Towards a neural transplantation therapy for Parkinson's disease: experimental principles from animal studies

Animal experimentation is necessary to identify the optimal parameters and procedures for clinical application of neural tissue transplantation. Experiments in animal models of Parkinson's disease are briefly reviewed. Embryonic nigral tissues survive transplantation well and yield good functional recovery on a variety of motor tests. The age of the donor, the implantation technique, and the site of placement in the host brain all influence graft efficacy. Nevertheless there are theoretical limits to the power of current procedures, and even under optimal circumstances full recovery cannot be expected.