# A Constant Pressure-Driven Podocyte-on-Chip Model for Studying Hypertension-Induced Podocytopathy Pathomechanism and Drug Screening

## TL;DR

A new lab-on-a-chip model simulates how high blood pressure harms kidney cells, offering a tool to study disease mechanisms and test drugs.

## Contribution

A novel pressure-driven podocyte-on-chip model is introduced for studying hypertension-induced podocytopathy and drug screening.

## Key findings

- Higher hydrostatic pressures caused increased macromolecule infiltration, especially for larger dextran molecules.
- Mature podocytes showed pressure-dependent cytoskeleton rearrangements and irreversible injury at higher pressures.
- Dynamic mRNA expression of Synaptopodin and ACTN4 correlated with observed morphological changes.

## Abstract

Podocytopathy, characterized by proteinuria, contributes significantly to kidney diseases, with hypertension playing a key role in damaging podocytes and the glomerular filtration barrier (GFB). The lack of functional in vitro models, however, impedes research and treatment development for hypertensive podocytopathy. We established a novel constant pressure-driven podocyte-on-chip model, utilizing our previously developed dynamic staining self-assembly cell array chip (SACA chip) and 3D printing. This platform features a differentiated podocyte monolayer under controlled hydrostatic pressures, mimicking the epithelial side of the GFB. Using this platform, we investigated mechanical force-dependent permeability to three sizes of fluorescent dextran under varying hydrostatic pressures, comparing the results with a puromycin aminonucleoside (PAN)-induced injury model. We observed that external pressures induced size-dependent permeability changes and altered cell morphology. Higher pressures led to greater macromolecule infiltration, especially for larger dextran (70 kDa, 500 kDa). Mature podocytes exhibited immediate, pressure-dependent cytoskeleton rearrangements, with better recovery at lower pressures (20 mmHg) but irreversible injury at higher pressures (40, 60 mmHg). These morphological changes were also corroborated by dynamic mRNA expression of cytoskeleton-associated proteins, Synaptopodin and ACTN4. This platform offers a promising in vitro tool for investigating the pathomechanisms of hypertension-induced podocytopathy, performing on-chip studies of the GFB, and conducting potential drug screening.