 The rationale in the use of such product is in the presence of several tissue growth factors: P.D.G.F. Platelet Derived Growth Factor; E.G.F. Epidermal Growth Factor; T.G.F. Transforming Growth Factor; V.E.G.F. Vascular Endothelial Growth Factor; I.G.F. 1 e 2 Insulin Growth Factor 1 and 2; F.G.F. Fibroblast Growth Factor. Applying in situ the iper-concentrated and activated platelets as platelet gel, tissue regeneration processes are started and accelerated. In this setting, platelets are similar to cellular laboratory-tanks that process, store and then release if activated several growth factors able to stimulate mesenchymal stem cell regeneration as fibroblasts, osteoblasts and endothelial cells. This platelet ability to take part in tissue repair mechanisms has been the theoretical essential requirement to use the platelet gel in several circumstances, all associated with the requirement of tissue repair activation. 