Effect of human umbilical cord mesenchymal stem cells by intramuscular injection on cardiac function and microvascular regeneration in rats with dilated cardiomyopathy

Abstract

Objective To evaluate the effect of human umbilical cord mesenchymal stem cells (hUCMSCs) treatment through intramuscular administration on the heart function and angiogenesis of the myocardium in dilated car-diomyopathy (DCM) rats induced by Adriamycin(ADR). Methods One hundred male SD rats were randomly divided into the normal group and the DCM group.Rats in the DCM group were treated with ADR by intraperitoneal injection of 2.0 mg/kg dose per week for 8 weeks in order to induce DCM.Sixty modeled surviving rats with DCM were randomly divided equally into 3 groups, and they were treated with hUCMSCs or DMEM by intramuscular injection.Rats in the DMEM group (20 cases) received intramuscular infusion 2 mL DMEM alone; rats in the low-dose group (20 cases) underwent intramuscular infusion of 1×106 hUCMSCs/2 mL in DMEM; rats in the high dose group (20 cases) underwent intramuscular infusion of 10×106 hUCMSCs/2 mL in DMEM.Echocardiography and plasma brain natriuretic peptide(BNP) were used to assess cardiac function in modeled rats.The morphological changes in myocardial cells were observed by using HE and Masson staining after ADR injection stopped for one week.Four weeks after administration of hUCMSCs, echocardiography was performed to evaluate the cardiac function, and plasma BNP level was detected by enzyme immunoassay kit.Western blot was used to analyze the expression of vascular endothelial growth factor(VEGF) in myocardium of rats in each group.Myocardial microvessel density was detected by using anti-CD34 monoclonal antibody and transmission electron microscopy (TEM) were performed to observe the ultrastructure of microvessel. Results Left ventricular ejection (LVEF) and left ventricular fractional shortening (LVFS) in the DCM groups[( 66.17±3.54)%, (31.33±3.20)%] were significantly decreased compared to those in the normal group[(77.25±3.40)%, (41.00±2.94)%], and the differences were statistically significant(t=10.620, 10.328, all P<0.05); the morphological changes in myocardial cells was observed by using HE and Masson staining.Pit-induced typical histological lesion of myocardial tissue was observed in the DCM group, such as congestion, edema, a disorganization of myocytes and focal necrosis and myocardial tissue with wispy, broad collagen fibers predominating in the matrix.Four weeks after administration of hUCMSCs, LVEF in the low dose group or the high dose group were significantly higher compared with those in the DMEM group[(72.27±2.44)% or (70.92±2.68)% vs.(62.89±2.54) %], and the differences were statistically significant( t=2.145, 2.131, all P<0.05); and LVFS were significantly higher compared with that in the DMEM group [(34.96±2.08)% or (33.49±2.19)% vs.(30.98±2.22)%], and the differences were statistically significant (t=2.491, 4.086, all P<0.05). The plasma level of BNP was significantly declined in the hUCMSCs treated rats as compared to those before treatment[ low dose group (352.68±41.25) ng/L vs. (202.68±20.38) ng/L, t=2.052, P<0.05; high dose group (355.79±48.32) ng/L vs. (193.62±15.41) ng/L, t=2.074, P<0.05]. Quantitative analysis demonstrated that microvessel density was significantly hi-gher in low-dose and high-dose hUCMSCs treated DCM rats than that in the DMEM treated DCM rats [(84.00±19.18)/mm2 or (86.67±20.88) /mm2vs.(27.14±13.97) /mm2, t=2.109, 2.101, all P<0.05]; Western blot test showed that there had high expression of VEGF in myocardium and TEM in the high dose group, and vessel injury in DMEM treated rats were more serious than that of hUCMSCs treated rats. Conclusion It suggests that hUCMSCs intramuscular injection may improve heart function and angiogenesis of myocardium in DCM rats induced by adriamycin. Key words: Dilated cardiomyopathy; Cardiac function; Angiogenesis; Stem cell therapy; Intramuscular injection; Rat