Enhanced Angiogenic and Cardiomyocyte Differentiation Capacity of Epigenetically Reprogrammed Mouse and Human Endothelial Progenitor Cells Augments Their Efficacy for Ischemic Myocardial Repair

Abstract

Rationale While Bone-marrow endothelial progenitor cell based therapies (BM-EPC) improve the symptoms in patients with ischemic heart disease their limited plasticity and decreased function in patients with existing heart disease limits the full benefit of EPC therapy for cardiac regenerative medicine. Objective We hypothesized that reprogramming mouse and/or human EPCs using small molecules targeting key epigenetic repressive marks would lead to a global increase in active gene transcription, induce their cardiomyogenic potential and enhance their inherent angiogenic potential. Method and Results Mouse Lin-Sca1+CD31+ EPCs and human CD34+ cells were treated with inhibitors of DNA methyltransferases (5-Azacytidine), histone deacetylases (valproic acid) and G9a histone di-methyltransferase. Forty eight hour treatment led to global increase in active transcriptome including the reactivation of pluripotency associated and CMC specific mRNA expression while EC specific genes were significantly up-regulated. When cultured under appropriate differentiation conditions, reprogrammed EPCs showed efficient differentiation into CMC and vascular smooth muscle cells. Treatment with epigenetic modifying agents show marked increase in histone acetylation on cardiomyocyte and pluripotent cell specific gene promoters. Intra-myocardial transplantation of reprogrammed mouse and human EPCs in an acute myocardial infarction mouse model showed significant improvement in ventricular functions, which was histologically supported by their de novo CMC differentiation and increased capillary density and reduced fibrosis. Importantly, cell transplantation was safe and did not form teratomas. Conclusions Taken together, our results suggest that epigenetically reprogrammed EPCs display a safe, more plastic phenotype and improve post-infarct cardiac repair by both neo-cardiomyogenesis and neovascularization.

Alcohol Consumption Negates Estrogen-mediated Myocardial Repair in Ovariectomized Mice by Inhibiting Endothelial Progenitor Cell Mobilization and Function

“…Bottles were weighed before and after a 24-h drinking cycle to calculate the grams of ethanol consumed in the preceding 24 h. Control water bottles were also weighed for measuring water consumption, which did not differ significantly between groups. Following the chronic ethanol feeding cycle, all mice underwent surgery to induce acute myocardial infarction as described in our previous publications (22,23). Circulating blood ethanol levels were monitored weekly in each animal via assessment of the blood obtained from a tail vein using a commercially available ethanol detection kit (Sigma).…”

“…Induction of Acute Myocardial Infarction-AMI was induced as described previously (22,23). Briefly, mice were anesthetized, intubated orally, the chest was shaved, and under a dissecting microscope, a left thoracotomy was performed in the fourth intercostal space.…”

“…Harvest of Cardiac Tissue, Histology, and Immunofluorescent Assessments-All hearts were harvested after the 28-day echocardiographic analysis as described previously (25,26), embedded in paraffin, and cut into sections for immunohistochemical staining as described previously (22)(23)(24)27). Specimens were fixed in 10% (v/v) buffered formaldehyde, dehydrated with graded ethanol series, and embedded in paraffin.…”

Regulation of EPCs: The Gateway to Blood Vessel Formation

“…+ EPCs can enhance angiogenic potential [143]. As outlined in Table 2, treatment of Lin − /Sca + /CD31 + EPCs and human CD34 + EPCs with epigenetic modifying molecules, such as inhibitors of DNA methyltransferases, histone deacetylases, and G9a histone dimethyl transferases, removed epigenetic marks which restrict gene transcription, leading to an increase in expression of the pluripotency genes Oct4, Nanog, and Sox2 [143].…”

Experimental study of endothelial progenitor cells labeled with superparamagnetic iron oxide in vitro

“…Studies have reported the number of circulating EPCs was significantly increased under several pathological conditions that involved vascular injury or instability, including myocardial infarction and cancer (10,11). This therefore suggested that circulating EPCs may have provided an endogenous repair mechanism that counteracted the ongoing risk factor-induced endothelial injury and therefore protected against the development of vascular injuries, such as myocardial infarction (10)(11)(12)(13). Therefore, the present study hypothesized that changes in circulating levels of EPCs may act as a predictor for the incidence of acute myocardial infarction.…”