The Effects Of Intravenous Administration Of Human Umbilical Cord Blood Mononuclear Cells On The Expressiong Of Matrix Metalloproteinase 9 And Collagen After Myocardial Infarction

ObjectiveThis study was aimed to investigate the effects of intravenous administration of human umbilical cord blood mononuclear cells (HUCBMCs) on the expressiong of matrix metalloproteinase 9 and collagen after myocardial infaretion(AMI) in rabbit models.Methods45 Chinese rabbits were divided into three groups randomly:Cells transplantation group with 15 rabbits were intravenously administrated with HUCBMCs labeled with bromodexyuridine(BrdU) at 24h after myocardial infarction; Control group with 15 rabbits were intravenously administrated with saline at 24h after myocardial infarction. The sham operation group with 15 rabbits only not receiving ligation of coronary artery were intravenously administrated with saline at 24h after the operation. Cardiac function indexes encluding left ventricular fractional shortening (LVFS) and left ventricular ejection fraction (LVEF) was assessed by echocardiography at 1st week,2nd week and 4th week after transplantation. Expression of MMP-9 in the myocardium were detected by ELISA and RT-PCR. Collagen in cardiac tissue were observe by Masson staining. RESULTS1) The LVFS and LVEF in both control group and transplantation group were signficantly decreased compared with the sham operation group.Compared to control group,transplantation of HUCBMCs improved left ventricular function indexs such as LVFS, LVEF at all 3 examinations by echocardiography;2) Immunostaining examination showed that transplanted cells labeled with BrdU were found in the peri-myocardial infarction area in the transplanted group;3) Compared with sham operation group, the expressions of MMP-9 level and MMP-9 mRNA were significantly higher in the myocardial infarction area in the both control group and transplantation group by RT-PCR and ELISA; Compared to the control group, the expressions of MMP-9 level and MMP-9 mRNA were significantly reduced in the transplantation group. Collagen expression in MASSON staining was significantly decreased in the transplantation group compared to the control group.Conclusions1 HUCBMCs by intravenous administration could migrate to the infarct region and survive in the peri-myocardial infarction area in the transplantation group;2 Intravenous administration of HUCBMCs obviously improved the cardiac fuction and inhibited the MMP-9 level, MMP-9 mRNA and Collagen expression in the peri-infarcted area after myocardial infarction. The results suggested that inhibition of the myocardial fibrosis might be one of main mechanisms possible for stem cell transplatation for heart function after myocardial infarction.