Effect Of Paracrine Mechanisms On The Treatment Of Acute Myocardial Infarction In Rats By Transplantation Of Mesenchymal Stem Cells

Objective: To research the function of bone marrow mesenchymal stem cells conditioned medium on cardiac function after myocardial infarction and myocardial apoptosis; analysis cytokine secreted from stem cells in ischemia and hypoxia environment,reache the effect of paracrine mechanism in the treatment of Acute Myocardial Infarction in rats.Methord: According to the adherent characteristic,isolate and culture bone marrow mesenchymal stem cells ( MSCs) from the tibia and femur of 8 weeks aged SD rats. And the third passage cells were labled 72h in BrdU whoe final concentration was 20umol/L.we ligated left anterior descending coronary artery to established models of myocardial infarction. 20 SD rats either male or female, divided into 4 groups randomly: group A (the control group),2 weeks after the AMI estabilshed 200ul NS was injected via tail vein:group B (DMEM/F12 group), 2 weeks after the AMI estabilshed 200ulDMEM was injected via tail vein; group C(the MSCs group), a2 weeks after the AMI estabilshed 1×106MSCs in 200ul DMEM was injected via tail vein: group D(MSCs-CM group), 2 weeks after the AMI estabilshed 200u marrow mesenchymal stem cells conditioned medium was transplanted via tail vein. Cardiac function was detected by echocardiographic prior myocardial infarction,after myocardial infarction,after transplantation; 4 weeks after stem cell transplantation ontain the animal hearts, the density of neovascular was measured byⅧfactor immunohistochemistry; infarct size was calculated via TTC; rate of cardiomyocyte apoptosis was detected by TUNEL. detect of myocardial stem cells homing to myocardial by BrdU immunohistochemistry ;the cytokine of stem cell conditioned medium was detected by ELISA method. Result:(1) cardiac function deteced by doppler echocardiography before and after myocardial infarction: group C, D compared wth group A,B, 4 weeks after transplantation LVEDd,LVEDs,EF Improved significantly, statistically significant (P<0.05); (2)myocardial infarct size was detected by TTC: group C, D compared wth group A,B, infarct size significantly reduced statistically significant (P<0.05); (3)the rate of cardiomyocyte apoptosis was detected via TUNEL: group C, D compared wth group A,B ,apoptosis was significantly lower, statistically significant (P<0.05)(;4)homing of stem cells was observed by BrdU immunohistochemistry: the homing stem cells is detected in group C;(5)vascular density was observed byⅧfactor immunohistochemistry :group C, D compared wth group A,B,neovascularization increased significantly, statistically significant (P<0.05); (6)we detect VEGF,bFGF,IL-6,but do not detect IL-6,IL-2.in Conditioned stem cell culture media .Conclusion:(1)Mesenchymal Stem Cells conditioned medium, could increase cardiac function of myocardial infarction of rats,(2)Mesenchymal Stem Cells can stimulate angiogenesis, depress secretion myocardial cells apoptosis,which might be the result of joint action of VEGF, bFGF(3) Mesenchymal Stem Cells express IL-6, may be involved in inhibition of Th0 cells differentiation into Th1 cells, which play a role in immune regulation.