From neural development to regenerative medicine: A research journey in stem cell biology, spinal cord repair, and iPSC-based drug discovery.

This commemorative article reflects on a research journey spanning neural development, stem cell biology, regenerative medicine, and iPSC-based drug discovery. My early work focused on RNA-mediated regulation in the nervous system, including studies on myelin basic protein gene regulation and the identification and functional characterization of the RNA-binding protein Musashi. These studies contributed to the conceptual foundation of neural stem cell biology and helped establish methods for identifying and isolating neural stem/progenitor cells, including those present in the adult human brain. Building on this foundation, my colleagues and I pursued translational research in spinal cord injury, ranging from analyses of injury pathophysiology and molecular interventions to preclinical studies using rodent and non-human primate models. These efforts ultimately led to the first-in-human clinical study of induced pluripotent stem cell-derived neural stem/progenitor cell transplantation for subacute spinal cord injury. In parallel, we developed patient-derived iPSC platforms for neurological disease modeling and drug discovery, particularly for amyotrophic lateral sclerosis, where iPSC-based screening identified Ropinirole as a therapeutic candidate and enabled reverse translational research linking cellular phenotypes with clinical responses. Looking ahead, I argue that the future of regenerative therapy will depend on the continued integration of developmental biology, stem cell science, disease modeling, rehabilitation, and clinical translation to address unmet medical needs in disorders of the central nervous system.