Platelet-Derived Growth Factor (PDGF) is a mitogenic peptide growth hormone carried in the alpha -granules of platelets and is released when platelets adhere to traumatized tissues. Connective tissue cells near the traumatized region respond by initiating the process of replication. The synthesis of PDGF can be induced by IL-1, IL-6, TNF- alpha , TGF- beta and EGF. Recombinant PDGF-BB is a non-glycosylated, disulfide-linked homodimer, containing two 109 amino acid chains, with a total molecular weight of 24.3 kDa.