Updated project metadata. Innovative pro-regenerative treatment strategies for progressive multiple sclerosis (PMS), combining neuroprotection and immunomodulation, represents an unmet need. Neural precursor cells (NPCs) transplanted in animal models of multiple sclerosis promote neuroprotection and remyelination by releasing molecules sustaining trophic support and neural plasticity. We present the results of STEMS, a single dose escalation phase I clinical trial, evaluating the feasibility, safety, and tolerability of intrathecally transplanted human fetal NPCs (hfNPCs) in 12 PMS patients.