Optimal Hypoxic Preconditioning of Human Embryonic Stem Cell-Derived Mesenchymal Stem Cells (hES-MSCs) and Their Characteristics

Background and Objectives: Hypoxia is frequently used to enhance stem cell function. However, the optimal level of hypoxia for growth and function of human embryonic stem cell-derived mesenchymal stem cells (hES-MSCs) is yet to be determined. The purpose of this study was to find the optimal level of hypoxia for hES-MSCs and characteristics of hES-MSCs cultured under these optimal hypoxic conditions. Methods and Results: Cell viability and changes in the morphology of hES-MSCs were determined through cell proliferation and CCK-8 assay. The hES-MSCs were preconditioned under various hypoxic conditions (0.5 similar to 5% O-2 and 24 similar to 72 h). The expression of cytokines in each culture condition was compared using cytokine array analysis. The morphology of hES-MSCs did not change under various hypoxic culture conditions. hES-MSCs viability after 48 h incubation in 2% O-2 condition was higher than that in normoxic condition. HIF1 alpha expression was increased up to six folds after 48 h of hypoxic preconditioning. HIF1 alpha expression in hES-MSCs peaked after 48 h of incubation in 1% O-2 condition. The expressions of PDGF-BB, IGFBP-6, VEGF-A, and angiogenin were increased after hES-MSCs were incubated for 48 h in 2% O-2 condition. Conclusions: The hES-MSCs viability and expressions of PDGF-BB, IGFBP-6, VEGF-A, and angiogenin increased after 48 h incubation in 2% O-2 condition.