Discordant xenografts: Different outcome after mouse and rat neural tissuetransplantation to guinea-pigs

Embryonic neural tissue obtained from other species has been considered as a donor tissue source in repair strategies for human neurodegenerative diso rders. The neuro- and immunobiology of distantly related species combinatio ns, discordant xenografts, need to be characterised. For this purpose, a sm all animal model would be an important research tool. Adult guinea-pigs, an d adult rats as controls, received intrastriatal grafts of either mouse or rat embryonic ventral mesencephalic tissue. The survival rates and types of host immune response were assessed at 2 weeks after grafting using stereol ogical techniques and semi-quantitative evaluations, In the mouse-to-guinea -pig group, all transplants were rejected and no tyrosine hydroxylase-immun o reactive (TH-IR) cells remained. In the rat-to-guinea-pig group, there wa s good survival of TH-IR cells (5050 SEM +/- 1550), similar to that in the rat-to-rat group (4900 SEM +/- 1540). In the mouse-to-rat group, half of th e animals had no surviving TH-IR cells (520 SEM +/- 230 for the whole group ). These species combinations offer inexpensive, efficient, and suitable co nditions to study important survival factors for discordant xenogeneic neur al tissue transplants. The factors responsible for the divergent graft outc omes between the two combinations might provide clues on how to manipulate xenogeneic tissue to increase survival rates in the future. (C) 1999 Elsevi er Science Inc.