Context-dependent miRNA regulation in intervertebral disc degeneration: an IDD-focused dynamic network framework for...

Intervertebral disc degeneration (IDD) is a progressive, mechanically regulated, and inflammation-associated disease in which microRNAs (miRNAs) participate in extracellular matrix remodeling, cell death, inflammatory signaling, and intercellular communication. However, the reported functions of individual miRNAs in IDD are often inconsistent across studies, with the same miRNA being associated with protective, neutral, or pro-degenerative outcomes under different experimental or pathological conditions. This inconsistency highlights a central knowledge gap: whether miRNA function in IDD is determined primarily by intrinsic molecular identity or by the dynamic pathological context in which the miRNA is embedded. In this Hypothesis and Theory article, we propose the Context-Dependent miRNA Switching Model (CDMSM), an IDD-focused conceptual framework in which degeneration stage, mechanical loading, inflammatory intensity, oxidative stress, extracellular matrix status, and ceRNA-network remodeling jointly reshape miRNA-target interactions and thereby alter biological output. The model predicts that selected miRNAs may display stage-dependent target bias, altered effective concentration due to ceRNA competition, and different therapeutic effects across early, intermediate, and chronic/late-stage IDD. We further discuss how CDMSM may guide stage-specific miRNA therapeutics, including engineered exosomes, miRNA inhibitors, and microenvironment-responsive biomaterials. Finally, we outline experimental strategies required to test the model, including longitudinal animal models, controlled mechanobiology systems, single-cell and spatial transcriptomics, and functional perturbation of miRNA-target networks.