BLOOD PLATELET STORAGE MEDIUM

Abstract: The present invention provides a blood component storage medium that can be sterilized, through autoclaving, and has improved shelf storage properties. The blood component storage medium comprises a first solution including at least one sugar and having a pH of less than 7. A second, distinct solution, including a bicarbonate buffer is provided having a pH greater than 7. The two solutions are stored separately and are mixed together prior to use as a storage medium.

Description: S P E C I F I C A T I O N TITLE "BLOOD PLATELET STORAGE MEDIUM" BACKGROUND OF THE INVENTION The present invention relates generally to the storage of blood components. More specifically, the present invention relates to the storage of blood components, such as red blood cells and platelets. Blood comprises two principal parts. When blood is collected and centrifuged, the blood separates into: plasma; and packed red cells. Plasma is comprised of water and inorganic and organic substances as well as dissolved gases and miscellaneous foreign components. The inorganic substances contained in plasma are primarily electrolytes. The electrolytes include: sodiur.; potassium; calcium; magnesium; chloride; bicarbonate; phosphate; and sulfate. The most significant organic substances found in plasma are: lactic acid; urea; ar.ino acids; creatinine; glucose; hormones; proteins; albumins; and globulins. In certain disease states and traumas, it is necessary to infuse into a patient red blood cells and/or platelets. For example, if the platelet count in the circulatory system drops below a lower limit of approximately 70,000 per cubic millimeters, thrombocytopenia can result. Thrombocytopeni results in a tendency to bleed, similar to hemophiliacs, except that bleeding is typically from many small capillaries rather than from large vessels as in hemophilia. A person suffering from thrombocytopenia typically suffers small hemorrhages throughout their body tissue. The infusion of platelets is particularly important to repair the minute breaks in capillaries and other small vessels. Platelets can be obtained as a by-product from whole blood donations and from plateletpheresis. Typically, platelets are stored in their own plasma within a plastic container. Usually, the plasma contains all of the ingredients found in physiological plasma and an anticoagulant, typically a citrate. Additionally, dextrose is present at an amount greater than the physiological level, for example five (5) times the physiological level, for the benefit of red cells that require it during storage and is generally accepted tc be required for platelet storage as well. There are known methods for storing platelets and red blood cells. In one type of method, the platelets are suspended in plasma; there are several disadvantages to storing platelets or red blood cells in large volumes of plasma, and then infusing the platelets or red blood cells into a recipient. One of the principal disadvantages is the transmission of diseases due to the infusion of plasma. Certain disease states including hepatitis-B and nonA, nonB - hepatitis and acquired immune deficiency syndrome (AIDS) can be transmitted through plasma infusion. Furthermore, patients can also exhibit allergic reactions to plasma. Additionally, plasma is valuable because it can be fractioned into its various components such as albumin and coagulation factors for treatment of specific disease states. The use of plasma as a storage medium for platelets or red blood cells wastes valuable plasma. There have been many attempts at creating a plasma free storage medium for platelets and red blood cells. Examples of such attempts at creating platelet storage medium are set forth in U.S. Patent Nos. 4,695,460, Re. 32,874, and European Patent Application No. EP 0 142 339. Additionally, various preservatives in culture medium are described as being useful in conjunction with the storage of platelets. EPO 142 339 notes that examples of such preservatives are set forth in U.S. Patent Nos.: 2,786,014; 3,629,071; 3,753,357; 3,814,687; 3,850,174; 4,152,208; 4,205,126; 4,267,269; and 4,390,619; as well as GB-A-1,283,273. Blood cell component storage solutions are also disclosed in U.S. Patent Nos.: 4,704,352; 4,675,185; 4,585,735; and EP 0 044 864. In order to store human blood components such as red blood cells and platelets, the storage medium must provide cell nutrients, simple sugars, such as glucose. Glucose is known to degrade under autoclaving (heat) sterilization conditions unless the medium being heated is acidic, i.e., has a pH of less than 7. If the solution is not acidic, when heated, glucose will caramelize. In order to remain viable, a cell must generate ATP (adenosine triphosphate) to meet its requisite energy requirements. ATP can be generated through two pathways, glycolysis and oxidative phosphorylation. Cell glycolysis (glycolytic pathway) results in the production of quantities of lactic acid (one mole of glucose is converted to two moles of lactic acid to achieve two molecules of ATP) . Lactic acid (having a pKa = 3) is immediately neutralized by plasma bicarbonate buffer (pKa = 6.3) to produce sodium lactate and carbonic acid (H 2 C0 3 ) . Carbonic acid is at equilibrium with carbon dioxide and water (H 2 C0 3 _=≥-C0 2 + H 2 0) . During blood component storage, especially platelet storage, the carbonic acid (H 2 C0 3 ) is removed by the diffusion of C0 2 through a permeable container. A buffer system therefore offers a potential for acid removal via gas diffusion. However, the buffer system is not stable under low pH conditions due to the high level of H 2 cc 3 and associated high C0 2 tensions unless it is packaged in an impermeable container, such as glass. Furthermore, in addition to production and storage problems of a buffered nutrient blood component storage medium, it must also be noted that the medium for storing plasma depleted cells, such as platelets and red blood cells, must be at a proper physiological pH. Recently, white blood cells have been collected as a separate component for a number of reasons, e.g. , gene transfer therapy. The white blood cells are preserved and/or manipulated for such purposes. Typically, the white blood cells have been stored in complex storage solutions. Accordingly, there is a need for an improved storage medium for storing blood components such as red blood cells and platelets. SUMMARY OF THE INVENTION The present invention provides a blood component storage medium that can be sterilized, through autoclaving, has improved shelf storage properties, and provides an improved method for storing blood cell components. In an embodiment, the blood component storage medium provides a medium for storing platelets for a period of approximately five (5) days. To this end, a blood component storage medium is provided comprising a first solution including at least one sugar and having a pH of less than 7. A second, distinct solution, including a bicarbonate buffer is provided having a pH greater than 7. The two solutions are stored separately and are mixed together prior to use as a storage medium. The two solutions, when so stored separately, have a shelf life of at least approximately three (3) years. In an embodiment, the first solution includes glucose. In an embodiment, the first solution includes citric acid, sodium citrate, dextrose, adenine, sodium chloride, potassium chloride, calcium chloride, and magnesium chloride. In an embodiment, the second solution includes sodium phosphate and sodium bicarbonate. In an embodiment, the present invention provides a blood platelet storage system comprising a first plastic gas permeable container including a first solution having at least one sugar nutrient and a pH of less than 7. A second plastic gas permeable container is also provided including a second buffer solution having a pH of greater than 7. The first and second solutions are mixed together prior to use to create a blood component storage medium. After being mixed together, the solutions can be combined with a platelet button. The platelets can then be resuspended in the solution, and the resultant solution can be distributed to the first and second gas permeable containers. In an embodiment, a red blood cell storage solution is provided. In an embodiment, a white blood cell storage solution is provided. The present invention also provides a method for storing blood components. The method comprises the steps of providing a first container including a first solution having a sugar nutrient and a pH of less than 7. A second container is provided including a buffer solution having a pH of greater than 7. The solutions in the first and second containers are mixed together to create a storage medium. After the storage medium is created, the blood component is added to the storage medium. In an embodiment, after the blood component is resuspended in the solution, the resultant combination is redistributed into the first and second containers. Additional features and advantages of the present invention are described in, and will be apparent from, the detailed description of the presently preferred embodiments and from the drawings. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 illustrates a perspective view of a first and second container including the first and second solutions of the present invention and a third container including a plasma depleted blood component. Figure 2 illustrates a perspective view of the first and second containers after the redistribution of the storage medium and resuspended plasma depleted blood component to the first and second containers. DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS A blood component storage medium is provided that has improved shelf storage properties. Pursuant to the present invention, the blood storage medium comprises two distinct solutions. By providing two distinct solutions, - 1 - improved manufacturing and storage properties are achieved. As illustrated in Figure 1, a first and second container, 10 and 12, respectively, are provided. The containers 10 and 12 are constructed from a gas permeable plastic material, such as, for example, ethylenevinyl acetate. The permeability of the plastic containers lc and 12 allows C0 2 to diffuse through the container removing carbonic acid (H 2 C0 3 ) from the solution housed in the container. This is especially critical when the blood component is suspended in the storage medium. The first container 10 includes a first solution 11 including a nutrient source for the blood component. Although, preferably, the nutrient source is a simple sugar, any sugar that can be metabolized will provide the nutrient source. In an embodiment, the nutrient source is dextrose (glucose) . The dextrose provides an energy source for the cells of the blood component and allows the cells to generate the necessary ATP to meet the requisite energy requirements of the blood component. The first solution 11 also preferably includes necessary electrolytes and anticoagulants and other components necessary for the storage of the blood components. For example, in an embodiment, the first solution includes: citric acid; sodium citrate; dextrose; adenine; sodium chloride; potassium chloride; calcium chloride; and magnesium chloride. Due to its components, the first solution 11 must be maintained, during its sterilization and storage, in an acidic condition. To this end, the first solution is maintained at a pH of less than 7, preferably, the pK of the solution is less than 6. It has been found that the first solution 11 should have a pH of approximately 5 tc about 6. The second solution 13, that acts as a buffer, is also housed in a gas permeable container 12. In a embodiment, the second solution preferably includes a bicarbonate buffer. In an embodiment, the second solution 13 includes sodium phosphate and sodium £icarbonate. The second solution 13 is maintained at a basic pH and accordingly has a pH of greater than 7. Preferably, the pH of the buffer is greater than 8. It has been found that a pH of approximately 8 to about 9 functions satisfactorily. In use, the first and second solutions are mixed together to create the blood component storage medium. The storage medium is added to the plasma depleted b. joa cell component. To this end, the first solution 11 is drained into the second container 12, or vice versa, utilizing a tubing 18 that prevents communication between the containers 10 and 12. As is known in the art, frangible members are located in the tubing 18 that can be fractured to establish fluid flow between the first container 10 and second container 12, and ultimately a third container 14. The resultant solution, from the mixing of the first and second solutions, is then added to a third container 14 that includes the plasma depleted blood cell component 15. The third container 14 can contain, for example, a platelet, a white blood cell, or red blood cell button. The blood cell components 15 are then resuspended in the resultant solution by gentle agitation of the third container 14. The solution 17 containing the blood cell components is then redistributed into the first and second containers 10 and 12, respectively. As illustrated in Figure 2, after the solution 17 is redistributed, the first and second containers 10 and 12 are then sealed, by cutting and sealing the tubing 18, creating two containers of solution and blood cell component, for example, platelets in a storage medium. Because the first and second containers are gas permeable, they can be used to house the blood cell component and storage medium. The first and second solutions are constructed so that when they are combined they have a physiologically acceptable pH. To this end, the two solutions when combined have a pH of approximately 6.8 to about 7.4. Most preferably, the two solutions when combined have a pH of approximately 7.0 to about 7.2. The present invention also provides a method for storing blood components. The method comprises the steps of providing a first container 10 including a first solution 11 having a sugar nutrient and a pH of less than 7. A second container 12 is provided including a buffer second solution 13 and having a pH greater than 7. The first and second solutions 11 and 13 are mixed together to create a storage medium. The storage medium is added to a plasma depleted collection of blood components 15, such as platelets. The blood component and storage medium can then be redistributed to the containers that are then sealed. The containers can then house the blood component until it is infused into a patient. In an embodiment, the solution can be used to store white blood cells. White blood cells can be collected for a number of purposes. For example, the white blood cells can be collected and modified for gene transfer therapy. To this end, a gene can be inserted into the white blood cells using a retrovirsus. By way of example, and not limitation, an example of the present invention is set forth below. A first 1000 ml container available from Baxter Healthcare International under the designation PI 732 plastic is provided that includes a first solution A. A second 1000 ml container, that is the same type of container as the first container, is provided and includes a second solution B. The solutions A and B are as follows: SOLUTION A COMPONENT HYDRATE mg/dL mM SOLUTION B SODIUM PHOSPHATE - 85 0.6 SODIUM BICARBONATE - 504 6.0 100 milliliters of solution A is present in the firsi container and 100 milliliters of solution B is present in the second container. Plasma depleted platelets are obtained from whole blood and housed in a container, for example, a container available from Baxter Healthcare under the designation PI 732 plastic, as a platelet button. The platelet button can be obtained by plateletpheresis of the whole blood. Approximately 3 x 10 11 to about 6 x 10 11 platelet cells are present in the button. The first and second solutions are mixed together and then added to the third container. The platelets are then resuspended in the solution and the platelets and solution are distributed to the first and second containers creating two containers housing 100 ml of platelets in storage medium. The platelets can be stored in the medium for approximately five (5) days. It should be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the present invention and without diminishing its attendant advantages. It is therefore intended that such changes and modifications be covered by the appended claims.

Claims: WE CLAIM: 1. A blood component storage medium comprising: a first solution including at least one sugar nutrient and a pH of less than 7; and a second, distinct solution including a bicarbonate buffer and having a pH of greater than 7, the two solutions being separately stored and being mixed together prior to use as a storage medium. 2. The blood component storage medium of Claim 1 wherein the first solution includes dextrose. 3. The blood component storage medium of Claim 1 wherein the first solution includes: citric acid; sodium citrate; dextrose; adenine; sodium chloride; potassium chloride; calcium chloride; and magnesium chloride. 4. The blood component storage medium of Claim 1 wherein the second solution includes sodium phosphate and sodium bicarbonate. 5. The blood component storage medium of Claim 1 wherein the pH of the first solution is less than 6. 6. The blood component storage medium of Claim l wherein the pH of the second solution is at least 8. 7. The blood component storage medium of Claim 1 wherein when mixed together the storage medium has a pH of approximately 6.8 to about 7.4. 8. A blood platelet storage system comprising: a first plastic gas permeable container including a first solution having at least one sugar nutrient and a pH of less than 7; a second plastic gas permeable container including a second solution having a pH of greater than 7; and wherein the first and second solutions are mixed together prior to use to create a blood component storage medium. 9. The blood platelet storage medium of Claim s wherein the first solution includes dextrose. 10. The blood platelet storage medium of Claim 8 wherein the first solution includes: citric acid; sodium citrate; dextrose; adenine; sodium chloride; potassium chloride; calcium chloride; and magnesium chloride. 11. The blood platelet storage medium of Claim 8 wherein the second solution includes sodium phosphate and sodium bicarbonate. 12. The blood platelet storage system of Claim 8 wherein the pH of the first solution is between approximately 5 to about 6. 13. The blood platelet storage system of Claim 8 wherein the pH of the second solution is between approximately 8 to about 9. 14. The blood platelet storage system of Claim 8 wherein when the solutions are mixed together they have a pH of approximately 6.8 to about 7.4. 15. A method for storing blood components comprising the steps of: providing a first container including a first solution having a sugar nutrient and a pH of less than 7; providing a second container including a buffer second solution and a pH of greater than 7; mixing the first and second solutions to create a storage medium; and adding the blood component to the storage medium. 16. The method of Claim 15 including the step of autoclaving the first and second containers including the solutions to sterilize the first and second containers prior to mixing the solutions to create the storage medium. 17. The method of Claim 15 including the step of redistributing the blood component and storage medium to the first and second containers after the blood component is resuspended in the storage medium. 18. The method of Claim 15 wherein the blood component is plasma depleted platelets. 19. The method of Claim 15 wherein the blood component is plasma depleted red blood cells. 20. The method of Claim 15 wherein the blood component is plasma depleted white blood cells. 21. The method of Claim 15 wherein the pH of the first solution is between approximately 5 to about 6. 22. The method of Claim 15 wherein the pH of the second solution is between approximately 8 to about 9. 23. The method of Claim 15 wherein when the solutions are mixed together they have a pH of approximately 6.8 to about 7.4. 24. A method for storing blood components comprising the steps of: providing a gas permeable first container including a first solution having a sugar nutrient and a pH of less than 7 ; providing a gas permeable second container including a buffer second solution and a pH of greater than 7; mixing the first and second solutions to create a storage medium; adding a blood component to the storage medium; resuspending the blood component in the storage medium; and redistributing the blood component and storage medium into the first and second container. 25. The method of Claim 24 wherein the blood component is plasma depleted platelets. 26. The method of Claim 24 wherein the blood component is plasma depleted red blood cells. 27. The method of Claim 24 wherein the blood component is plasma depleted white blood cells.

Inventors: BISCHOF DANIEL, GOLDHABER RICHARD, GRODE GERALD A, BISCHOF, DANIEL, GOLDHABER, RICHARD, GRODE, GERALD, A.
Applicants: BAXTER INT, BAXTER INTERNATIONAL INC.
Application year: 1991
Main classification: A01N1
IPC codes: A01N1, A61L2