Purpose: The purpose of this study was to evaluate the effects of 1,25-dihydroxyvitamin D3 on the proliferation, differentiation, and matrix mineralization of MC3T3-E1 osteoblast-like cells in vitro.
Methods: MC3T3-E1 osteoblastic cells and 1,25-dihydroxyvitamin D3 were prepared. Cytotoxic effects and osteogenic differentiation were evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, alkaline phosphatase (ALP) activity assay, ALP staining, alizarin red S staining, and reverse transcription-polymerase chain reaction (RT-PCR) for osteogenic differentiation markers such as ALP, collagen type I (Col-I), osteocalcin (OCN), vitamin D receptor (VDR), and glyceraldehyde 3-phosphate dehydrogenase.
Results: The MTT assay showed that 1,25-dihydroxyvitamin D3 did not inhibit cell growth and that the rate of cell proliferation was higher than in the positive control group at all concentrations. ALP activity was also higher than in the positive control group at low concentrations of 1,25-dihydroxyvitamin D3 (10-10, 10-12, and 10-14 M). RT-PCR showed that the gene expression levels of ALP, Col-I, OCN, and vitamin D receptor (VDR) were higher at a low concentration of 1,25-dihydroxyvitamin D3 (10-12 M). Alizarin red S staining after treatment with 1,25-dihydroxyvitamin D3 (10-12 M) showed no significant differences in the overall degree of calcification. In contrast to the positive control group, formation of bone nodules was induced in the early stages of cell differentiation.
Conclusions: We suggest that 1,25-dihydroxyvitamin D3 positively affects cell differentiation and matrix mineralization. Therefore, it may function as a stimulating factor in osteoblastic bone formation and can be used as an additive in bone regeneration treatment.
Keywords: Bone regeneration; Calcitriol; Osteoblasts.