Japan Performs World's First Stem Cell Transplant in a Patient with Parkinson's Disease

The procedure was performed in October at Kyoto University Hospital, following the conditional approval of the therapy by Japanese regulators in March.

The method involves transplanting millions of cells derived from donor iPS cells into the brain. These cells are created by reprogramming mature, specialized cells into an earlier state in which they can develop into various types of cells in the body. In the new therapy, they are used to grow precursors of dopamine-producing neurons. Dopamine is essential for the normal functioning of the motor system, and these neurons are gradually lost in people with Parkinson's disease.

Seven patients aged between 50 and 69 received the treatment as part of a clinical trial. Each patient had five or ten million cells implanted into each side of the brain. The participants were monitored for two years. No serious adverse effects were reported, while four patients experienced improvements in their symptoms.

Parkinson's disease is a chronic, progressive neurological disorder that affects the motor system and can cause tremors, muscle stiffness and difficulty moving. According to the Parkinson's Foundation, more than 10 million people worldwide are living with the condition. Existing treatments help manage symptoms but do not stop or slow the progression of the disease.

Sumitomo Pharma plans to perform transplants in another 20–30 patients by March 2029. The company is also testing the therapy in the United States. In Japan, its approval remains conditional: to obtain full regulatory approval, the company must demonstrate the treatment's safety and efficacy over the next seven years, according to local media reports.

The new procedure marks another milestone in the development of cell-based therapies in Japan. A month earlier, a hospital in Osaka performed the world's first procedure using sheets of heart muscle tissue created from iPS cells. The tissue was expected to help promote the formation of new blood vessels and restore heart function. This therapy also received conditional approval from Japanese regulators in March.