Abstract
IntroductionmicroRNAs (miRs), a novel class of small non-coding RNAs, are involved in cell proliferation, differentiation, development, and death. In this study, we found that miR-221 translocation by microvesicles (MVs) plays an important role in cardioprotection mediated by GATA-4 overexpressed mesenchymal stem cells (MSC).Methods and ResultsAdult rat bone marrow MSC and neonatal rat ventricle cardiomyocytes (CM) were harvested as primary cultures. MSC were transduced with GATA-4 (MSCGATA-4) using the murine stem cell virus (pMSCV) retroviral expression system. Empty vector transfection was used as a control (MSCNull). The expression of miRs was assessed by real-time PCR and localized using in situ hybridization (ISH). MVs collected from MSC cultures were characterized by expression of CD9, CD63, and HSP70, and photographed with electron microscopy. Cardioprotection during hypoxia afforded by conditioned medium (CdM) from MSC cultures was evaluated by lactate dehydrogenase (LDH) release, MTS uptake by CM, and caspase 3/7 activity. Expression of miR-221/222 was significantly higher in MSC than in CM and miR-221 was upregulated in MSCGATA-4. MSC overexpression of miR-221 significantly enhanced cardioprotection by reducing the expression of p53 upregulated modulator of apoptosis (PUMA). Moreover, expression of PUMA was significantly decreased in CM co-cultured with MSC. MVs derived from MSC expressed high levels of miR-221, and were internalized quickly by CM as documented in images obtained from a Time-Lapse Imaging System.ConclusionsOur results demonstrate that cardioprotection by MSCGATA-4 may be regulated in part by a transfer of anti-apoptotic miRs contained within MVs.
Highlights
MicroRNAs, a novel class of small non-coding RNAs, are involved in cell proliferation, differentiation, development, and death
Our results demonstrate that cardioprotection by MSCGATA-4 may be regulated in part by a transfer of antiapoptotic miRs contained within MVs
mesenchymal stem cells (MSC) derived conditioned medium (CdM) protects CM against hypoxic injury MSC obtained from femurs and tibias appeared as a morphologically heterogeneous population
Summary
MicroRNAs (miRs), a novel class of small non-coding RNAs, are involved in cell proliferation, differentiation, development, and death. We found that miR-221 translocation by microvesicles (MVs) plays an important role in cardioprotection mediated by GATA-4 overexpressed mesenchymal stem cells (MSC). Mesenchymal stem cells (MSC) obtained from bone marrow have been reported to improve cardiac function, reduce infarct size, and enhance myocardial regeneration following transplantation into infarcted myocardium [3,4,5,6,7]. It has been reported that transplanted MSC participate in the myocardial tissue repair process by either transdifferentiation into CM and endothelial cells [4,6,13,14], or by release of biologically active pro-angiogenic and cardioprotective factors [15,16,17,18,19,20]. It has been reported that MVs contain soluble factors, and miRs and mRNA
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