Autophagy Prevents Oxidative Stress-Induced Loss of Self-Renewal Capacity and Stemness in Human Tendon Stem Cells by Reducing ROS Accumulation

Abstract

Background/Aims: Tendon stem cells (TSCs) exhibit a high self-renewal capacity, multi-differentiation potential, and low immunogenicity; thus, these cells might provide a new cell source for tendon repair and regeneration. TSCs are exposed to increased oxidative stress at tendon injury sites; however, how TSCs maintain their stemness under oxidative stress is not clear. Methods and Results: In this study, we found that H₂O₂ treatment increased ROS accumulation in human TSCs (hTSCs) and resulted in loss of self-renewal capacity and stemness, as reflected in reduced colony formation and proliferation, decreased expression of the stemness markers Nanog, Oct-4, NS, and SSEA-4, and impaired differentiation capability. These H₂O₂-induced damages were prevented by pretreatment with starvation or rapamycin. Pretreatment with starvation or rapamycin prior to H₂O₂ exposure also led to decreased intracellular and mitochondrial ROS accumulation along with increased autophagic activity, as manifested in increased LC3 cleavage, Beclin-1 expression, and GFP-LC3-labeled autophagosome formation. Autophagy inhibition by 3-MA or CQ, or by shRNA silencing of Agt-7 or Beclin-1 reduced the protective effects of starvation and rapamycin on H₂O₂-treated hTSCs. Conclusion: Thus, the findings of this study suggest that autophagy prevents oxidative stress-induced loss of self-renewal capacity and stemness in hTSCs through suppression of ROS accumulation.