Capturing and Quantifying Particle Transcytosis with Microphysiological Intestine-on-Chip Models

Understanding the intestinal transport of particles is critical in several fields ranging from optimizing drug delivery systems to capturing health risks from the increased presence of nano- and micro-sized particles in human environment. While Caco-2 cell monolayers grown on permeable supports are the traditional in vitro model used to probe intestinal absorption of dissolved molecules, they fail to recapitulate the transcytotic activity of polarized enterocytes. Here, an intestine-on-chip model is combined with in silico modeling to demonstrate that the rate of particle transcytosis is approximate to 350x higher across Caco-2 cell monolayers exposed to fluid shear stress compared to Caco-2 cells in standard static configuration. This relates to profound phenotypical alterations and highly polarized state of cells grown under mechanical stimulation and it is shown that transcytosis in the microphysiological model is energy-dependent and involves both clathrin and macropinocytosis mediated endocytic pathways. Finally, it is demonstrated that the increased rate of transcytosis through cells exposed to flow is explained by a higher rate of internal particle transport (i.e., vesicular cellular trafficking and basolateral exocytosis), rather than a change in apical uptake (i.e., binding and endocytosis). Taken together, the findings have important implications for addressing research questions concerning intestinal transport of engineered and environmental particles.

Automated summary

Understanding the intestinal transport of particles is crucial for optimizing drug delivery systems and assessing health risks associated with nano- and micro-sized particles in human environment. This study combines an intestine-on-chip model and in silico modeling to demonstrate that particle transcytosis across Caco-2 cell monolayers is significantly higher under fluid shear stress compared to static conditions. The findings reveal the importance of mechanical stimulation in altering cell phenotype and polarity, and highlight the energy-dependent transcytosis process involving clathrin and macropinocytosis.