Tissue engineered vessel from a biodegradable electrospun scaffold stimulated with mechanical stretch

Abstract

A tissue engineered vessel has the potential to provide an alternative small diameter vascular graft for patients with cardiovascular disease in need of surgical revascularization. In this study, a polyglycolic acid (PGA) electrospun scaffold seeded with human dermal fibroblasts was stimulated with circumferential mechanical stretch by a pulsatile perfusion system. The PGA scaffold was fabricated using a custom electrospinning set-up to co-electrospray a sacrificial polyethylene oxide microparticle to increase pore size and bulk porosity. The tissue engineered vessel exposed to circumferential mechanical stretch was compared to an engineered vessel cultured under static conditions without any mechanical stimulation. The histology cross-sections demonstrated a similar thickness of engineered vessels with mechanical stretch and static, but on Masson’s Trichrome stain there was nearly twice the amount of staining for collagen. The collagen content was quantified, and the collagen content was 60% greater in the human tissue engineered vessel exposed to mechanical stretch compared to the static vessel. The total collagen cross-linking was similar, but on a per collagen basis there was significantly more cross-linking in the static vessel over the stretch vessel. The stress-strain curve of the tissue engineered vessel with mechanical stretch demonstrated a statistically significantly greater ultimate tensile strength (UTS) of 1.86 ± 0.14 MPa (n = 6) and elastic modulus (EM) of 7.62 ± 0.39 MPa (n = 6) versus the static engineered vessel UTS of 0.31 ± 0.07 MPa (n = 5) and EM of 1.37 ± 0.21 MPa (n = 5). The primary determinant of the mechanical properties of the tissue engineered vessel correlated to the collagen content with minimal contribution of the collagen cross-linking. Therefore, the versatile properties of an electrospun scaffold are ideal in combination with a biomimetic culture system to generate a tissue engineered vessel composed of extracellular matrix suitable as a vascular graft.