OBJECTIVETo observe the proliferation state of transplanted cells in acute myocardial infarction (AMI) rats, and the endothelial progenitor cells (EPCs) preconditioned by salvianolic acid B in different ratios with the bone mesenchymal stem cells (BMSCs).

METHODSThe cultivation and purification of EPCs were performed by density-gradient centrifugation and plastic adherence method. Two types of cells were identified by immunocytochemical method (CD34, CD133, and CD44). The rat model of AMI was prepared by ligation of left anterior descending artery. The EPCs were pre-treated with the optimal concentration of salvianolic acid B (8 microg/ mL). They were mixed with BMSCs in different proportions (EPCs/BMSCs in the ratio of 1:1, 2:1, 4:1, and 8:1, respectively). BMSCs and EPCs were injected into the myocardial infarction area. The infarcted area was determined by the N-BT staining and hematoxylin-eosin staining. The expression of Ki-67 was detected by immunohistochemical assay.

RESULTSCompared with the model group (19.60% +/- 3.23%), the myocardial infarction area of each implanted group obviously decreased (P < 0.05). Of them, the decrease was most obvious in the 4:1 group (11.37% +/- 2.18%) and the 8:1 group (9.23% +/- 2.35%, P < 0.05). Compared with the model group (cell/high magnification, 5.17 +/- 2.31), the Ki-67 positive cell number of each implanted groups significantly increased (P < 0.05). Of them, the Ki-67 positive cell number was obviously higher in the 8:1 group (15.00 +/- 3.16, P < 0.05).

CONCLUSIONSEPCs pretreated by salvianolic acid B combined with BMSCs could reduce the myocardial infarcted area, improve the proliferation of BMSCs in the peripheral infarction and local ischemia. Besides, along with the increase of the implant proportion of EPCs, the infarct area was gradually reduced, and the proliferative expression was gradually enhanced.