Angiomyogenesis with HIF-11 responsive microRNAs Summary: Stem cells promote functional recovery in experimental animal models and patients with myocardial infarction through multifactorial mechanisms. We hypothesize that stem cells reprogrammed with hypoxia inducible factor-11 (HIF-11) responsive microRNAs (HRMs) will promote angiomyogenesis in the infarcted heart. Ranging from maintenance of lineage commitment to angiogenic paracrine activity and differentiation potential, MicroRNAs (miRs) determine the inherent properties of stem cells which possess a discrete miRs profile. Hence, reprogramming of stem cells by manipulation of miRs can improve their paracrine activity and angiomyogenic potential. We have identified a number of HRMs which are down- or upregulated in mesenchymal stem cells (MSCs) during reprogramming by intermittent cycles of brief anoxia/re-oxygenation (A/R) in parallel with activation of HIF-11. The most significantly altered HRMs were miR-210 and miR-107 which markedly influenced the survival and angiogenic paracrine behavior of MSCs (Preliminary results). The overall goal of this proposal is to elucidate the mechanistic involvement of HRMs and their target genes during reprogramming which mediate stem cell functions of paracrine activity, angiomyogenic differentiation and survival. Our proposal is aimed to validate three hypotheses. Hypothesis-1: HRMs regulate angiogenic paracrine activity in stem cells.
The specific aims pertinent to hypothesis-1 will define the expression profile of the discrete set of HRMs in the reprogrammed MSCs (RePMSCs) with special emphasis on their angiogenic paracrine activity. Hypothesis-2: HRMs are mechanistic determinants of functional consequences of the reprogrammed stem cells. The relevant specific aim will involve in vitro models of angiogenesis and experimental animal model of acute coronary artery ligation to show that the reprogramming accentuate the angiogenic potential of stem cells with the mechanistic participation of HRMs. The end-points of in vivo studies will include blood vessel density analysis, maturation index and improved regional blood flow in the ischemic heart and preservation of global cardiac function. A comparison between RePMSCs engraftment and direct injection of HRMs to the ischemic heart will also be carried out. Hypothesis-3: HRMs mechanistically participate in stem cell survival. We have already shown that HRMs significantly improve stem cell survival. Our preliminary studies showed that 4 different anti-apoptotic genes were up-regulated in the stem cells treated with repeated cycles of A/R. We will elucidate the role of each one of the identified target genes of HRMs in stem cell survival. We will also establish that changes in HRMs in the infarcted heart after RePMSCs engraftment constitute an integral and novel mechanism of cardiac repair. Put together, we propose that stem cells reprogrammed by intermittent cycles of A/R with mechanistic involvement of HRMs, will promote their paracrine, angiomyogenic and cytoprotective responses in the infarcted heart. These studies will facilitate the development of novel therapeutic approaches based on manipulation of HRMs in donor stem cells.
This proposal is designed to investigate angiomyogenic and paracrine behavior of stem cells reprogrammed by manipulation of HIF-11 responsive microRNAs (HRMs) using our novel approach of treating the cells with intermittent multiple short cycles of anoxia/reoxygenation. We anticipate improved angiomyogenic response in the infarcted heart after treatment with reprogrammed stem cells. Our proposal will be the first to elucidate the mechanistic participation of HRMs in paracrine behavior, angiomyogenic potential and cytoprotection.
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