A Comparative In Vivo Study of Small-Diameter Vascular Grafts Fabricated from Electrospun Tecothane and Tecoflex Polyurethanes

This study aimed to compare the in vivo performance of small-diameter vascular prostheses (VPs) electrospun from protein-enriched aromatic (Tecothane) and aliphatic (Tecoflex) polyurethanes versus standard expanded polytetrafluoroethylene (ePTFE) grafts in a rat aortic model. The unsatisfying long-term patency and excessive neointimal hyperplasia of clinically used ePTFE small-diameter grafts motivate the search for alternative materials with improved biocompatibility and mechanical compliance. SDVGs were implanted into the infrarenal aorta of Wistar rats for up to 6 months. Evaluations included graft patency (Doppler ultrasound), mechanical properties (tensile testing), histology (H&E staining), immunohistochemistry (CD31, α-SMA, and collagen IV), and analysis of neointimal formation as well as peri-graft tissue response. Polyurethane (PU) grafts demonstrated superior surgical handling, with shorter anastomosis times and better needle-puncture sealing than ePTFE. Tecothane grafts exhibited higher tensile strength but lower elasticity than Tecoflex. Both PU grafts maintained stable mechanical properties post-implantation and showed better patency than ePTFE. Notably, neointimal hyperplasia was markedly reduced in PU grafts (2–3-fold increase in thickness vs. 6-fold for ePTFE). Tecothane grafts developed a denser, more organized thinner neointima with a well-defined CD31+ endothelial layer and elicited less peri-graft tissue encapsulation than Tecoflex. Critically, no calcification was observed in any PU grafts, unlike ePTFE controls. The electrospun Tecothane graft demonstrated an optimal balance of mechanical properties, biocompatibility, and hemodynamic performance, favoring rapid endothelialization and suppressing pathological remodeling (excessive neointimal hyperplasia and calcification). These results support Tecothane SDVG as a promising alternative to ePTFE for small-diameter vascular replacement.