Arterial replacement with compliant hierarchic hybrid vascular graft: biomechanical adaptation and failure.
ABSTRACT Two types of hybrid vascular grafts were hierarchically structured with an autologous smooth muscle cell (SMC)-inoculated collagen gel layer and an endothelial cell (EC) monolayer, and wrapped with different elasomeric scaffolds. Type A graft was wrapped with poly(urethane)-nylon mesh, and type B graft was wrapped with an excimer laser-directed microporous segmented polyurethane (SPU) film as the scaffold. Type A graft was more compliant than canine carotid arteries, whereas compliance of type B graft was close to that of native arteries. After implantation into canine carotid arteries for 1 month, all type A grafts were dilated due to loosening of the mesh, resulting in loss of prelined ECs and thrombus formation. In contrast, type B grafts developed a well-organized neoarterial wall composed of a confluent EC monolayer and SMC-resided medial tissue, resulting in only slightly appreciable thrombus and minimal tissue ingrowth 6 months after implantation. Compliance of type B graft was reduced at 6 month's implantation, which is mostly due to encapsulated connective tissue formed around the graft.
SourceAvailable from: George W. Dombi[Show abstract] [Hide abstract]
ABSTRACT: Type I, bovine skin collagen was allowed to gel in the presence of various concentrations of a carbon nanotube material covered with a polystyrene/polyaniline copolymer, called a carbon nanobrush (CNB). The rate of collagen gelation was enhanced by the presence of the CNB in a dose dependent manner. The extent of collagen gelation was due to the concentration of collagen and not the amount of CNB. Collagen D-periodicity, and average fibril diameter were unchanged by the CNB material as seen in transmission electron micrographs. Gel tensile strength was reduced by the presence of the CNB in a dose related manner. The collagen-CNB mixture may have a role in the repair and reconstruction of wounds or degenerated connective tissue.Journal of Materials Science Materials in Medicine 01/2015; 26(1):5356. DOI:10.1007/s10856-014-5356-4 · 2.38 Impact Factor
[Show abstract] [Hide abstract]
ABSTRACT: There is an acute clinical need for small-calibre (<6 mm) vascular grafts for surgery. The aim of this study was to evaluate the long-term performance of a small-calibre graft produced from a nanocomposite biomaterial, polyhedral oligomeric silsesquioxane poly(carbonate-urea)urethane (POSS-PCU), in a large animal model following Good Manufacturing Practice (GMP) and Good Laboratory Practice (GLP) protocols. Grafts were characterised and implanted into the left carotid artery (LCA) of senescent sheep (n = 11) for a period of 9 months. In vivo compliance and blood flow rates were measured using ultrasound wall tracking software and a Transonic flow meter. Graft patency and degree of intimal hyperplasia (IH) were examined at the study end point. Seven of the POSS-PCU grafts were free from thrombosis, IH, calcification and aneurysmal dilation, with 4 occluding within 14 days. All of the ePTFE controls (n = 4) were found to be occluded by day 32. The lumen of the patent POSS-PCU grafts was free from any cellular deposits, whilst perigraft tissue could be seen to be infiltrating into the body of the graft from the adventitia. No significant differences were detected between the blood flow rates (p = 0.3693) and compliance (p = 0.9706) of the POSS-PCU grafts and the native artery, either post-operatively or after 9 months implantation. Small-calibre vascular grafts produced from POSS-PCU offer a viable option for the clinical use in revascularisation procedures with a patency rate of 64%.Biomaterials 08/2014; 35(33). DOI:10.1016/j.biomaterials.2014.07.008 · 8.31 Impact Factor