Measuring EPC function in an in vitro assay. Cardiomyocyte survival (A) and endothelial cell apoptosis (B) after exposure to hypoxia-reoxygenation (18 h-4 h) ischemia-reperfusion. Cells were incubated with: endothelial progenitor cells (EPCs); EPCs transfected with Tβ4 short hairpin RNA (shRNA); EPCs transfected with scrambled (SC) shRNA in transwell plate; Tβ4 were added directly into culturing well. Control cells were not treated beside hypoxia-reoxygenation *P < 0.05 compared with the control group; †P < 0.05 compared with the Tβ4 group; ‡P < 0.05 compared with the EPC group; §P < 0.05 compared with the EPCs + SC shRNA group. Data are presented as mean ± standard deviation (n = 6 per group).