Apical Medium Flow Influences the Morphology and Physiology of Human Proximal Tubular Cells in a Microphysiological System

Abstract

There is a lack of physiologically relevant in vitro human kidney models for disease modelling and detecting drug-induced effects given the limited choice of cells and difficulty implementing quasi-physiological culture conditions. We investigated the influence of fluid shear stress on primary human renal proximal tubule epithelial cells (RPTECs) cultured in the micro-physiological Vitrofluid device. This system houses cells seeded on semipermeable membranes and can be connected to a regulable pump that enables controlled, unidirectional flow. After 7 days in culture, RPTECs maintained physiological characteristics such as barrier integrity, protein uptake ability, and expression of specific transporters (e.g., aquaporin-1). Exposure to constant apical side flow did not cause cytotoxicity, cell detachment, or intracellular reactive oxygen species accumulation. However, unidirectional flow profoundly affected cell morphology and led to primary cilia lengthening and alignment in the flow direction. The dynamic conditions also reduced cell proliferation, altered plasma membrane leakiness, increased cytokine secretion, and repressed histone deacetylase 6 and kidney injury molecule 1 expression. Cells under flow also remained susceptible to colistin-induced toxicity. Collectively, the results suggest that dynamic culture conditions in the Vitrofluid system promote a more differentiated phenotype in primary human RPTECs and represent an improved in vitro kidney model.

Consideration of Commercially Available Hepatocytes as Cell Sources for Liver-Microphysiological Systems by Comparing Liver Characteristics

“…MPS comprise culture techniques for reconstructing the specific functions of human organs or tissues in a limited space, creating miniaturized human test systems. These have been actively developed in recent years [ 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ]. In MPS development, the choice of cell source to mount on the MPS is as important as the design of the device.…”

“…Additionally, pharmacokinetics, which must take into account the absorption, distribution, metabolism, and excretion of compounds in the body (ADME), is known to be species-dependent and extrapolation of animal data to humans is limited. In recent years, microphysiological systems (MPS) have been actively developed to shorten the test period and reduce animal experiments for drug development [ 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ]. MPS is an in vitro culture system in which culture cells in a precisely controlled environment in a microspace manufactured using MEMS (micro-electromechanical systems) technology, in order to bring out in vivo-like functions from human cells.…”

The evolving role of investigative toxicology in the pharmaceutical industry

“…Substantial progress is also being made on other MPS tissue models, including of the gastrointestinal tract (primary tissue and stem cell-derived organoids, including ‘stretch’ models to mimic peristalsis) 137 , 138 , lung (air–liquid interface epithelia with stretch to mimic breathing dynamics coupled to endothelia) 139 , 140 and kidney (mini-kidneys under microphysiological flow) 141 , 142 . These models still need to be developed and validated as fit for purpose for use in drug discovery and safety testing.…”

Comparative Analysis of the Physiological and Transport Functions of Various Sources of Renal Proximal Tubule Cells Under Static and Fluidic Conditions in PhysioMimix{trade mark, serif} T12 Platform

“…Shear stress can be modelled in vitro by introducing lateral medium movement across a monolayer of cells which is critical for correct organization of renal proximal tubule epithelial cell (RPTEC) cytoskeleton and tight junctions (Duan et al, 2008). Indeed, most advanced 3D cultures of RPTECs focus on 6 introducing shear stress into either membrane-based (Gao et al, 2011;Jang et al, 2013;Shaughnessey et al, 2022;Specioso et al, 2022), or tubule-based (Weber et al, 2016;Vormann et al, 2018;Ross et al, 2021) microfluidic designs.…”

“…Physiological ranges for shear stress in vivo range from 0.3 to 1.2 dyne/cm 2 in healthy individuals, with values <0.5 generally regarded as corresponding to renal disease (Ross et al, 2021). In continuous flow-based kidney-focused organ-on-chip devices, reported values vary from 6.5×10 -4 (Specioso et al, 2022) to 0.7 dyne/cm 2 (Shaughnessey et al, 2022). In some tubule-based models, the shear could be highly intermittent, reaching as high as 1.7 dyne/cm 2 for a few seconds, then quickly decaying over the next 1-2 min to nearly static condition (Vormann et al, 2018).…”