Endothelial Seeding for Abdominal Aortic Aneurysms

In this edition of Circulation , Franck and colleagues1 report a novel approach to modulate the growth of aortic aneurysms in an animal model by using endothelial cells (ECs) or outgrowth ECs grown in culture that were then delivered directly into an aortic xenograft before implantation. The authors report that this therapeutic approach resulted in modulation of the inflammatory process in the aortic wall and decreased the rate of growth of the xenograft aneurysms. They propose that endothelial seeding may be a promising technique for managing the growth of aneurysms in humans. This article brings back memories of the herculean efforts initiated by a number of laboratories to seed ECs on vascular grafts with the hope that this technique would improve the patency of the grafts and decrease perianastomotic neointimal hyperplasia and loss of ischemic limbs.2,3 In vitro assessment of the growth potential of adult human sources of endothelium suggested that there was adequate in vitro growth of cells to theoretically cover the surface of commonly used grafts.4 In vitro studies also demonstrated that human EC proliferation and morphology were modulated by both extracellular matrix and growth factors.5 Human trials of EC seeding gave variable results, none convincing6,7 enough to try to bring the technique to widespread use. Because of concerns that the surface of prosthetic grafts would never provide a hospitable environment for EC growth and development, the focus of these efforts changed to first lining the matrix with proteins such as fibronectin8 or with growth factors that would potentiate EC growth9 along the luminal surface of grafts. Eventually, as research into endothelial and smooth muscle cell biology progressed, this led to attempts at ex vivo construction of complete living cellular vessels.10 With the previous efforts of …