Highly Biomimetic Ectodermal Epithelial Organoids for Epithelial Barrier Stimulation Assays

ABSTRACT Evaluating the potential toxicity of pharmaceuticals and biomaterials to ectodermal epithelia, such as the oral mucosa and skin, is indispensable in pre‐clinical assessments. However, this remains a challenge primarily owing to the lack of physiologically relevant and accurate screening models. To address this need, we referred to developmental patterns of the ectodermal epithelium in vivo and adopted the strategic downregulation of the TGF‐β signaling pathway in organoid fabrication. Our novel ectodermal epithelial organoids (EEOs) recapitulate the cellular and histological complexities of native epithelial tissues and improve fabrication efficiency. EEOs can accurately capture essential barrier components, including the stratum corneum and intercellular junctions, which are crucial for maintaining epithelial barrier integrity. Validation studies revealed that EEOs are capable of modeling the dose‐dependent cytotoxic effects of pharmaceuticals on the oral mucosa and identifying previously undetectable nanomaterial‐induced damage to intercellular junctions. These findings indicate that the model system is a robust platform for epithelial barrier stimulation tests, and that this technology is poised to transform pre‐clinical assessment paradigms by enabling more accurate toxicity prediction and accelerating the development of safer pharmaceuticals and biomaterials.