Improving cellularisation of tissue endgineered vascular grafts using functionalised peptide hydrogels

Abstract

Tissue engineered vascular grafts have the potential to replace saphenous vein for multiple small diameter (<6mm) coronary artery bypass grafts, which offer relatively poor long term patency rates, often leading to repeat surgeries. Despite their potential, first generation vascular grafts have failed to provide superior patency rates when compared to saphenous vein grafts. One of main reasons for early graft failure is thrombus formation, which is attributed to an inadequate or absent luminal endothelial monolayer. In this study we aimed to determine whether the incorporation of a small mimetic peptide (RGDS) to functionalise a peptide hydrogel improves cell attachment, growth and survival of seeded cells. Gels were synthesised using standard solid-phase peptide synthesis protocols on a CEM “Liberty” microwave-assisted peptide synthesizer. Human adipose-derived adult stem cells were seeded onto the peptide hydrogels with and without an incorporated RGDS cell adhesion peptide (RGDS+ and RGDS- hydrogel). Cells were fixed and permeabilised, stained with DAPI (nuclei) and Phalloidin (actin), and imaged using confocal laser scanning microscopy. The RGDS+ hydrogel showed increased cell number and enhanced distribution compared to the RGDS- hydrogel. Cells showed enhanced infiltration on the RGDS+ hydrogel and looked morphologically healthy on both gels. Our initial findings suggest incorporating a specific RGDS mimetic peptide into a peptide hydrogel can beneficially affect cell behaviour, perhaps through enhanced adherence and survival. We will incorporate these with a PLGA scaffold and determine its potential as a tissue engineered graft in a bioreactor in future studies.