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.
The bilateral dose that will be administered to the 18 patients (initially 3 groups of 6 patients, randomised 4:2 NTCELL:sham surgery) enrolled in this trial will be up to a total of twice the human equivalent dose administered unilaterally in LCT's non-human primate study. Thus up to 240 NTCELL microcapsules (± 5%) administered on each side of the brain.
If there are no significant safety issues after implantation of the first group of patients, the second group of patients will then be scheduled to receive implants of NTCELL.
If there are no significant safety issues after implantation of the second group of patients, the third group of patients will then be scheduled to receive implants of NTCELL.
This study will adopt an adaptive design in respect to the choice of dose of NTCELL for the fourth group of patients (those patients who originally received sham surgery in Groups 1-3). Following unblinding of the study after Groups 1-3 have reached 26-week follow-up, an interim analysis, for safety and efficacy, will be undertaken.
If there are no significant safety issues, the last group of patients, Group 4, (who originally received sham surgery) will be scheduled to receive NTCELL implants. The dose of NTCELL given will be determined by the DSMB following a proposal from the Principal Investigator, based on the results of the interim analysis.
Parkinson's disease patients will be followed up for 26 weeks after receiving either an implantation of NTCELL or sham surgery.
