Exogenously expressed VEGF promotes myocardial repair at least in part through SDF-1α/CXCR4-mediated recruitment of CSC.

The MSCs over-expressing the SDF-1alpha can produce effective angiogenesis, resulting in the prevention of progressive heart dysfunction after a myocardial infarction.

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Mesenchymal stem cells (MSCs) are a promising source for cell-based treatment of myocardial infarction (MI), but existing strategies are restricted by low cell survival and engraftment. We examined whether SDF-1 transfection improve MSC viability and paracrine action in infarcted hearts. We found SDF-1-modified MSCs effectively expressed SDF-1 for at least 21 days after exposure to hypoxia. The apoptosis of Ad-SDF-1-MSCs was 42% of that seen in Ad-EGFP-MSCs and 53% of untreated MSCs. In the infarcted hearts, the number of DAPI-labeling cells in the Ad-SDF-1-MSC group was 5-fold that in the Ad-EGFP-MSC group. Importantly, expression of antifibrotic factor, HGF, was detected in cultured MSCs, and HGF expression levels were higher in Ad-SDF-MSC-treated hearts, compared with Ad-EGFP-MSC or control hearts. Compared with the control group, Ad-SDF-MSC transplantation significantly decreased the expression of collagens I and III and matrix metalloproteinase 2 and 9, but heart function was improved in d-SDF-MSC-treated animals. In conclusion, SDF-1-modified MSCs enhanced the tolerance of engrafted MSCs to hypoxic injury in vitro and improved their viability in infarcted hearts, thus helping preserve the contractile function and attenuate left ventricle (LV) remodeling, and this may be at least partly mediated by enhanced paracrine signaling from MSCs via antifibrotic factors such as HGF.

Gene and stem-cell therapies hold promise for the treatment of ischemic cardiovascular disease. Combined stem cell, chemokine, and angiogenic growth factor gene therapy could augment angiogenesis, and better improve heart function in the infarcted myocardium. In order to prove this action, we established the animal model of myocardial infarction (MI) was by occlusion of the left anterior descending artery in rats. Seven days after surgery, 5.0 x 10(6) Ad-EGFP-MSC, 5.0 x 10(6) Ad-SDF-1-MSC, 5.0 x 10(6) Ad-VEGF-MSC, or 5.0 x 10(6) Ad-SDF-VEGF-MSC (Ad-SDF-1-VEGF-MSC) suspension in 0.2 ml of serum-free medium was injected into four sites in the infarcted hearts. Results showed that MSCs transfected with Ad-VEGF and Ad-SDF-1 produced more SDF-1 and VEGF protein than MSCs alone, the increased protein levels of VEGF and SDF-1 activated Akt in MSCs transfected with Ad-VEGF and Ad-SDF-1, and improved the survival capability of the MSCs in vitro and in vivo. These transplanted cells showed that the characteristic phenotype of cardiomyocyte (e.g., cTnt) and endothelial cells (e.g., CD31). Four weeks after transplantation, reduced infarct size and fibrosis, greater vascular density, and a thicker left ventricle wall were observed in Ad-SDF-VEGF-MSC group. Measurement of hemodynamic parameters showed an improvement in left ventricular performance in Ad-SDF-VEGF-MSC group compared with other groups. These results demonstrated that combination of chemokine and angiogenic factor gene and stem cells could enhance angiogenesis and improves cardiac function after acute myocardial infarction in rats.

Acetylcholine (ACh) plays an important role in neural and non-neural function, but its role in mesenchymal stem cell (MSC) migration remains to be determined. In the present study, we have found that ACh induces MSC migration via muscarinic acetylcholine receptors (mAChRs). Among several mAChRs, MSCs express mAChR subtype 1 (m1AChR). ACh induces MSC migration via interaction with mAChR1. MEK1/2 inhibitor PD98059 blocks ERK1/2 phosphorylation while partially inhibiting the ACh-induced MSC migration. InsP3Rs inhibitor 2-APB that inhibits MAPK/ERK phosphorylation completely blocks Ach-mediated MSC migration. Interestingly, intracellular Ca2+ ATPase specific inhibitor thapsigargin also completely blocks ACh-induced MSC migration through the depletion of intracellular Ca2+ storage. PKCα or PKCβ inhibitor or their siRNAs only partially inhibit ACh-induced MSC migration, but PKC-ζ siRNA completely inhibits ACh-induced MSC migration via blocking ERK1/2 phosphorylation. These results indicate that ACh induces MSC migration via Ca2+, PKC and ERK1/2 signal pathways.

Aim The objective of this study is to determine if exuberant sympathetic nerve activity is involved in muscle satellite cell differentiation and myoblast fusion. Methods and results By using immunoassaying and western blot analyses, we found that β1 and β2-adrenergic receptors (AdR) were expressed in C2C12 cells. The differentiated satellite cells exhibited an increased expression of β2-AdR, as compared with the proliferating cells. Continuous exposure of isoprenaline (ISO), a β-AdR agonist, delayed C2C12 cell differentiation, and myoblast fusion in time- and dose-dependent manner. ISO also increased short myotube numbers while decreasing long myotube numbers, consistent with the greater reduction in MyHC1, MyHC2a, and MyHC2x expression. Moreover, continuous exposure of ISO gradually decreased the ratio of PKA RI/RII, and PKA RI activator efficiently reversed the ISO effect on C2C12 cell differentiation and myoblast fusion while PKA inhibitor H-89 deteriorated the effects. Continuous single-dose ISO increased β1-AdR expression in C2C12 cells. More importantly, the cells showed enhanced phospho- ERK1/2 levels, resulting in increasing phospho- β2-AdR levels while decreasing β2-AdR levels, and the specific effects could be abolished by ERK1/2 inhibitor. Furthermore, continuous exposure of ISO induced FOXO1 nuclear translocation and increased the levels of FOXO1 in nuclear extracts while reducing pAKT, p-p38MAPK, and pFOXO1 levels. Conversely, blockade of ERK1/2 signaling partially abrogated ISO effects on AKT, p38MAPK, and FOXO1signaling, which partially restored C2C12 cell differentiation and myoblast fusion, leading to an increase in the numbers of medium myotube along with the increased expression of MyHC1 and MyHC2a. Conclusion Continuous exposure of ISO impedes satellite cell differentiation and myoblast fusion, at least in part, through PKA-ERK1/2-FOXO1 signaling pathways, which were associated with the reduced β2-AdR and increased β1-AdR levels. Electronic supplementary material The online version of this article (10.1186/s13287-019-1160-x) contains supplementary material, which is available to authorized users.

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