Endothelial Seeding for Abdominal Aortic Aneurysms: Lessons Learned from the Past and Present
In this edition of Circulation, Gervais and colleagues1 report a novel approach to modulate the growth of aortic aneurysms in an animal model by using endothelial cells (EC) or outgrowth EC grown in culture which were then delivered directly into an aortic xenograft prior to 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 paper brings back memories of the herculean efforts that were initiated by a number of laboratories to seed EC on vascular grafts with the hope that this technique would improve the patency of the grafts, 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 grafts4. In vitro studies also demonstrated that human EC proliferation and morphology was modulated by both extracellular matrix and growth factors5. Human trials of EC seeding gave variable results, none convincing6, 7 enough to try to bring the technique to wide spread use. Because of concerns that the surface of prosthetic grafts would never provide a hospitable environment for endothelial cell growth and development, the focus of these efforts changed to first lining the grafts matrix proteins such as fibronectin8 or with growth factors that would potentiate endothelial cell growth9 along the luminal surface of grafts. Eventually as research into endothelial and smooth muscle cell biology progressed, this then led to attempts at ex vivo construction of complete living cellular vessels10. With the previous efforts of endothelial seeding of grafts in mind, it is useful to consider the similarities and differences of the efforts of Gervais et al to seed EC onto aortic xenografts. First we should discuss the similarities.
- Received March 31, 2013.
- Revision received April 5, 2013.
- Accepted April 5, 2013.