Stemness of Human Pluripotent Cells: Hypoxia-Dependent Effect of Nitric Oxide

Optimization of conditions to promote in vitro the stemness of pluripotent cells is instrumental for their use in advanced therapies. We show here that exposure of human (iPSC) and human (ESC) to low concentrations of the chemical NO donor DETA/NO leads to stabilization of hypoxia-inducible factors (HIF-1α and HIF-2α) under normoxia, this effect being dependent on diminished Pro 402 hydroxylation and decreased degradation by the proteasome. Moreover, the master genes of pluripotency NANOG and OCT4 were upregulated. NO also induces a shift in the metabolic profile of PSCs with increased expression of hypoxia response genes in glycolysis. Furthermore, a reduction in the mitochondrial membrane potential with lower oxygen consumption and increased expression of mitochondrial fusion regulators, such as DRP1 was observed. The results reported here indicate that NO mimics hypoxia response in human PSCs and enhances their stemness properties when cultured under normoxic conditions.