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Object The purpose of this study was to explore whether melatonin could protect mesenchymal stem cells (MSCs) against ischaemic injury, by inhibiting endoplasmic reticulum (ER) stress and autophagy both in vivo and in vitro. Materials and Methods To confirm the protective effect of melatonin against ER stress in MSCs, markers of cell viability, apoptosis and autophagy were analysed. To further investigate the regenerative effect of melatonin‐treated MSCs in ischaemic tissues, a murine hindlimb ischaemic model was established. Results Under oxidative stress conditions, treatment with melatonin suppressed the activation of ER stress–associated proteins and autophagy‐associated proteins acting through upregulation of cellular prion protein (PrPC) expression. Consequently, inhibition of apoptotic cell death occurred. Melatonin also promoted the activation of MnSOD and catalase activities in MSCs. In a murine hindlimb ischaemia model, melatonin‐treated MSCs also enhanced the functional limb recovery as well as neovascularization. These beneficial effects of melatonin were all blocked by knock‐down of PrPC expression. Conclusion Melatonin protects against ER stress/autophagy‐induced apoptotic cell death by augmenting PrPC expression. Thus, melatonin‐treated MSCs could be a potential cell‐based therapeutic agent for ER stress–induced ischaemic diseases, and melatonin‐induced PrPC might be a key molecule in ameliorating ER stress and autophagy.

OBJECTIVES: The purpose of this study was to explore the effectiveness of concurrent GRP78 overexpression combined with Cripto on hMSC proliferation and migration both in vitro and in vivo. Specifically, we explored whether the treatment enhances effectiveness of hMSC transplantation in ischaemic tissue. MATERIALS AND METHODS: Human MSCs obtained from human adipose tissue were cultured in α‐minimum essential medium (Hyclone, Logan, UT, USA) supplemented with 10% (v/v) foetal bovine serum (Hyclone), 100 U mL(−1) penicillin and 100 μg mL(−1) streptomycin. Murine hindlimb ischaemic model was generated with 8‐week‐old male nude BALB/c mice (Biogenomics, Seoul, Korea) maintained under a 12‐h light/dark cycle following the established protocol with minor modification. Cellular injection was performed no later than 3 hour after surgery. Lipofectamine transfection, single‐cell cultivation assay, transwell assay, scratch wound‐healing migration assay, immunohistochemistry and western blotting assays were performed. RESULTS: Overexpression of GRP78 along with Cripto enhanced hMSC proliferation, migration and invasion. It increased interaction of surface GRP78 receptor with Cripto via JAK2/STAT3 pathway. We confirmed our proposed mechanism by showing that treatment with GRP78 antibody blocks the enhancement in vitro. In vivo, we observed that Cripto induced by the hypoxic environment in hindlimb ischaemic model interacts with the overexpressed GRP78 and increases hMSC proliferation, migration and invasion potentials as well as angiogenesis around transplanted ischaemic site via cytokine secretions. CONCLUSIONS: These results demonstrate supporting evidences that GRP78‐Cripto combination technique offers novel strategy to enhance MSC proliferation, migration and invasion potentials as well as angiogenesis around ischaemic site, ultimately facilitating MSC‐based transplantation therapy in ischaemic conditions.