Dimethyloxaloylglycine Increases the Bone Healing Capacity of Adipose-Derived Stem Cells by Promoting Osteogenic Differentiation and Angiogenic Potential

Hypoxia inducible factor-1 alpha (HIF-1 alpha) plays an important role in angiogenesis-osteogenesis coupling during bone regeneration, which can enhance the bone healing capacity of mesenchymal stem cells (MSCs) by improving their osteogenic and angiogenic activities. Previous studies transduced the HIF-1 alpha gene into MSCs with lentivirus vectors to improve their bone healing capacity. However, the risks due to lentivirus vectors, such as tumorigenesis, should be considered before clinical application. Dimethyloxaloylglycine (DMOG) is a cell-permeable prolyl-4-hydroxylase inhibitor, which can activate the expression of HIF-1 alpha in cells at normal oxygen tension. Therefore, DMOG is expected to be an alternative strategy for enhancing HIF-1 alpha expression in cells. In this study, we explored the osteogenic and angiogenic activities of adipose-derived stem cells (ASCs) treated with different concentrations of DMOG in vitro, and the bone healing capacity of DMOG-treated ASCs combined with hydrogels for treating critical-sized calvarial defects in rats. The results showed that DMOG had no obvious cytotoxic effects on ASCs and could inhibit the death of ASCs induced by serum deprivation. DMOG markedly increased vascular endothelial growth factor production in ASCs in a dose-dependent manner and improved the osteogenic differentiation potential of ASCs by activating the expression of HIF-1 alpha. Rats with critical-sized calvarial defects treated with hydrogels containing DMOG-treated ASCs had more bone regeneration and new vessel formation than the other groups. Therefore, we believe that DMOG enhanced the angiogenic and osteogenic activity of ASCs by activating the expression of HIF-1 alpha, thereby improving the bone healing capacity of ASCs in rat critical-sized calvarial defects.