Conditions for successful stem cell therapy for Parkinson's disease, the second most common degenerative neurological disorder after Alzheimer's disease, have been proposed.
A research team led by Professor Kim Dong-wook of the Department of Physiology at Yonsei University College of Medicine compared and analyzed the outcomes of Parkinson's stem cell therapy clinical trials in Korea, the United States, and Japan, and proposed key guidelines for successful treatment, the team said on the 27th, adding that the findings were published in Cell Stem Cell. Kim also serves as S.Biomedics(304360) chief technology officer (CTO).
The main point of the study is that to enhance the therapeutic effect of stem cell-derived dopaminergic neuron–based cell therapy, the entire pre-treatment process must be standardized, from cell quality control to patient selection, transplantation methods, and immune response management.
Parkinson's disease is a degenerative neurological disorder in which dopaminergic neurons in the substantia nigra of the midbrain gradually deteriorate, causing tremors, muscle rigidity, and slow movement.
Current stem cell therapy for Parkinson's disease involves differentiating human embryonic stem cells (ES cells) or induced pluripotent stem cells (iPS cells) into midbrain dopaminergic neurons and transplanting them into the patient's brain. The goal is for the transplanted cells to survive long term in the brain, secrete dopamine, and form consolidation with existing neural circuits to improve motor symptoms.
Recently, research teams in Korea, the United States, and Japan have successively released early clinical trial results in which dopaminergic neurons derived from stem cells were transplanted into patients. None of the three studies identified major safety issues related to the transplanted cells, and brain imaging results suggesting dopamine function recovery were also observed. However, the therapeutic effects differed considerably among patients.
The team cited not only cell quality but also the patient's age, disease progression, symptom subtype, cell transplantation site and infusion method, and immune response as reasons for the differences in therapeutic effect. The analysis is that these factors act in combination to determine treatment outcomes.
Accordingly, the team proposed that for successful cell therapy, it is necessary to: ▲ establish cell quality assessment criteria that can predict treatment effects ▲ precisely select patients suited for therapy ▲ standardize the transplantation site and infusion method ▲ systematically manage histocompatibility and immune responses ▲ adopt unified clinical evaluations and long-term follow-up.
Professor Kim Dong-wook said, "Early clinical trials in Korea, the United States, and Japan showed that stem cell–derived dopaminergic neurons can survive and function in the brains of actual Parkinson's patients," adding, "Now it is important to identify why treatment effects differ from patient to patient, and to integratively manage cell quality, patient selection, transplantation methods, and immune management."
However, the team noted that because the current results are based on early clinical trials with a small number of patients, large-scale follow-up trials and long-term monitoring are needed to establish therapeutic efficacy.
Research teams in Korea, the United States, and Japan are preparing phase 3 trials, and Japan has granted conditional approval based on small-scale clinical results in light of the urgency of treatment.
References
Cell Stem Cell (2026) DOI: https://doi.org/10.1016/j.stem.2026.07.002