02426nas a2200253   4500000000100000008004100001260001500042100001900057700001900076700001800095700001600113700002500129700001800154700001800172700001500190700001800205700002100223245011200244856004400356300001600400490000700416520173500423022001402158       2025                            d  c2025-07-011 aEliah R Shamir1 aCharles Havnar1 aMike Reichelt1 aMiriam Baca1 aLenitza Nieves Lopez1 aLoryn Holokai1 aAllison Zajac1 aBecca Hsia1 aLinda Rangell1 aMeredith Sagolla00aMultimodal Histologic and Imaging-based Readouts of Complex in vitro Models for Research and Drug Discovery  uhttps://doi.org/10.1093/mam/ozaf048.401  aozaf048.4010 v313 aComplex in vitro models (CIVMs) serve as tractable experimental systems that seek to recapitulate key aspects of in vivo tissue biology using a variety of different cellular inputs (e.g. primary cells, stem cells) and culture formats [1]. CIVMs derived from human cells play increasingly multifaceted roles in drug discovery: in exploratory research to ask a scientific question or test a therapeutic hypothesis; in predictive assays to confirm target expression or molecule activity; and in preclinical toxicity studies. Despite the increasing number and complexity of CIVMs available, there exist key gaps in our ability to perform comprehensive model evaluation and characterization and to assess model translatability to in vivo findings and human disease. To address this need, we hypothesized that applying traditional analytical approaches from pathology for tissue evaluation could provide complementary experimental readouts at the tissue, cellular, or subcellular level. In particular, we sought to enable direct histologic and ultrastructural comparison of different models of human airway and colon that use the same cellular input but different culture formats, including organoids 3D-embedded in an extracellular matrix (ECM), mechanically supported culture on a transwell insert, and microfluidic organ-on-chip models, which allow fluid flow, mechanical stretch, and the ability to interface epithelium with other cell types (e.g. endothelium) [2]. However, routine tissue processing of CIVMs is challenging due to a number of variables, including their small size, limited cellular material, and frequent placement within either an ECM such as Matrigel or chip housing material such as polydimethylsiloxane (PDMS).  a1431-9276