A physiological oxygen gradient liver-zonation-on-a-chip reveals HIF-2α intervention in hepatic lipotoxicity

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a prevalent liver disease characterized by lipid zonation, which is closely linked to the functional zonation of liver lobules. However, existing models cannot faithfully replicate the oxygen gradient that regulates liver zonation, hindering a clear understanding of the progression and intervention mechanisms in MASLD. Here, we constructed a MASLD liver-zonation-on-a-chip that utilizes an engineering strategy based on "environmental oxygen convection and diffusion", achieving a controllable oxygen concentration gradient (3.7 %-8.9 %) that closely mimics the in vivo hepatic microenvironment. This platform successfully recapitulates the typical features and clinicopathological phenotypes of the liver lobule while enabling continuous monitoring of liver injury. We found that upregulation of the oxygen-sensing factor HIF-2α does not directly promote lipid accumulation. Instead, it indirectly facilitates the progression of MASLD by enhancing the transcriptional activity of β-catenin through the WNT signaling pathway (e.g., AXIN2, DVL1). As regulators of the damage process, HIF-2α and β-catenin may be targeted to improve outcomes in MASLD. STATEMENT OF SIGNIFICANCE: Metabolic dysfunction-associated steatotic liver disease (MASLD) is a common liver disorder characterized by lipid zonation, which is closely related to the functional zonation of liver lobules. However, existing models are unable to accurately replicate the oxygen (O₂) gradients that regulate liver zonation, a limitation that hinders their ability to accurately reflect hepatocyte pathophysiology and obstructs understanding of the mechanisms underlying MASLD progression. This study constructs a liver-zonation-on-a-chip with a controllable physiological O₂ gradient and integrated biosensing for non-destructive injury monitoring. The O₂ gradient chip successfully replicates liver lobule zonation, providing an engineering approach to overcoming the challenge of low regional heterogeneity in liver organoids. The application of the liver-zonation-on-a-chip in pathological assessments has also been thoroughly evaluated, offering potential solutions for MASLD interventions.