficiently small to prevent escape of the gel beads from the chamber concentration chamber during the final centrifugal separation of the PRP concentrate from the gel beads. 
         [0155]      FIGS. 24-27  illustrate the device of  FIGS. 19-23  during the phases of the blood separation and concentration.  FIG. 24  is a cross-sectional drawing of the device of  FIGS. 19-23  after blood has been added,  FIG. 25  is a cross-sectional drawing of the device during the centrifugal separation stage producing PRP,  FIG. 26  is a cross-sectional drawing of the device during the slow rotation concentration stage, and  FIG. 27  is a cross-sectional drawing of the device of during the centrifugal PRP concentrate separation stage. 
         [0156]    The blood separation and concentration with the device of this invention proceeds as follows: 
         [0157]    Referring to  FIG. 24 , a quantity of blood  458  that approximates the volume that can be concentrated (dewatered) by the gel beads is introduced into the blood reservoir  416  through the inlet opening  442  and distribution tube  444 . The blood  458  can be introduced through the needle of the original sample syringe or another device. The blood is shown after is has settled in the bottom of the blood reservoir  416 . 
         [0158]    In  FIG. 25 , the motor  384  is energized to rotate the separator and concentrator assembly  378  at a fast spin rate that effects centrifugal separation of the more dense erythrocytes in the blood from the PRP. The central tube  360  and attached rake  440  remain stationary during this rapid rotation, and the gel beads  460  are spun by the rotary components and held by the centrifugal force against the screen  430 , beyond the reach of the tips  452  of the stationary rake tips  440 . The centrifugal force causes the blood  458  to flow up the tapered inside wall  418  of the blood reservoir  416  and over the tip edge  449 , to collect against the depth filter  424  as shown in  FIG. 25 . The separation is achieved as a function of cell density, sending the most dense erythrocytes outward and through the passageways of the depth filter  424 . The platelets remain in the PRP layer  462  that forms against the depth filter  424 . 
         [0159]    After separation of the cells is complete, the rotation of the separator and concentrator assembly  378  is slowed. PRP flow passageways  451  lead from the outer separator chamber  453  to the concentrator basket  429 . The PRP  462  flows from the pores and surface of the depth filter  424  downward through the PRP flow passageway  451  into the concentrating basket  429 . Erythrocytes remain trapped in the pores and passageways of the depth filter  424  so that the PRP  463  reaching the basket  429  is substantially free of erythrocytes. 
         [0160]    As shown in  FIG. 26 , the PRP  463  flows into contact with the desiccated gel beads  460  that have collected on the base  432  of the concentrating basket  429 . As the beads absorb water from the PRP, they swell, and the PRP immediately adjacent the bead surface thickens and becomes tacky. The continuing slow movement of the concentration basket  429  past the stationary rake  440  and the vertical supports  434  stirs the beads  460 , reducing gel polarization on the bead surface, and breaking up the bead clumps. This slow stirring movement of the rotary components is continued until the water removal stage is completed. 
         [0161]    The motor speed is then increased to a fast spin mode, and the centrifugal force moves the gel beads  460  to the surface of the screen  430 . The centrifugal force generated by the spin caused the PRP concentrate  464  to flow away from the surfaces of the beads and through the screen  430  to collect the PRP concentrate in the PRP reservoir as shown in  FIG. 27 . The PRP concentrate is removed with a syringe through tube  398  and PRP outlet port  360 . 
         [0162]      FIG. 28  is a cross-sectional view of a portable embodiment of this invention. This embodiment includes a blood separation and concentration system in the upper housing  354  that is identical to the blood separation and concentration system described with respect to  FIGS. 19-23 . Because these components are identical and to avoid unnecessary redundancy, no separate description of the identical components is provided herein, the description of these elements with respect to  FIGS. 19-27  being incorporated by reference. For details about the blood separation and concentration systems, see the description of the components provided hereinabove with respect to  FIGS. 19-23 . 
         [0163]    The system shown in  FIGS. 19-23  comprises a disposable blood separation and concentration unit and a permanent motor control unit. This assembly is optimum of use in a laboratory or surgical setting found in a hospital or medical clinic. 
         [0164]    For applications where a permanent motor and control system powered from conventional power sources is not practical, a portable fully integrated embodiment of this invention is provided. The major difference between the embodiment shown in  FIG. 24  is the integration of the motor, power supply and control system in a unitary system with the blood separation and concentration system. The lower casing or housing  470  encloses the motor  472 , power supply  474  and control system  476 . The motor  472  is secured to a motor support plate  478  mounted on the motor support suspension  480 . The motor support suspension  480  is secured the lower surface  482  of the base  484  in a position to maintain axial alignment of the motor with the axis of the rotary elements of the separator and concentrator unit. The motor drive shaft is secured to the separator and concentrator assembly by a coupling  485 . The motor  472  is connected to the battery power supply  474  and control system  476  with conventional electrical circuitry (not shown). The battery power supply is electrically connected to the control system  476  with conventional electrical connections  486 . A conventional removable plate  487  can be removably secured to the lower portion of the lower housing  489  in a position that permits insertion of the power supply battery  474  when it is removed. This allows insertion of an active battery immediately before deployment or use of the system. 
         [0165]    The control system  476  is a conventional motor controller and timer that establishes and controls the motor speeds during the rapid rotation centrifugation phases of the blood separation and during the concentration stages, and during the slow rotation concentration stage. These stages are the same as are described hereinabove with respect to  FIGS. 24-27 . 
         [0166]    The weight and size of the separator and concentrator elements are selected to conserve energy and to be fully operational with a standard 9 volt battery. This enables the device to be a completely portable system that does not require external power. It is thus suitable for use in mobile field units and field hospitals where self-powered, fully portable units are needed. 
         [0167]    The operation of the embodiment shown in  FIG. 28  is the same as is described above with respect to  FIGS. 24-27 .