Evaluation of a Xenogeneic Acellular Collagen Matrix as a Small-Diameter Vascular Graft in Dogs-Preliminary Observations

Abstract

Autogenous veins are the materials of choice for arterial reconstruction. In the absence of autogenous material, prosthetic materials are used. However, vascular prostheses of less than 0.4 cm in diameter have low long-term patency. This study was designed to determine if cells would infiltrate an engineered xenogeneic biomaterial used as a small diameter arterial graft in dogs and, if so, to determine the phenotype of the infiltrating cells. Nine acellular xenogeneic grafts (0.4 cm in diameter, 5 cm long), composed of porcine collagen derived from the submucosa of the small intestine and type I bovine collagen, were implanted as end to-end interposition grafts in femoral arteries of five male mongrel dogs (total of nine grafts). All dogs received daily aspirin (325 mg). Patency of implanted grafts was monitored weekly by Duplex ultrasonography. After 9 weeks, or earlier in case of blood flow reduction by at least 75%, grafts were explanted and prepared for light or electron microscopy to evaluate cellularization. Eight of nine grafts remained patent up to 9 weeks. At explant, diameters were 0.31 +/- 0.02 cm at the midgraft, and 0.14 +/- 0.01 and 0.19 +/- 0.01 cm at the proximal and distal anastomoses. At explant, cells of mesenchymal origin (endothelial cells, smooth muscle cells, myofibroblasts) were embedded in the extracellular matrix of the graft scaffold. Minimal evidence of cellular inflammatory reaction and no aneurysmal dilatation or thrombus formation was detected. Variable degrees of hyperplasia were present at proximal and distal anastomoses. This preliminary study demonstrates that a collagen-based xenogeneic biomaterial provides a scaffold for cellularization when used for arterial reconstruction in dogs.

Time‐related Histopathologic Changes in Fresh Frozen Carotid Xenografts in a Pig‐to‐Goat Implantation Model

“…The patency rate obtained during the present study is comparable to those of related studies, that is, 100% patency at 3 months for cryopreserved allografts in a sheep model (10), 87% patency in xenografts treated using a crosslinking technique during 30 days of observation in a sheep-to-dog model (11), and 89% patency for xenogenic acellular collagen matrix grafts (12).…”

Effect of Decellularization Protocol on the Mechanical Behavior of Porcine Descending Aorta

“…Recent studies on arterial allografts [16–18] and xenografts [14, 19–21] have shown that an arterial extracellular matrix may be preserved and seeded with the host's endothelial cells to prevent immunogenic rejection. These processes are advantageous because the graft is available in days rather than weeks or months.…”

A Novel Ovine ex vivo Arteriovenous Shunt Model to Test Vascular Implantability

“…Natural biopolymers, such as collagen and fibrin, support enhanced cellular functions but lack adequate mechanical strength for arterial implantation [Swartz et al, 2005;Yao et al, 2005Yao et al, , 2008Isenberg et al, 2006;Shaikh et al, 2008]. On the other hand, native decellularized tissues such as arteries and small intestine submucosa (SIS) demonstrate sufficient mechanical strength and may provide inherent biological signals to guide tissue repair and remodeling [Huynh et al, 1999;Nemcova et al, 2001;Conklin et al, 2002;Gui et al, 2009;Tottey et al, 2010]. Regardless of the cell source or material, the difficulty in engineering vascular substitutes lies in matching the appropriate mechanical properties of bioactive materials with desirable blood compatibility and immunity characteristics, which are essential for longterm patency [Dahl et al, 2011;Desai et al, 2011].…”