Hypoxic culture maintains cell growth of the primary human valve interstitial cells with stemness

Characterization of aortic valve interstitial cells (VICs) maintained in an optimized culture is es-sential for understanding the molecular mechanism underlying aortic valve stenosis. Here, we propose 2% hypoxia as an optimum VIC culture condition. Harvested leaflets from patients with aortic valve regurgitation were digested using collagenase and VICs were cultured under the 2% hypoxic condition. Significant elevation in VIC growth was observed in the 2% hypoxia group (hypo-VICs), compared to the normoxia group (normo-VICs). RNA-sequencing revealed that downregulation of oxidative stress-marker genes (such as superoxide dismutase) and upregula-tion of cell cycle accelerators (such as cyclins) were detected in hypo-VICs. To characterize VICs cultured in hypoxic condition (hypo-VICs), we examined the gene expression profiles of hypo-VICs using RNA-sequencing and evaluated their ability to differentiation into osteoblasts.