VEGF promotes cardiac stem cells differentiation into vascular endothelial cells via the PI3K/Akt signaling pathway.

Recent research suggested that cardiac stem cells (CSCs) may have the clinical application for cardiac repair. However, their characteristics and the regulatory mechanisms of their growth and differentiation have not been fully investigated. Vascular endothelial growth factor (VEGF, VEGF-A) is a major regulator of physiological and pathological angiogenesis. But the homing role of VEGF for CSCs is unclear. In this report, CSCs were isolated, purified, and expanded in vitro from rat heart. VEGF, SU5416 (VEGF receptor blocker), and Wortmannin (PI3K/Akt signaling pathway inhibitor) were used for differentiation into vascular endothelial cells (VECs). Real-time qPCR was selected to confirm the role of PI3K/Akt signaling pathway in VECs differentiation from rat CSCs. The result of real-time qPCR demonstrated that PI3K/Akt signaling pathway plays an important role in rat CSCs differentiated into VECs. So, our research provides a theoretical basis and experimental evidence for therapeutic application of rat CSCs to treat cardiac repair.

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.

[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.

The catecholamine-beta-adrenoreceptor-cAMP system and prediction of cardiovascular events in hypertension.

Although the importance of elevated circulating plasma catecholamines on cardiac structural and functional remodelling of hypertension is well documented, it is unclear whether the catecholamine-beta-adrenoreceptor (beta AR)-cAMP system can predict different cardiovascular events. 2. A total of 601 identified hypertensive patients with baseline and follow-up plasma levels of noradrenaline (NA) and adrenaline (Adr), lymphocyte beta AR density (B(max)) and intra-lymphocyte cAMP levels in peripheral blood (last examination 60+/-26 months apart) were followed up for an additional 24+/-12 months. 3. After the last follow up, a composite end-point of cardiovascular death, non-fatal myocardial infarction (MI) and stroke occurred in 139 patients (23.1%). In Cox analyses, adjusting for other standard factors as well as treatment effect, NA (hazard ratio 1.22; 95% confidence interval (CI) 1.17-1.28; P=0.0008), Adr (hazard ratio 1.53; 95% CI 1.18-2.00; P=0.002), beta AR (hazard ratio 1.12; 95% CI 1.06-1.17; P=0.007) and cAMP (hazard ratio 1.15; 95% CI 1.09-1.21; P=0.005) separately predicted cardiovascular mortality. Noradrenaline, Adr, beta AR and intra-lymphocyte cAMP separately predicted fatal/non-fatal MI; NA and Adr predicted fatal/non-fatal stroke, whereas B(max) and intra-lymphocyte cAMP levels were not a significant predictor of fatal/non-fatal stroke. When stratifying the study population by NA or Adr (median 4 nmol/L), B(max) (median 600 fmol/10(7) cells) and cAMP (median 5.0 pmol/mg protein) above and below the median values in both parameters categories, patients above the median had composite cardiovascular end-point (all P<0.001) and high cardiovascular death (all P<0.01, log-rank test). 4. These results suggest that plasma NA and Adr are significant predictors of cardiovascular mortality, MI and stroke. The B(max) and intra-lymphocyte cAMP levels are significant predictors of cardiovascular mortality and MI, but not stroke.