Application of\nan Injectable Thermosensitive Hydrogel\nDrug Delivery System for Degenerated Intervertebral Disc Regeneration

Intervertebral disc degeneration is characterized by\na localized,\nchronic inflammatory response leading to a synthesis/catabolism imbalance\nwithin the nucleus pulposus (NP) and progressive functional impairment\nwithin the NP. Polyphenol molecules have been widely used in anti-inflammatory\ntherapies in recent years; therefore, we designed an injectable, temperature-sensitive\nhydrogel PLGA-PEG-PLGA-based drug delivery system for local and sustained\ndelivery of two drugs tannic acid (TA) and resveratrol (Res), with\nthe hydrogel carrying TA directly and Res indirectly (carried directly\nby inflammation-responsive nanoparticles). The delivery system presents\ngood injectability at room temperature and forms a gel in situ upon\nentering the intervertebral disc. The delivery system can rapidly\nrelease TA and sustain Res release. In vitro and in vivo experiments\nhave shown that this hydrogel drug delivery system is effective in\nanti-inflammation of degenerated intervertebral discs and promotes\nthe regeneration of extracellular matrix in the NP.