Three-Dimensional Dynamic Cell Models for Metabolic Dysfunction-Associated Steatotic Liver Disease Progression.

Objective: Metabolic dysfunction-associated steatotic liver disease (MASLD) is a complex, progressive disorder involving multiple cell types, ranging from simple steatosis to metabolic dysfunction-associated steatohepatitis (MASH), characterized by pro-inflammatory macrophage activation, and can eventually advance to fibrosis, initiated by hepatic stellate cells (HSCs). In vitro multi-cell coculture models are vital tools for elucidating the mechanisms underlying MASLD. Impact Statement: Existing in vitro models for MASLD, including traditional 2-dimensional (2D) cultures and advanced organ-on-a-chip and organoid systems, face challenges in representing multiple cell types and analyzing them individually. Here, utilizing a cell carrier developed in our laboratory, we introduce a series of 3D dynamic coculture models that simulate different stages of MASLD progression and enable individual cell type analysis. Introduction: Currently, no single system provides an optimal balance of control, reproducibility, and analytical convenience. Most in vitro models lack the ability to isolate and analyze individual cell types post-culture, making it difficult to study cell-specific responses in MASLD progression. Methods: The 3D hollow porous sphere cell carrier allows cells to grow on its surface, while the culture device (mini-bioreactor) creates a dynamic environment. The 3 distinct MASLD models were established based on cocultured cell types: steatosis (hepatocytes only), MASH (hepatocytes and macrophages in a 4:1 ratio), and fibrosis (hepatocytes, macrophages, and HSCs in an 8:2:1 ratio). Well-established MASLD mouse models were employed to validate our in vitro 3D dynamic MASLD models, using 7-week-old male C57BL/6J mice fed a high-fat diet. Results: Our models demonstrate a progressive decline in hepatocyte viability and increased lipid accumulation, mirroring in vivo pathology. Additionally, gene expression profiles of our models align with those observed in MASLD-affected mouse livers. Notably, comparative analysis highlights the role of pro-inflammatory macrophages in disrupting hepatocyte lipid metabolism. Conclusion: These models offer a robust platform for investigating MASLD mechanisms and show potential for screening anti-MASLD therapeutics.