Applications of Functionalized Hydrogels in the Regeneration of the Intervertebral Disc

Abstract

Intervertebral disc degeneration (IDD) is caused by genetics, aging, and environmental factors and is one of the leading causes of low back pain. The treatment of IDD presents many challenges. Hydrogels are biomaterials that possess properties similar to those of the natural extracellular matrix and have significant potential in the field of regenerative medicine. Hydrogels with various functional qualities have recently been used to repair and regenerate diseased intervertebral discs. Here, we review the mechanisms of intervertebral disc homeostasis and degeneration and then discuss the applications of hydrogel-mediated repair and intervertebral disc regeneration. The classification of artificial hydrogels and natural hydrogels is then briefly introduced, followed by an update on the development of functional hydrogels, which include noncellular therapeutic hydrogels, cellular therapeutic hydrogel scaffolds, responsive hydrogels, and multifunctional hydrogels. The challenges faced and future developments of the hydrogels used in IDD are discussed as they further promote their clinical translation.

Recent advances in GelMA hydrogel transplantation for musculoskeletal disorders and related disease treatment

“…Hydrogels are viewed as an effective alternative strategy to treat this disease due to their good physicochemical tunability 90 . Ideal IVD repair hydrogel material for regenerating IVD should possess the following features: (1) excellent biocompatibility and biodegradability; (2) injectability for conservative management or minimally invasive intervention; (3) in situ curing to avoid leakage; (4) strong biomechanical characteristics; (5) good drug-loading and release performance; (6) successful integration and adherence with target to prevent poor localization 91 .…”

Research progress in decellularized extracellular matrix hydrogels for intervertebral disc degeneration

“…[134][135][136] The dECM hydrogel can maintain stability of the ECM within the IVD, and the ideal dECM hydrogel should have the following properties to prevent and control IDD: (1) injectability, as most of these hydrogels are temperature-sensitive and since the hydrogel precursor is liquid and gels rapidly in vivo at 37 °C; (2) natural extracellular matrix activity; (3) absence of immunogenic cellular material after decellularization; (4) a three-dimensional structure so that the gel can serve as a vehicle for cells, therapeutic drugs or other biologically active molecules; (5) slow degradation during treatment so that the gel gradually releases the drugs and growth factors encapsulated inside, which can maintain optimal drug concentration locally. 137 For this review, we searched the PubMed, Cochrane, Embase, and Web of Science databases using the terms "Decellularized hydrogel or ECM hydrogel" and "Intervertebral discs", and the search time was from the establishment of the database until October 2022. In all, the 15 papers that were screened (Table 4) are summarised and outlined.…”

Silk fibroin-based biomaterials for disc tissue engineering

“…The ideal hydrogel at this point should have the following properties: (1) good biodegradability; (2) high water content; (3) injectability; (4) in situ curability to prevent leakage; (5) suitable mechanical properties; (6) good substance carriage and slow release properties; (7) the ability to combine with the target site to prevent poor localization; and (8) the ability to complement the extracellular matrix (ECM) to provide a microenvironment for repairing or regenerating NP cells. 97 Unfortunately, the available natural and synthetic hydrogels cannot satisfy the above-required properties. Thus, natural hydrogels or synthetic hydrogels have been modified to enable their use for NP repair.…”