Development of Novel Ridge-and-Valley Form Small-Caliber Compliant Vascular Grafts Based on a Modified Near-Field Coaxial Electrospinning Technique

Limited attention has been paid to the macroscopic topology of small-caliber electrospinning artificial vascular grafts. Here, we fabricated an elastic vascular graft of 2 mm diameter featuring a "ridge-and-valley" macrostructure using a modified near-field coaxial electrospinning technology, which combines the near-field electrospinning direct-writing technique and coaxial electrospinning technology, employing polyurethane (PU) as the outer shell and poly(l-lactide-co-ε-caprolactone) (PLCL) as the inner core. By adjusting the PLCL/PU ratio, the viscosity of the blended solution was tuned to meet electrospinning requirements. The electrospun grafts exhibited oriented filament alignment in the ridge regions and a relatively disordered configuration in the valley regions, demonstrating significantly enhanced kinking resistance in macroscopic testing. In vitro cell experiments and in situ rat abdominal aorta transplantation models verified the graft's ability in inducing vascular smooth muscle cell (vSMC) alignment generated by oriented fiber alignment. Importantly, partial endothelial coverage and circumferentially aligned vSMC proliferation were observed. Critically, the PLCL/PU 0.5/0.5 group showed a great patency rate and a desirable functional structure at the 12-week endpoint. These findings present a novel strategy for fabricating small-caliber biocompatible vascular grafts with favorable mechanical properties via a straightforward, continuous single-step process.