Fig.6 Assessment of activated platelets using flow cytometry. X axis represents anti-CD41a antibody (platelet marker) and the Y axis represents anti-CD62P antibody (marker for activated platelets)^［20］.

(a) Fresh PRP immediately after preparation (before activation).

(b) Activated fresh PRP

(a, c) Activated freeze dried PRP (8 weeks after preparation)

The percentages of activated platelets in freeze dried samples after 8 weeks were almost the same as in fresh PRP.