TRANSPLANTED XENOGENEIC NEURAL CELLS IN NEURODEGENERATIVE DISEASE-MODELS EXHIBIT REMARKABLE AXONAL TARGET SPECIFICITY AND DISTINCT GROWTH-PATTERNS OF GLIAL AND AXONAL FIBERS

Clinical trials are under way using fetal cells to repair damaged neur onal circuitry. However, little is known about how transplanted immatu re neurons can grow anatomically correct connections in the adult cent ral nervous system (CNS). We transplanted embryonic porcine neural cel ls in vivo into adult rat brains with neuronal and axonal loss typical of Parkinson's or Huntington's disease. Using complementary species-s pecific cellular markers, we found donor axons and CD44(+) astroglial fibres in host white matter tracts up to 8 mm from CNS transplant site s, although only donor axons were capable of reaching correct gray mat ter target regions. This work demonstrates that adult host brain can o rient growth of transplanted neurons and that there are differences in transplant donor glial and axonal growth patterns in cellular repair of the mature CNS.