High strength HA-PEG/NAGA-Gelma double network hydrogel for annulus fibrosus rupture repair

The low back pain (LBP) caused by intervertebral disc (IVD) herniation and degeneration bring huge physical and economic burden to individuals and families. Since current clinical treatment methods could not change the degeneration process of the intervertebral disc, annulus fibrosus (AF) repair as a method to seal defects of the IVD and prevent reherniation after lumbar discectomy has attracted increasing interest. In this study, a porous HA-PEG/NAGA-GelMA double network hydrogel with the multiple hydrogen bonds was designed and prepared by a two-step method, in which the multiple hydrogen bonds produced by NAGA endowed excellent mechanical properties (compressive strength up to 1.19 ​MPa and compressive modulus up to 0.55 ​MPa) to resist the pressure from the AF and the hyaluronic acid provided good biological activity. In vitro cell experiment indicated that the double network hydrogel possessed good cytocompatibility and supported cell proliferation and penetration. In addition, further organ experiments also showed that the double network hydrogel could restore the disc height and mechanical function of the injured intervertebral disc, and display good integration with the host AF, showing a promising application in annulus fibrosus tissue repair after lumbar discectomy.