| Background and objective Myocardial infarction is one of the disease that can harm one,s heath and cause lethal events. Coronary flow supplied by collateral vessels and compensation of necrosis myocardium may protecct the myocardium from ischemia,reduce infarction size,save the myocardium on the risk of death. The experimental studies aim:1. To test the hypothesis that bone marrow stromal cells(MSCs), when implanted into myocardium, can undergo milium-depenendent differentiation and survival in the myocardial muscle.2.To evaluat the effect of the implanted MSCs on the functional restoration of damaged heart, promote angiogenesis of ischimic cardiac muscle,improved the supply of blood flow for ischimic cardiac muscle.Methods The first part The separation of bone marrow stromal cells,amplification in vitro,and its biological character Sternal bone marrow stromal cells was drew from doner rabbit leg bones,and MSCs were culture-expanded,amplification, traced MSCs labled with 4,6-diamidino-2-phenylindole(DAPI).We observed biological character of MSCs,and identified multi-potential differentiation of MSCs into lipoblast in vitro under approprite environment。The second part MSCs microenvironment dependent differentiation in cardiac muscle MSCs isolated from doner rabbit leg bones were culture-expanded,labeled with DAPI,and then injected into the myocardium of the same rabbit.The hearts were harvested from 1 day to 6 weeks after implantated.The implanted sites were examined to indentify the migration and survival of implanted cells,observe the changes of the labled implanted marrow stromal cells.The third part MSCs effection on reconstitution and repeated pouraton of infracted cardiac muscle ,and recovery of cardiac function Establish the model of rabbit acute myocardial infarction. MSCs draw from rabbits were culture in cell cuture medium,labeled with DAPI.Employing a rabbit ischemic heart modeling,MSCs were injected directly into the ischemic area and the number of vessels was examined immunohistochemically using the anti-CD31 monoclonal antibody.Cardiac function was measured by echocardiographybefore the cell implantation and 1 week, 4 weeks after MSCs transplanted. The pathological changes of ischemic cardiac muscle were observed. Results The first part Most of cultured MSCs were adherent to the culture plate within 24 hours,the adherent cells were seen as colonies only a few cells on 5-7 days,by the end of 12-14 days,the colonies of adherent cells had expanded in 80-90 percent size of the culture plate.Adhenent twice-passed MSCs had similar morphologic characteristics,most being fibroblastic in appearance. 88 percent cultured MSCs in static-stage cell cycle,about 96 percent were alive.Under electron microscope,The cultured MSCs were seen as primary unmature phenotype.7 days dying with oil red, most differentiated cells were positive.The second part Viable cells labeled with 4, 6-diamidino-2-phenylindole can be indentified in the implanted sites at all time points after implantated.The implanted marrow stromal cells show the growth potential in a myocardial microenvironmemt.After 6 weeks, doner cells contained sarcomeres and were connected by junctions composed of desmosomes and fasvia adherens.The third part Labled MSCs survived in ischemic myocardium；labled MSCs were found within the wall of small vessels in area adjacent to myocardial infarction, the cardiac function of the MSCs group was higher than that in medium injected(EF of MSCs prompted 0.46±0.03 vs 0.50±0.03 P<0.05)；FS was higher than that in medium injected(23.85±1.69 vs 27.02±1.27 P<0.05)；reduced the infarct size(4.43±1.0% vs 13.72±0.92%)；light microscpic analysis of the vessel count positively stained by anti-CD31 in the ischemic area showed that angiogenesis had been induced to a significantly greater degree in the group implanted with MSCs than that in the group injected with cell culture medium 4 weeks after MSCs implanted.(163.00±25.85 vs 96.00±16.61 P<0.05)；MSCs induced angiogenesis...
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