System and method for platelet removal during mononuclear cell collection

1. A method of collecting mononuclear cells, comprising:

separating with a separator whole blood from a whole blood source into cellular components and platelet-rich plasma;

removing the cellular blood components and the platelet-rich plasma from the separator;

returning the cellular components to the whole blood source without returning at least a portion of the platelets in the platelet-rich plasma to the whole blood source to reduce platelet concentration of whole blood subsequently flowing into the separator from the whole blood source; and

separating lower platelet concentration whole blood from the whole blood source into mononuclear cells and at least one component.

2. The method of claim 1 , further comprising stopping the separation of whole blood from the whole blood source into cellular components and platelet-rich plasma when an optical sensor disposed downstream of the separator detects that the platelet-rich plasma removed from the separator has a target platelet concentration.

3. The method of claim 1 , wherein the separator comprises a spinning membrane separator.

4. The method of claim 1 , wherein the separator comprises a centrifugal separator.

5. The method of claim 1 , wherein said separating whole blood into cellular components and platelet-rich, plasma and said separating lower platelet concentration whole blood into mononuclear cells and at least one component are performed substantially in series.

6. The method of claim 1 , wherein said separating lower platelet concentration whole blood from the whole blood source into mononuclear cells and at least one component includes separating the lower platelet concentration whole blood into mononuclear cells, a primarily plasma component, and remaining cellular components.

7. The method of claim 1 , further comprising

returning the platelet-rich plasma to the separator,

separating the platelet-rich plasma in the separator into platelet-poor plasma and platelet concentrate, and

removing the platelet-poor plasma from the separator.

8. The method of claim 7 , further comprising returning the platelet-poor plasma to the whole blood source without returning the platelet concentrate to the whole blood source.

9. The method of claim 7 , wherein said separating whole blood into cellular components and platelet-rich plasma and said separating the platelet-rich plasma into platelet-poor plasma and platelet concentrate are performed substantially in series.

10. The method of claim 7 , wherein said separating whole blood into cellular components and platelet-rich plasma and said separating the platelet-rich plasma into platelet-poor plasma and platelet concentrate are performed substantially at the same time.

11. A blood separation system, comprising:

a separator including a controller; and

a disposable fluid circuit configured to work in association with the separator, wherein the controller is configured to control the separator to

separate whole blood from a whole blood source into cellular components and platelet-rich plasma,

remove the cellular blood components and the platelet-rich plasma from the separator,

return the cellular blood components to the whole blood source without returning at least a portion of the platelets in the platelet-rich plasma to the whole blood source to reduce platelet concentration of whole blood subsequently flowing into the separator from the whole blood source, and

separate lower platelet concentration whole blood from the whole blood source into mononuclear cells and at least one component.

12. The blood separation system of claim 11 , further comprising an optical sensor disposed downstream of the separator, wherein the controller is configured to stop separation of whole blood from the whole blood source into cellular components and platelet-rich plasma when the optical sensor detects that the platelet-rich plasma removed from the separator has a target platelet concentration.

13. The blood separation system of claim 11 , wherein the separator comprises a spinning membrane separator.

14. The blood separation system of claim 11 , wherein the separator comprises a centrifugal separator.

15. The blood separation system of claim 11 , wherein the controller is configured to control the separator to separate whole blood into cellular component and platelet-rich plasma and to separate lower platelet concentration whole blood into mononuclear cells and at least one component substantially in series.

16. The blood separation system of claim 11 , wherein the controller is configured to control the separator to separate lower platelet concentration whole blood from the whole blood source into mononuclear cells and at least one component by separating the lower platelet concentration whole blood into mononuclear cells, a primarily plasma component, and remaining cellular components.

17. The blood separation system of claim 11 , wherein the controller is configured to control the separator to

return the platelet-rich plasma to the separator,

separate the platelet-rich plasma in the separator into platelet-poor plasma and platelet concentrate, and

remove the platelet-poor plasma from the separator.

18. The blood separation system of claim 17 , wherein the controller is configured to control the separator to return the platelet-poor plasma to the whole blood source without returning the platelet concentrate to the whole blood source.

19. The blood separation system of claim 17 , wherein the controller is configured to control the separator to separate whole blood into cellular components and platelet-rich plasma and to separate the platelet-rich plasma into platelet-poor plasma and platelet concentrate substantially in series.

20. The blood separation system of claim 17 , wherein the controller is configured to control the separator to separate whole blood into cellular components and platelet-rich plasma and to separate the platelet-rich plasma into platelet-poor plasma and platelet concentrate substantially at the same time.