High-throughput microfluidic platform for modelling inflammatory responses of human articular chondrocytes under variable fluid shear stress.

Abstract

Inflammation plays a critical role in osteoarthritis (OA), a debilitating joint disease characterized by cartilage degradation, chronic pain, and disability. The absence of approved disease-modifying OA drugs underscores the need for physiologically relevant <i>in vitro</i> models to accelerate preclinical screening. Cartilage-on-chip platforms integrating 3D matrices and mechanical cues have emerged as promising tools to replicate cartilage microenvironments and OA phenotypes; however, their complexity limits scalability for high-throughput applications. Here, we exploited and optimized a streamlined, pumpless microfluidic system enabling dynamic culture of human articular chondrocytes under controlled gradients of fluid shear stress and cytokine-induced inflammation. Each chip accommodates 24 replicates and generates shear stresses ranging from 0.06 to 0.9 Pa. The platform supports long-term culture of healthy chondrocytes, maintaining high viability, enhanced collagen type II and aggrecan expression, and formation of 3D aggregates and contracted microtissue-like structures over 21 days. Inflammatory conditions induced by stimulation with recombinant interleukin-1β (IL-1β) led to extracellular matrix degradation, disrupted tissue architecture, and reduced expression of cartilage-specific markers. Elevated levels of metalloproteinases and pro-inflammatory cytokines, characteristics of OA, were detected even at minimal IL-1β concentrations, demonstrating the model's sensitivity to inflammatory stimuli. This microfluidic system provides a robust, scalable approach for modeling OA-related inflammation in a dynamic environment, offering strong potential for high-throughput drug screening targeting inflammatory pathways.