Inhibition of mircoRNA-34a Enhances Survival of Human Bone Marrow Mesenchymal Stromal/Stem Cells Under Oxidative Stress

BACKGROUND: Mesenchymal stromal/stem cells (MSCs) are broadly used for many diseases, but the efficacy of MSC engraftment is very low due to low viability and high cell death rate under a stressful microenvironment. The present study aimed to investigate whether microRNA-34a (miR-34a), which is a downstream target of P53, is involved in H(2)O(2)-induced MSC cell death. MATERIAL/METHOD: Human bone marrow MSCs (hMSCs) were purchased from Lonza and were cultured as previously described. hMSCs were transfected with miR-34a inhibitor and exposed to H(2)O(2). Cell proliferation assay was used to assess the survival rate of hMSCs. Real-time PCR and Western blot analysis were used to examine proliferation and survival ability of hMSCs. RESULTS: H(2)O(2) exposure significantly increased miR-34a expression in human bone marrow MSCs. H(2)O(2) challenge induced massive MSC cell death along with reduction of expression of proliferation marker Ki67 and survival-related genes Bcl-2 and Survivin. Transfection of miR-34a inhibitor anti-34a led to a significant protective effect and rescued MSC cell death triggered by H(2)O(2) exposure by 50%. Moreover, anti-34a dramatically increased Bcl-2 and Ki67 mRNA expression levels by over 10-fold compared to the mock control group under H(2)O(2) exposure. The protein levels of Bcl-2 and Survivin were also rescued by anti-34a treatment by 50%. CONCLUSIONS: Our results suggest that miR-34a plays a key role in oxidative stress-induced MSC cell death, and targeting miR-34a might be a promising strategy to enhance the survival rate of engrafted stem cells, which may improve therapeutic outcome.