A phase IIb, randomised, double-blind, placebo-controlled, dose-ranging investigation of the safety and efficacy of NTCELL® [immunoprotected (alginate-encapsulated) porcine choroid plexus cells for xenotransplantation] in patients with Parkinson's disease.

Regenerative therapies in Parkinson's disease aim to slow neurodegeneration and re-establish damaged neuronal circuitry. Neurotrophins are potent endogenous regulators of neuronal survival, development and regeneration. They represent an attractive regenerative treatment option in Parkinson's disease. Porcine choroid plexus produces a number of neurotrophins, and can be safely delivered to the striatum in an encapsulated formulation (termed NTCELL^®) to protect them from immune attack. NTCELL^® has shown regenerative potential in animal models of stroke, Huntington's disease and Parkinson's disease. Following promising results from an initial open label safety study of intra-striatal delivery of NTCELL^® in human subjects, we sought to specifically investigate the safety and efficacy of NTCELL^® for the treatment of Parkinson's disease.

18 patients aged 56-65 years with idiopathic Parkinson's disease of at least 5 years duration were randomised to receive either sham surgery (general anaesthesia and partial thickness burr holes) or intra-striatal delivery of NTCELL^® (the 3 groups in the treatment arm receiving incremental NTCELL^® doses).

At 26 weeks, we found no significant difference in total UPDRS scores ('on' and 'off'), UPDRS motor scores ('on' and 'off'), PDQ-39, UDysRS, timed walk or modified Hoehn and Yahr stage between patients implanted with NTCELL^® and patients undergoing sham procedure. There were no serious adverse events or xenogeneic viral transmission during the study.

The study did not meet its primary efficacy end-point of a change in UPDRS at 26 weeks post-intervention compared with baseline. Stereotactic NTCELL^® implantation was safe and well tolerated.