Catalpol promotes the generation of cerebral organoids with <scp>oRGs</scp> through activation of <scp>STAT3</scp> signaling

The generation of human cortical organoids containing outer radial glia (oRG) cells is crucial for modeling neocortical development. Here we show that Catalpol, an iridoid glucoside derived from <i>Rehmannia glutinosa</i>, significantly enhances the generation of cerebral organoids with expanded oRG populations and increased neurogenic potential. Catalpol-treated organoids exhibited thicker ventricular zone/subventricular zone (VZ/SVZ) and outer subventricular zone (oSVZ) regions, with increased numbers of SOX2 + HOPX+ and SOX2 + TNC+ oRG cells and elevated expression of oRG markers HOPX and FAM107A. We found that Catalpol promoted oRG generation through non-vertical divisions of ventricular radial glia (vRG) cells, indicating enhanced oRG generation via asymmetrical divisions. Furthermore, we demonstrated that Catalpol augmented oRG cell numbers through activation of the STAT3 signaling pathway. These findings highlight Catalpol's potential in promoting the generation of cerebral organoids with expanded oRG populations and increased neurogenic potential through STAT3 activation, offering new insights into neocortical development modeling.