Concise review: tissue-engineered vascular grafts for cardiac surgery: past, present, and future

Abstract

In surgical repair for heart or vascular disease, it is often necessary to implant conduits or correct tissue defects. The most commonly used graft materials to date are (a) artificial grafts; (b) autologous tissues, such as pericardium and saphenous vein; (c) allografts; and (d) xenografts. However, none of these four options offer growth potential, and all are associated with varying levels of thrombogenicity and susceptibility to infection. The lack of growth potential of these four options is particularly important in pediatric cardiac surgery, where patients will often outgrow their vascular grafts and require additional operations. Thus, developing a material with sufficient durability and growth potential that will function as the child grows older will eliminate the need for reoperation and significantly reduce morbidity and mortality of some types of congenital heart defects. Vascular tissue engineering is a relatively new field that has undergone enormous growth over the last decade. The goal of vascular tissue engineering is to produce neovessels and neo-organ tissue from autologous cells using a biodegradable polymer as a scaffold. The most important advantage of tissue-engineered implants is that these tissues can grow, remodel, rebuild, and respond to injury. Once the seeded autologous cells have deposited an extracellular matrix and the original scaffold is biodegraded, the tissue resembles and behaves as native tissue. When tissue-engineered vascular grafts are eventually put to use in the clinical arena, the quality of life in patients after surgery will be drastically improved.

Figure 1.

Imaging results after transplantation in human and in sheep. (A, B): Three-dimensional (3D) computed tomography angiogram (A) and angiography (B) of tissue-engineered vascular graft (TEVG) seeded with bone marrow-derived mononuclear cells as an extracardiac total cavopulmonary connection conduit after implantation in clinical trial. There was no stenosis, aneurysmal dilatation, or ectopic calcification noted. (C, D): Ex vivo photo (C) and two-dimensional image with magnetic resonance angiography (D) of TEVG at 6 months after inferior vena cava implantation in sheep. (E): 3D-rendered image of the outside surface of TEVG at 1 month (red) and 6 months (green) after rigid alignment of the surfaces. Mean TEVG luminal volume growth was 126.9 ± 9.9% over 6 months compared with mean growth for the right pulmonary artery over the same period, being 140 ± 12%. From [40] with permission from Wolters Kluwer Health.