Induction of differentiation and mineralization in rat tooth germ cells on PVA through inhibition of ERK1/2

Poly(vinyl alcohol) (PVA) has been widely used in the field of biomedical applications because of its hydrophilic properties for desired functions. Nonetheless, the role of PVA in tooth germ (TG) cell differentiation and mineralization has seldom been explored. To test the capacity of PVA in regulating TG cell differentiation and mineralization, TG cells obtained from 4-day-old Wistar rats were cultured on the PVA substrate. It was found that PVA was able to promote TG cell exhibiting high levels of alkaline phosphatase (ALP) activity, mineralization, and mRNA expression of osteocalcin (OCN), osteopontin (OPN), dentin matrix protein 1 (DMP1) and enamelin. Even when the additives routinely administrated in the differentiation medium such as dexamethasone, β-glycerophosphate and ascorbic acid were removed from the culture system, PVA itself still stimulated TG cells with the differentiation and mineralization ability. By showing the direct suppression of extracellular signaling-regulated kinase1/2 (ERK1/2) of TG cells treated with U0126, known to suppress the activation of ERK1/2, and significant synergistic effects between PVA and U0126, we demonstrated the suppression of ERK1/2 pathway is one of the effects of PVA-promoted TG cell differentiation and mineralization. Taken together, this study demonstrated a novel role of PVA in promoting the differentiation and mineralization of TG cells through ERK1/2 acting as a negative regulator.