Abstract 12391: High Density Lipoprotein in Coronary Artery Disease Impairs Vascular Endothelial Growth Factor- Induced Angiogenesis

Abstract

Aims: Previous clinical trials designed to stimulate coronary vascular growth (therapeutic angiogenesis) using growth factors, e.g, vascular endothelial growth factor (VEGF), in patients with coronary artery disease (CAD) were unsuccessful. Although many reasons were postulated for the failure, e.g., endothelial dysfunction, refractory response to VEGF, no consensus was achieved to explain these unsuccessful attempts. To further interrogate this conundrum, we found that high density lipoprotein from healthy subjects (nHDL) is pro-angiogenic; however, HDL from patients with CAD (pHDL) has oxidative modifications. Accordingly we postulate that this modified pHDL is proinflammatory and “switches” to an anti-angiogenic effect. To test this possibility we determined the angiogenic capacity of pHDL and of pHDL on VEGF induced-angiogenesis. Methods and Results: Human umbilical vein endothelial cells (HUVECs) were cultured; murine hearts were isolated and sectioned, and the sections were cultured under condition in which endothelial cells sprout from the sections. HUVECs and the heart sections were treated with nHDL (100 μg/ml) or pHDL (100 μg/ml) with or without VEGF stimulation. We measured proliferation, migration, tube formation of HUVECs, and number and length of sprouts from the sections. pHDL (compared to nHDL) reduced endothelial cell proliferation, migration, tube formation, and the length of the sprouts from the sections under basal conditions and also in response to VEGF (all P<0.05). To elucidate the mechanism of this negative effect of pHDL, we measured nitric oxide (NO) production, superoxide anion (O2[[Unable to Display Character: ˙]] − ) generation, phosphorylation of endothelial nitric oxide synthase (eNOS), and Akt in HUVECs. Compared to nHDL, pHDL reduced the phosphorylation of eNOS, and Akt; and, also inhibited NO production, but increased eNOS-dependent O2[[Unable to Display Character: ˙]] − generation. Conclusions: HDL from patients with CAD impaired VEGF-induced angiogenesis via eNOS/Akt signaling pathway. Taken together, our findings suggest that oxidatively modified HDL from patients with CAD may be a contributing factor to reasons why therapeutic angiogenesis trials failed using VEGF recombinant protein or VEGF gene therapy.