CYTOARCHITECTONIC DEVELOPMENT, AXON GLIA RELATIONSHIPS, AND LONG-DISTANCE AXON GROWTH OF PORCINE STRIATAL XENOGRAFTS IN RATS

Porcine fetal lateral ganglionic eminence cells were transplanted into the quinolinic-acid-lesioned corpus striatum of immunosuppressed adul t rats. The resulting grafts were analyzed for graft development with respect to donor age, donor cell dosage, and survival time from 5 to 2 2 weeks postimplantation. Graft development is prolonged by a factor o f 3-4 times in porcine xenografts as compared to rat allografts. As gr afts matured, neuronal somata developed in clusters that expressed ace tylcholinesterase (AChE), tyrosine hydroxylase, and dopamine- and cAMP -associated phosphoprotein. These clusters were interspersed with AChE -poor graft regions consisting of small densely packed cells that stai ned for glial fibrillary acidic protein and porcine cluster of differe ntiation factor 44 (a species-specific glial marker). Graft axons coul d be selectively stained for 70-kDa neurofilament and were preferentia lly associated with AChE-poor, glial-rich regions in younger grafts (8 weeks), but AChE-rich neuronal regions in older grafts (22 weeks). Bo th graft axons and graft glial fibers projected for long distances int o the host internal capsule, external capsule, corpus callosum, and an terior commissure. Donor axons also innervated host target structures including the globus pallidus and substantia nigra. This demonstrates a prolonged development of striatal cells that is appropriate to the d onor species and which produces long-distance target-specific axonal g rowth within the adult host brain. (C) 1994 Academic Press, Inc.