Stem cell therapies for Parkinson’s disease

Subjects

Tabar and colleagues report the results of a first-in-human, multisite, open-label phase I trial (NCT04802733) that evaluated the safety and tolerability of bemdaneprocel (a human embryonic stem cell-derived dopaminergic neuron progenitor cell product), which was grafted bilaterally into the putamen of twelve patients with PD. Sawamoto and colleagues report the results of a single-center, phase I/II open-label trial (jRCT2090220384) that investigated the safety and efficacy of the transplantation of allogeneic induced pluripotent stem cell-derived dopaminergic progenitor cells bilaterally into the putamen of seven patients diagnosed with PD. In both trials, participants were divided into two cohorts that received either a low or high dose of the cell product. The primary end point was to assess the safety and tolerability 12–24 months after transplantation. Secondary and exploratory outcomes included motor and nonmotor end points, such as neuroimaging (fluorine-18-l-dihydroxyphenylalanine (¹⁸F-DOPA) PET) to assess dopamine terminal integrity.

In both trials, transplantation was generally well-tolerated: predefined primary safety criteria were met after transplantation and no graft-induced dyskinesias were observed. In addition, both studies showed an increase in ¹⁸F-DOPA uptake after transplantation (as compared with baseline), which suggests increased synthesis of dopamine in the striatum and survival of the transplanted dopaminergic neurons, and supports the therapeutic potential of the transplanted cells. Finally, both studies demonstrated improved motor function (compared with baseline) following stem cell transplantation therapy, as measured by the Movement Disorder Society Unified Parkinson’s Disease Rating Scale (MDS-UPDRS) Part III.

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