Platelet-rich plasma (PRP) is an autologous source of platelet-derived growth factors, and has been used successfully in oral surgery repair. However, little is known about the underlying release mechanisms for these factors or the manner in which stimulation of human dental pulp cells is regulated. The present study investigated the efficacy of PRP as a stimulator of human dental pulp cell proliferation. Cell proliferation was weakly stimulated by treatment with PRP, while washed platelet (WPLT) treatment was more effective in stimulating cell growth. Moreover, platelet-poor plasma (PPP) dose-dependently inhibited the growth of cultured human dental pulp cells. Indomethacin and dexamethazone, a selective inhibitor of prostaglandins, markedly inhibited the WPLT-induced cell proliferation. In addition, SB431542, a specific inhibitor of TGF-β1 and TGF-β1, completely inhibited WPLT-induced PGE2 production and cell proliferation of the cells. WPLT rapidly induced COX-2 expression and PGE2 production, which in turn stimulated cell proliferation. These results suggest that WPLTs are potent stimulators of human dental pulp cells, and that the local release of the TGF-β-induced PGE2 is involved in WPLT-induced cell proliferation.
