L-ascorbic acid 2-phosphate promotes osteoblastic differentiation of MC3T3-E1 mediated by accumulation of type I collagen.

L-Ascorbic acid 2-phosphate (Asc-P: a stable ascorbic acid derivative) markedly stimulated synthesis of marker proteins for osteoblastic differentiation such as alkaline phosphatase and osteocalcin in a murine osteoblastic cell line, MC3T3-E1, suggesting that Asc-P could promote osteoblastic differentiation. L-Azetidine 2-carboxylate (AzC) diminished the stimulatory effects of Asc-P on the synthesis of alkaline phosphatase and osteocalcin due to its inhibitory effects on mature collagen secretion. Growing cells on the dishes coated with type I collagen resulted in an increased expression of osteoblastic phenotypes even in the presence of AzC. Coating with fibronectin, however, failed to promote differentiation. These results suggest that the promotion of cell differentiation caused by Asc-P is mediated by the accumulation of mature collagen.