Effects of aFGF, bFGF, TGFbeta1 and IGF-I on odontoblast differentiation in vitro

In this work, we investigated the effects of aFGF and bFGF alone or combined with TGFbeta1 or IGF-I on odontoblast differentiation. Trypsin-isolated dental papillae from day 17 mandibular first molar were cultured in semisolid-agar medium for 6 d. Our results demonstrated that aFGF, bFGF or combinations of these promoted cell polarization at the periphery of the dental papillae. Moreover, simultaneous addition of aFGF and TGFbeta1 to dental papillae cultures induced both polarization and functional differentiation of odontoblast-like cells, as well as extracellular matrix deposition. Combination of aFGF or bFGF with IGF-I caused cell polarization at the surface of dental papillae, but matrix secretion was restricted to a few explants. In the presence of bFGF and TGFbeta1, the explants had pronounced cell elongations but no matrix deposition. These results indicate that aFGF or bFGF is not able to induce odontoblast differentiation alone. However, both aFGF and bFGF can act synergistically with TGFbeta1 and IGF-I to strengthen their inductive effects and promote gradients of cytological and functional changes in odontoblast-like cells.