Near-field electrospinning of polydioxanone small diameter vascular graft scaffolds

The ideal "off the shelf" tissue engineering, small-diameter (SD) vascular graft hinges on designing a scaffold to act as a template that facilitates transmural ingrowth of capillaries to regenerate an endothelized neointimal surface. Towards this goal, we explored two types of near-field electrospun (NFES) polydioxanone (PDO) architectures, as SD vascular graft scaffolds. The first architecture type consisted of a 200 × 200 μm and 500 × 500 μm grid geometry with random fiber infill, while the second architecture consisted of aligned fibers written in a 45°/45° and 20°/70° offset from the long axis written, both on a 4 mm diameter cylindrical mandrel. These vascular graft scaffolds were evaluated for their effective pore size, mechanical properties, and platelet-material interactions compared to traditionally electrospun (TES) scaffolds and Gore-Tex® vascular grafts. It was found that effective pore size, given by 9.9 and 97 μm microsphere filtration through the scaffold wall for NFES scaffolds, was significantly more permeable compared to TES scaffolds and Gore-Tex® vascular grafts. Furthermore, ultimate tensile strength, percent elongation, suture retention, burst pressure, and Young's modulus were all tailorable compared to TES scaffold characterization. Lastly, platelet adhesion was attenuated on NFES scaffolds compared to TES scaffold which approximates the low level of platelet adhesion measured on Gore-Tex®, with all samples showing minimal platelet activation given by P-selectin surface expression. Together, these results suggest a highly tailorable process for the creation of the next generation of small-diameter vascular grafts.