Intracerebral transplantation of genetically engineered cells for Parkinson's disease: toward clinical application

Over the last decade, molecular biology has progressively developed, leading to new technology with subsequent clinical application for various cerebral diseases including Parkinson's disease (PD), one of the most investigated neurodegenerative disorders. The therapy for PD is mainly composed of medication, including drug replacement therapy, surgical treatment, and cell transplantation. Cell therapy for PD has been explored by using fetal nigral cells as an allo- or xenograft, autologous sympathetic ganglion, adrenal medulla, and carotid body in clinical settings. In addition, neurotrophic factors, including glial cell line-derived neurotrophic factor (GDNF), have a strong potency to rescue degenerating dopaminergic cells. Protein and/or gene therapy also might be a therapeutic option for PD. In this review, genetically engineered cell transplantation for animal models of PD, including catecholamine/neurotrophic factor-secreting cell transplantation with or without encapsulation, as performed in our laboratories, and their potential future as clinical applications are described with recent clinical studies in this field.