In a Phase 1/2 open-label trial out of a collaboration between Lund and Cambridge universities, and conducted in Skåne University Hospital. Researchers evaluated the therapeutic potential of transplanting laboratory-produced dopaminergic progenitor cells into the brains of Parkinson’s patients. Earlier approaches relied on fetal tissue donations, which face significant supply constraints. The progenitor cells used in this study can be cultured at scale under standardised manufacturing conditions, enabling broader clinical application with consistent quality assurance.
Eight participants received the STEM-PD cell product across two dose levels, four received a lower dose and four received a higher dose. The surgical technique mirrored previous fetal cell trials, facilitating direct comparison. Five implantation trajectories were established in the putamen, receiving either four or eight cell deposits depending on dose assignment. Participants were monitored at six and twelve months to evaluate graft survival and clinical outcomes.
Brain imaging (PET and MRI) showed elevated dopamine activity in the implantation zones, suggesting successful cell survival in both groups. Most participants reduced their medication requirements during the 12-month period, and most demonstrated improvement in motor symptoms during off-medication assessments. Researchers continue monitoring participants through 36 months to track long-term durability.
Safety assessment identified immunosuppression-related complications as the primary concern. The necessity for anti-rejection medication creates a tension between preventing graft rejection and reducing susceptibility to infection. Individualised immunosuppression protocols may be needed, though uniform dosing was maintained here to minimise confounding variables. The study authors note that immunosuppression remains a balancing act between rejection risk and infection susceptibility.
This work establishes feasibility for stem cell-derived dopamine neuron replacement in Parkinson’s disease. Unlike conventional approaches that suppress symptoms with medications, this strategy aims to address the underlying neuronal loss driving disease progression.
Declaration of AI use: This article was written with the assistance of Lumo AI for grammar, spelling and proofreading.
Reference
Paul, G., Bjartmarz, H., Kirkeby, A. et al. Human embryonic stem cell-derived dopaminergic cells for Parkinson’s disease: a phase 1/2 open-label trial. Nat Med (2026). https://doi.org/10.1038/s41591-026-04525-0
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