Bringing Microphysiological Systems to Practical Use: Evaluation of transporter‐mediated DDI and Renal Clearance

Abstract

Active tubular secretion of drugs from the blood to urine is mediated by multiple drug transporters expressed on both basolateral and apical membrane of the proximal tubule. Human proximal tubule microphysiological system (MPS) has been proposed as a more physiologically relevant in vitro system to assess nephrotoxicity and tubular reabsorption.[1,2] However, drug-transporter studies in MPSs are currently sparse and quantitative translation of MPS data to in vivo is not yet established. This study aimed to assess the feasibility of NORTIS MPS to study quantitatively OAT1-mediated transport of pyridoxic acid (PDA) in the absence and presence of 1mM probenecid (prototypical OAT inhibitor). Conditionally immortalized proximal tubule epithelial cells overexpressing OAT1 (ciPTEC-OAT1) were seeded in the NORTIS MPS and were cultured for at least 5 days to allow cell maturation and tight tubule formation prior to transport experiments. PDA secretion rate in the apical channel effluent was linear up to 8h and plateaued between 8-24h. Inhibition of PDA secretion rate by probenecid ranged between 14 – 46% over 2-8h time period. PDA CLu,int,invitro obtained from the initial linear uptake phase was 0.07 and 0.09 µL/min/mm2 in the absence and presence of probenecid, respectively. PDA CLu,int,invitro was quantitatively scaled via total human proximal tubule surface area to CLu,int,invivo which was subsequently used to predict PDA CLR. Translation of MPS transporter data resulted in 5-fold under-prediction of PDA CLR obtained from clinical data (48.2 vs. 215 mL/min). The findings of this study demonstrate a first attempt of quantitative translation of MPS transporter data. The study also highlighted that the extent of inhibition by probenecid was not fully captured in the MPS-ciPTEC-OAT1. Further investigations of the feasibility to derive additional scaling factors for in vitro-in vivo extrapolation of transporter data from MPS are ongoing. [1] Weber, E. J., Chapron, A., Chapron, B. D., Voellinger, J. L., Lidberg, K. A., Yeung, C. K., … & Shen, D. D. (2016). Development of a microphysiological model of human kidney proximal tubule function. Kidney international, 90(3), 627-637. [2] Sakolish, C., Chen, Z., Dalaijamts, C., Mitra, K., Liu, Y., Fulton, T., … & Chiu, W. A. (2020). Predicting tubular reabsorption with a human kidney proximal tubule tissue-on-a-chip and physiologically-based modeling. Toxicology in Vitro, 63, 104752.