Figure 2.

Preparation of different plasma formulations for lyophilization. Single spinning of anticoagulated whole blood yields platelet-rich plasma (PRP) with moderate concentration of platelets (and optionally leukocytes), for the purpose of this study designed as (1); alternatively, double spinning or plateletpheresis systems produce platelet concentrates (PCs) designed as (2). The pellet can be resuspended in a determined volume of Platelet-Poor Plasma (PPP) and platelet count adjusted, or platelets can be used without plasma. When PRP or PC products are freeze-thawed multiple times (commonly 3) or sonicated, the resultant platelet lysates (PLs) contains platelet secretome along with platelet membranes (ghost platelets) designed as (3) and (4), respectively. Alternatively, the platelet secretome can be obtained after the activation of platelets by adding calcium chloride/ thrombin. The supernatant released from the clot (from PRP (5) or PCs (6)) contains the whole platelet secretome. PRF (7) is obtained by centrifuging noncoagulated peripheral blood and disposing of the formed hydrogel the red blood cells. Terminology: PRP, platelet-rich plasma; PC, platelet concentrate; PPP, platelet-poor plasma; PL, platelet lysate; PRF, platelet-rich fibrin; FD-PRP, freeze-dried platelet-rich plasma; FD-PC, freeze-dried platelet concentrate; FD-PL, freeze-dried platelet lysate; FD-PRF, freeze-dried platelet-rich fibrin.