CELL TRANSPLANTATION FOR CENTRAL-NERVOUS-SYSTEM DISORDERS

Initially, the specific aim of transplantation studies was to investig ate the regenerative capabilities of the mammalian nervous system. Fro m this underlying impetus, a myriad of knowledge, spanning from molecu lar biology to neurobiology, has enhanced our understanding of regener ation and the applicability of fetal tissue transplantation in treatin g various neurodegenerative diseases. Current evidence suggests that t ransplantation of fetal neural tissue ameliorates the neurobiological and behavioral changes observed in animal models of central nervous sy stem (CNS) disorders. In light of numerous basic science studies, clin ical trials have begun to evaluate the potential of neural transplanta tion in treating human diseases. Indeed, modest progress has been repo rted in the treatment of Parkinson's disease. However, whereas fetal t issue transplantation has reached considerable success, it has also be en observed to produce either no beneficial effects, magnify existing behavioral abnormalities, or even produce a unique constellation of de ficits. Thus, while the prospects are promising, further investigation s aimed at improving and refining existing transplantation paradigms a re warranted before neural transplantation techniques can be of widesp read value. This review article attempts to provide an overview of the neuroanatomical, neurochemical, and behavioral effects produced by tr ansplanted fetal tissue in several animal models of CNS disorders. We have attempted to present both positive and adverse effects and to cri tically analyze the suitability of neural transplantation as a therapy for the various neurological disorders. In addition, alternative appr oaches, including the use of encapsulated neural tissue implants and g enetically engineered cell lines along with their clinical potential, are discussed when appropriate.