Hamster vein xenografts for arterial replacements in rats

Experimental studies of vein homografts in rats have shown prolonged patency resulting from an attenuated immune response. This study examined the response to Golden Syrian hamster vein xenografts. While one group of Sprague-Dawley rats served as a control, a second group was sensitized with 5 X 10(6) viable hamster splenic lymphocytes given i.m. ten days and two days prior to microvascular replacement of a 2-cm. segment of infrarenal abdominal aorta with hamster vena cava. Graft patency was assessed daily by palpation and Doppler examination of femoral pulses. A technical error resulted in graft thrombosis in one sensitized rat at two days, but the remaining 19 grafts remained patent up to four months. The assay of lymphocytotoxicity by trypan blue excision revealed significant antibody response in all sensitized animals (average 64% cytotoxicity at 1/20 serum dilution) at the time of and subsequent to graft placement. There was no significant antibody response in the nonsensitized group (10% cytotoxicity for undiluted serum). The minimal degree of intimal thickening and medial degeneration on histological examination of grafts did not differ between the two groups. The patency of hamster venous xenografts may be well maintained in the rat despite a vigorous antibody response to lymphocyte antigens.