Third Harmonic Generation Microscopy Reveals Structure and Mucus Dynamics in Human Airway Epithelium Models

Airway epithelium plays a major role as the primary interface between human body and the external environment, acting both as a physical and functional barrier. In vitro airway models that reproduce the epithelium architecture are therefore a valuable tool for studying infection, inflammation, and transport processes. In this work, we present a label-free, non-invasive method to visualize and measure mucociliary transport in air-liquid human models using third-harmonic generation (THG) microscopy with an optical parametric amplifier laser source at 1300 nm. By exploiting the intrinsic nonlinear contrast at optical heterogeneities, THG provides high-resolution images of both epithelial structures and of the overlying mucus layer without the need for fluorescence staining or sample processing. Time-lapse THG imaging reveals depth-dependent transport dynamics within the mucus, offering new insights into mucociliary transport mechanism. Our approach offers a physiologically relevant way to assess mucociliary function in vitro and could support studies on respiratory diseases, drug delivery and efficacy, and epithelial remodeling. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=117 SRC="FIGDIR/small/717621v1_ufig1.gif" ALT="Figure 1"> View larger version (52K): org.highwire.dtl.DTLVardef@62e8acorg.highwire.dtl.DTLVardef@199a8b7org.highwire.dtl.DTLVardef@113bb84org.highwire.dtl.DTLVardef@7be3f8_HPS_FORMAT_FIGEXP M_FIG For Table of Contents Only C_FIG