Functional Efficacy\nof Tissue-Engineered Small-Diameter\nNanofibrous Polyurethane Vascular Grafts Surface-Modified by Methacrylated\nSulfated Alginate in the Rat Abdominal Aorta

Improved design to imitate natural vascular scaffolds\nis critical\nin vascular tissue engineering (VTE). Smooth muscle cells originating\nfrom surrounding tissues require larger pore sizes relative to those\nof endothelial progenitor cells found in the bloodstream. Furthermore,\nbiofunctionalized scaffolds mimic the microenvironment, cellular function,\nand tissue morphogenesis. Here, we fabricated macroporous and nanofibrous\npolyurethane (PU) bilayer tissue-engineered vascular grafts (TEVGs)\nby a salt-leaching method to achieve high porosities up to 30 μm.\nThese grafts have a low porosity on the luminal side and a high porosity\non the abluminal side. To enhance their properties, we surface-modified\nthe PU scaffolds using heparin-mimicking methacrylated sulfated alginate\n(PU-MSA). We then evaluated these tubular scaffolds for their anticoagulation\neffect, protein adsorption, and cell attachment in vitro. The results\nrevealed that TEVGs modified with sulfated alginate (PU-MSA) exhibited\nbetter anticoagulation (25 ± 1 min) and higher VEGF protein adsorption\n(75 ± 5 ng/mL) compared to other scaffolds. Moving to in vivo\ntesting, we examined the TEVGs in a rat model for either 1 or 5 months.\nThrough ultrasonication and various histological analyses, we assessed\nthe functionality and biocompatibility of the TEVGs. Notably, the\nPU-MSA scaffold created a microenvironment conducive to cell homing\nand regeneration in the field of VTE.