Modulation of miRNAs by vitamin C in H2O2­exposed human umbilical vein endothelial cells.

Vitamin C plays a protective role in oxidative damage by blocking the effects of free radicals. The present study investigated the mechanisms through which vitamin C partly mediates anti­apoptotic and antioxidant functions via the regulation of microRNAs (miRNAs or miRs). For this purpose, a global miRNA expression analysis on human umbilical vein endothelial cells (HUVECs) treated with vitamin C was conducted using microarrays containing human precursor and mature miRNA probes. The results revealed that there were 42 identical miRNAs among the differentially expressed miRNAs in the HUVEC group and H2O2 + vitamin C­treated HUVEC group compared to the H2O2­exposed HUVEC group, including 41 upregulated miRNAs and 1 down­regulated miRNA. Using bioinformatics analysis, differentially expressed miRNAs were investigated to identify novel target mRNAs and signaling pathways. Pathway enrichment analyses revealed that apoptosis, the mitogen­activated protein kinase (MAPK) signaling pathway, phosphoinositide 3­kinase (PI3K)/Akt signaling pathway and oxidative phosphorylation were significantly enriched. The results from western blot analysis demonstrated that the interleukin (IL)10, matrix metalloproteinase (MMP)2, cAMP­response element binding protein (CREB) and p­CREB protein expression levels in HUVECs transfected with hsa­miR­3928­5p and induced by H2O2 were significantly downregulated; the MAPK9, caspase­3 (CASP3) and p­CASP3 protein expression levels in HUVECs transfected with hsa­miR­323a­5p and induced by H2O2 were significantly downregulated. The present study therefore demonstrates that vitamin C partly exerts protective effects on HUVECs through the regulation of miRNA/mRNA axis expression.

IGF-1 enhances BMSC viability, migration, and anti-apoptosis in myocardial infarction via secreted frizzled-related protein 2 pathway.

BACKGROUND: Bone marrow mesenchymal stem cell (BMSC) transplantation represents a promising therapeutic strategy for ischemic heart disease. However, its effects are hampered by the poor viability of transplanted cells and the hostile microenvironment of the ischemic region. Insulin-like growth factor-1 (IGF-1) is an important paracrine growth factor of BMSC and plays an important role in the properties of BMSC. Here, we investigated whether overexpressing IGF-1 could enhance the BMSC viability, migration, anti-apoptosis, and protective effects of cardiomyocytes, and explore the underlying mechanisms' focus on the role of the AKT/secreted frizzled-related protein 2 (SFRP2)/ß-catenin pathway. METHODS: We constructed BMSCs overexpressing insulin-like growth factor-1 (BMSCs-IGF-1) or empty vector (BMSCs-NC) using lentivirus, and evaluated cell survival, proliferation, and migration under normoxic and hypoxic conditions. Co-culture of rat cardiomyoblasts with BMSCs was performed to explore the paracrine effect of BMSCs-IGF-1 for rescuing cardiomyoblasts under hypoxia. Transplantation of BMSCs in acute myocardial infarction rats was used to explore the effect of BMSCs-IGF-1 therapy. RESULTS: BMSCs-IGF-1 exhibited a higher cell proliferation rate, migration capacity, and stemness, and were more resistant to apoptosis under hypoxia. Overexpression of IGF-1 upregulated the expression of total and nuclear ß-catenin via the AKT-secreted frizzled-related protein 2 (SFRP2) pathway, which enhanced cell survival. Inhibition of AKT or SFRP2 knockdown by siRNA significantly antagonized the effect of IGF-1 and decreased the expression of ß-catenin. The expression of ß-catenin target genes, including cyclin D1 and c-Myc, were accordingly decreased. Moreover, BMSCs-IGF-1 could rescue cardiomyoblasts from hypoxia-induced apoptosis and preserve cell viability under hypoxia. Transplantation of BMSCs-IGF-1 into myocardial infarction rats greatly reduced infarct volume than BMSCs-NC, with significantly greater expression of SFRP2 and ß-catenin. CONCLUSIONS: These results suggest that in BMSCs overexpressing IGF-1, SFRP2 is an important mediator for the enhancement of stem cell viability via activating, rather than antagonizing, the Wnt/ß-catenin pathway.