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

Abstract

Hearts of the snails Physa virgata and Biomphalaria glabrata were implanted into the hemocoel of B. glabrata. Implants either were microencapsulated in 2.5% agarose or were unencapsulated. Unencapsulated xenografts from P. virgata underwent complete necrosis within 3 days post-implantation (DPI), whereas allografts were still alive at 7 DPI. In the case of microencapsulated implants, both allografts and xenografts were alive at 3 DPI, showing 4.8 and 14.9% pyknosis among myofiber nuclei, respectively. These results suggest 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 necrotic at 7 DPI. This necrosis may have resulted from oxygen deprivation brought about both by the agarose and by the heterotopic implantation site, inasmuch as microencapsulated allografts and xenografts cultured in saline for 7 days showed only 1.98 and 30% pyknosis, respectively.