CSE/H2S system protects mesenchymal stem cells from hypoxia and serum deprivation­induced apoptosis via mitochondrial injury, endoplasmic reticulum stress and PI3K/Akt activation pathways.

Mesenchymal stem cells (MSCs) have the potential to facilitate cardiac repair following acute myocardial infarction. However, MSC therapy is limited by apoptosis of the stem cells following transplantation. Hydrogen sulfide (H2S) has recently been proposed as an endogenous mediator of cell apoptosis in various systems. The aim of the present study was to investigate the mechanism underlying the antiapoptotic effect of the endogenous cystathionine γ-lyase (CSE)/H2S system in MSCs cultivated in conditions of hypoxia and serum deprivation (H/SD). Western blotting was performed in order to determine the expression of proteins associated with the mitochondrial injury pathway, endoplasmic reticulum stress and the phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway. It was demonstrated that H/SD is able to significantly induce apoptosis in MSCs. CSE overexpression, which enhances the endogenous H2S level, protects MSCs from H/SD-induced apoptosis via attenuation of the mitochondrial injury pathway, inhibition of endoplasmic reticulum stress and activation of the PI3K/Akt signaling pathway. In conclusion, the present findings suggest that modulation of the CSE/H2S system may a therapeutic approach with which to promote the viability of transplanted MSCs.

Reduction of isoproterenol-induced cardiac hypertrophy and modulation of myocardial connexin43 by a KATP channel agonist.

Cardiac hypertrophy is a compensatory mechanism that occurs in conjunction with cardiovascular diseases. Although hypertrophy of the myocardium provides certain benefits during the early stages of cardiovascular disease, prolonged hypertrophy is potentially harmful to the heart and can result in arrhythmia and heart failure. The aim of this study was to investigate whether an ATP­sensitive K+ (KATP) channel agonist was capable of reducing isoproterenol (Iso)­induced cardiac hypertrophy and modulating myocardial connexin43 (Cx43) expression. Fifty male Sprague Dawley rats were randomly assigned to five groups: Normal, vehicle, nicorandil, glibenclamide and nicorandil plus glibenclamide. Rats in the four treatment groups received Iso injection for seven days, followed by administration with saline, nicorandil, glibenclamide or a combination of nicorandil and glibenclamide, respectively, for four weeks. Cardiac hypertrophy was then evaluated by measuring body weight, heart weight and left­ventricular weight, and plasma B­type natriuretic peptide levels were evaluated by ELISA. Immunocytochemistry and a reverse transcription­polymerase chain reaction were performed to detect the spatial distribution and gene expression of myocardial Cx43, respectively. The KATP channel agonist nicorandil markedly attenuated the degree of myocardial hypertrophy induced by Iso as compared with the vehicle group. Myocardial Cx43 expression was significantly decreased and redistributed following cardiac hypertrophy. The decrease and redistribution of Cx43 was reduced following treatment with the KATP channel agonist nicorandil. Addition of the KATP channel blocker glibenclamide eliminated the beneficial effects of nicorandil against hypertrophy and on connexin43. In conclusion, the present study indicated that chronic use of KATP channel agonists following cardiac hypertrophy can attenuate ventricular remodeling and upregulate the expression level and spatial distribution of Cx43.

Co-treating mesenchymal stem cells with IL­1ß and TNF-α increases VCAM-1 expression and improves post-ischemic myocardial function.

Inflammatory mediators are released by the myocardium following myocardial ischemia as a response to tissue injury, and contribute to cardiac repair and adaptive responses. Treating mesenchymal stem cells (MSCs) with various inflammatory factors activates a series of biological processes that enhance cell-mediated cardioprotection following myocardial infarction (MI). The present study was designed to examine the effect of interleukin-1ß (IL-1ß) and tumor necrosis factor-α (TNF-α) treatment on vascular cell adhesion molecule-1 (VCAM-1) expression in MSCs, and to identify whether cytokine-treated MSCs improve post-ischemic myocardial function in a rat model. MSCs were stimulated with IL-1ß and/or TNF-α for 24 h, the production of vascular cell adhesion molecule-1 (VCAM-1) and the adhesion ability of MSCs were assessed by flow cytometry, adhesion assays, quantitative polymerase chain reaction and western blot analysis. The cardiac function was examined by two-dimensional echocardiography. The results demonstrated that in treated MSCs, the secretion of VCAM-1 and the cell adhesion ability were significantly increased, thus markedly improving cardiac function compared with that of the control group (P<0.01). Of all the groups, the rats stimulated with a combination of IL-1ß and TNF-α exhibited the greatest cardiac improvements. However, there was no significant difference between the 10 and 20 ng/ml groups which were stimulated with one of the cytokines alone (P>0.05). In conclusion, stimulating MSCs with IL-1ß and TNF-α promoted the expression of VCAM-1 and improved post-ischemic cardiac function recovery. Treating MSCs with two cytokines in combination may be a useful method to maximize the potential of cell-based therapy for MI.