[The principles of tissue engineering: role of growth factors in the bone regeneration]

In this article the principles of tissue engineering are analyzed. The growth factors release from platelets, TGF-beta, PDGF, IGF-I and -II, are accurately described and the structure and functions of these growth factors are reported. Then a simple model of bone regeneration is proposed. This model is used every time that bone grafts are used in oral and maxillofacial surgery. On the basis of this model of bone regeneration, the cells and biochemical indicators (pH and pO2) of bone wound where the bone graft is placed, and of surrounding tissues, are described. Then three phases of bone regeneration are analyzed: the beginning, the second (or immature bone), the third or mature bone with lamellar architecture. In each phase the importance of growth factors are evaluated. The conclusion is drawn that factors influence the bone regeneration and that their increased concentration leads to a quick bone formation and quantity. Moreover, the techniques of regeneration in vivo with autogenous bone, are better than those in vitro, since the bone structure, is also the result of the biomechanical environment, where the bone graft grows up.