Effect of Hypoxia on Self-Renewal Capacity and Differentiation in Human Tendon-Derived Stem Cells

BACKGROUND Hypoxic conditions play roles in functioning of human tendon-derived stem cells (hTSCs). The goal of this study was to investigate the effect of various hypoxic conditions in self-renewal capacity and differentiation of TSCs. MATERIAL AND METHODS hTSCs was obtain from supraspinatus tendon donors. Colony formation and cell proliferation assay were used to assess the self-renewal of hTSCs. qRT-PCT and Western blot analysis were used to examine stemness and multi-differentiation potential of hTSCs. RESULTS We found that culturing at 5% O2 is more beneficial for the self-renewal of hTSCs than the other 3 culture conditions, with larger colony size and numbers. The proliferation of hTSCs in 5%, 10%, and 20% O2 cultures increased after seeding. The number of cells in the 5% O2 condition was higher than that in other culture; however, self-renewal capacity of hTSCs in 0.5% O2 was inhibited. The expression levels of stem cell markers, including NS, Nanog, Oct-4, and SSEA-4, were highest in 0.5% O2 culture. Furthermore, hTSCs cultured in 20% O2 exhibited significantly higher expression of the 3 markers (PPAR-γ, Sox-9, and Runx-2). CONCLUSIONS Hypoxic condition of culture encouraged self-renewal capacity of hTSCs, but inhibited their multi-differentiation potential, compared to normoxic condition of culture. Moreover, excessively low oxygen concentration impaired the capacity of hTSCs.