Nature, Published online: 16 April 2025; doi:10.1038/s41586-025-08845-yBilateral grafts of cryopreserved human embryonic stem cell-derived dopaminergic neuron progenitor cells into the putamen of patients with Parkinsons disease in a phase I clinical trial showed safety, improvements in off-drug motor function and graft survival at 18months after transplant.