Ex vivo and in vivo evaluation of the blood compatibility of surface-modified polyurethane catheters.
Catheter model tubes were prepared from a medical-grade polyetherurethane and their outer surfaces modified by surface-graft polymerization of acrylamide and dimethyl acrylamide (DMAA). The surface-graft layer was characterized by means of dry staining, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy, and protein adsorption. Ex vivo evaluation for the blood compatibility of the surface-modified polyurethane was carried out using the polyurethane tube as an arterio-venous shunt between the carotid artery and the jugular vein of rabbits. When the surface density of grafted polymer was in the range of 10-30 microg/cm2, the in vitro adsorption of IgG exhibited a minimum value and platelet adhesion to the grafted polyurethane surface was insignificant, in marked contrast with that to the virgin (nonmodified) surface. The in vivo blood compatibility of polyurethane was evaluated by implanting the catheter tube in the inferior vena cava of rabbits from the femoral vein after ligation of a distal site of the exposed femoral vein. After remaining there for predetermined periods of time, the implanted catheters were taken out together with the veins of the rabbits that had been heparinized and sacrificed just prior to excision of the veins. After exchange of the blood in the veins for saline, the excised veins were opened by cutting longitudinally to inspect for clot formations on the surfaces of the implanted catheters. Occlusion of the inferior vena cava was not observed for any of the catheters, nor was there any apparent damage or microembolizations in the lungs and kidneys. Many small-sized clots were observed on the surfaces of the nonmodified polyurethane tubes after a 2-week implantation whereas the catheter surfaces grafted with DMAA polymer chains had a much smaller number of clots. When the blood compatibility of polyurethane surfaces was graded for relative evaluation from one (marked clotting) to five (no clotting) based on the size and number of the clots, the evaluation results were as follows: 3.1 (virgin, 2 weeks), 4.0 (grafted, 1 week), 4.1 (grafted, 2 weeks), and 3.5 (grafted, 1 month).
Inoue
H
H
Research Center for Biomedical Engineering, Kyoto University, Sakyo-ku, Japan.
Fujimoto
K
K
Uyama
Y
Y
Ikada
Y
Y
D000178:Acrylamides; D000327:Adsorption; D000818:Animals; D001166:Arteriovenous Shunt, Surgical; D001777:Blood Coagulation / Q000187:drug effects*; D002408:Catheters, Indwelling / Q000009:adverse effects; D006648:Histocompatibility; D007074:Immunoglobulin G / Q000276:immunology; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D011140:Polyurethanes / Q000009:adverse effects; D011817:Rabbits; D013499:Surface Properties; D013997:Time Factors
D000178:Acrylamides; D007074:Immunoglobulin G; D011140:Polyurethanes