High-throughput 3D phenotypic screening identifies repurposed MEK inhibitors as drivers of chondrogenesis for cartilage regeneration

Background and purpose: Chondrogenesis is essential for cartilage repair and regeneration, particularly in treating osteoarthritis and cartilage injuries. While conventional therapies rely heavily on growth factors, recent interest has turned toward drug repurposing strategies involving small-molecule inhibitors. This study aims to evaluate the chondrogenic potential of selected bioactive compounds, with a particular focus on Trametinib, a MEK inhibitor. Experimental approach: A library of 55 bioactive compounds was screened using high-content imaging and a 3D hydrogel model that mimics the native cartilage microenvironment. Cellular morphology, migration, and cytoskeletal organization were assessed to identify chondrogenic phenotypes. Trametinib, along with Panobinostat, SAHA, and Brefeldin A, was further evaluated via dose-response analyses and molecular assays to determine their impact on chondrogenic differentiation. Key Results: Trametinib was identified as a potent modulator of chondrogenesis-related cellular phenotypes. It significantly altered cell morphology, promoted a chondrogenic-like shape, and enhanced cell migration. Changes in actin organization were quantified using SER-Spot and SER-Ridge metrics, showing patterns consistent with chondrogenic differentiation. Molecular analysis revealed upregulation of Collagen II and aggrecan, key markers of cartilage formation. Conclusion and implications: These findings support the potential of MEK inhibitors like Trametinib, and other selected bioactive compounds, as promising agents for cartilage regeneration. Their repurposing could offer innovative therapeutic strategies for treating cartilage-related disorders, including osteoarthritis.