Hydrogel-coated, Bilayered Vascular Graft Prepared by Electrospinning and Phase-inversion Spray Techniques

Peripheral artery disease and related revascularization procedures are increasing, due to the ageing population and growing incidence of diabetes mellitus. Synthetic grafts are successfully used to replace large diameter vessels, but they fail in small diameters (<6 mm) due to poor hemocompatibility and compliance mismatch with the host vessel. Electrospinning allows the production of nanopatterned fibrous structures that resembles the native ECM, thus supporting endothelial cell attachment, alignment, proliferation and maintenance of their functions. However, the small pores size of an electrospun graft hinders cell infiltration and formation of a 3D structure similar to the tunica media. Spray, phase-inversion technique was successfully employed to fabricate microporous vascular grafts able to support 3D cell organization throughout the wall thickness. In this work a hydrogel-coated, bilayered vascular graft was developed combining electrospinning, phase-inversion spraying and protein coagulation techniques. In particular, an inner nanofibrous layer was prepared by electrospinning and an external highly porous layer was fabricated by spray, phase-inversion technique. This bilayered graft was then impregnated with a cell-conducive hydrogel layer. Graft morphology and thickness, fiber size, pore size and layer adhesion was evaluated. SEM analysis revealed a firm adhesion of sprayed layer onto the electrospun surface of graft. This study demonstrated the possibility to integrate different techniques to manufacture a novel vascular graft with improved functionalities.