The future of cell therapies in the treatment of Parkinson's disease.

Parkinson's disease (PD) is a common neurological disorder of the brain which has as a part of its core pathology the progressive degeneration of the dopaminergic nigrostriatal pathway. Therefore, cell therapies that aim to restore this degenerated dopaminergic network represent a promising strategy in helping to cure PD. In this review, the authors start by discussing the progress of research on the use of fetal ventral mesencephalic (VM) tissue in transplantation therapies in PD, both from the clinical and experimental perspectives. Then the issues pertinent to its adoption in the clinic are discussed, including the ethical and practical problems with its use, the varied composition of VM tissue that is implanted with the graft and how this may account for some of the problems seen in the clinical trials using this tissue, especially graft-induced dyskinesia. Finally other promising sources of tissue for PD cell therapy are described, including mesenchymal and embryonic stem cells, before concluding on what is the best approach to the cellular repair of the parkinsonian brain.