In the April 2025 issue of the prestigious journal Nature, the results of a phase I/II clinical study conducted in Japan were published, investigating the use of dopaminergic cells derived from induced pluripotent stem cells (iPSCs) for the treatment of Parkinson’s disease, a neurodegenerative condition characterized by the progressive loss of dopaminergic neurons responsible for movement control.

Currently available therapies are symptomatic and tend to lose effectiveness over time, whereas the transplantation of dopaminergic cells aims to address the root of the problem.

What was done

Researchers selected and transplanted dopaminergic neuron progenitors derived from iPSCs into patients, after previously testing them in animal models to assess their efficacy and safety. Seven patients with Parkinson’s disease were treated at Kyoto University Hospital. Following careful initial monitoring of the first patient, the remaining six received bilateral transplants into the putamen, a key brain region involved in motor control.

The iPSCs used in the study were obtained from a healthy donor through the reprogramming of peripheral blood cells (the same approach also used by EternaCell) and were carefully selected to ensure maximum safety and efficacy, minimizing the risk of side effects.

Results

Patients were followed for 24 months with neurological assessments, brain imaging (MRI and PET), and monitoring of motor function. None of the patients developed serious adverse events or side effects attributable to the transplant. The transplanted cells showed stable behavior, with no abnormal growth, and demonstrated the ability to synthesize dopamine, as confirmed by PET imaging.

In terms of efficacy, four out of six patients showed improvements in motor function during the “off” period (without medication), with an average reduction of symptoms of 20%, and five out of six also experienced benefits during the “on” period (with medication). Additionally, dopamine levels in the putamen (measured using PET tracers) increased, particularly in the group that received a higher dose of cells.

What does this mean for the future?

This study provides the first clinical demonstration of the safety and potential efficacy of transplanting dopaminergic progenitors derived from iPSCs in patients with Parkinson’s disease. Although this is a preliminary study and further large-scale research is needed, the results open the door to new regenerative therapeutic possibilities.

For those who choose to preserve their cells with EternaCell today, this represents a further concrete example of the future potential of advanced cell therapies. Cryopreserved cells can in fact be reprogrammed into iPSCs and, in the future, used for personalized treatments in areas that are still experimental today but increasingly closer to clinical application.