Effect of melatonin on the secretion of angiogenic cytokines in MSCs. (A-C) Secretion of the angiogenic cytokines, VEGF (A), FGF (B), and HGF (C), in MSCs treated with melatonin. Secretion of angiogenic cytokines was assessed by ELISA. Values represent the mean ± SEM. **p<0.01 vs. control; ##p<0.01 vs. MSCs+melatonin; $$p<0.01 vs. MSCs+melatonin+siPGC-1α. (D-F) Secretion of the angiogenic cytokines, VEGF (D), FGF (E), and HGF (F), in ischemic tissues after transplantation of PBS, MSCs, melatonin-treated MSCs (Melatonin+MSC), melatonin-treated MSCs pretreated with PGC-1α siRNA (Melatonin+MSC+siPGC-1α), and melatonin-treated MSCs pretreated with scrambled siRNA (Melatonin+MSC+si-Scr) in murine hindlimb ischemia model at postoperative day 3. Secretion of angiogenic cytokines in ischemic tissues was assessed by ELISA. Values represent the mean ± SEM. **p<0.01 vs. PBS; #p<0.05, ##p<0.01 vs. MSC; $$p<0.01 vs. Melatonin+MSC.