Aim We applied transplantation of activated platelet-rich plasma supernatant(APRPS) to the infarcted region,to investigate its role in the ventricular remodeling after myocardial infarction in rats.Methods 105 Wistar male rats were randomized to platelet-rich group that received APRPS,platelet-poor group that received activated platelet-poor plasma supernatant(APPPS),and sham operation group.Platelet-rich plasma(PRP) and platelet-poor plasma(PPP) were harvested from healthy rats by centrifugation and activated with thrombin.After thrombin activation,the level of vascular endothelial growth factor(VEGF) in PRP and PPP was measured by enzyme-linked immunosorbent assay.Ligation of the left anterior descending coronary artery(LAD) was performed and 100 μL APRPS or APPPS was injected in five different sites at the infarcted border zone immediately after ligation of LAD.Rats were sacrificed in 7 and 28 days for determination of left ventricular passive pressure-volume relationship,and prepared for picrosirius red staining and fluorescence analysis.Results Compared with platelet-poor group,platelet-rich group was associated with a leftward shift of diastolic pressure-volume curve in 28 days.APRPS transplantation may limit infarct size,thicken left ventricular free wall,and attenuate hypertrophy of viable cardiomyocytes,which accompanied by increased arteriogenesis and angiogenesis.Conclusions Transplantation of activated platelet-rich supernatant could accelerate healing process and improve ventricular remodeling after myocardial infarction.