Effect of Vitamin C on pre-osteoblast gene expression.

Ascorbic acid (AA), also known as Vitamin C, is a cofactor required for the function of several hydroxylases. It is not synthesised in humans and has to be provided by diet. Its absence is responsible for scurvy, a condition related to the defective synthesis of collagen by the reduced function of prolylhydroxylase. AA is also a risk factor for periodontal disease. Recently, it has been shown that AA induces embryonic stem cells to differentiate into osteoblasts. The mechanism by which AA sustains pre-osteoblast proliferation and commitment is mediated through the synthesis of collagen type I, interaction with alpha2- and beta1-integrin, activation of the mitogen-activated protein kinase pathway, and phosphorylation of osteoblast-specific transcription factors. However, the multifunctional role of AA is not fully elucidated. MC3T3-E1 mouse calvaria-derived cell line is a well-defined in vitro model of pre-osteoblast differentiation, and AA is essential for the proliferation and differentiation of MC3T3-E1. By using DNA micro-arrays containing 15,000 genes, we identified several genes in MC3T3-E1 cultured with AA for 24h whose expression was significantly up or downregulated. The differentially expressed genes covered a broad range of functional activities: (1) cell growth; (2) metabolism; (3) morphogenesis; (4) cell death; (5) cell communication. The data reported are, to our knowledge, the first genetic portrait of early stage stimulation of pre-osteoblasts by AA, and may be relevant to better understand the molecular mechanism of pre-osteoblast proliferation and commitment. Elucidation of the molecular mechanism has important clinical implications because it may facilitate the correct use of AA to accelerate bone regeneration.