Stem Cell Therapy Shows Promise for Parkinson’s Disease in Landmark Trials: Study

New Delhi: Two independent clinical trials have demonstrated the safety and potential effectiveness of stem cell-based therapies in treating Parkinson’s disease, according to new research published in the journal Nature.

The studies—conducted separately in Japan and the United States—explored the use of dopaminergic neuron progenitor cells derived from human stem cells to replace the loss of dopamine-producing neurons in patients with Parkinson’s disease, a progressive neurodegenerative disorder marked by motor dysfunction due to dopamine deficiency.

The first trial, led by researchers at Kyoto University, involved seven participants aged 50 to 69. These individuals received transplants of dopaminergic progenitors derived from human induced pluripotent stem cells (iPSCs) into both sides of their brains. Over a 24-month follow-up period, the treatment was found to be safe, with no serious adverse effects, tumour formation, or abnormal cell overgrowth. Encouragingly, four out of six patients who completed the efficacy phase showed improvement in motor symptoms when off their regular medication, and five showed improvements while on medication.

In a parallel trial, a team from Memorial Sloan Kettering Cancer Center in the US investigated a similar treatment using a product called bemdaneprocel, derived from human embryonic stem cells. Twelve patients, with a median age of 67, underwent transplantation of the cells into the putamen region of the brain. The group was split into low-dose (five patients) and high-dose (seven patients) cohorts. Over an 18-month follow-up period, the therapy was well tolerated, and no severe adverse events were linked to the stem cell treatment. Notably, none of the patients developed dyskinesia—a common side effect of traditional Parkinson’s treatments. Motor function improvements were observed in patients across both dosing groups.

Despite the relatively small sample sizes and the early-phase nature of these trials, the findings support the safety of allogeneic stem cell-derived therapies in Parkinson’s disease. Researchers emphasized the significance of these results as a step forward in developing regenerative treatments that may offer longer-lasting symptom control with fewer side effects compared to conventional medications like L-dopa, whose benefits wane over time.

Both studies call for larger, more comprehensive trials to further assess the efficacy and long-term outcomes of these therapies, which could eventually transform the treatment landscape for millions living with Parkinson’s disease.