Challenges in the clinical advancement of cell therapies for Parkinson’s disease

Cell therapies as potential treatments for Parkinson’s disease first gained traction in the 1980s, owing to the clinical success of trials that used transplants of foetal midbrain dopaminergic tissue. However, the poor standardization of the tissue for grafting, and constraints on its availability and ethical use, have hindered this treatment strategy. Recent advances in stem cell technologies and in the understanding of the development of dopaminergic neurons have enabled preclinical advancements of promising stem cell therapies. However, to advance to the clinic, challenges in the appropriate levels of safety screening and optimization needed for the cell products as well as in the scalability of their manufacturing will need to be overcome. In this Review Article, we discuss how current challenges, pertaining to cell source, functional and safety testing, manufacturing and storage, and clinical-trial design, are being addressed to advance the translational and clinical development of cell therapies for Parkinson’s disease.