Open-label Investigation of the Safety and Clinical Effects of NTCELL in Patients With Parkinson's Disease

To assess the safety of xenotransplantation of NTCELL \[immunoprotected (alginate-encapsulated) choroid plexus cells\] in patients with Parkinson's disease, assessed over the duration of the study, by monitoring the occurrence of adverse events and serious adverse events, including clinical and laboratory evidence of xenogeneic infection in transplant recipients and their partners/close contacts. Subsequent safety follow-up will include lifelong monitoring for clinical and laboratory evidence of xenogeneic infection. To assess the clinical effects of NTCELL \[immunoprotected (alginate-encapsulated) choroid plexus cells\] in patients with Parkinson's disease. This will be quantified by testing the secondary endpoints of the trial as described below (see Endpoints/Outcome Measures).

Parkinson's disease is characterized by widespread neural degeneration, particularly in the substantia nigra and its projections to the basal ganglia. Current therapy for Parkinson's disease is purely symptomatic. There is a pressing need for a treatment that reverses or slows the degeneration of the nigrostriatal pathway. Numerous transplant-based therapies have attempted to support, repair or replace the degenerating nigrostriatal neurons. These have included the transplantation of foetal and other neuronal stem cells, gene transfers, and the implantation of devices releasing neural growth factors. All these have been shown to have some effectiveness in animal models, but have been generally disappointing in human studies. Intracranial choroid plexus cell transplantation has the potential to deliver biological neural agents for the treatment of Parkinson's disease which cannot be achieved by conventional treatment. The overall aim of delivering neural proteins and compounds over many months to the basal ganglia of the brain is to enhance neural repair currently not possible with antiparkinsonian medication or deep brain stimulation (DBS). As animal-derived tissues have to be protected from immune rejection when transplanted into humans, transplants are usually accompanied by immunosuppressive therapy. However, porcine choroid plexus cells are preferably implanted without the use of immunosuppressive drugs which cause significant morbidity. To protect them from immune rejection, the cells can be encapsulated in alginate microcapsules which permit the inward passage of nutrients and the outward passage of biologic neural proteins and compounds normally secreted by choroid plexus cells. Alginate-encapsulated porcine choroid plexus cells implanted into the brain without immunosuppressive drugs have survived rejection for many months in animal studies. NTCELL comprises neonatal porcine choroid plexus cells encapsulated in alginate microcapsules. NTCELL has been safely implanted in rats, and non-human primates. Following NTCELL implants, animals with chemically-induced Parkinson's-like lesions showed improvement of functional neurological motor abnormalities that was associated with histologic changes consistent with amelioration of the lesion. The initial dose for intracranial implantation of the current NTCELL preparation for the treatment of Parkinson's disease in humans is based on the effective dose in a non-human primate (rhesus monkey) model. Parkinson's disease patients will be followed up for 26 weeks after receiving an implantation of NTCELL administered into the putamen of the corpus striatum on the side contralateral to the greatest clinical deficit. Based upon the data obtained during the 26-week follow-up period a decision will be made as to whether the patient will receive: * an implantation of a second dose of NTCELL * unilateral DBS * bilateral DBS * no further intervention The data will be reviewed by the investigators and the Data Safety Monitoring Board (DSMB), the data will consist of clinical outcomes and clinimetric data, an MRI scan, PET scanning, and adverse events. Patients will be followed up for a further 48 weeks if there is no further intervention, however if it is decided that either DBS or implantation of a second dose of NTCELL occurs then the frequency of follow-up will be the subject of a protocol amendment.