Effect of hypoxia on proliferation and differentiation of induced pluripotent stem cell-derived mesenchymal stem cells.

Although mesenchymal stem cells (MSCs) are extensively applied in the regenerative field, the majority of MSCs die after a few weeks of transplantation. Therefore, hypoxia pre-conditioning is a crucial step in increasing the MSCs' tolerance to physiological conditions. Meanwhile, induced pluripotent stem cell-derived MSCs (iMSCs) were proposed as a possible alternative to MSCs, and recently, the interest is growing in applying iMSCs in the regenerative field. This study examined the effect of hypoxia pre-conditioning on the proliferation, viability, and differentiation of iMSCs. Both iMSCs and MSCs were subjected to two rounds of severe short-term hypoxia (1 % O for 24h). After that, iMSCs and MSCs were characterized by testing their surface markers' expression, proliferation, viability, oxidative stress, and differentiation potential. Our findings revealed that hypoxia did not have a consistent effect among all the analyzed lines: the severe short-term hypoxia (1 % O) reduced iMSCs proliferation, cell viability, and MMP while showing a benign effect on surface markers expression, colony formation, ROS accumulation, and osteogenic and adipogenic differentiation. Though hypoxia adversely affected iMSCs' proliferation, this does not necessarily mean that hypoxia is harmful to iMSCs; on the contrary, our results suggest that short-term hypoxia might have a beneficial long-term effect on the proliferation of iMSCs. Thus, the effect of hypoxia on proliferation, viability, and differentiation should also be tested after a long recovery period from iMSCs. Our next step will be to test the effect of hypoxia for a longer period besides uncovering the changes in the expression profile of hypoxic iMSCs.