[Effect of bone mesenchymal stem cells transplantation on malignant ventricular arrhythmia induced byelectrophysiological stimulation in a mini-swine model of acute myocardial infarction].

OBJECTIVE: To investigate the effects of autologous bone mesenchymal stem cells (MSC) transplantation on malignant arrhythmia induced by electrophysiological (EP) stimulation and cardiomyocyte ion channels remodeling in a mini-swine model of acute myocardial infarction (AMI). METHODS: Immediately after AMI (LAD occluded for 120 min), MSC (10 x 10(7), labeled by colloidal gold and co-cultivated with 5-azacytidine, 5-aza, n = 12) or equal volume saline (n = 10) were injected through over-the-wire (OTW) balloon in LAD at distal over D(1). EP stimulation is performed after 2 hours and 4 weeks in both groups to induce arrhythmia. The variance of heterogeneity of sodium currents (I(Na)) and I(Na) steady-state inactivation curves in different zones of infracted wall were investigated by patch clamp technology and the relationship between ionic channel and ventricular arrhythmia is analyzed. RESULTS: EP induced malignant ventricular arrhythmia (VT) rate was similar (MSC 75% vs. saline 90%, P = 0.455) at 2 hours post AMI and was significantly lower in MSC group (25% vs. 80%, P = 0.012) at 4 weeks post AMI. The Peak I(Na) current densities of the Endo, Media and Epi were significantly lower in MSC group [(-14.04 +/- 3.82) pA/pF, (-29.26 +/- 5.70) pA/pF, (-12.43 +/- 3.04) pA/pF] compared those in saline group [(-9.71 +/- 3.38) pA/pF, (-18.98 +/- 4.05) pA/pF, (-8.47 +/- 3.34) pA/pF, all P < 0.05]. The I(Na) steady-state inactivation curves of the Epi, Endo and Media in mini-swine with VT in MSC group [(-126.2 +/- 10.9) mV, (-106.7 +/- 11.9) mV, (-105.4 +/- 11.0) mV] were similar as those in saline group with VT [(-129.1 +/- 10.9) mV, (-112.2 +/- 9.9) mV, (-109.7 +/- 9.2) mV, all P > 0.05] while significantly lower compared to MSC group without VT [(-93.1 +/- 13.8) mV, (-95.2 +/- 15.5) mV, (-103.4 +/- 8.7) mV, all P < 0.05]. The multiple logistic regression analysis showed that I(Na) current density (RR = 1.449, 95% CI 1.276 - 2.079, P = 0.029) and I(Na) steady-state inactivation curves (RR = 1.092, 95% CI 1.008 - 1.917, P = 0.012) were the independent factors for reduced VT. CONCLUSIONS: Autologous MSC attenuated malignant ventricular arrhythmia induced by EP at 4 weeks in mini-swine with AMI which might due to altered cardiomyocyte ion channels remodeling induced by MSC.

Mechanisms of improvement of left ventricle remodeling by trans-planting two kinds of autologous bone marrow stem cells in pigs.

BACKGROUND: The necrosis of a large number of myocardial cells after acute myocardial infarction (AMI) results in a decrease of cardiac function and ventricle remodeling. Stem cell transplantation could improve cardiac function after AMI, but the involving mechanisms have not been completely understood. The present study aimed to investigate the effects of transplantation of autologous bone marrow mononuclear cells (BM-MNC) and mesenchymal stem cells (MSCs) via the coronary artery on the ventricle remodeling after AMI as well as the mechanisms of the effects of transplantation of different stem cells on ventricle remodeling. METHODS: A total of 36 male pigs were enrolled in this study, which were divided into 4 groups: control group, simple infarct model group, BM-MNC transplantation group, and MSCs transplantation group. At 90 minutes when a miniature porcine model with AMI was established, transplantation of autologous BM-MNC ((4.7 +/- 1.7) x 10(7)) and MSCs ((6.2 +/- 1.6) x 10(5)) was performed in the coronary artery via a catheter. Ultrasound, electron microscope, immunohistochemical examination and real time reverse transcriptase-polymerase chain reaction were used respectively to observe cardiac functions, counts of blood vessels of cardiac muscle, cardiac muscle nuclear factor (NF)-kappaB, myocardial cell apoptosis, and the expression of the mRNA of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) in cardiac muscles. Multivariate Logistic regression was used to analyze the correlation factors of left ventricular end-diastolic diameter (EDD). RESULTS: The number of blood vessels in the infarct zone and around its border in the BM-MNC transplantation group was more than those in the infarct model group and MSCs group (P = 0.0001) and there was less myocardial cell apoptosis in the stem cell transplantation group than that in the infarct model group (all P < 0.01). The positive rate of NF-kappaB in the stem cell transplantation group was lower than that in the infarct model group (P = 0.001). The gene expression of VEGF in the infarct border zone of the BM-MNC group was higher than that in the MSCs group (P = 0.0001). The gene expression of bFGF in the infarct border zone in the MSCs transplantation group was higher than that in the infarct model group and the BM-MNC group (P = 0.0001). Left ventricular ejection fraction was inversely proportional to the apoptotic rate of myocardial cells and cardiac muscle NF-kappaB but positively correlated with the number of blood vessels and the expression of VEGF and bFGF in the infarct zone and infarct border zone. The Multivariate Logistic regression analysis on the factors influencing the left ventricular end-diastolic diameter after stem cell transplantation showed that the expression of VEGF mRNA in the cardiac muscles in the infarct zone, the number of apoptotic myocardial cells and the expression of NF-kappaB in the infarct border zone were independent factors for predicting the inhibitory effect on the dilation of left ventricular EDD after stem cell transplantation. CONCLUSIONS: Transplantation of autologous BM-MNC and MSCs in pigs can improve the condition of left ventricular remodeling and recover the cardiac functions after AMI. The improvement of cardiac functions is related to the increase of blood vessels, the increased expression of VEGF and bFGF, the reduction of myocardial cell apoptosis, and the decrease of NF-kappaB level in cardiac muscle tissues after stem cell transplantation.