Title of Invention

A METHOD AND A DEVICE FOR SEPARATING PLATELETS FROM WHOLE BLOOD

Abstract

1754/CHENP/2003 "A method and a device for separating platelets from whole blood" The invention relates to a method for separating platelets from whole blood, comprising: providing whole blood which includes platelets, leukocytes, erythrocytes, and blood plasma; selectively aggregating the platelets by adding an aggregating agent such as herein described to form platelet aggregates that are larger in size than said leukocytes and said erythrocytes; and substantially separating the platelet aggregates from the leukocytes, erythrocytes, and blood plasma in a known manner, washing said separated platelets disaggregating and for suspending the same in a desired solvent. This invention also relates to a device for separating platelets from whole blood.

Full Text

The present invention relates to a method and a device for separating platelets from whole blood. More specifically, by separating platelets from whole blood, growth factor rich platelets can be harvested, concentrated, and delivered for wound healing in accordance with embodiments of the present invention. An attractive emerging clinical approach for augmenting wound healing is the rapidly expanding clinical and surgical use of recombinant or autologous growth factors for improved therapeutic outcomes. Examples of areas where such wound healing compositions are useful include intractable decubitus and pressure ulcers; orthopedic bone defect repair and bone ingrowth in fixation and implantation procedures; plastic and maxillofacial surgery; burn skin grafts; connective tissue repair; periodontal surgery, etc., as described by: Knighton D R, Surgery, Gynecology & Obstetrics 170: 56-60. 1990; and in Slater M, J Orthop Res 13: 655-663. 1995. The widespread clinical and surgical acceptance of growth factor-based wound healing therapies are currently limited to some degree by the high cost associated with both recombinant and autologous growth factor healants, and the additional inconvenience of processing autologous cells intraoperatively. Although only few controlled comparisons have been made between autologous growth factor cocktails and purified protein recombinant growth factors for wound healing * ———_— Alternatively, a wound healant for application to tissue can comprise a combination of platelet aggregates and single platelets, wherein the platelet aggregates and the single platelets are suspended in a physiological solution and carried by a clinical carrier substrate. An advantage of utilizing such a combination includes the possibility that aggregated platelets may provide immediate release of growth factor to a tissue, whereas individual, non-aggregated platelets may provide growth factor to a tissue site over time. Therefore, such a wound healant can provide immediate growth factor treatment to a tissue, as well as provide some sustained release of growth factor over time. In either of the above embodiments, substantially intact platelets can be delivered directly in, for example, a physiological solution such as isotonic saline solutions. In one embodiment of such a wound healant, the autologous platelets with contained growth factors can be present at a concentration greater than three times normal levels compared to that present in blood, wherein the platelet is not substantially activated by degranulating agents such as thrombin. Further, the physiological solution that acts as the wound healant can be essentially free of serum or plasma proteins. As described herein with respect to a process of the present invention, the platelets can be prepared and be present as single cells or small aggregates of cells that are distributed within a clinical carrier substrate, thereby providing a dispersed and prolonged release of growth factors. The healant can be delivered as suspended cells in a physiological solution, in a patch such as a poly-glycolic acid patch, a polyester patch such as a Darcon patch, or as a gel such as part of a gel suture system. Additionally, such a wound healant can also be combined with a hemostatic sealant to contribute growth-promoting properties of the wound healant. Further, such a wound healant can also be incorporated into aneurysm substrates or fillers such as coils or gels to accelerate the healing and/or re-integration of an aneurysm. Accordingly, the present invention provides a method for separating platelets from whole blood, comprising: providing whole blood which includes platelets, leukocytes, erythrocytes, and blood plasma; selectively aggregating the platelets by adding an aggregating agent such as herein described to form platelet aggregates that are larger in size than said leukocytes and said erythrocytes; and substantially separating the platelet aggregates from the leukocytes, erythrocytes, and blood plasma in a known manner, washing said separated platelets disaggregating and for suspending the same in a desired solvent. Accordingly, the present invention also provides a device for separating platelets from whole blood, comprising: (i) a mixing chamber provided with a conventional mixing mechanism for mixing whole blood and aggregating agent, (ii) a filtering chamber for collecting platelet aggregates which allows the residual blood components to substantially pass, said filtering chamber being provided with filter means, (iii) a valve disposed between said mixing chamber and filtering chamber, (iv) said mixing chamber having an inlet for supplying whole blood and said aggregating agent, and an outlet for removing components of whole blood that are not collected in the filter. In the accompanying drawings which illustrate embodiments of the invention: WE CLAIM: 1. A method for separating platelets from whole blood, comprising: providing whole blood which includes platelets, leukocytes, erythrocytes, and blood plasma; selectively aggregating the platelets by adding an aggregating agent such as herein described to form platelet aggregates that are larger in size than said leukocytes and said erythrocytes; and substantially separating the platelet aggregates from the leukocytes, erythrocytes, and blood plasma in a known manner, washing said separated platelets disaggregating and for suspending the same in a desired solvent. 2. The method as claimed in claim 1, wherein the platelet aggregates are washed with an isotonic solution after the separating step. 3. The method as claimed in claim 1, wherein the platelet aggregates are at least partially deaggregated after the separating step. 4. The method as claimed in claim 1, wherein the platelet aggregates are suspended in a physiological isotonic solution after the separating step. 5. The method as claimed in claim 3, wherein the deaggregated platelets are concentrated to a therapeutic level for delivery to a wound site. 6. The method as claimed in claim 1, wherein the separating step is carried out without centrifuging the treated blood. 7. The method as claimed in claim 1, wherein the separating step is carried out by filtration. The method as claimed in claim 1, wherein the separating step is carried out by sedimentation of said aggregate. The method as claimed in claim 1, wherein the aggregating agent is selected from the group consisting of thrombin, ristocetin, arachidonic acid, collagen, epinephrine, adenosine di-phosphate, and combinations thereof. The method as claimed in claim 9, wherein the aggregating agent is adenosine diphosphate. The method as claimed in claim 2, wherein the platelets are washed with a physiological solution at a temperature from 18°C to 25°C and for 1 to 3 minutes to remove residual components including agonists, red blood cells, white blood cells, and plasma proteins. The method as claimed in claim 1, wherein said platelet aggregates are aspired after deaggregation and then resusp ended to minimize degranulation for recovering single cells or small cell aggregates, said physiological solution capable of preserving growth factors of said platelets. The method as claimed in claim 12, wherein said platelets are aspirated with plasma. The method as claimed in claim 12, wherein said aspiration step is carried out in the presence of ACD-saline or albumin solution. The method as claimed in claim 12, wherein said aspiration step is carried out under controlled temperatures from 33°C to 37°C, and at a pH from 6 to 8. The method as claimed in claim 7, wherein the step of filtering is carried out with a biodegradable filter that may be placed directly on a wound site. The method as claimed in claim 16, wherein the biodegradable filter comprises a material selected from the group consisting of polyglycolic acid, polylactic acid, polypeptide, collagen, and combinations thereof. The method as claimed in claim 1, wherein said aggregated platelets are separated from whole blood within 15 mts of aggregation to enable emergency reinfusion or transfusion of platelets. The method as claimed in claim 1, wherein the step of selectively aggregating the platelets is enhanced by mixing the whole blood and the aggregating agent at a temperature from 20°C to 37°C for 60 to 180 seconds. A method for separating platelets from a platelet suspension, comprising: selectively aggregating platelets in a platelet suspension using an aggregating agent to form platelet aggregates; and separating the platelet aggregates from platelet suspension by filtration. The method as claimed in claim 20, wherein the separating step occurs without centrifugation. The method as claimed in claim 20, wherein the aggregating agent is selected from the group consisting of thrombin, ristocetin, arachidonic acid, collagen, epinephrine, adenosine di-phosphate, and combinations thereof. The method as claimed in claim 20, wherein the platelet aggregates are washed with a known physiological solution after filtration. The method as claimed in claim 20, wherein the platelet aggregates are at least partially deaggregated after filtration. The method as claimed in claim 20, wherein the platelet aggregates are suspended in a known physiologically neutral solution after filtration. The method as claimed in claim 20, wherein the platelet suspension is platelet rich plasma. The method as claimed in claim 20, wherein the platelet suspension is whole blood. The method as claimed in claim 20, wherein the platelet suspension is a platelet pack. A device for separating platelets from whole blood, comprising: (i) a mixing chamber provided with a conventional mixing mechanism for mixing whole blood and aggregating agent, (ii) a filtering chamber for collecting platelet aggregates which allows the residual blood components to substantially pass, said filtering chamber being provided with filter means, (iii) a valve disposed between said mixing chamber and filtering chamber, (iv) said mixing chamber having an inlet for supplying whole blood and said aggregating agent, and an outlet for removing components of whole blood that are not collected in the filter. The device as claimed in claim 29, wherein the mixing mechanism is a magnetic stir bar controlled by a microprocessor to optimize mixing and to prevent substantial premature release of growth factor contents from the platelets. The device as claimed in claim 29, wherein the filter has a pore size from 15 to 500 pin. The device as claimed in claim 31, wherein the pore size is from 15 to 100 jam. The device as claimed in claim 29, wherein the outlet port is also used for injecting a physiological solution into the mixing/filtering chamber for washing. The device as claimed in claim 29, wherein said mixing mechanism is an electromagnetic motor and a magnetic stir bar. The device as claimed in claim 29, wherein the filter comprises a material selected from the group consisting of metal, polymer, biomaterial, biodegradable material, and combinations thereof. The device as claimed in claim 35, wherein the filter comprises a material selected from the group consisting of stainless steel, nylon, poly-tetra-fluoro-ethylene, polyester, hyaluronic acid, and combinations thereof. The device as claimed in claim 29, wherein the deaggregating agent is injected into the filtering chamber with a syringe, through the outlet port. The device as claimed in claim 29, which is fully automated. A method for separating platelets from whole blood substantially as herein described with reference to the accompanying drawings. A device for separating platelets from whole blood substantially as herein described with reference to the accompanying drawings.

Documents:

1754-chenp-2003- abstract.pdf

1754-chenp-2003- claims duplicate.pdf

1754-chenp-2003- claims original.pdf

1754-chenp-2003- correspondence others.pdf

1754-chenp-2003- correspondence po.pdf

1754-chenp-2003- descripition complete duplicate.pdf

1754-chenp-2003- descripition complete original.pdf

1754-chenp-2003- drawings.pdf

1754-chenp-2003- form 1.pdf

1754-chenp-2003- form 3.pdf

1754-chenp-2003- form 5.pdf

1754-chenp-2003- other documents.pdf

1754-chenp-2003- pct.pdf