Heparinized Polyurethane/Polycaprolactone Nanofibers via Oxygen Plasma for Enhanced Endothelialization And Angiogenesis in Small-Diameter Grafts

Cardiovascular diseases, among which atherosclerosis is the most prevailing, are leading causes of death worldwide. Coronary artery bypass grafting (CABG) is one common surgical treatment. However, synthetic vascular grafts in small-diameter vessels are still limited due to their relatively high incidences of thrombosis and intimal hyperplasia. To overcome these limitations, advanced tissue-engineered vascular grafts (TEVGs) that possess characteristics similar to those of natural blood vessels and hold promise for better biocompatibility are desirable. In this study, heparinized polyurethane (PU)/polycaprolactone (PCL) composite nanofibers were fabricated by electrospinning for use as small-caliber TEVG scaffolds. Heparin was covalently attached onto PU/PCL (2:1 ratio) composite nanofibers through cross-linking chemistry. Scaffolds were systematically characterized with respect to physicochemical properties, heparin distribution uniformity, and in vitro biocompatibility. The results indicated that the incorporation of heparin into PU/PCL nanofibers enhanced the expression of markers associated with endothelialization and angiogenesis. Modified scaffolds exhibited better biocompatibility with increased cell proliferation and reduced platelet adhesion compared to pure PU scaffolds or neat blends PCL/PU ones. This work provides a promising method of improving results using small-diameter TEVGs by rational biochemical modifications for facilitating CABG and the development of other vascular replacement surgeries.