A tri-layer tissue engineering heart valve scaffold based on atelocollagen, hyaluronic acid, and elastin

Abstract

Aim: This study aims to fabricate and characterise a novel tri-layer scaffold based on type I atelocollagen, hyaluronic acid (HA), and a novel fibrillar elastin gel, mimicking the native heart valve leaflets in structure, composition, and mechanical properties, among which, the bending anisotropic behaviour in both the with curvature (WC) and the against curvature (AC) directions, is the most desired. The use of atelocollagen is of significant importance in highlighting the non-antigenic potential of the design. Methods: Porous scaffolds were freeze-dried, then crosslinked using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and N-hydroxysuccinimide (NHS). The fibrillogenesis occurrence and the scaffold microstructure were imaged using scanning electron microscopy (SEM). Fourier transform infrared spectroscopy (FITR) investigated the effect of fabrication and crosslinking on the backbone structure. Dynamic mechanical analysis (DMA) characterised the compressive and bending properties of the scaffolds in hydrated and non-hydrated states. Three-point bending and a “self-deflection” test were performed on tri-layer scaffolds in both WC and AC directions. Results: Atelocollagen-based scaffolds were successfully produced, rendering this study the first to report a tri-layer structure using atelocollagen, HA, and elastin fibrillar gel. The scaffolds’ porosity was tailored to accommodate potential future biological studies and the transition between layers appeared seamless. FITR unveiled effective crosslinking and the backbone structure preservation. The scaffolds exhibited lightly crosslinked polymer resembling mechanical responses when non-hydrated, and the desired J-curve stress-strain response was observed when hydrated. The tri-layer scaffolds showed anisotropic bending behaviour with a bending modulus of 5.41 ± 1.14 kPa (WC) and 7.98 ± 2.22 kPa (AC). Conclusions: The tri-layer scaffolds fabricated resemble the native aortic valve leaflets in structure and composition, and successfully introduced bending anisotropy in physiological conditions. Together with the suitable microstructure and promising mechanical properties, the design is reckoned to be a potential tissue engineering heart valve candidate.