Method for preparing platelet rich plasma and concentrates thereof

1. A method for separating platelet rich plasma from a blood sample with a system comprising an inner wall having a top edge and a central axis surrounded by a depth filter having a capacity to receive all of the erythrocytes in the blood sample but insufficient to receive all of the plasma in the blood sample, an inner surface of the inner wall having an angle of at least about 0.2 degrees from the central axis of the inner wall, the method comprising the steps of:

a) spinning an inner cylinder about its central axis at a speed that centrifugally separates erythrocytes from plasma and platelets of the blood sample and causes the erythrocytes to collect against an inner surface of the depth filter;

b) continuing spinning for a time sufficient to allow substantially all of the erythrocytes to flow up the inner surface and over the top edge into the depth filter, leaving platelet enriched plasma behind in the inner cylinder; and

c) slowing or discontinuing the spinning to permit the platelet enriched plasma to flow to the bottom of the inner cylinder.

2. The method of claim 1 , further comprising:

segmenting the inner surface of the inner wall by radially extending plates to form separation zones;

balancing distribution of the blood in the separation zones with the plates during rotation of the inner cylinder, thereby reducing vibration and erythrocyte displacement from the depth filter.

3. The method of claim 1 wherein a rotational speed of the inner cylinder is accelerated to centrifugal speeds at a rate that allows balanced distribution of blood in separation zones, and after the centrifuging is complete, the rotation speed of the inner cylinder is decelerated to below centrifugal speeds at a rate that allows balanced distribution of the blood sample in the separation zones, thereby reducing vibration and erythrocyte displacement from the depth filter.

4. The method of claim 1 further comprising concentrating the platelet enriched plasma by contacting the platelet enriched plasma with desiccating beads in a concentration chamber while the beads are agitated with a rake to form a platelet rich plasma concentrate.

5. The method of claim 4 wherein the concentration chamber includes an outer screened cylinder for the desiccating beads, and the platelet rich plasma concentrate is separated from the beads by rotating the concentrating chamber about its central axis at a speed that separates platelet rich plasma concentrate from the beads.

6. The method of claim 1 further comprising retaining at least about 85 volume percent of a hematocrit value of the blood and less than a major portion of the platelet enriched plasma remaining after the erythrocyte separation.

7. The method of claim 1 further comprising retaining at least about 97 volume percent of a hematocrit value of the blood and less than a major portion of the platelet enriched plasma remaining after the erythrocyte separation.

8. The method of claim 1 further comprising retaining at least about 99 volume percent of a hematocrit value of the blood sample and less than a major portion of the platelet enriched plasma remaining after the erythrocyte separation.

9. The method of claim 1 further comprising retaining at least about 100 volume percent of a hematocrit value of the blood and less than a major portion of the platelet enriched plasma remaining after the erythrocyte separation.

10. The method of claim 9 further comprising retaining less than a significant portion of the enriched plasma remaining after the erythrocyte separation.

11. A method for separating platelet rich plasma from a blood sample with a system comprising an inner wall having a top edge surrounding a central axis, a depth filter having a capacity to receive erythrocytes from the blood sample, an inner surface of the inner wall having an angle from the central axis, the method comprising:

a) spinning an inner cylinder about the central axis at a speed that centrifugally separates erythrocytes from the blood sample;

b) continuing spinning for a time sufficient to allow a selected portion of the erythrocytes to move up the inner surface of the inner wall and over a top edge of the inner wall into the depth filter, leaving platelet enriched plasma in the inner cylinder; and

c) slowing or discontinuing the spinning to permit the platelet enriched plasma to flow to a bottom of the inner cylinder.

12. The method of claim 11 , further comprising:

balancing distribution of the blood during the spinning of the inner cylinder in a plurality of separation zones thereby reducing vibration and erythrocyte displacement from the depth filter, wherein the separation zones are defined by plates radially extending from the inner wall.

13. The method of claim 12 , further comprising:

increasing a speed of spinning of the inner cylinder at a rate that allows balanced distribution of blood in the separation zones; and

wherein slowing or discontinuing the spinning includes decelerating the inner cylinder at a rate that allows balanced distribution of the blood sample in the separation zones.

14. The method of claim 11 , further comprising:

concentrating the platelet rich plasma by contacting the platelet rich plasma with desiccating beads in a concentration chamber while the beads are agitated with a rake to form a platelet rich plasma concentrate.

15. The method of claim 14 wherein the concentration chamber includes an outer screened cylinder to contain the desiccating beads, and the platelet rich plasma concentrate is separated from the beads by rotating the concentrating chamber about its central axis at a speed that separates platelet rich plasma concentrate from the beads.

16. The method of claim 11 , further comprising:

retaining at least about 85 volume percent of a hematocrit value of the blood and less than a major portion of the erythrocyte free platelet enriched plasma remaining after the erythrocyte separation.

17. The method of claim 11 , further comprising:

retaining at least about 97 volume percent of a hematocrit value of the blood and less than a major portion of the platelet enriched plasma remaining after the erythrocyte separation.

18. The method of claim 11 further comprising:

retaining less than a significant portion of the platelet enriched plasma remaining after the erythrocyte separation.

19. A method for separating at least erythrocytes from a blood sample the method comprising:

placing the blood sample in a system having a central axis surrounded by an inner wall extending to a top edge and the inner wall having an inner surface having an angle from the central axis, the system further having a depth filter to receive erythrocytes from the blood sample;

accelerating the system to spin around the central axis;

continuing spinning of the system for a time sufficient to allow a selected portion of the erythrocytes to move up the inner surface of the inner wall and over the top edge of the inner wall into the depth filter, leaving platelet enriched plasma in an inner cylinder defined at least in part by the inner wall; and

decelerating or discontinuing the spinning of the system to permit the platelet enriched plasma to collect in the system.

20. The method of claim 19 , further comprising:

balancing distribution of the blood during the spinning of the system in a plurality of separation zones thereby reducing vibration and erythrocyte displacement from the depth filter, wherein the separation zones are defined by plates radially extending from the inner wall.

21. The method of claim 19 , further comprising:

concentrating the platelet enriched plasma by contacting the platelet enriched plasma with desiccating beads in a rotating concentration chamber while the beads are agitated with a rake to form a platelet rich plasma concentrate.

22. The method of claim 21 , wherein the concentration chamber includes an outer screened cylinder to contain the desiccating beads, and the platelet rich plasma concentrate is separated from the beads by rotating the concentrating chamber about its central axis at a speed that separates platelet rich plasma concentrate from the beads.