Phenotypic screening of human iPSC-derived neurons identifies thienopyridones as neuritogenic small molecules.

Human induced pluripotent stem cell (iPSC)-derived neurons provide a platform for modeling brain disorders. Among disease-relevant cellular phenotypes, impaired neurite outgrowth has emerged as an indicator reflecting key aspects of neurological disease pathophysiology. We conducted a high-throughput phenotypic screening of over 21,000 small molecules to identify compounds that enhance neurite outgrowth in iPSC-derived neurons, and we identified three bioactive compounds sharing a common indazole scaffold. Notably, one of these compounds selectively targets TNIK, a kinase involved in neuronal development. Scaffold expansion led to the discovery of thienopyridone derivatives with potent neurite-promoting activity. Two thienopyridone compounds were further validated in a human neural organoid model, in which their neurite outgrowth-promoting effects were reproducibly confirmed. Transcriptomic profiling revealed activation of signaling pathways associated with neurotrophic stimulation. These findings identify thienopyridones as a scaffold for neuritogenic small molecules, suggesting their potential as a therapeutic strategy for brain disorders and for promoting neural regeneration.