Overactive inflammatory cascade accompanied by oxidative stress in the nucleus pulposus exacerbates intervertebral disc degeneration (IVDD). Hydrogels have been demonstrated to be promising in treating IVDD, yet they remain less efficacious in the case of anti-inflammation associated with antioxidation. In this study, we designed an injectable self-antioxidant hydrogel (HA/CS) with enhanced inflammation inhibitory performance for delivering chondroitin sulfate (CS) with well-documented anti-inflammatory property to treat IVDD. The hydrogel was rapidly formed via dynamic boronate ester bonding between furan/phenylboronic acid and furan/dopamine-modified hyaluronic acid (HA), and mechanically enhanced by Diels–Alder reaction-induced secondary crosslinking, partial dopamine groups of which contribute to grafting phenylboronic acid-modified CS (CS-PBA). This hydrogel exhibits favorable injectability, mechanical property, and pH-responsive delivery behavior. The dopamine moiety endows the hydrogel with efficient antioxidative property. By sustained delivery of CS, the HA/CS hydrogel is well competent to inhibit inflammatory cytokine expression and maintain anabolic/catabolic balance in an inflammation-simulated environment. Most importantly, the HA/CS hydrogel significantly ameliorates degeneration in a puncture-induced IVDD rat model. The self-antioxidant HA/CS hydrogel designed in this work may serve as a novel and promising therapeutic platform for IVDD.
Yan Ju,Shiyuan Ma,Meimei Fu,Min Wu,Yue Li,Yue Wang,Meihan Tao,Zhihui Lu,Jinshan Guo
Discectomy is the surgical standard of care to relieve low back pain caused by intervertebral disc (IVD) herniation. However, there remains annulus fibrosus (AF) defect and nucleus pulposus (NP) degeneration, which often result in recurrent herniation (re-herniation). Herein, we develop a polyphenol-modified waterborne polyurethane bioadhesives (PPU-glues) to promote therapy prognosis after discectomy. Being composed of tannic acid (TA) mixed cationic waterborne polyurethane nanodispersions (TA/WPU + ) and curcumin (Cur) embedded anionic waterborne polyurethane nanodispersions (Cur-WPU - ), PPU-glue gels rapidly (<10 s) and exhibits low swelling ratios, tunable degradation rates and good biocompatibility. Due to the application of an adhesion strategy combing English ivy mechanism and particle packing theory, PPU-glue also shows considerable lap shear strength against wet porcine skin (≈58 kPa) and burst pressure (≈26 kPa). The mismatched particle sizes and the opposite charges of TA/WPU + and Cur-WPU - in PPU-glue bring electrostatic interaction and enhance particle packing density. PPU-glue possesses superior reactive oxygen species (ROS)-scavenging capacity derived from polyphenols. PPU-glue can regulate extracellular matrix (ECM) metabolism in degenerated NP cells, and it can promote therapy biologically and mechanically in degenerated rat caudal discs. In summary, this study highlights the therapeutic approach that combines AF seal and NP augmentation, and PPU-glue holds great application potentials for post discectomy therapy. Statement of Significance Currently, there is no established method for the therapy of annulus fibrosus (AF) defect and nucleus pulposus (NP) degeneration after discectomy. Herein, we developed a polyphenol-modified biomimetic polyurethane bioadhesives (PPU-glue) with strong adhesive strength and superior bioactive property. The adhesion strategy that combined a particle packing theory and an English ivy mechanism was firstly applied to the intervertebral disc repair field, which benefited AF seal. The modified method of incorporating polyphenols was utilized to confer with ROS-scavenging capacity, ECM metabolism regulation ability and anti-inflammatory property, which promoted NP augmentation. Thus, PPU-glue attained the synergy effect for post discectomy therapy, and the design principle could be universally expanded to the bioadhesives for other surgical uses.
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