Fig. 1

Metformin dampens MSC therapeutic efficacy in MI. a Representative images of TTC-stained heart sections obtained from Sham, MI + PBS, MI + metformin, MI + MSCs, and MI + metformin + MSCs groups at 4 weeks after MI. b LV infarct sizes expressed as the ratio of the area of the infarct band to the total area of LV (n = 23). c Representative M-mode images of hearts with sham surgery or MI at 4 weeks after PBS, metformin, MSCs, and metformin + MSCs treatment. Scale bar: X axis: 0.1 s; Y axis: 0.2 cm. d Heart rates were controlled to be similar in different groups (n = 23). e–g LV fraction shortening (e), LV ejection fraction (f), and diastolic left ventricle internal diameter (LVIDd) (g) at 4 weeks after treatment (n = 23). *p < 0.05 vs. sham; ^#p < 0.05 vs. MI + metformin; ^&p < 0.05 vs. MI + MSCs, by one-way ANOVA