Review of Vascular Graft Studies in Large Animal Models

Abstract

As the incidence of cardiovascular disease continues to climb worldwide, there is a corresponding increase in demand for surgical interventions involving vascular grafts. The current gold standard for vascular grafts is autologous vessels, an option often excluded due to disease circumstances. As a result, many patients must resort to prosthetic options. While widely available, prosthetic grafts have been demonstrated to have inferior patency rates compared with autologous grafts due to inflammation and thrombosis. In an attempt to overcome these limitations, many different materials for constructing vascular grafts, from modified synthetic nondegradable polymers to biodegradable polymers, have been explored, many of which have entered the translational stage of research. This article reviews these materials in the context of large animal models, providing an outlook on the preclinical potential of novel biomaterials as well as the future direction of vascular graft research.

Different degradation rates of nanofiber vascular grafts in small and large animal models

“…Sheep were chosen for the large animal model because the anatomy allows for the necessary exposure required to implant a long interposition graft in the IVC. In contrast, pigs for example have thicker rib bones, making it more challenging to obtain adequate exposure to implant the graft (Liu, Ong, Fukunishi, Ong, & Hibino, 2018).…”

Preparation of Small‐Diameter Tissue‐Engineered Vascular Grafts Electrospun from Heparin End‐Capped PCL and Evaluation in a Rabbit Carotid Artery Replacement Model

“…In addition to administration of drugs as a supplementary treatment, an artificial blood vessel substitute implantation has been a primary treatment for cardiovascular and peripheral vascular diseases to achieve revascularization. Various synthetic vascular prostheses such as ePTFE and Dacron (ID >6 mm) as effective large vessels have been validated through decades of clinical applications for most bypass operations, such as hemodialysis access for end‐stage renal disease, as well as lower extremity bypasses. Although autograft is the golden standard for implantation, its extensive application is hindered due to prior harvesting or pathologies.…”

Tissue engineered vascular grafts

“…These polymers have been extensively studied as they have the capacity to degrade in a controllable manner, allowing for the endothelialization of the graft by the host's cells. As they gradually secrete the extracellular matrix, the graft will be replaced by the endogenous vessel (Liu et al, 2018). Most commonly used materials are polyglycolic acid, polylactic acid, poly(lactide-co-glycolic) acid, poly εcaprolactone, polyurethanes, and poly(glycerol-sebacate) (Liu et al, 2018, Carrabba andMadeddu, 2018).…”

“…Polyurethanes and poly(glycerol-sebacate) are bioresorbable polymers with remarkable properties in terms of biocompatibility, hemocompatibility, and low thromboreactivity, allowing for endothelial cell proliferation and elastin production (Carrabba and Madeddu, 2018). Although the mechanical properties and the degradation speed can be modulated by applying combinations of polymers (Liu et al, 2018), there is still need for improvements, since the burst pressure of these grafts is 0.19 mmHg (Carrabba and Madeddu, 2018). However, biodegradable polymers exhibit enhanced mechanical properties and high reproducibility compared to natural polymers.…”