Gene therapy for Parkinson's disease

Significant progress has been made in the field of gene therapy for Parkinson's disease (PD). Successful vehicles for gene transfer into the central nervous system have been developed and clinical efficacy and safety have both been shown in various animal models of PD. Further optimisation of dosing, timing and location of gene therapy delivery as well as the ability to regulate and prolong gene expression will be important for the commencement of human trials. Current gene therapy models for PD have focused on two treatment strategies. One is the replacement of biosynthetic enzymes for dopamine synthesis and the second strategy is the addition of neurotrophic factors for protection and restoration of dopaminergic neurones. Concepts of neuroprotection and restoration of the nigrostriatal pathway will become important themes for future genetic treatment strategies for PD and may include, in addition to neurotrophic factors, genes to prevent apoptosis or detoxify free radical species. This review will highlight the recent literature on gene therapy for PD and summarise general approaches to gene therapy.