The invention provides for a method of preparing an isolated serum fraction of platelet rich fibrin (PRF), comprising the steps of a. providing platelet rich plasma (PRP) without the addition of an anticoagulant； b. clotting the PRP to obtain a coagel of PRF； and c. separating the coagel to isolate the serum fraction which comprises an activated platelet releasate； and further provides for the isolated serum fraction obtained by such method, and its medical use.
