Stimulation of the dentine–pulp complex of rat incisor teeth by transforming growth factor-β isoforms 1–3 in vitro

Expression of transforming growth factor-β (TGF-β) isoforms by odontoblasts leads to their sequestration within dentine matrix. TGF-β1 and -β3 stimulate matrix secretion and also initiate odontoblast cytodifferentiation in vitro and in vivo. Using a recently established organ-culture model, the aim here was to examine the effects of TGF-β isoforms on the response of the dentine–pulp complex during culture. Agarose beads were soaked in isoforms 1–3, and placed on the odontoblast area of slices of 28-day-old rat incisor tooth. The slices were maintained in Trowel-type cultures for 7 days. Both TGF-β1 and -β3 stimulated a local increase in predentine secretion at the site of the bead application when compared to control cultures. Mitogenic effects on the cells of the subodontoblast layer were also seen and occasionally small foci of newly differentiated odontoblast-like cells could be observed a little distant from the application site of TGF-β3. TGF-β2 had a minimal effect on the cultured tissues. These results demonstrate that TGF-β1 and -β3 can stimulate secretion of extracellular matrix by odontoblasts, are mitogenic to pulp cells, and that TGF-β3 may have inductive effects on pulpal cells. Such activities might be important during reparative processes in the dentine–pulp complex after tissue injury.