In situ endothelialisation potential of a biofunctionalised nanocomposite biomaterial-based small diameter bypass graft

Endothelial dysfunction or the lack of an endothelium associated with cardiovascular grafts is a major cause of graft failure which is linked to thrombosis and related complications. This study was aimed to (1) biofunctionalise a nanocomposite biomaterial, Polyhedral Oligomeric silsesquioxane modified polycarbonate urea-urethane (POSS-PCU), based small diameter vascular graft and to (2) induce endothelialisation with EPC containing monocytes, which were extracted from peripheral blood. (1) Biofunctionalisation of the nanocomposite polymer: bioactive RGD peptide, which is a functional domain of an extracellular matrix component, fibronectin, was synthesised using fmoc chemistry. A lauric acid hydrophobic "tail" was attached to optimise the RGD orientation on the biomaterial. The peptide was cross linked to POSS-PCU. The presence of RGD on the nanocomposite was tested with water contact angle measurements and specificity tests were carried out with the peptide RAD (2) Progenitor cells were extracted from peripheral blood of adult healthy volunteers and cultured on porous biofunctionalised nanocomposite polymer under static conditions. Cells were also introduced to a circuit to which the grafts are connected and non static pulsatile flow conditions were introduced after 72 h following cell introduction. The degree of cell growth was tested with Alamar Blue assay. Endothelialisation was confirmed with SEM and by immunostaining for endothelial cell markers, CD34, CD31 and eNOS. Water contact angle measurement indicated that biofunctionalisation had increased hydrophilicity of the nanocomposite polymer. Alamar blue indicated a greater presence of cells on biofunctionalised nanocomposite and this relative increase in cell viability was specific to RGD as confirmed with RAD peptides. SEM provided evidence for endothelial cell morphology and this was confirmed with endothelial cell markers with immunostaining. Biofunctionalised nanocomposite polymer-based small diameter bypass graft demonstrated the potential for relatively rapid endothelialisation from cells extracted from peripheral blood.