VASCUGRAFT(R) MICROPOROUS POLYESTERURETHANE ARTERIAL PROSTHESIS AS A THORACOABDOMINAL BYPASS IN DOGS

In their progression towards clinical acceptance, any new synthetic va scular grafts under development must undisputedly prove that the chemi stry and structure used in the construction of the prostheses is safe and that their biocompatibility and performance as arterial substitute s are satisfactory without degradation or weakening of the device. Thi s study was conducted to evaluate the safety of the microporous polyes terurethane Vascugraft(R) by investigating its biocompatibility in ter ms of cellular proliferation, morphology and adhesion of human fibrobl asts on virgin and blood-soaked Vascugraft(R) prostheses, and its perf ormance in vivo as a large calibre graft in a canine thoraco-abdominal bypass model for periods of implantation ranging from 4 h to 6 months . After 3 d incubation, better cell proliferation and adhesion were ob served on blood-soaked Vascugraft(R) than on a non-porous polyurethane graft, Mitrathane(R), and two other polytetrafluorethylene prostheses , Impra(R) and Goretex(R) Furthermore, no leachable cytotoxic contamin ants were released from the prostheses. In vivo, the Vascugraft(R) has demonstrated a good performance with the development of an endothelia lised internal capsule at both anastomoses 2 weeks after implantation, reaching the medial portion of the graft at 4 months. During this per iod, the prostacyclin I-2/thromboxane A(2) ratio increased and was hig her than 1.0 at 2 months. In addition, the Vascugraft(R) exhibited low surface thrombogenicity in terms of radiolabelled platelets and fibri n deposited. Chemically, as revealed by ESCA and FTIR analyses, a slig ht decrease in carbonate content was observed on the external surface of the Vascugraft(R) during the early post-implantation periods. Break s in the microfibrous structure were also observed at 4 and 6 months, occurring mainly in the anastomotic regions and believed to be stress- related. This study shows that the polymer used in the Vascugraft(R) i s biocompatible in terms of fibroblast proliferation and promotes fair healing characteristics. However, the chemical and structural surface modifications noted in this study are disturbing and question the tot al inocuity of the Vascugraft(R). Consequently, the decision by B. Bra un Melsungen AG to end this project is both highly conscientious and p rofessional. Copyright (C) 1996 Elsevier Science Limited