Abstract
Cerebral organoids generated according to unguided protocols produce neural tissue with exceptional cell diversity and fidelity to in vivo. However, with only minimal extrinsic intervention, the importance of high-quality starting material becomes paramount. Understanding quality and how to maintain it throughout prolonged culture is therefore a crucial foundation for successful organoid differentiation. In this study, we investigate the proteome and phosphoproteome of human pluripotent stem cells to uncover the mechanisms that drive neural organoid competence. We identify aberrant cell-extracellular matrix interaction and increased oxidative metabolism as hallmarks of poor neural differentiators. Drawing on the proteomic data and published literature, we test culture conditions with improved coating matrix, reduction of oxidative stress, and sustained fibroblast growth Factor 2 (FGF2) supply. These adjustments provide some improvement to differentiation, highlighting the importance of optimal culture conditions to maintain high-quality stem cells but also suggesting cell-intrinsic sources of variability.