Abstract 13854: Effects of High Fat vs Normal Diet on Extracellular Vesicles-Induced Angiogenesis in a Swine Model of Chronic Myocardial Ischemia

Background:Mesenchymal Stem Cell-derived extracellular vesicles (EVs) are purported to promote angiogenesis in the ischemic myocardium. This study examines the difference in vascular density, myocardial perfusion, and molecular signaling between Normal Diet (ND) and High Fat Diet (HFD) groups at baseline and following intra-myocardial injection of EVs.Methods and Results:Intact male Yorkshire swine fed either a Normal Diet, (n=23) or a high fat diet (n=19) underwent placement of an ameroid constrictor on their left circumflex coronary artery. Subsequently, animals received either intramyocardial injection of vehicle-saline e.g. controls; (NDC n=7, HFDC, n= 6) or serum-starved EVs- treatment groups; (ND-EV n=7, HFD-EV n= 8) into the ischemic territory. Five weeks later, myocardial function, perfusion, vascular density, and cell signaling were examined. Ischemic LV myocardium in the ND group showed significantly higher absolute blood flow and hence collateral dependent perfusion in response to EV therapy. This response was abrogated in the HFD group. Interestingly, quantification of alpha smooth muscle actin as percentage surface area of paraffin fixed ischemic myocardial slides revealed significantly higher basal arteriolar density in tissue from HFD animals when compared to their ND counterparts (P<0.01). However, EV therapy had a more pronounced effect in promoting arteriogenesis in the ND group (P<0.01). We observe a trend - increased CD31-labeled endothelial cell density in response to EV treatment in ND animals (P=0.18). This trend was not observable in the HFD group. Levels of total eNOS, FOXO1, TGF- B, pVEGFR2, (P<0.01) and pMAPK ERK1/ERK2 (P<0.05) were all higher in ischemic myocardial lysates from ND animals compared to those from the HFD group. Conversely, HFD tissue showed increased expression of peNOS, pFOXO1, VEGFR2, and MAPK ERK1/ERK2 (P<0.01) when compared to ND. No appreciable changes in protein expression could be attributed to EV therapy in either group.Conclusion:Collectively, we demonstrate that hypercholesterolemia accentuates basal myocardial arteriolar density which is associated with paradoxical molecular signaling and a reduced angiogenic response to EVs in our swine model of Chronic Myocardial Ischemia.