Platelet collection method and platelet collection system

1. A platelet collection method comprising:

conducting whole blood collected from a donor into a first chamber;

separating the whole blood into a first blood component including a large number of platelets and a remaining component by centrifugal separation;

applying at least one centrifugal force during the steps of separating the whole blood and separating the first blood component and

applying a centrifugal force differing from said at least one centrifugal force during the step of separating the platelet-containing component in the third chamber;

transferring the first blood component from the first chamber to a second chamber;

separating the first blood component transferred to the second chamber into a platelet-containing component and a second blood component by centrifugal separation;

transferring the platelet-containing component from the second chamber to a third chamber;

separating the platelet-containing component transferred to the third chamber into platelets and another component by performing centrifugal separation;

introducing a platelet additive solution into the third chamber and replacing the another component with the platelet additive solution; and

collecting the platelets remaining in the third chamber along with the platelet additive solution.

2. The platelet collection method according to claim 1 , wherein the third chamber has two outlets having different distances from a centrifugal center at the time of the centrifugal separation.

3. The platelet collection method according to claim 1 , wherein the blood components flow in sequence from the first chamber through the second chamber to the third chamber through tubes.

4. The platelet collection method according to claim 1 , further comprising separating leukocytes in the second chamber as part of the second blood component.

5. The platelet collection method according to claim 1 , wherein the platelets remain in the third chamber while the another component flows to an outside of the third chamber and while the platelet-containing component is introduced into the third chamber during the centrifugal separation of the platelet-containing component.

6. The platelet collection method according to claim 5 , wherein the another component flows to a reservoir of the remaining component during the centrifugal separation of the platelet-containing component and the another component and the platelet additive solution are allowed to flow to a disposal container during the introduction of the platelet additive solution into the third chamber.

7. The platelet collection method according to claim 1 wherein the platelet-containing component and the platelet additive solution inflow into the third chamber through a single inflow port.

8. The platelet collection method according to claim 7 , wherein inflow of the platelet-containing component is stopped during the inflow of the platelet additive solution into the third chamber.

9. The platelet collection method according to claim 1 , wherein a speed of inflow of the platelet additive solution into the third chamber is higher during the collection of the platelets than during the replacement of the other component with the platelet additive solution.

10. A platelet collection system comprising:

a primary separation unit including a first chamber for receiving whole blood collected from a donor and for separating the whole blood into a first blood component including a large number of platelets and into a remaining component, said first chamber being adapted to be mounted on a centrifugal separation apparatus;

a secondary separation unit including a second chamber in fluid communication with the first chamber for receiving the first blood component transferred from the primary separation unit and for separating the first blood component into a platelet-containing component and a second blood component, said second chamber being adapted to be mounted on said centrifugal separation apparatus;

a tertiary separation unit including a third chamber in fluid communication with said second chamber for receiving the platelet-containing component transferred from the secondary separation unit and for separating the platelet-containing component into platelets and another component, said third chamber being adapted to be mounted on said centrifugal separation apparatus;

a supply of platelet additive solution in fluid communication with said third chamber;

a first flow path portion allowing the platelet-containing component to flow into the third chamber; and

a second flow path portion allowing the platelet additive solution to flow into the third chamber and

means for introducing the platelet additive solution into the third chamber after an inflow of the platelet-containing component is stopped and for allowing the platelets to flow out of said third chamber along with the platelet additive solution comprising

a first clamp opening and closing the first flow path portion; and

a second clamp opening and closing the second flow path portion, and wherein the second clamp is closed when the first clamp is opened and the second clamp is opened when the first clamp is closed.

11. The platelet collection system according to claim 10 wherein the third chamber comprises a step wall between a first bottom portion and a second bottom portion.

12. The platelet collection system according to claim 11 wherein the third chamber further comprises an inlet port adjacent said first bottom portion, said inlet port being in fluid communication with said supply of platelet additive solution and with said second chamber; and an outlet port adjacent said second bottom portion.

13. A centrifugal blood separation system comprising

a primary separation unit including a first chamber for receiving whole blood collected from a donor and for separating the whole blood into a first blood component including a large number of platelets and into a remaining component, said first chamber being adapted to be mounted on a centrifugal separation apparatus;

a secondary separation unit including a second chamber in fluid communication with the first chamber for receiving the first blood component transferred from the primary separation unit and for separating the first blood component into a platelet-containing component and a second blood component, said second chamber being adapted to be mounted on said centrifugal separation apparatus;

a tertiary separation unit including a third chamber in fluid communication with said second chamber for receiving the platelet-containing component transferred from the secondary separation unit and for separating the platelet-containing component into platelets and another component, said third chamber being adapted to be mounted on said centrifugal separation apparatus; and

a supply of platelet additive solution in fluid communication with said third chamber and

means for introducing the platelet additive solution into the third chamber after an inflow of the platelet-containing component is stopped and for allowing the platelets to flow out of said third chamber along with the platelet additive solution;

a first flow path portion allowing the platelet-containing component to flow into the third chamber; and

a second flow path portion allowing the platelet additive solution to flow into the third chamber; and

said centrifuge separation apparatus comprising

a rotor;

a first clamp opening and closing the first flow path portion; and

a second clamp opening and closing the second flow path portion, and

means for controlling said clamps whereby the second clamp is closed when the first clamp is opened and the second clamp is opened when the first clamp is closed.