Curcumin pretreatment protects against hypoxia/reoxgenation injury via improvement of mitochondrial function, destabilization of HIF-1 alpha and activation of Epac1-Akt pathway in rat bone marrow mesenchymal stem cells

Bone marrow mesenchymal stem cells (BMSCs) possess promising therapeutic effects and have been considered as a highly desirable agent for tissue injury treatment. However, little survived cells after transplanting due to severe relocated conditions (characterized by prolonged hypoxia and oxidative stress) lead to hampered benefits of BMSCs-based cell therapy. Curcumin, a natural dietary product, has attracted increasing attention owing to its profound pharmacologic properties. Here, we report the protective effects of curcumin pretreatment in BMSCs against hypoxia and reoxygenation (H/R) triggered injury, which mimick ischemia/reperfusion in vivo. We found that curcumin pretreatment remarkably inhibited H/R-induced cell viability loss, cell nuclei condensation, LDH leakage, as well as caspase-3 activity increase in BMSCs. Furthermore, curcumin pretreatment prevented H/R-induced mitochondrial dysfunction through expediting adenosine triphosphate production and suppressing reactive oxygen species accumulation and mitochondrial membrane potential decline. In addition, curcumin pretreatment notably induced HIF-1 alpha destabilization, Epac1 and Akt activation, and Erk1/2 and p38 deactivation. However, Epacl inhibitor ESI-09 obviously restrained the increase of p-Akt induced by curcumin, but not p-Erk1/2 or p-p38, and abrogated the protective effect of curcumin on BMSCs' survival and arrested cell cycle in G0/G1 phase. Taken together, these results demonstrated that curcumin pretreatment conferred BMSCs the ability to survive from H/R injury, which might attribute to its protection on mitochondrial function, destabilization of HIF-1 alpha and activation of Epac1-Akt signaling pathway. Thus, this study provides more pharmacologic aspects of curcumin, and suggests that pre-conditioning of BMSCs with curcumin could serve as an attractive approach for facilitating cell therapy in tissue repair treatment.