Material-dependent oxygen transport governs ischemia-reperfusion injury and drug response in a kidney...

Oxygen availability is a critical yet often overlooked factor in cell culture, and discrepancies between nominal oxygen settings and the actual cellular microenvironment can compromise model validity. This limitation is particularly relevant in modeling ischemia-reperfusion (I/R) injury, where dynamic changes in oxygen supply critically influence cellular responses. In particular, the role of oxygen transport in microphysiological systems and conventional culture platforms remains insufficiently understood, limiting the reproducibility of disease models and the interpretation of drug responses. In this study, we systematically evaluated oxygen supply and cellular responses in three culture platforms: cell culture inserts, polydimethylsiloxane (polydimethylsiloxane)-based microfluidic chips, and polyethylene terephthalate (polyethylene terephthalate)-based microfluidic chips with identical geometries but different oxygen permeabilities. Oxygen distribution and oxygen consumption rate (OCR) were estimated using finite element method (FEM) simulations, and the resulting predictions were interpreted in the context of experimental observations obtained with RPTEC/TERT1 cells under I/R conditions. Cellular responses were assessed by morphology, viability, and gene expression analysis, and pharmacological responses were evaluated using the renoprotective compound CDDO. finite element method analysis revealed that oxygen availability at the cell surface varied markedly among platforms despite identical nominal oxygen conditions. PDMS chips maintained high oxygen levels due to high gas permeability, preventing the establishment of oxygen-limited conditions, whereas PET chips and inserts exhibited significant oxygen depletion. These differences were consistent with experimental observations: PDMS chips failed to induce I/R-associated cellular injury, whereas PET chips and inserts enabled hypoxia-induced responses. Furthermore, drug responses varied across platforms, with CDDO exhibiting distinct efficacy profiles depending on the severity of oxygen limitation. These findings indicate that oxygen transport, rather than nominal oxygen settings, is a major determinant of cellular phenotype and drug response in vitro. This study provides a framework for designing physiologically relevant cell culture systems based on oxygen transport principles and highlights the importance of integrating material properties, device design, and culture conditions to achieve accurate and reproducible biological outcomes.