STUDY ON SMALL VASCULAR GRAFT DEVELOPMENT

Purpose: In development of small diameter vascular graft, major disadvantages are occlusion of small diameter vessel and low blood flow rate result in graft failure. The seeding of autologous endothelial cells on the luminal surface of vascular graft is a promising method for improving the patency of small diameter prostheses. Surface characteristics of polymer scaffold play a critical role in the internal surface area available for cell attachment. Method: Two types of 3-D porous polyurethane (PU) vascular grafts were made in small diameter (4mm): the first type was made using a mold by utilization of the salt leaching method and thermal phase transition (S/P). Porosity and pore size were controlled by salt mass and size. The alternative type was developed by solvent exchanging and dipping (S/D). To improve attachment of endothelial cell, the luminal surface was modified with plasma treatment and immobilization of fibronectin. Constructed small porous PU-cell vascular grafts were evaluated with tensile testing, MTT assay, and scanning electron microscopy (SEM). After the vascular graft was implanted for two weeks, histological test was conducted. Result: Scaffold fabrication method of salt leaching and thermal phase transition was proper to create 3-D small diameter graft with high porosity value. Therefore the surface modified vascular graft showed enhanced cell attachment. The vascular graft showed respectable mechanical properties in S/P versus S/D. At two weeks after implantation, the patency of graft was more desirable in S/P.