Abstract 14820: Pericardial Adipose Tissue Thrombospondin-1 Associates With Anti-Angiogenesis in Ischemic Heart Disease

Abstract

Defective angiogenesis contributes to mechanisms of ischemic heart disease. Accumulation of ectopic pericardial adipose tissue has been associated with cardiovascular complications which, in part, may relate to adipose tissue-derived factors. We sought to characterize adipose tissue microvascular angiogenic capacity in individuals undergoing elective cardiac surgeries including aortic, valvular, and coronary artery bypass grafting (CABG). Pericardial fat was collected intraoperatively and examined for capillary sprouting capacity using an established ex vivo Matrigel-based methodology quantified for growth over seven days. Angiogenic capacity was significantly blunted (2.5-fold, p<0.001) in subjects with CAD (age 59±2 years, BMI 32±1 kg/m 2 , LDL-C 92±45 mg/dl, n=37) compared to age-, BMI-, and LDL-cholesterol matched individuals without angiographic obstructive CAD (age 56±4 years, BMI 32±1 kg/m 2 , LDL-C 110±40 mg/dl, n=14). To garner potential mechanistic insight, we performed transcriptomic analyses using quantitative RT- PCR for select angiogenic regulators. We observed no significant differences in pericardial fat gene expression for pro-angiogenic mediators vascular endothelial growth factor-A (VEGF-A), fibroblast growth factor-2 (FGF-2), and angiopoietin-1, or anti-angiogenic factors including soluble fms-like tyrosine kinase-1 (sFlt-1) and endostatin. In contrast, mRNA expression of anti-angiogenic thrombospondin-1 (TSP1) was significantly upregulated (2-fold, p<0.05) in CAD subjects compared to the non-CAD group, which was confirmed by protein western-immunoblot analysis. Plasma concentrations of TSP-1 quantified by ELISA were not significantly different between the two groups. In summary, pericardial fat in subjects with CAD may be associated with an anti-angiogenic transcriptome linked to functional defects in vascularization capacity. Local paracrine actions of TSP1 in adipose depots surrounding the heart may play a role in mechanisms of ischemic heart disease.