“…It is well established that stem cells from one region will, when placed to ectopic CNS sites, differentiate with a terminal phenotype appropriate for that ectopic site (Gage et al, 1995;Lundberg and Bjorklund, 1996;Hammang et al, 1997;Snyder et al, 1997;Brustle et al, 1999;Akiyama et al, 2001). The extra-cellular environment into which transplanted stem cells has an important influence on their fate in vivo (Lundberg and Bjorklund, 1996;Hammang et al, 1997;Snyder et al, 1997;Brustle et al, 1999;Akiyama et al, 2001). Pathological CNS tissue is a different environment than intact CNS tissue and markedly alters the terminal differentiated phenotype of transplanted cells (Gage et al, 1995).…”