Apparatus for cryopreservation and recovery of red blood cells

Abstract

A system dynamically adjusts the delivery rate of a cryopreservation solution to red blood cells to permit freezing. The delivery rate is preferably determined according to an equation that maintains a linear change of red blood cell osmolarity over time so as to prevent osmolarity shock of the red blood cells. In the preferred embodiment, the system includes a controller that is preconfigured to automatically deliver the cryopreservation solution to the red blood cells in accordance with the equation. The system may also support the recovery of thawed red blood cells by diluting the red blood cells and washing them of the cryopreservative. Again, the system preferably adjusts the delivery rate of a dilution solution so as to prevent osmolarity shock of the red blood cells during the recovery phase. The recovered red blood cells may be suspended in a preservation solution to further increase their shelf-life following the recovery phase.

1. An apparatus for preparing a blood component for cryopreservation by mixing the blood component with a volume of cryopreservation solution that exposes the blood component to a risk of osmolarity shock, the apparatus comprising:
 at least one variable-speed pump coupled to the volume of cryopreservation solution and to the blood component, operation of the pump at a given speed defining a respective flow rate of cryopreservation solution to the blood component; and  
 a controller operably coupled to the at least one pump so as to control the rate at which cryopreservation solution is delivered to the blood component, the controller configured to dynamically adjust the flow rate of the cryopreservation solution to reduce the risk of osmolarity shock to the blood component.  
 
     
     
       2. The apparatus of  claim 1  further comprising an anti-bacterial filter disposed between the cryopreservation solution and the blood component. 
     
     
       3. The apparatus of  claim 2  wherein the controller dynamically adjusts the cryopreservation flow rate so as to maintain a substantially linear increase of blood component osmolarity. 
     
     
       4. The apparatus of  claim 3  wherein the controller is further configured to determine repeatedly the amount of cryopreservation solution added to the blood component, calculate a new flow rate based on the determined amount of cryopreservation solution and adjust the at least one pump to deliver cryopreservation solution at the new flow rate. 
     
     
       5. The apparatus of  claim 4  wherein the controller determines the amount of cryopreservation solution, calculates the new flow rate and adjusts the at least one pump on a real time basis. 
     
     
       6. The apparatus of  claim 5  wherein the controller is further configured to determine a requisite volume of cryopreservation solution to achieve a desired cryopreservative concentration within the blood component. 
     
     
       7. The apparatus of  claim 6  wherein a tube connects the cryopreservation solution to the blood component and a pressure probe is disposed in the tube downstream of the at least one pump, the pressure probe providing a corresponding pressure signal to the controller which is further configured to de-activate the at least one pump if the pressure signal exceeds a predetermined threshold. 
     
     
       8. The apparatus of  claim 2  wherein the anti-bacterial filter has an operating pressure range and the controller is further configured to prevent the pressure of cryopreservation solution at the anti-bacterial filter from exceeding the operating range. 
     
     
       9. The apparatus of  claim 1  wherein the blood component is red blood cells and the controller is configured to adjust the speed of the at least one pump so that the flow rate of cryopreservation solution is substantially given by the following equation:
   K[V i *(W*Hct i /100)+V g ] 2 /[V i *(W*Hct i /100)*(O i −O g )] 
 
       where,
 K is the selected rate of increase in osmolarity of the red blood cells,  
 V i  is the volume of red blood cells,  
 W is the volumetric percentage of water in the red blood cells,  
 Hct i  is the hematocrit level of the red blood cells before cryopreservation,  
 V g  is the volume of cryopreservation solution that has already been added to the red blood cells prior to the current flow rate calculation,  
 O i  is the osmolarity of the red blood cells before cryopreservation, and  
 O g  is the osmolarity of the cryopreservation solution.  
 
     
     
       10. The apparatus of  claim 9  wherein the controller is configured to initially adjust the speed of the at least one pump so that the initial flow rate of cryopreservation solution is substantially given by the following equation:
   K*V i *(W*Hct i /100)/(O i −O g ).  
 
     
     
       11. The apparatus of  claim 10  wherein the controller is further configured to determine the volume of red blood cells, V i , substantially in accordance with the following equation:
   NW i /[(1.1*Hct i /100)+1.026*(1-Hct i /100) 9   
 
       where,
 NW i  is the net weight of the red blood cells prior to cryopreservation.  
 
     
     
       12. The apparatus of  claim 11  further comprising a shaker platform for agitating the blood component as the cryopreservation solution is being delivered thereto. 
     
     
       13. The apparatus of  claim 1  further comprising a shaker platform for agitating the blood component as the cryopreservation solution is being delivered thereto. 
     
     
       14. An apparatus for diluting a thawed, cryopreserved blood component with a volume of a dilution solution that exposes the blood component to a risk of osmolarity shock, in preparation for recovery of the blood component, the apparatus comprising:
 means for coupling the dilution solution to the blood component;  
 at least one variable-speed pump disposed in the coupling means, operation of the at least one pump at a given speed defining a respective flow rate of dilution solution to the blood component; and  
 a controller operably coupled to the at least one pump so as to control the rate at which dilution solution is delivered to the blood component; the controller configured to dynamically adjust the flow rate of the dilution solution to reduce the risk of osmolarity shock to the blood component.  
 
     
     
       15. The apparatus of  claim 14  wherein the controller dynamically adjusts the dilution solution flow rate so as to maintain a linear decrease of blood component osmolarity. 
     
     
       16. The apparatus of  claim 15  wherein the blood component is red blood cells and the controller is configured to adjust the speed of the at least one pump so that the flow rate of dilution solution is substantially given by the following equation:
   K D [V i *(W*Hct i /100)+V S ] 2 /[V i *(W*Hct i /100)*(O i −O S )] 
 
       where,
 K D  is the desired osmolarity rate decrease,  
 V i  is the volume of the thawed red blood cells after dilution with the hypertonic solution,  
 W is the volumetric percentage of water in the red blood cells,  
 Hct i  is the hematocrit level of the thawed red blood cells after dilution with the hypertonic solution,  
 V S  is the volume of washing solution that has already been delivered to the thawed red blood cells,  
 O i  is the osmolarity of the thawed red blood cells after dilution with the hypertonic solution, and  
 O S  is the osmolarity of the washing solution.  
 
     
     
       17. The apparatus of  claim 16  wherein the controller is configured to initially adjust the speed of the at least one pump so that the initial flow rate of dilution solution is substantially satisfied by the following equation:
   K D *V i *(W*Hct i /100)/(O i −O S ).  
 
     
     
       18. The apparatus of  claim 17  further comprising a shaker platform for agitating the blood component as the dilution solution is being delivered thereto. 
     
     
       19. An apparatus for preparing a blood component for cryopreservation by mixing the blood component with a volume of cryopreservation solution that exposes the blood component to a risk of osmolarity shock, and for diluting a thawed, cryopreserved blood component with a volume of a dilution solution that also exposes the blood component to a risk of osmolarity shock, in preparation for recovery of the blood component, the apparatus comprising:
 at least one variable-speed pump coupled to the blood component and selectively coupled to either the volume of cryopreservation solution or the volume of dilution solution, operation of the pump at a given speed defining a respective flow rate of either cryopreservation solution or dilution solution to the blood component; and  
 a controller operably coupled to the at least one pump so as to control the rate at which either cryopreservation solution or dilution solution is delivered to the blood component, the controller configured to dynamically adjust the flow rate of either the cryopreservation solution or the dilution solution to reduce the risk of osmolarity shock to the blood component.  
 
     
     
       20. An apparatus for preparing a blood component by mixing the blood component with a volume of solution that exposes the blood component to a risk of osmolarity shock, the apparatus comprising:
   at least one variable - speed pump coupled to the volume of solution and to the blood component, operation of the pump at a given speed defining a respective flow rate of solution to the blood component; and        a controller operably coupled to the at least one pump so as to control the rate at which solution is delivered to the blood component, the controller configured to dynamically adjust the flow rate of the solution to reduce the risk of osmolarity shock to the blood component.     
     
     
       21. The apparatus of  claim 20  further comprising an anti- bacterial filter disposed between the solution and the blood component.   
     
     
       22. The apparatus of  claim 21  wherein the controller dynamically adjusts the solution flow rate so as to maintain a substantially linear increase of blood component osmolarity. 
     
     
       23. The apparatus of  claim 22  wherein the controller is further configured to determine repeatedly the amount of solution added to the blood component, calculate a new flow rate based on the determined amount of solution and adjust the at least one pump to deliver solution at the new flow rate. 
     
     
       24. The apparatus of  claim 23  wherein the controller determines the amount of solution, calculates the new flow rate and adjusts the at least one pump on a real time basis. 
     
     
       25. The apparatus of  claim 24  wherein the controller is further configured to determine a requisite volume of solution to achieve a desired solution concentration within the blood component. 
     
     
       26. The apparatus of  claim 25  wherein a tube connects the solution to the blood component and a pressure probe is disposed in the tube downstream of the at the least one pump, the pressure probe providing a corresponding pressure signal to the controller which is further configured to de- activate the at least one pump if the pressure signal exceeds a predetermined threshold.   
     
     
       27. The apparatus of  claim 21  wherein the anti- bacterial filter has an operating pressure range and the controller is further configured to prevent the pressure of solution at the anti - bacterial filter from exceeding the operating range.   
     
     
       28. The apparatus of  claim 21  further comprising a shaker platform for agitating the blood component as the solution is being delivered thereto. 
     
     
       29. An apparatus for washing a blood component with a volume of a wash solution that exposes the blood component to a risk of osmolarity shock, in preparation for recovery of the blood component, the apparatus comprising:
   means for coupling the wash solution to the blood component;        at least one variable - speed pump disposed in the coupling means, operation of the at least one pump at a given speed defining a respective flow rate of wash solution to the blood component; and        a controller operably coupled to the at least one pump so as to control the rate at which wash solution is delivered to the blood component; the controller configured to dynamically adjust the flow rate of the wash solution to reduce the risk of osmolarity shock to the blood component.     
     
     
       30. The apparatus of  claim 29  wherein the controller dynamically adjusts the wash solution flow rate so as to maintain a linear decrease of blood component osmolarity. 
     
     
       31. The apparatus of  claim 29  further comprising a shaker platform for agitating the blood component as the wash solution is being delivered thereto.