Effect of Retinoic Acid on Osteogenesis of Umbilical-Cord Stem Cells

Background. Retinoic acid (RA) is known to induce osteogenic differentiation in many cell types including mesenchymal stem cells obtained from various sources. Objective. The objective of this study was to investigate the potential of retinoic acid as an inducer of osteogenic differentiation in human umbilical cord derived mesenchymal stem cells (hUMSCs) and its use in bone tissue engineering for the repair and regeneration of craniofacial bony defects. Methods. The hUMSCs obtained from Sciencell (Carlsbad, CA) were cultured in complete medium containing low glucose Dulbecco’s modified eagle medium with 10% of fetal bovine serum and 1% antibiotic and antimycotic solution at 37°C in 5% CO2. Subconfluent cells were treated with retinoic acid (0.5, 1 and 2μM) in the presence of complete medium along with ascorbic acid and β glycerophsophate. Cell proliferation was measured by MTT assay and osteogenic marker gene expression was measured by RT-PCR. The activity of alkaline phosphatase (ALP) enzyme was determined using colorimetric assay. Matrix mineralization was assessed by alizarin red staining. Results. Cell proliferation was significantly decreased in dose dependent manner in the cells exposed to retinoic acid when compared to control. The ALP gene expression was significantly down regulated by RA in a dose dependent manner. The ALP activity showed a significant decrease in the cells treated with retinoic acid. hUMSCs did not show matrix mineralization. Conclusion. The results of this study