Experimental Studies On The Effects Of Bone Marrow Mesenchymal Stem Cells Transplantation And Hemangio-poietin On Isoproterenol-Induced Cardiomyopathy In Rats

Part I and IIDespite of advancement in medical and surgical procedures, congestive heart failure remains the leading cause of cardiovascular morbidity and mortality. Idiopathic dilated cardiomyopathy (DCM) is a primary myocardial disease of unknown etiology and an important cause of heart failure, characterized by loss of cardiomyocytes and an increase in fibroblasts. Encouragingly, cell therapy is becoming of great effects as a new therapy for patients with DCM accompanied by advanced heart failure. Bone marrow mesenchymal stem cells(BMSCs) have been shown to have beneficial effects on cardiac pump function and regeneration of cardiomyocytes. However, it's still unknown about which method of BMSCs transplantation is better. In this study, we compared the effects of MSC transplantation by left ventricular cavity infusions with those of intramyocardial injections on the cardiac function, cardiomyocyte regeneration, vascularity and cell apoptosis in the rat model of Isoproterenol-induced cardiomyopathy.Method: Isoproterenol (85mg/kg per day for three times, im) was introduced into Lewis rats,which were randomly divided into 3 groups 4 weeks past injection: Group A (BMSCs [1×10~7] transplanted by left ventricular cavity infusions, n=10), Group B (BMSCs [1×10~7] implanted by left ventricular intramyocardial injections, n=10) and Group C (DCM control group). Four weeks after implantation, the cardiac function were evaluated by echocardiography and cardiac catheterization. Cardiomyocyte regeneration was testified by immuno -fluerescence and the apoptosis related protein Bcl-2 and Bax were detected by Western blot. RT-PCR was used to assay mRNA expression of SDF-1 and VEGF. CD34 stained and histologic study were also performed.Result: Group A and group B had significant reduction in systolic left ventricular diameter(LVDs), diastolic left ventricular diameter (LVDd) and left ventricular end-diastolic pressure(LVEDP), and apparent increase in fractional shortening(FS), ejection fraction(EF), left ventricular systolic pressure(LVSP), the maximum rate of LV systolic pressure rise(+dp/dtmax) and the maximum rate of LV systolic pressure descend(-dp/dtmax) compared with DCM control group(all P<0.05). There was no significant difference in the alleviation of heart dysfunction between group A and group B(all P<0.05). The apoptosis of cardiomyocytes was significantly inhibited by the transplantation of BMSCs(P<0.05). Bcl-2 protein expression was up-regulated and Bax protein expression was evidently down-regulated in the group A and group B than that in the control group, with nearly same extents in the two treatment groups. The location of labeled BMSCs were scattered in group A, while it was in belts in group B. Moreover, there were more CD34 stained cells in group A than group B.Conclusion: BMSCs transplantation by either left ventricular cavity infusions or intramyocardial injections can both contribute to the improvement of cardiac function and the inhibition of cardiomycyte apoptosis equally in the rat model of Isoproterenol-induced cardiomyopathy. The delivery of BMSCs by left ventricular cavity infusions has more advantages in cardial myogenesis and angiogenesis.Part IIIAlmost a half of the new cases of heart failure encountered in clinical practice are nonischemic dilated cardiomyopathy (DCM). Stem cell transplan-tion and cytokine administration are becoming increasing important as a new potential therapy for patients with DCM. It's reported that angiogenesis, inhibition of cardiomyocyte apoptosis and alleviation of ventricular remodelling play important roles in its repairing process. Consequently, we administrated hemangiopoietin, a novel human growth factor for the primitive cells of both hematopoietic and endothelial cell lineages, to investigate the repairing effect on DCM.Method: Wistar rats were randomly grouped into DCM control group and hemangiopoietin treatment group (n=10). Isoproterenol (85mg/kg per day for three times, IM) was introduced into the rats. Subsequently, hemangiopoietin (300|ig/kg/day for 14 days) was administered subcutaneously in Iso + hemangiopoietin group and was replaced by N.S in Iso +N.S group. Four weeks later, the cardiac functions were evaluated by echocardiography and cardiac catheterization. Apoptosis related protein Fas were detected by Western blot. RT-PCR was used to assay mRNA expression of SDF-1 and VEGF. CD34 stained and histologic study were also performed.Result: In comparison with control group, the hemangiopoietin treatment group showed significant increase in EF(87.43±7.21% vs 78.96±6.03%), FS (59.74±3.65% vs 35.28±3.24%), LVSP(132.74±5.36% vs 75.15±7.35%), +dp/dt max(6418.8±378.53 vs 4353.8±265.84mmHg/s) and -dp/dtmax (6170.3±202.34 mmHg/s vs 4271±256.62 mmHg/s), whereas apparent decrease in LVDd (4.82±0.19 vs 6.52±0.53mm), LVDs(2.43±0.22mm vs 4.52±0.32mm) and LVEDP(13.03±1.76 mmHg vs 19.5± 2.62mmHg) (PO.05). The expression of apoptosis related protein Fas was evidently down-regulated in treatment groupthan that in control group. Hemangiopoietin significantly increased mRNA levels of VEGF and collagen type I, whereas those of TGF- P 1 -. MMP-2 and MMP-9 decreased. There were more CD34 stained cells in group A than group B also.Conclusion: The results suggested that hemangiopoietin treatment improved contractile function of DCM, presumably by acceleration of angiogenesis, inhibition of cardiomyocyte apoptosis and suppression of left ventricle remodeling.