Aims: Increased angiogenesis, chronic inflammation, and extracellular matrix degradation are the major pathological features of abdominal aortic aneurysm (AAA). We sought to elucidate the role of vascular endothelial growth factor (VEGF)-A, a potent angiogenic and proinflammatory factor, in the development of AAA.
Methods and results: Human AAA samples showed increased VEGF-A expression, neovascularization, and macrophage infiltration compared with normal aortic walls. AAA was induced in mice by periaortic application of CaCl(2). AAA mice were treated with soluble VEGF-A receptor (sFlt)-1 or phosphate-buffered saline and sacrificed 6 weeks after the operation. Treatment with sFlt-1 resulted in reduced aneurysm size, restored wavy structure of the elastic lamellae, reduced Mac-2(+) monocytes/macrophages, CD3(+) T-lymphocytes, and CD31(+) vessels, and attenuated matrix metalloproteinase (MMP)-2 and 9 activity in periaortic tissue of AAA. Increased aortic mRNA expression of monocyte chemotactic protein-1, tumour necrosis factor-α, and intercellular adhesion molecule-1 in AAA was attenuated by sFlt-1 treatment.
Conclusion: VEGF-A was overexpressed in the aortic wall of human and experimental AAA. Treatment with sFlt-1 inhibited AAA development in mice, in association with reduced neoangiogenesis, infiltration of inflammatory cells, MMP activity, and extracellular matrix degradation. These findings suggest a crucial role of VEGF-A in the development of AAA.