The development of an intestinal microphysiological system to model oral drug disposition

Abstract

The intestine has important gate‐keeping functions that can profoundly impact the systemic blood exposure of orally administered drugs. Over the past decade, there has been growing effort to develop advanced in vitro tissue models that better predict in vivo DMET processes. One such novel model is the microphysiological system (MPS), which provides a more physiologically and anatomically relevant epithelial cell culture platform than traditional, static cell culture models. The MPS incorporates flow of media down luminal and abluminal channels, with accompanying shear forces that have been shown to be beneficial for multicellular viability and function. In this study, we cultured the immortalized cell line, LS180, in the Microfluidic ChipShop’s “Fluidic 480” MPS. LS180 cells have demonstrated high metabolic activity, particularly for CYP3A substrates, but display poor performance for monolayer permeability studies due to a lack of tight junction formation and uncertain transporter function. We assessed CYP3A metabolic activity, cell monolayer integrity, and global RNA expression for LS180 cells cultured in the MPS versus traditional TranswellTM culture. To measure CYP3A activity, we incubated LS180 cells cultured MPS and TranswellTM with the CYP3A probe substrate, midazolam, and monitored total product formation and parent midazolam appearance in the basolateral media of the two culturing platforms (with static or dynamic flow). LS180 cells cultured in MPS display a 2‐3‐fold greater midazolam extraction ratio (ER) compared to LS180 cells cultured in TranswellTM. We then compared cell monolayer integrity in the two culture platforms by measuring the apparent permeability (Papp) of the paracellular transport probe, atenolol. LS180 cells cultured in MPS display a 3‐fold lower Papp for atenolol than LS180 cells cultured in TranswellTM, indicating improved barrier integrity and tight junction formation for LS180 cells cultured in MPS. Using RNA‐seq, we compared global RNA expression for LS180 cells cultured in MPS versus TranswellTM. There were minimal expression differences for phase I and II metabolic enzymes between the two groups. Interestingly, transporter expression differed greatly between the two groups, with some transporters displaying greater expression in MPS compared to TranswellTM (e.g., P‐gp, MRP‐2) while others displayed a decrease in expression (e.g., OATP2B1, ENT1). Further testing is required to assess whether the changes in transporter RNA expression leads to changes in transporter protein abundance and localization. The sum of these results suggest that culturing LS180 cells in a MPS improves their performance and ability to predict the disposition of orally administered drugs.