Core Viewpoint - Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by the selective loss of dopaminergic neurons, leading to dopamine depletion and motor symptoms. Current treatments alleviate symptoms but do not halt neuronal loss [2][5]. Group 1: Research and Development - PD has long been considered a suitable candidate for cell replacement therapy due to its clear pathological features, specifically the loss of certain dopaminergic neuron populations [5]. - A recent study published in the journal Cell reported a Phase 1/2a clinical trial of human embryonic stem cell (hESC)-derived dopamine progenitors (A9-DPC) showing good safety and effective improvement in motor symptoms for PD patients [3][12]. - The development of hPSC, including hESC and induced pluripotent stem cells (iPSC), has provided scalable sources for generating dopamine progenitor cells, enabling large-scale production of high-purity dopamine progenitor cells [5][6]. Group 2: Clinical Trial Findings - The Phase 1/2a trial involved 12 patients with severe PD, where A9-DPC was transplanted into the bilateral shell nucleus under an immunosuppressive regimen. The low-dose group received 3.15 million cells, while the high-dose group received 6.3 million cells [8][9]. - Results indicated excellent safety with no dose-limiting toxicities or transplant-related adverse events. Motor function improved significantly, with the high-dose group showing greater improvement [8][9]. - PET imaging confirmed increased dopamine uptake in the bilateral posterior shell nucleus, particularly in the high-dose group, indicating cell survival post-transplant [9][12]. Group 3: Conclusion and Implications - The study concluded that hESC-derived dopamine progenitor cells (A9-DPC) transplantation into the bilateral shell nucleus demonstrates good safety and effectively improves motor symptoms in PD patients, exhibiting dose-dependent efficacy [12].