Authors:
Stephen E McIlhenny, Jason A Comeau, Sarah I Fernandez, Matthew C Ferroni, Elizabeth J Faul, Gabor Bagameri, Irving M Shapiro, Thomas N Tulenko, Paul J DiMuzio
Summary:
Background - An appropriate alternative to synthetic vascular bypass grafts remains a goal of tissue engineers. We have previously reported the ability of adult adipose-derived stem cells (ASC) to acquire markers of the endothelial phenotype, attach to the lumen of decellularized vein scaffolds under physiological shear, and produce nitric oxide (NO) following transfection of endothelial nitric oxide synthase (eNOS). Herein we report the successful in vivo ability of our grafts to serve as arterial interposition conduits.
Methods - ASC were isolated from male rabbits and transfected with eNOS and differentiated in endothelial cell growth supplement (ECGS) for 1w prior to seeding on the lumen of a decellularized vein scaffold. Grafts were flow conditioned for 1w and implanted as abdominal aortic interposition grafts in rabbits. Grafts were monitored via ultrasound every 2w. At 2w and 2m, grafts were pressure fixed, explanted and analyzed via confocal and scanning electron microscopy, and histological methods. Unseeded decellularized scaffolds served as control.
Results - Tissue engineered grafts demonstrated patency throughout the implant period and upon harvest were well incorporated into the host circulation. ASC remained attached to the lumen. Histological analysis demonstrated an intact endothelial lining, de novo collagen production, and repopulation of the tunica media with smooth muscle-like cells. Control grafts were prone to acute thrombosis leading to animal sacrifice as early as 1w. Even when occlusive events did not occur (up to 2m), thrombin was observed on the lumina of the control grafts. No cells were detectable on the control lumina and intimal hyperplasia was observed.
Conclusions - These results demonstrate the efficacy of a tissue engineered vascular bypass graft with a neo-lumen comprised of pre-conditioned, autologous, eNOS+ ASC. Our graft is an improvement over synthetic and other tissue engineered grafts in that it: 1) can be manufactured within 2w, 2) provides a non-thrombogenic luminal lining, and 3) inhibits intimal hyperplasia. We believe these results indicate the first clinically feasible method for the creation of an alternative bypass conduit for use in vascular surgery.
Source:
Arteriosclerosis, Thrombosis and Vascular Biology 2010 Scientific Sessions; I-Poster Session, P206, Grand Ballroom A, 5:30PM-7:30PM (04/08/10)