Advances and mechanisms of hydrogel-based interventions for intervertebral disc degeneration repair.

Intervertebral disc degeneration (IVDD) is a leading cause of low back pain and remains difficult to treat because of its progressive pathology, complex microenvironment, and limited intrinsic repair capacity. Conventional conservative therapies rarely prevent degeneration, while surgical interventions fail to restore disc biology and are associated with substantial complications. These challenges have motivated increasing interest in biomaterial-based therapeutic strategies. Hydrogels have emerged as adaptable platforms for IVDD intervention owing to their injectability, tunable mechanical properties, and biocompatibility. By functioning as supportive scaffolds and delivery systems for cells, bioactive factors, or drugs, hydrogel-based approaches can modulate inflammation, regulate extracellular matrix metabolism, and stabilize the disc microenvironment. This review critically examines recent advances in hydrogel-based strategies for IVDD, emphasizing the interplay between material design. Key limitations and translational considerations are discussed to guide the rational development of hydrogel systems that support structural and functional repair of degenerated intervertebral discs.