Cell and Hydrogel-Integrated Therapies for Intervertebral Disc Regeneration.

Intervertebral disc degeneration (IDD) is a major cause of low back pain (LBP), significantly affecting on global disability and healthcare costs. Traditional treatments primarily focus on symptom management rather than addressing the underlying causes, such as the decline in nucleus pulposus (NP) cells and reduced extracellular matrix (ECM) synthesis. Cell therapy shows promise by replenishing NP cells, activating resident cells, and enhancing ECM deposition. However, the harsh microenvironment of IDD can hinder the survival of transplanted cells. Biocompatible hydrogels, with their ECM-like properties, provide controlled delivery of therapeutics and biologics, creating a supportive environment for cell therapy and demonstrating strong regenerative potential. This review covers an overview of fundamental concepts underlying IDD progression, current clinical treatments, and the potential of stem/progenitor cell therapy. It highlights the unique properties of hydrogels as delivery systems to address these challenges, details common cell therapy methods for IDD, and explores the use of various hydrogels in treatment strategies. Recent advances in hydrogel-assisted cell therapy are also discussed, including current limitations and challenges, and future directions for the field.