Promoting Osteogenesis of Human Umbilical Cord Mesenchymal Stem Cells Using 1α, 25-(OH)2D3 to Change Intracellular Calcium Concentration

: Vitamin D plays a major role in the regulation of calcium homeostasis and affects bone metabolism. There is currently limited detailed knowledge about the vitamin D endocrine system in human bone cells. Here, we investigated the direct effects of 1α, 25-dihydroxyvitamin D₃ (1α, 25-(OH)₂D₃ or 'VD3') on osteogenesis of human umbilical cord mesenchymal stem cells (HUCMSCs). We also studied the impact of VD3 on intracellular Ca2+ concentrations in osteogenic cells. The results of alizarin red staining and alkaline phosphatase activity tests showed that VD3 could not induce osteogenic differentiation in HUCMSCs. However, addition of VD3 to the osteogenic differentiationinducing medium could promote HUCMSC to differentiate into osteoblasts. Calcium imaging showed that the addition of VD3 increased intracellular Ca2+ concentrations in osteogenic HUCMSCs. Thus, we concluded that adding VD3 increased intracellular Ca2+ concentrations in osteogenic HUCMSCs and promoted their osteogenesis.