Intestinal absorption is a key toxicokinetics parameter. While the colon carcinoma cell line Caco-2 is the most used in vitro model to estimate human drug absorption, models representing other intestinal segments are developed. We characterized the morphology, tissue-specific markers and functionality of three human intestinal cell types: Caco-2, primary human enteroid-derived cells from jejunum (J2), and duodenum (D109) when cultured in the OrganoPlate® 3-lane 40 microphysiological system (MPS) or static 24-well Transwells™. In both conditions, J2 and D109 formed dome-like structures; Caco-2 formed uniform monolayers. In MPS, only Caco-2 formed tubules. Cells grown on Transwells™ formed a thicker monolayer. All cells and conditions exhibited expression of ZO-1 (tight junctions). Polarization markers Ezrin and Villin were highest in J2 and D109 in MPS, highest expression of Mucin was observed with J2. However, J2 and D109 exhibited poor barrier (70 kDa TRITC-dextran) in MPS, while robust barrier was recorded in Transwells™. Barrier function and drug transport were evaluated using caffeine, indomethacin, and propranolol. The gel lane in MPS acted as a blockade; only a small fraction crossed, even without cells. The permeability ratios were used to parameterize the probabilistic compartmental absorption model to determine whether in vitro data could reduce uncertainty. The most accurate prediction of the fraction absorbed was achieved with Transwell™-derived data from Caco-2, combined with the experimentally-derived segment-specific absorption ratios. The impact of this study includes demonstration that enteroid-derived cells cultured in MPS show most physiological morphology, but that studies of drug permeability in this MPS are challenging.
Read full abstract