Abstract:
A plasma concentrator for producing plasma concentrate from a plasma from which erythrocytes have been substantially removed. The device comprises a concentrating chamber having an inlet port and an concentrate outlet, the concentrating chamber containing hydrogel beads and at least one inert agitator; and a concentrate chamber having an inlet communicating with the concentrator outlet through a filter, and having an plasma concentrate outlet port. A process for producing plasma concentrate from plasma from which erythrocytes have been substantially removed, comprising the steps of a) moving the plasma into a concentrating chamber containing hydrogel beads and an agitator to form a hydrogel bead-plasma mixture; b) causing the agitator to stir the hydrogel bead-plasma mixture, facilitating absorption of water by the beads from the plasma, until a hydrogel bead-plasma concentrate is formed; and c) separating the plasma concentrate from the hydrogel beads by passing the plasma concentrate through a filter. The concentrator can be one or more syringe devices coupled for multiple concentrations.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention concerns devices and methods for making concentrated plasma. The present invention concerns apparatus and methods for separation and concentration of plasma and plasma platelet mixtures from plasma and is particularly applicable to the preparation and use of autologous plasma concentrates.  
           [0002]    Rapid fractionation of blood into erythrocyte, plasma or plasma-platelet fractions is desirable for the preparation of autologous concentrates from blood obtained from a patient during surgery. Each fraction can be modified or returned to the blood donor. Useful plasma fractions, with our without platelets, have value as sealants when concentrated without precipitation of fibrinogen, that is, when concentrated by removal of water therefrom in accordance with this invention. This invention has particular value for rapidly preparing autologous concentrated plasma fractions to help or speed healing, or as a hemostatic agent or tissue sealant.  
         BACKGROUND OF THE INVENTION  
         [0003]    Blood may be fractionated and the different fractions of the blood used for different medical needs. For instance, anemia (low erythrocyte levels) may be treated with infusions of erythrocytes. Thrombocytopenia (low thrombocyte (platelet) levels) may be treated with infusions of platelet concentrate.  
           [0004]    Under the influence of gravity or centrifugal force, blood spontaneously sediments into 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). Plasma per se has limited use in medicine but may be further fractionated to yield proteins used, for instance, to treat hemophilia (factor VIII) or as a hemostatic agent (fibrinogen).  
           [0005]    Following sedimentation, 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 high specific gravity. Packed erythrocytes, matched for blood type, are useful for treatment of anemia caused by, e.g., bleeding. The relative volume of whole blood that consists of erythrocytes is called the hematocrit, and in normal human beings can range from about 38% to about 54%.  
           [0006]    Depending upon the time and speed of the centrifugation, an intermediate layer can be formed which is the smallest, appearing as a thin white band on top the erythrocyte layer and below the plasma; it is called the buffy coat. The buffy coat itself generally has two major components, nucleated leukocytes (white blood cells) and anuclear smaller bodies called platelets (thrombocytes). Leukocytes confer immunity and contribute to debris scavenging. Platelets seal ruptures in the blood vessels to stop bleeding and deliver growth and wound healing factors to the wound site. If the centrifugation is of short duration, the platelets can remain suspended in the plasma layer.  
           [0007]    The sedimentation of the various blood cells and plasma is based on the different specific gravity of the cells and the viscosity of the medium. This may be accelerated by centrifugation according approximately to the Svedberg equation:  
             V =((2/9)ω 2   R ( d   cells   −d   plasma ) r   2 )/η t    
           [0008]    where  
           [0009]    V=sedimentation velocity,  
           [0010]    ω=angular velocity of rotation,  
           [0011]    R=radial distance of the blood cells to the center of the rotor,  
           [0012]    d=specific gravity,  
           [0013]    r=radius of the blood cells, and  
           [0014]    η t =viscosity of the medium at a temperature of t° C.  
           [0015]    Characteristics of blood components are shown in Table A.  
                                                     TABLE A                           Diameter   Specific gravity               Component   (μm)   (g/ml)   Deformability   Adhesion                                Red cells   5.4   1.100   +++   −       Granulocytes   9.6   1.085   +   ++       Lymphocytes   7.6   1.070   ±   ±       Monocytes   11.2   1.063   ±   +       Platelets   3.2   1.058   ±   +++       Plasma   NA   1.026   NA   NA       Additive   NA   1.007   NA   NA       solution                  
 
           [0016]    When sedimented to equilibrium, the component with the highest specific gravity (density) eventually sediments to the bottom, and the lightest rises to the top. But the rate at which the components sediment is governed roughly by the Svedberg equation; the sedimentation rate is proportional to the square of the size of the component. In other words, at first larger components such as white cells sediment much faster than smaller components such as platelets; but eventually the layering of components is dominated by density.  
           [0017]    Soft Spin Centrifugation  
           [0018]    When whole blood is centrifuged at a low speed (up to 1,000 g) for a short time (two to four minutes), white cells sediment faster than red cells and both sediment much faster than platelets (per Svedberg equation above). At higher speeds the same distribution is obtained in a shorter time. This produces layers of blood components that are not cleanly separated and consist of (1) plasma containing the majority of the suspended platelets and a minor amount of white cells and red cells, and (2) below that a thick layer of red cells mixed with the majority of the white cells and some platelets. The method of harvesting platelet-rich plasma (PRP) from whole blood is based on this principle. The term “platelet-rich” is used for this component because most of the platelets in the whole blood are in the plasma following slow centrifugation so the concentration of platelets in the plasma has increased.  
           [0019]    Centrifugal sedimentation that takes the fractionation only as far as separation into packed erythrocytes and PRP is called a “soft spin”. “Soft spin” is used herein to describe centrifugation conditions under which erythrocytes are sedimented but platelets remain in suspension. “Hard spin” is used herein to describe centrifugation conditions under which erythrocytes sediment and platelets sediment in a layer immediately above the layer of erythrocytes.  
           [0020]    Two Spin Platelet Separation  
           [0021]    Following a soft spin, the PRP can removed to a separate container from the erythrocyte layer, and in a second centrifugation step, the PRP may be fractioned into platelet-poor plasma (PPP) and platelet concentrate (PC). In the second spin the platelets are usually centrifuged to a pellet to be re-suspended later in a small amount of plasma or other additive solution.  
           [0022]    In the most common method for PRP preparation, the centrifugation of whole blood for 2 to 4 min at 1,000 g to 2,500 g results in PRP containing the majority of the platelets. After the centrifugation of a unit (450 ml) of whole blood in a 3-bag system the PRP is transferred to an empty satellite bag and next given a hard spin to sediment the platelets and yield substantially cell-free plasma. This is termed “two-spin” platelet separation.  
           [0023]    To recover the platelets following two-spin separation, most of the platelet poor plasma (PPP) is removed except for about 50 ml and the pellet of platelets is loosened and mixed with this supernatant. Optionally one can remove about all plasma and reconstitute with additive solution. To allow aggregated platelets to recover the mixture is given a rest of one to two hours before platelets are again re-suspended and then stored on an agitator.  
           [0024]    It is believed that two-spin centrifugation can damage the platelets by sedimenting the platelets against a solid, non-physiological surface. The packing onto such a surface induces partial activation and may cause physiological damage, producing “distressed” platelets which partially disintegrate upon resuspension.  
           [0025]    Hard Spin Centrifugation  
           [0026]    If the centrifugation is continued at a low speed, the white cells will sediment on top of the red cells whereas the platelets will remain suspended in the plasma. Only after extended low speed centrifugation will the platelets also sediment on top of the red cells.  
           [0027]    Experiments with a blood processor have shown that centrifugation at a high speed (2,000 g-3,000 g) produces a similar pattern of cell separation in a shorter time. Initially the cells separate according to size, i.e., white cells sediment faster than red cells and platelets remain in the plasma. Soon the red cells get ‘packed’ on each other squeezing out plasma and white cells. Because of their lower density, white cells and platelets are pushed upwards to the interface of red cells and plasma whereas the platelets in the upper plasma layer will sediment on top of this interface, provided the centrifugal force is sufficiently high and sedimentation time is sufficiently long. Plasma, platelets, white cells and red cells will finally be layered according to their density. Platelets sedimented atop a layer of red cells are less activated than those isolated by the “two spin” technique.  
           [0028]    Leukoreduction  
           [0029]    The PC&#39;s resulting from both two spin processing and apheresis methods contain donor leukocytes. The white cells negatively affect platelet storage and may induce adverse effects after transfusion due to cytokine formation. Removal of leukocytes (leukoreduction) from PRP and PC is important because non-self leukocytes (allogeneic leukocytes) and the cytokines they produce can cause a violent reaction by the recipient&#39;s leukocytes. In 1999 the FDA Blood Product Advisory Committee recommended routine leukoreduction of all non-leukocytes components in the US (Holme 2000). Therefore, much of the prior art focuses on leukoreduction of platelet concentrates because non-autologous leukocytes excite deleterious immune reactions. Since the process of this invention provides a convenient way to quickly harvest autologous platelets from the patient&#39;s blood, immune reactions are not a risk, and the presence of leukocytes is of little or no concern.  
           [0030]    Plasma concentrates and their utility in hemostasis and wound healing have been described in U.S. Pat. No. 5,585,007. Plasma concentrates can be made in a two-step method, first separating of plasma from the majority of erythrocytes and then concentrating the plasma by removing water. The plasma can be separated from the erythrocytes by centrifugation. The water can be removed from the plasma using a semipermeable membrane or by contact with a desiccated hydrogel bead. The membrane and hydrogel bead pores allow passage of water, salts and other low molecular weight components while blocking passage of cells, platelets (thrombocytes), cell fragments and larger molecules such as fibrinogen. The passage of water and low molecular weight components through the membrane or into the bead concentrates the plasma and the cells and high molecular weight components contained therein. The dry hydrogel beads can be dextranomer or polyacrylamide.  
           [0031]    Recent publications report that platelet preparations enhance the healing rate of hard and soft tissue defects. Activated cytokine proteins, released from activated platelets, signal the migration, proliferation and activation of monocyte cells. Monocyte cells sense a gradient of cytokines and migrate towards the source.  
           [0032]    Fibers of polymerized fibrin form pathways by which monocyte cells translocate into the wound. Translocation is enhanced by tension on these fibers imparted by the action of platelet microtubules during clot retraction. Therefore, in situ polymerization of platelet-containing fibrinogen solutions provides an enhanced setting for wound healing. Plasma concentrates containing platelets provide enhanced signals and pathways for wound healing cell migration.  
           [0033]    Platelets have a limited half-time in vivo, and platelet activity declines rapidly ex vivo. An optimal wound-healing compound therefore would contain freshly isolated platelets. To minimize risk of disease transmission and maximize beneficial patient response to platelet activity the platelet/plasma concentrate would preferably be prepared from the patient&#39;s own blood, i.e. autologously. The amount of blood withdrawn from the patient should be as small as possible to minimize morbidity caused by blood loss.  
           [0034]    The present invention provides methods and apparatus for rapidly contacting patient plasma with dry hydrogel beads, concentrating said plasma and separating the resulting plasma concentrate from the beads for application to patient wounds.  
         SUMMARY OF THE INVENTION  
         [0035]    This invention includes a plasma concentrator for producing plasma concentrate from plasma from which platelets and erythrocytes have been substantially removed and for producing concentrate from platelet-rich plasma. The plasma concentrator can comprise a concentrating chamber having an inlet port and a concentrate outlet port, the concentrating chamber containing hydrogel beads and at least one inert agitator. The plasma concentrator also has a concentrate chamber having an inlet communicating with the concentrator outlet through a filter, and having a plasma concentrate outlet port. The agitator can be a dense object such as a smooth ball which can be stainless steel or other dense material with an inert surface which will not impair the blood proteins. The filter can be a porous frit.  
           [0036]    One embodiment of this plasma concentrator comprises a syringe device, the syringe device including a syringe barrel with a proximal concentrating zone and a distal concentrate zone with an inlet/outlet port. A filter separates the concentrating zone from the concentrate zone, and a plunger is positioned for axial movement in the concentrating zone. Hydrogel beads and at least one agitator are positioned in the concentrating zone between the plunger and the filter. The agitator can be a dense object such as a smooth ball which can be stainless steel or other dense material with an inert surface which will not impair the blood proteins. The filter can be a porous frit. The syringe barrel has an inner wall surface, and the plunger can be a piston forming a sealing engagement with said inner wall surface.  
           [0037]    Another embodiment of the plasma concentrator of this invention comprises first and second syringe devices. Each syringe device includes a syringe barrel with a proximal concentrating zone and a distal concentrate zone with an inlet/outlet port, and a filter separating the plunger zone from the concentrate zone. A plunger is positioned for axial movement in the proximal portion of the concentrating zone, and hydrogel beads and at least one agitator are positioned in the concentrating zone between the plunger and the filter. The inlet/outlet port of the first syringe communicates with the inlet/outlet port of the second syringe. The inlet/outlet ports can have a coupling for a plasma transfer syringe, and optionally, they can communicate through a check valve.  
           [0038]    A process of this invention for producing plasma concentrate from plasma from which erythrocytes have been substantially removed, comprises (a) moving the plasma into a concentrating chamber containing hydrogel beads and an agitator to form a hydrogel bead-plasma mixture; (b) causing the agitator to stir the hydrogel bead-plasma mixture, facilitating absorption of water by the beads from the plasma, until a hydrogel bead-plasma concentrate is formed, and (c) separating the plasma concentrate from the hydrogel beads by passing the plasma concentrate through a filter. The hydrogel beads can have the effective absorption capacity to remove at least 10 percent of the water from the plasma, at least 25 percent of the water from the plasma or at least 50 percent of the water from the plasma.  
           [0039]    In a modification of this process for producing greater concentration of the plasma, the plasma concentrate from step (c) is further processed by the steps of (d) moving the plasma concentrate into a second concentrating chamber containing hydrogel beads and an agitator to form a hydrogel bead-plasma mixture; (e) causing the agitator to stir the hydrogel bead-plasma concentrate mixture, facilitating further absorption of water by the beads from the plasma concentrate, until a more concentrated hydrogel bead-plasma concentrate is formed; and (f) separating the more concentrated plasma concentrate from the hydrogel beads by passing the more concentrated plasma concentrate through a filter.  
           [0040]    In a process of this invention for producing plasma concentrate with a plasma concentrator using a syringe device, the syringe device includes a syringe barrel with a proximal concentrating zone and a distal concentrate zone having an inlet/outlet port. A filter separates the plunger zone from the concentrate zone, and a plunger is positioned for axial movement in the proximal portion of the concentrating zone. Hydrogel beads and at least one agitator are positioned in the concentrating zone between the plunger and the filter. The process comprises drawing plasma, from which erythrocytes have been substantially removed, through the inlet/outlet port and the filter, by axial movement of the plunger in the proximal direction away from the filter. Then (b) the syringe is moved in alternative distal and proximal directions along the central axis to stir the hydrogel bead-plasma mixture, facilitating absorption of water by the beads from the plasma, until a hydrogel bead-plasma concentrate is formed. Then (c) plasma concentrate is separated from the hydrogel beads by moving the plasma concentrate through the filter and into the concentrate chamber. In step (c) the plasma concentrate can be moved through the filter and into the concentrate chamber by moving the plunger in the distal direction toward the filter. Alternatively, the plasma concentrate can be forced through the inlet/outlet port by moving the plunger in the distal direction toward the filter. The hydrogel beads can have the effective absorption capacity to remove at least 10 percent of the water from the plasma, at least 25 percent of the water from the plasma, or at least 50 percent of the water from the plasma.  
           [0041]    A process of this invention for producing plasma concentrate from whole blood comprising the steps of (a) removing erythrocytes from whole blood to form a plasma which is substantially free from erythrocytes; (b) moving the plasma into a concentrating chamber containing hydrogel beads and an agitator to form a hydrogel bead-plasma mixture; (c) causing the agitator to stir the hydrogel bead-plasma mixture, facilitating absorption of water by the beads from the plasma, until a hydrogel bead-plasma concentrate is formed; and (d) separating the plasma concentrate from the hydrogel beads by passing the plasma concentrate through the filter.  
           [0042]    In a process of this invention for producing plasma concentrate from whole blood using a syringe device, the syringe device can include a syringe barrel with a proximal concentrating zone and a distal concentrate zone having an inlet/outlet port. A filter separates the plunger zone from the concentrate zone; a plunger is positioned for axial movement in the proximal portion of the concentrating zone; and hydrogel beads and at least one agitator positioned in the concentrating zone between the plunger and the filter. The process comprises (a) removing erythrocytes from whole blood to form a plasma which is substantially free from erythrocytes; (b) drawing plasma from which erythrocytes have been substantially removed through the inlet/outlet port and the filter, by axial movement of the plunger in the proximal direction away from the filter; (c) moving the syringe in alternative distal and proximal directions along the central axis to stir the hydrogel bead-plasma mixture, facilitating absorption of water by the beads from the plasma, until a hydrogel bead-plasma concentrate is formed; and (d) separating plasma concentrate from hydrogel beads by moving the plasma concentrate through the filter and into the concentrate chamber. In step (c) the plasma concentrate is moved through the filter and into the concentrate chamber by moving the plunger in the distal direction toward the filter. The plasma concentrate can be forced through the inlet/outlet port by moving the plunger in the distal direction toward the filter. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0043]    [0043]FIG. 1 is a cross-sectional schematic view of the apparatus of this invention for producing plasma concentrate from plasma.  
         [0044]    [0044]FIG. 2 is a cross-sectional schematic view of a syringe embodiment of this invention for producing plasma concentrate from plasma.  
         [0045]    [0045]FIG. 3 is a cross-sectional schematic view of the syringe embodiment of FIG. 2 coupled with a plasma syringe filled with plasma.  
         [0046]    [0046]FIG. 4 is a cross-sectional schematic view of the syringe embodiment of FIG. 2 after plasma has been transferred to its concentrating chamber from the plasma syringe.  
         [0047]    [0047]FIG. 5 is a cross-sectional schematic view of the syringe embodiment of FIG. 2 after plasma concentrate has been transferred to a plasma concentrate syringe.  
         [0048]    [0048]FIG. 6 is a cross-sectional schematic view of a two stage check valve syringe embodiment of this invention for producing plasma concentrate from plasma.  
         [0049]    [0049]FIG. 7 is a cross-sectional schematic view of the two stage check valve syringe embodiment of FIG. 6 after plasma has been transferred from the plasma syringe to the concentrating chamber of a first concentrator syringe.  
         [0050]    [0050]FIG. 8 is a cross-sectional schematic view of the two stage check valve syringe embodiment of FIG. 6 after transfer of first stage plasma concentrate from the first concentrator syringe to the concentrating chamber of a second concentrator syringe.  
         [0051]    [0051]FIG. 9 is a cross-sectional schematic view of the two stage check valve syringe embodiment of FIG. 6 after transfer of second stage plasma concentrate from the second concentrator syringe to the plasma concentrate syringe.  
         [0052]    [0052]FIG. 10 is a cross-sectional schematic view of a two stage open channel syringe embodiment of this invention for producing plasma concentrate from plasma.  
         [0053]    [0053]FIG. 11 is a cross-sectional schematic view of the two stage open channel syringe embodiment of FIG. 10 after plasma has been transferred from the plasma syringe to the concentrating chamber of a first concentrator syringe.  
         [0054]    [0054]FIG. 12 is a cross-sectional schematic view of the two stage open channel syringe embodiment of FIG. 10 after transfer of first stage plasma concentrate from the first concentrator syringe to the concentrating chamber of a second concentrator syringe.  
         [0055]    [0055]FIG. 13 is a cross-sectional schematic view of the two stage open channel syringe embodiment of FIG. 10 after transfer of second stage plasma concentrate from the second concentrator syringe to the plasma concentrate syringe.  
         [0056]    [0056]FIG. 14 is a cross-sectional schematic view of a two stage open channel integral syringe embodiment of this invention for producing plasma concentrate from plasma before the concentrator syringes are coupled to a plasma transfer syringe.  
         [0057]    [0057]FIG. 15 is a cross-sectional schematic view of a two stage open channel integral syringe embodiment of FIG. 14 after coupling of the plasma transfer syringe and transfer of plasma to a first concentrating chamber.  
         [0058]    [0058]FIG. 16 is a cross-sectional schematic view of a two stage open channel integral syringe embodiment of FIG. 14 after transfer of first stage plasma concentrate to the concentration chamber of a second concentrating chamber.  
         [0059]    [0059]FIG. 17 is a cross-sectional schematic view of a two stage open channel integral syringe embodiment of FIG. 14 after transfer of plasma concentrate from the second concentrating chamber to the plasma concentrate syringe.  
         [0060]    [0060]FIG. 18 is a cross-sectional schematic view of a two stage open channel integral syringe embodiment of FIG. 14 after decoupling of the plasma concentrate syringe, carrying plasma concentrate, from the integral syringe concentrator.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0061]    The term “plasma” as used in this application includes plasma containing a substantial concentration of platelets and plasma that does not contain a significant concentration of platelets.  
         [0062]    The apparatus and methods of this invention offer inexpensive streamlined systems for rapidly preparing plasma concentrates. The entire concentration process can be accomplished in less than ten minutes. The product can be cell-free plasma concentrate, or if desired, plasma concentrates containing platelets.  
         [0063]    [0063]FIG. 1 is a cross-sectional schematic view of the apparatus of this invention for producing plasma concentrate from plasma.  
         [0064]    The concentrator comprises a concentrator vessel  2  having a concentrating chamber  4  and a concentrate chamber  6  separated from the concentration chamber  4  by a porous filter  8 . Desiccated beads  10  and one or more agitators  12  are positioned in the concentrating chamber  4 . A plasma inlet port  14  and an air vent port  16  communicate with concentrating chamber  4 . Concentrate extraction tube  18  having an extraction port  20  extends into the concentrate chamber  4  and communicates therewith.  
         [0065]    The device shown in FIG. 1 can be used to concentrate plasma by removing water from the plasma without precipitating fibrinogen. The plasma can be free of cells, or it can contain platelets. The method for concentrating plasma from which erythrocytes and plasma have been removed, without precipitating fibrinogen, comprises introducing plasma through port  14  into the concentrating chamber  4  where it contacts hydrogel beads  10  and an agitator  12 , to form a plasma-hydrogel bead mixture. The plasma-hydrogel bead mixture is agitated by shaking the mixture in a reciprocal motion along the central axis (not shown) of the vessel  2 , thereby repeatedly passing the agitator through the plasma-hydrogel mixture. Water is removed from the plasma by the hydrogel beads  10 . The vessel  2  is then centrifuged to pass the plasma concentrate through the filter  8  and into the concentrate chamber  6 . The liquid plasma concentrate is then drawn up the tube  18 , for example with a syringe (not shown) attached to extraction port  20  to remove it from the concentrate chamber  6 .  
         [0066]    The desiccant hydrogel beads  10  are insoluble beads or disks which will absorb a substantial volume of water and do not introduce any undesirable contaminant into the plasma. They can be dextranomer or acrylamide beads which 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 absorbants (available from Pharmacia), silica gel, zeolites, cross-linked agarose, etc., in the form of insoluble inert beads or discs.  
         [0067]    The agitator  12  is a dense object which can be an inert metal sphere. It will be readily apparent to a person skilled in the art that the shape, composition and density of the agitator  12  can vary widely without departing from the invention so long as the agitator has a density substantially greater than hydrated hydrogel beads. It is advantageous that the agitator be a metal sphere such as a titanium or stainless steel sphere which will not react with blood components, or a dense sphere coated with an inert coating such as TEFLON which will not react with blood components.  
         [0068]    The filter  8  can be any inert mesh or porous materials which will permit the passage of plasma and exclude 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 plasma and not the hydrogel beads and agitator, effectively separating the plasma from the hydrogel beads and agitator as will be described in greater detail with respect to the embodiments of FIGS. 2, 6,  10 , and  14  hereinafter.  
         [0069]    [0069]FIG. 2 is a cross-sectional schematic view of a syringe embodiment of this invention for producing plasma concentrate from plasma. The syringe device  30  includes a process chamber  32  having an outer wall  34 . In the process chamber  32 , a plunger  36  is positioned above filter  38 , the plunger and the filter  38  defining a concentrating chamber  40 . The plunger has an actuator  42 . The concentrator chamber  40  contains desiccated hydrogel beads  44  and an agitator  46 . A concentrate chamber  48 , positioned below or downstream of filter  38 , includes an inlet/outlet port  50 .  
         [0070]    As with the embodiments described hereinabove, the desiccated hydrogel beads  44 , actuator  42  and filter  38  can be the same as is described with respect to the device of FIG. 1. The hydrogel beads  44  can be insoluble beads or disks which will absorb a substantial volume of water and not introduce any undesirable contaminant into the plasma. They can be dextranomer or acrylamide beads which 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 absorbants (available from Pharmacia), silica gel, zeolites, cross-linked agarose, etc., in the form of insoluble inert beads or discs.  
         [0071]    The agitator  46  can be a dense object which can be an inert metal sphere. It will be readily apparent to a person skilled in the art that the shape, composition and density of the agitator  46  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 which will not react with blood components, or an dense sphere coated with an inert coating which will not react with blood components.  
         [0072]    The filter  38  can be any inert mesh or porous materials which will permit the passage of plasma and exclude 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 plasma and not the hydrogel beads and agitator, effectively separating the plasma from the hydrogel beads and agitator as will be described in greater detail hereinafter.  
         [0073]    [0073]FIG. 3 is a cross-sectional schematic view of the syringe embodiment of FIG. 2 after it has been coupled with a plasma syringe  52  filled with plasma  54 . The inlet/outlet port  50  of the syringe of FIG. 2 communicates through coupling  56  with the inlet/outlet port  58  of the plasma transport syringe  52 . Movement of plunger  60  toward the inlet/outlet port  58  displaces the plasma  54  through the coupling and inlet/outlet port  50  and through the filter  38  into contact with the desiccated hydrogel beads  44  to the position shown in FIG. 4. Alternatively, the plunger  36  can be moved away from the filter  38 , drawing plasma  54  from the syringe  52  into the concentration chamber  32 .  
         [0074]    Reciprocal motion of the syringes along their vertical axis moves the agitator  46  through the plasma-hydrogel mixture, stirring the mixture to minimize gel polarization and facilitating transfer of water from the plasma into the hydrogel beads  44 .  
         [0075]    [0075]FIG. 4 is a cross-sectional schematic view of the syringe embodiment of FIG. 2 after the plasma transferred to its concentrating chamber  40  from the plasma syringe  52  has been concentrated by removal of water from the plasma. The resulting plasma concentrate  62  and hydrated hydrogel beads  64  form a mixture in the concentration chamber.  
         [0076]    [0076]FIG. 5 is a cross-sectional schematic view of the syringe embodiment of FIG. 2 after plasma concentrate  62  has been transferred to the plasma syringe  54  from the concentrate or chamber  40  by movement of the plunger  36  toward the filter  38  or movement of the plunger  60  in a direction away from the inlet/outlet port  58 . The plasma syringe  52  now carrying the plasma concentrate is removed from the coupling  56  and taken to the physician for use. Alternatively, a clean plasma concentrate syringe (not shown) can be used for removal of the plasma concentrate.  
         [0077]    [0077]FIG. 6 is a cross-sectional schematic view of a two stage check valve syringe embodiment of this invention for producing plasma concentrate from plasma, the concentrator syringes being coupled to a plasma transfer syringe filled with plasma. This apparatus and the alternative embodiments shown in FIGS. 10 and 14 provide a two stage concentration device which, by successive concentrations, can reach a higher concentration of plasma than can be easily obtained with the single stage systems shown in FIGS. 1 and 2. For some applications, greater strength and adhesive values provided by the double concentrated plasma is desired, although a single stage concentrated product is satisfactory for most purposes. Single stage concentration can provide up to a 2.5 times (2.5×) concentration while a two stage concentration process can provide up to a 5 times (5×) concentration.  
         [0078]    The apparatus of FIG. 6 comprises first stage syringe  80  and second stage syringe  82 , each syringe having the same components and structure as the syringe  30  of FIG. 2. The inlet/outlet port  84  of the first stage syringe  80  communicates with a tee coupling  88 , one conduit of which communicates with one-way check valve  90  and the other conduit of which communicates with one-way check valve  92 . The inlet/outlet port  86  of the second stage syringe  82  communicates with a tee coupling  94 , one conduit of which communicates with one-way check valve  90  and the other conduit of which communicates with one-way check valve  96 . The check valve  92  communicates with one leg  98  of tee coupling  100 , and check valve  96  communicates with a second leg  102  of tee coupling  100 . The third leg  104  of tee coupling  100  is a coupling junction for the inlet/outlet port  106  of plasma transfer syringe  108 .  
         [0079]    Check valve  90  permits one-way liquid flow from tee  88  to tee  94  and prevents flow in the reverse direction from tee  94  to tee  88 . Check valve  92  permits one-way liquid flow from tee  100  to tee  88  and prevents flow in the reverse direction from tee  88  to tee  100 . Check valve  96  permits one-way liquid flow from tee  94  to tee  100  and prevents flow in the reverse direction from tee  100  to tee  94 . The function of the check valves in directing liquid flow will become clearer in the description of the process shown in FIGS. 6-9.  
         [0080]    [0080]FIG. 7 is a cross-sectional schematic view of the two stage check valve syringe embodiment of FIG. 6 after plasma has been transferred from the plasma syringe  108  to the concentrating chamber of a first concentrator syringe  80 , and water has been absorbed by the hydrogel beads yielding a mixture of hydrated beads  118  and first stage plasma concentrate  120 .  
         [0081]    Referring to FIG. 6 and FIG. 7, the plasma transfer syringe  108  is filled with plasma  110 . Movement of the plunger  113  of the first stage syringe  80  in a direction away from the filter  112  pulls the plasma  110  through the third leg  104 , first leg  98 , check valve  92 , coupling  88 , inlet/outlet port  84 , filter  112  and into the concentrating chamber of syringe  80 . As described with respect to FIGS. 3 and 4, reciprocal movement of the syringe  80  moves the agitator  116  through the hydrogel bead  114 —plasma mixture, minimizing gel polarization and facilitating water extraction from the plasma into the hydrogel beads.  
         [0082]    Syringe  82  has a concentrating chamber  125  defined by plunger  122  and filter  124 , the concentration chamber containing hydrogel beads  127  and agitator  126 .  
         [0083]    [0083]FIG. 8 is a cross-sectional schematic view of the two stage check valve syringe embodiment of FIG. 6 after transfer of first stage plasma concentrate from the first concentrator syringe  80  to the concentrating chamber of a second concentrator syringe  82 . Referring to FIG. 8 and FIG. 9, depression of the plunger  132  and/or movement of plunger  122  in a direction away from filter  124  causes movement of the first stage plasma concentrate  120  (FIG. 7) through inlet/out port  84 , tee  88 , check valve  90 , tee  94 , inlet/outlet port  86 , filter  124  into the concentrating chamber of syringe  82  and into contact with hydrogel beads  125  (FIG. 7). As described above, reciprocal movement of the syringe  82  moves the agitator  126  through the hydrogel bead-plasma concentrate mixture, minimizing gel polarization and facilitating water extraction from the plasma into the hydrogel beads and forming a mixture of the second stage plasma concentrate  128  and hydrated hydrogel beads  130 .  
         [0084]    [0084]FIG. 9 is a cross-sectional schematic view of the two stage check valve syringe embodiment of FIG. 6 after transfer of second stage plasma concentrate from the second concentrator syringe  82  to the plasma concentrate syringe  132 . Depression of plunger  122  toward the filter  124  displaces second stage plasma concentrate  128  (FIG. 8) through filter  124 , inlet/outlet port  86 , tee  94 , check valve  96 , second leg  102 , tee  104 , inlet/outlet port  106  of syringe  108  and into the barrel  135  of the plasma concentrate syringe  108 . The plasma concentrate syringe  108  carrying the plasma concentrate  128  is uncoupled from the tee  100  and taken to the physician for use. Alternatively, a clean plasma concentrate syringe (not shown) can be used for removal and movement of the plasma concentrate.  
         [0085]    The filters  114  and  124 , the hydrogel beads  114  and  127 , and agitators  116  and  226  of FIGS. 6-9 are described in detail with respect to FIG. 2.  
         [0086]    [0086]FIG. 10 is a cross-sectional schematic view of a two stage open channel syringe embodiment of this invention for producing plasma concentrate from plasma, plasma-platelet mixtures or whole blood, the concentrator syringes being coupled to a plasma transfer syringe filled with plasma.  
         [0087]    The apparatus of FIG. 10 comprises first stage syringe  140  and second stage syringe  142 , each syringe having the same components and structure as the syringe  30  of FIG. 2. The inlet/outlet port  144  of the first stage syringe  140  communicates with a first leg  148  of a tee coupling  150 . The inlet/outlet port  146  of the second stage syringe  142  communicates with the second leg  152  of the tee coupling  150 . The third leg  154  of tee coupling  150  is a coupling junction for the inlet/outlet port  156  of plasma transfer syringe  158 .  
         [0088]    In this embodiment, check valves are omitted, and the direction of plasma flow from one syringe to the other is controlled entirely by selective movement of the respective plungers.  
         [0089]    Referring to FIG. 10 and FIG. 11, the plasma transfer syringe  158  is filled with plasma  160 . Movement of the plunger  162  of the plasma transfer syringe  140  in a direction away from the filter  164  pulls the plasma  160  through the third leg  154 , first leg  148 , inlet/outlet port  144 , filter  164  and into the concentrating chamber  166  of syringe  140 . As described with respect to FIGS. 3 and 4, reciprocal movement of the syringe  140  moves the actuator  168  through the hydrogel bead  170 —plasma mixture, minimizing gel polarization and facilitating water extraction from the plasma into the hydrogel beads.  
         [0090]    [0090]FIG. 11 is a cross-sectional schematic view of the two stage open channel syringe embodiment of FIG. 10 after plasma has been transferred from the plasma syringe  158  to the concentrating chamber  166  of a first concentrator syringe  140 , and water has been absorbed by the hydrogel beads  170  yielding a mixture of hydrated beads  172  and first stage plasma concentrate  174 .  
         [0091]    [0091]FIG. 12 is a cross-sectional schematic view of the two stage open channel syringe embodiment of FIG. 11 after transfer of first stage plasma concentrate  174  from the first concentrator syringe  140  to the concentrating chamber  178  of a second concentrator syringe  142 . Referring to FIG. 11 and FIG. 12, movement of plunger  176  in a direction away from filter  180  causes movement of the first stage plasma concentrate  174  through filter  164 , separating the plasma concentrate from the hydrogel beads and agitator, and then through inlet/out port  144 , first leg  148 , tee  150 , second leg  152 , inlet/outlet port  146 , filter  180  into the concentrating chamber  178  of syringe  142 . As described above, reciprocal movement of the syringe  142  moves the actuator  182  through the hydrogel bead  184 —plasma concentrate mixture, increasing the rate of water extraction from the plasma into the hydrogel beads  184  and forming a mixture of the second stage plasma concentrate  186  and hydrated hydrogel beads  188 .  
         [0092]    [0092]FIG. 13 is a cross-sectional schematic view of the two stage check valve syringe embodiment of FIG. 12 after transfer of second stage plasma concentrate  186  from the second concentrator syringe  142  to the plasma syringe  158 .  
         [0093]    Referring to FIG. 12 and FIG. 13, movement of plunger  190  in a direction away from inlet/outlet port  156  draws second stage plasma concentrate  186  through filter  180 , inlet/outlet port  146 , second leg  152 , tee  150 , third leg  154 , inlet/outlet port  156  and into the barrel  192  of the plasma syringe  158 . The plasma concentrate syringe  158  carrying the plasma concentrate  186  is uncoupled from the tee  150  and taken to the physician for use. Alternatively, a clean plasma concentrate syringe (not shown) can be used for removal of the plasma concentrate.  
         [0094]    The filters  164  and  180 , the hydrogel beads  170  and  184 , and agitators  168  and  182  of FIGS. 10-13 are described in detail with respect to FIG. 2.  
         [0095]    [0095]FIG. 14 is a cross-sectional schematic view of a two stage open channel integrated concentrator housing embodiment of this invention for producing plasma concentrate from plasma, plasma-platelet mixtures or whole blood before the concentrator syringes are coupled to a plasma transfer syringe.  
         [0096]    The apparatus of FIG. 14 comprises a plasma concentrator housing  200  with a integral first concentrating chamber  202  and a integral second concentrating chamber  204 . Positioned in each chamber are the functional components of the syringe  30  of FIG. 2, integrated into a unitary system. The inlet/outlet conduit  206  of the first concentrating chamber  202  communicates with the inlet/outlet conduit  208  of the second concentrating chamber  204  and with the plasma transfer syringe junction  210 .  
         [0097]    In this embodiment, the direction of plasma flow from the plasma transfer syringe to the first concentrating chamber, from the first concentrating chamber to the second concentrating chamber, and from the second concentrating chamber to the plasma transfer syringe is controlled entirely by selective movement of the respective plungers as described in detail hereinafter.  
         [0098]    In FIG. 14, the plasma transfer syringe  212 , filled with plasma  214 , has an inlet/outlet port  216 . The first concentrating chamber  202  has a plunger  218  and a concentrating bead chamber  220 , hydrogel beads  222 , an agitator  224 , and a filter  226 . Movement of the plunger  218  in a direction away from the filter  226  pulls the plasma  214  through the inlet/outlet port  216 , plasma transfer syringe junction  210 , first leg  206 , filter  226  and into the concentrating chamber  220 . As described with respect to FIGS. 3 and 4, reciprocal movement of the unit  200  along the central axis of the concentration chambers moves the actuator  224  through the hydrogel bead  222 —plasma mixture, minimizing gel polarization and facilitating water extraction from the plasma into the hydrogel beads.  
         [0099]    [0099]FIG. 15 is a cross-sectional schematic view of the two stage open channel integrated housing embodiment of FIG. 14 after plasma has been transferred from the plasma transfer syringe  212  to the concentrating bead chamber  220 , and water has been absorbed by the hydrogel beads  222  yielding a mixture of hydrated beads  236  and first stage plasma concentrate  228 .  
         [0100]    The second concentrating chamber  204  has a plunger  230  and a concentrating bead chamber  232 , an agitator  234 , hydrogel beads  236  and a filter  238 .  
         [0101]    Referring to FIG. 15 and FIG. 16, movement of plunger  230  in a direction away from filter  238  causes movement of the first stage plasma concentrate  228  through filter  226 , separating the plasma concentrate from the hydrogel beads and agitator, and then through first leg  206 , second leg  208 , filter  238  and into the concentrating bead chamber  232  of concentrating chamber  204 . As described above, reciprocal movement of the syringe housing  200  along the central axis of the concentrating chambers  202  and  204  moves the actuator  234  through the hydrogel bead  236 —plasma concentrate mixture, minimizing gel polarization and facilitating water extraction from the plasma into the hydrogel beads  236 , and referring to FIG. 6, forming a mixture of the second stage plasma concentrate  240  and hydrated hydrogel beads  242 .  
         [0102]    [0102]FIG. 16 is a cross-sectional schematic view of the two stage open channel integrated housing embodiment of FIG. 15 after transfer of second stage plasma concentrate  240  from the second concentrating chamber  232  to the plasma transfer syringe  212 .  
         [0103]    Referring to FIG. 16 and FIG. 17, movement of plunger  244  of the plasma transfer syringe  212  in a direction away from the inlet/outlet port  216  draws second stage plasma concentrate  240  through filter  228 , second leg  208 , syringe junction  210 , syringe inlet/outlet port  216  (FIG. 17) and into the barrel  246  of the plasma transfer syringe  212 .  
         [0104]    [0104]FIG. 17 is a cross-sectional schematic view of the two stage open channel integrated housing embodiment of FIG. 16 after the second stage plasma concentrate  240  has been moved to the plasma transfer syringe  212 . Alternatively, a clean plasma concentrate syringe (not shown) can be used for removal and transfer of the plasma concentrate.  
         [0105]    [0105]FIG. 18 is a cross-sectional schematic view of the two stage open channel integrated housing embodiment of FIG. 17 after the plasma transfer syringe  212  has been uncoupled from the junction  210 , and is ready to be taken to the physician for use.  
         [0106]    The filters  226  and  238 , the hydrogel beads  222  and  236 , and agitators  224  and  234  of FIGS. 14-18 are described in detail with respect to FIG. 2.