A pioneering clinical trial has marked a major milestone in regenerative medicine for Parkinson’s disease (PD). Published in Nature in May 2025, the Phase I/II study led by Sawamoto, Doi, Takahashi and colleagues demonstrated that transplantation of dopamine‑producing neurons derived from induced pluripotent stem (iPS) cells is safe, well tolerated, and potentially effective in a small group of PD patients.
Seven patients aged 50 to 69 underwent bilateral transplantation of allogeneic (donor) iPS‑cell‑derived dopaminergic progenitors into the putamen—an area of the brain that suffers dopamine neuron loss in PD. The trial’s primary aim was safety over a 24‑month follow‑up; secondary outcomes included measures of motor function and dopamine synthesis
