First in-human clinical trial results show feasibility of new Parkinson cell therapy

In Parkinson’s disease, patients lose nerve cells in the brain that produce dopamine, leading to symptoms such as slowness of movement, stiffness, gait disturbance and tremor. The current treatments are medications that replace the lost dopamine, but over time these medications often become less effective and cause side effects.

The trial – known as STEM-PD – is led by Lund University, Sweden, in collaboration with the University of Cambridge. It tested a new approach which aims to replace the cells that produce dopamine through transplantation of a stem cell-based dopamine nerve cell product to the brain. The goal is that after being transplanted, they will mature into new dopamine-producing nerve cells in the brain.

Professor Roger Barker, from the Department of Clinical Neurosciences, University of Cambridge, and Honorary Consultant Neurologist, Cambridge University Hospitals NHS Foundation Trust, is clinical lead of STEM-PD and clinical principal investigator at the UK site. 

“This represents an exciting new departure on repairing the brain of individuals with Parkinson’s using dopamine cells, an approach pioneered in Lund some 40 years ago using fetal dopamine cells,” said Professor Barker. 

“The STEM-PD trial, harnessing the expertise of scientists and clinicians from Lund and Cambridge has enabled us to undertake and deliver on one of the first ever stem cell-derived dopamine cell therapies for patients with Parkinson’s and we hope this will be the beginning of an exciting new programme that may ultimately benefit the wider Parkinson’s community.” 

Eight individuals with Parkinson’s disease received the transplanted cell product at two different doses, followed by 12 months of immunosuppression to prevent graft rejection. Seven participants completed 12-month follow-up; one participant died from a pulmonary infection that was not directly related to the cell product. The surgical procedure was generally well tolerated and no graft-induced involuntary movements were observed in the transplanted participants.

Clinically, patients remained stable. Imaging using dopamine PET scans provided early indications of graft survival at both 6 and 12 months post-transplantation. Six of the seven participants substantially reduced their dopaminergic medication, a result that will be evaluated over time.

Professor Malin Parmar from Lund University, lead of the STEM-PD programme, said: “The possibility of replacing dopamine neurons that are lost in Parkinson’s disease has been a long-standing goal in the field. The findings represent an important milestone for regenerative medicine approaches in Parkinson’s disease and support continued clinical development of stem cell-based therapies.”

The results are published today in Nature Medicine.

Professor Gesine Paul-Visse, Lead PI at Skåne University Hospital, the Swedish clinical site where the patients were treated, said: “Reaching this primary endpoint and being able to show that the cell product is safe is a great achievement for this trial, our team, the participating patients, but also for all patients suffering from Parkinson’s disease. We are hopeful that the early signs of cell survival and clinical improvement we observe will continue to increase over the time and excited to continue the development of this cell therapy.” 

STEM-PD is the first pluripotent stem cell trial approved in Sweden and the first for Parkinson’s disease in Europe. The research team will now continue the long-term follow-up of the participants to further evaluate safety, graft function, and clinical benefit. 

Professor Parmar added: “The initiation and execution of this clinical trial have only been possible through close collaboration between scientists, clinicians, GMP manufacturing teams, regulatory experts and, most importantly, the participating patients.”

STEM-PD is an academic European clinical translation initiative, focused on developing stem cell-based therapies for Parkinson’s disease. The programme is lead from Lund University with partners from Skåne University Hospital, Cambridge University Hospital, and University College London, and combines expertise in stem cell biology, GMP manufacturing, neurosurgery, clinical neurology and regenerative medicine to advance pluripotent stem cell-derived dopamine neuron therapies toward clinical application. 

Reference

Paul, G et al. Human embryonice stem cell-dreived dopaminergic cells for Parkinson’s disease: a phase 1/2 open-label trial. Nat Med; 9 July 2026; DOI: TBD

Adapted from a press release by Lund University