Short-term immunoisolation of incompatible xenografts in a snail, Biomphalaria glabrata

Hearts of the snails Physa virgata and Biomphalaria glabrata were implanted into the hemocoel of B. glabrata. Implants either were microencapsulated i n 2.5% agarose or were unencapsulated. Unencapsulated xenografts from P. vi rgata underwent complete necrosis within 3 days post-implantation (DPI), wh ereas allografts were still alive at 7 DPI. In the case of microencapsulate d implants, both allografts and xenografts were alive at 3 DPI, showing 4.8 and 14.9% pyknosis among myofiber nuclei, respectively. These results sugg est that direct cytotoxicity by hemocytes, rather than toxic plasma factors or donor-recipient physiological incompatibility, is responsible for rapid xenograft death. However, both types of microencapsulated grafts were necr otic at 7 DPI. This necrosis may have resulted from oxygen deprivation brou ght about both by the agarose and by the heterotopic implantation site, ina smuch as microencapsulated allografts and xenografts cultured in saline for 7 days showed only 1.98 and 30% pyknosis, respectively. (C) 2000 Elsevier Science Ltd. All rights reserved.