The International Society for Stem Cell Research (ISSCR) today announced that it will present new clinical data from the STEM-PD Phase I/II clinical trial at the ISSCR 2026 Annual Meeting. This study reports 12-month results evaluating a cryopreserved off-the-shelf dopaminergic progenitor cell product derived from human pluripotent stem cells for the treatment of Parkinson’s disease.
The results of this study provide new insights into the safety, feasibility, and biological activity of stem cell-derived dopaminergic cell transplantation in Parkinson’s disease patients and represent another important step in the clinical application of regenerative medicine for neurodegenerative diseases.
“These data represent the culmination of decades of research aimed at translating stem cell biology into clinically viable treatments,” said Malin Palmer, professor of cellular neuroscience at Lund University in Sweden, who presented the findings today at the ISSCR 2026 Annual Meeting. “They demonstrate that stem cell-derived dopaminergic cell products can be manufactured, delivered, and evaluated within the framework of rigorous clinical trials. More broadly, they demonstrate that regenerative medicine is moving beyond proof of concept to a stage where stem cell-based therapies are tested in patients with complex neurodegenerative diseases.”
Parkinson’s disease is characterized by the progressive loss of dopamine-producing neurons, leading to worsening of motor symptoms over time. Current treatments can improve symptoms but do not replace neurons lost as the disease progresses. Stem cell-based approaches seek to restore dopamine production by replacing these cells, offering the potential for more durable and resilient treatment strategies.
The STEM-PD trial enrolled patients with moderately advanced Parkinson’s disease who continued to experience significant symptoms despite optimized drug therapy. Participants received transplants of human pluripotent stem cell-derived dopamine-producing progenitor cells engineered to replace dopamine-producing neurons lost during the course of the disease.
Researchers have been working for decades to overcome two major barriers to developing cell replacement therapies for Parkinson’s disease. The goal is to create authentic dopaminergic neurons suitable for clinical-scale transplantation and to demonstrate that these cells can be safely delivered to the human brain. Previous studies using fetal tissue established proof of principle but were limited by tissue availability and standardization. Advances in stem cell technology have enabled the development of standardized cell products, but reaching human clinical trials will require close collaboration across stem cell biology, manufacturing, regulatory science, and clinical medicine.
What is particularly encouraging is how closely these findings align with results from other ongoing stem cell-based Parkinson’s disease clinical trials around the world. Independent groups using different cell products and clinical protocols have reported comparable safety and other outcomes. This convergence strengthens confidence in the overall treatment concept. ”
Malin Parmar, Professor of Cellular Neuroscience, Lund University, Sweden
If confirmed through larger studies with longer follow-up, stem cell-derived dopaminergic cell transplants could establish a new type of regenerative therapy for Parkinson’s disease by replacing cells lost during disease progression, rather than repeatedly replacing dopamine loss with drugs.
Researchers will continue to follow participants in the STEM-PD trial to assess long-term safety and graft function. Future studies will investigate the durability of transplanted cells, identify which patients will benefit most, optimize cell administration, and improve the functional integration of transplanted cells into the brain. Researchers are also exploring strategies to reduce the need for immunosuppression, including approaches using autologous grafts and engineered cells designed to evade immune detection.
“This field has been driven by decades of research by scientists, clinicians, regulatory experts, medical ethicists, and patients who believed that stem cell therapy could become a reality,” Palmer added. “It is particularly meaningful to present results that demonstrate how discoveries in stem cell biology are now being translated into clinical trials. For me personally, these discoveries build directly on the pioneering work that began at Lund more than 40 years ago, when the concept of cell therapy for Parkinson’s disease first began to take shape.”
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International Stem Cell Research Association
