Melatonin reverses flow shear stress-induced injury in bone marrow mesenchymal stem cells via activation of AMP-activated protein kinase signaling.

Tissue-engineered heart valves (TEHVs) are a promising treatment for valvular heart disease, although their application is limited by high flow shear stress (FSS). Melatonin has a wide range of physiological functions and is currently under clinical investigation for expanded applications; moreover, extensive protective effects on the cardiovascular system have been reported. In this study, we investigated the protection conferred by melatonin supplementation against FSS-induced injury in bone marrow mesenchymal stem cells (BMSCs) and elucidated the potential mechanism in this process. Melatonin markedly reduced BMSC apoptotic death in a concentration-dependent manner while increasing the levels of transforming growth factor β (TGF-β), basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF) and B-cell lymphoma 2 (Bcl2), and decreasing those of Bcl-2-associated X protein (Bax), p53 upregulated modulator of apoptosis (PUMA), and caspase 3. Notably, melatonin exerted its protective effects by upregulating the phosphorylation of adenosine monophosphate-activated protein kinase (AMPK), which promotes acetyl-CoA carboxylase (ACC) phosphorylation. Further molecular experiments revealed that luzindole, a nonselective antagonist of melatonin receptors, blocked the anti-FSS injury (anti-FSSI) effects of melatonin. Inhibition of AMPK by Compound C also counteracted the protective effects of melatonin, suggesting that melatonin reverses FSSI in BMSCs through the AMPK-dependent pathway. Overall, our findings indicate that melatonin contributes to the amelioration of FSS-induced BMSC injury by activating melatonin receptors and AMPK/ACC signaling. Our findings may provide a basis for the design of more effective strategies that promote the use of TEHCs in patients.