One-year results published from STEM-PD trial for Parkinson's disease

A stem cell therapy designed to replace dopamine-producing nerve cells lost in Parkinson's disease has passed its first major clinical safety milestone.

Parkinson's disease is a neurodegenerative condition in which dopamine-producing nerve cells gradually die, leading to motor issues that can significantly impact daily life. Existing drugs can effectively relieve symptoms by replacing dopamine but do not stop disease progression. The Phase 1/2 STEM-PD clinical trial aims to evaluate the safety and feasibility of a new stem cell-based therapy which, unlike most current treatments, would directly replace lost dopamine-producing cells (see BioNews 1239). One year in, results presented at the International Society for Stem Cell Research 2026 Annual Meeting and published in Nature Medicine suggest that the therapy is well tolerated and could lead to clinical improvements.

'The possibility of replacing dopamine neurons that are lost in Parkinson's disease has been a long-standing goal in the field,' said Professor Malin Parmar, professor of cellular neuroscience at Lund University, Sweden, and lead of the STEM-PD programme. '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 therapy, originally developed at Lund University and now licensed to Cellular Intelligence, relies on dopamine neuron progenitor cells derived from human embryonic stem cells. The neurons are grown in the laboratory and then transplanted into patients' brains, where they are expected to further mature and eventually start producing dopamine.

In the trial, the treatment was generally well tolerated, with no serious side effects attributed to the transplantation. Brain imaging also provided early evidence that the transplanted cells had survived the procedure.

Many participants reduced their Parkinson's medication following treatment, with some also showing improvements in motor symptoms. One of the first recipients, Thomas Matsson, previously described returning to activities such as skiing and golfing after receiving the transplant. However, as the trial was a small, open-label study primarily designed to assess safety, these early positive signs will need to be confirmed in larger controlled trials.

'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', said Professor Roger Barker, professor of clinical neuroscience at the University of Cambridge and clinical lead of STEM-PD.

Participants will continue to be followed for three years to assess the long-term safety and function of the transplanted cells, with Cellular Intelligence planning to lead the next phase of clinical development. Overall, the findings from the STEM-PD trials add to a growing body of evidence showing encouraging results for stem cell therapies against Parkinson's disease (see BioNews 1309 and 1326).