The in vivo characterization of electrospun heparin-bonded polycaprolactone in small-diameter vascular reconstruction

Objective To evaluate the possibility of using heparin-bonded polycaprolactone grafts to replace small-diameter arteries. Methods Polycaprolactone was bonded with heparin. The activated partial thromboplastin time of heparin-bonded polycaprolactone grafts was determined in vitro. Small-diameter grafts were electrospun with heparin-bonded polycaprolactone and polycaprolactone and were implanted in dogs to substitute part of the femoral artery. Angiography was used to investigate the patency and aneurysm of the grafts after transplantation. After angiography, the patent grafts were explanted for histology analysis. The degradation of the grafts and the collagen content of the grafts were measured. Results Activated partial thromboplastin time tests in vitro showed that heparin-bonded polycaprolactone grafts exhibit obvious anticoagulation. Arteriography showed that two heparin-bonded polycaprolactone and three polycaprolactone grafts were obstructed. Other grafts were patent, without aneurysm formation. Histological analysis showed that the tested grafts degraded evidently over the implantation time and that the luminal surface of the tested grafts had become covered by endothelial cells. Collagen deposition in heparin-bonded polycaprolactone increased with time. There were no calcifications in the grafts. Gel permeation chromatography showed the heparin-bonded polycaprolactone explants at 12 weeks lose about 32% for Mw and 24% for Mn. The collagen content on the heparin-bonded polycaprolactone grafts increased over time. Conclusion This preliminary study demonstrates that heparin-bonded polycaprolactone is a suitable graft for small artery reconstruction. However, heparin-bonded polycaprolactone degrades more rapidly than polycaprolactone in vivo.