Decellularized, xenogeneic small‐diameter arteries: Transition from a muscular to an elastic phenotype in vivo

Abstract

Reports regarding the biocompatibility of xenogeneic, decellularized bioprosthetic implants differ between bioinertness and complete graft degradation. We investigated heparin-crosslinked and nonheparinized, xenogeneic vascular substitutes in a rat model. Porcine arteries (15 x 1.5 mm) were decellularized by multistep detergent and enzymatic techniques, which were followed by heparin-crosslinking in 50% of the implants. Prostheses were implanted into the abdominal aorta of 76 rats for 1 day and up to 6 months. Retrieved specimens were evaluated by histology, immunohistochemistry, laser scanning, and scanning electron microscopy. Graft patency did not differ between groups (97.3%). Heparinized grafts showed a statistically significant lower rate of aneurysm formation (p = 0.04 %). Implants revealed infiltration with granulocytes and macrophages up to 3 months. Recellularization with endothelial cells and myofibroblasts was detectable within 1 month. After 6 months elastin biosynthesis and complete graft remodeling toward an elastic vessel was evident. These results indicate that temporary inflammation does not interfere with long-term vascular remodeling.

Acellular Endocardium as a Novel Biomaterial for the Intima of Tissue‐Engineered Small‐Caliber Vascular Grafts

“…Data from a study showed that fewer than 30% of cells remained on the surface after only 1 h of exposure to physiological levels of shear stress. Nonheparinized decellularized arteries revealed up to an 11.1% ratio of aneurysm formation after implantation to substitute abdominal aorta (25). Although much effort has been made to improve the adherence of ECs such as optimizing the cell seeding technique, surface coating, manipulation of the extracellular matrix composition and geometry, and exposing ECs to physiologic mechanical forces (20), we hypothesize that the material selected is the key to solving the problem.…”

“…The defect of this graft is that the acellular matrix will be over-degenerated, leading to a decrease in the graft strength and formation of aneurysms over time. Nonheparinized decellularized arteries revealed up to an 11.1% ratio of aneurysm formation after implantation to substitute abdominal aorta (25).…”

The in vivo performance of small-caliber nanofibrous polyurethane vascular grafts

“…Different synthetic grafts vary in the time required for endothelialization, typically ranging from 10 days to 6 months [13-16]. Endothelialization is affected by multiple factors, including patient’s ethnicity and age, and presence of other disorders.…”

Mechanocompatible Polymer‐Extracellular‐Matrix Composites for Vascular Tissue Engineering

“…Small‐diameter prosthetic vascular grafts for the treatment of peripheral arterial disease (PAD) have faced great challenges in the clinical setting due to poor long‐term patency . Alternatively, biological grafts using acellular allogenic or xenogenic vascular extracellular matrices (ECM) exhibit excellent mechanical strength and stability in vitro, and maintain the capability to remodel in vivo . However, absence of a functional, intact endothelium leading to exposure of the vascular ECM to flowing blood may precipitate thrombosis and intimal hyperplasia, which are major challenges for ECM‐based small‐diameter vascular grafts .…”