Abstract：
Presently, the clinical treatment of intervertebral disc degeneration (IVDD) remains challenging, but the strategy of simultaneously overcoming the overactive inflammation and restoring the anabolic/catabolic balance of the extracellular matrix (ECM) in the nucleus pulposus (NP) has become an effective way to alleviate IVDD. IL-1ra, a natural antagonist against IL-1β, can mitigate inflammation and promote regeneration in IVDD. Chondroitin sulfate (CS), an important component of the NP, can promote ECM synthesis and delay IVDD. Thus, these were chosen and integrated into functionalized microspheres to achieve their synergistic effects. First, CS-functionalized microspheres (GelMA-CS) with porous microstructure, good monodispersion, and about 200 μm diameter were efficiently and productively fabricated using microfluidic technology. After lyophilization, the microspheres with good local injection and tissue retention served as the loading platform for IL-1ra and achieved sustained release. In in vitro experiments, the IL-1ra-loaded microspheres exhibited good cytocompatibility and efficacy in inhibiting the inflammatory response of NP cells induced by lipopolysaccharide (LPS) and promoting the secretion of ECM. In in vivo experiments, the microspheres showed good histocompatibility, and local, minimally invasive injection of the IL-1ra-loaded microspheres could reduce inflammation, maintain the height of the intervertebral disc (IVD) and the water content of NP close to about 70% in the sham group, and retain the integrated IVD structure. In summary, the GelMA-CS microspheres served as an effective loading platform for IL-1ra, eliminated inflammation through the controlled release of IL-1ra, and promoted ECM synthesis via CS to delay IVDD, thereby providing a promising intervention strategy for IVDD. STATEMENT OF SIGNIFICANCE: The strategy of simultaneously overcoming the overactive inflammation and restoring the anabolic/catabolic balance of the extracellular matrix (ECM) in nucleus pulposus (NP) has shown great potential prospects for alleviating intervertebral disc degeneration (IVDD). From the perspective of clinical translation, this study developed chondroitin sulfate functionalized microspheres to act as the effective delivery platform of IL-1ra, a natural antagonist of interleukin-1β. The IL-1ra loading microspheres (GelMA-CS-IL-1ra) showed good biocompatibility, good injection with tissue retention, and synergistic effects of inhibiting the inflammatory response induced by lipopolysaccharide and promoting the secretion of ECM in NPCs. In vivo, they also showed the beneficial effect of reducing the inflammatory response, maintaining the height of the intervertebral disc and the water content of the NP, and preserving the integrity of the intervertebral disc structure after only one injection. All demonstrated that the GelMA-CS-IL-1ra microspheres would have great promise for the minimally invasive treatment of IVDD.
摘要：
目前,椎间盘退变（IVDD）的临床治疗仍然具有挑战性，但是同时克服过度活跃的炎症和恢复髓核（NP）中细胞外基质（ECM）的合成代谢/分解代谢平衡的策略已成为缓解IVDD的有效方法。IL-1ra,一种针对IL-1β的天然拮抗剂，可以减轻炎症并促进IVDD中的再生。硫酸软骨素（CS），NP的重要组成部分，可以促进ECM合成和延迟IVDD。因此，这些被选择并整合到功能化微球中，以实现它们的协同作用。首先,具有多孔微结构的CS功能化微球(GelMA-CS),良好的单分散性,使用微流体技术有效地制造了约200μm的直径。冻干后，具有良好的局部注射和组织保留的微球作为IL-1ra的负载平台并实现了持续释放。在体外实验中,负载IL-1ra的微球具有良好的细胞相容性和抑制脂多糖（LPS）诱导的NP细胞炎症反应和促进ECM分泌的功效。在体内实验中,微球表现出良好的组织相容性，当地的,微创注射负载IL-1ra的微球可以减轻炎症，假手术组保持椎间盘高度(IVD)和NP含水量接近70%,并保留集成的IVD结构。总之,GelMA-CS微球作为IL-1ra的有效负载平台，通过控制释放IL-1ra消除炎症，并通过CS促进ECM合成以延迟IVDD，从而为IVDD提供了一个有希望的干预策略。重要性声明：同时克服过度活跃的炎症和恢复髓核（NP）中细胞外基质（ECM）的合成代谢/分解代谢平衡的策略已显示出缓解椎间盘退变（IVDD）的巨大潜力。从临床翻译的角度来看，本研究开发了硫酸软骨素功能化微球作为IL-1ra的有效递送平台，白细胞介素-1β的天然拮抗剂。IL-1ra负载微球(GelMA-CS-IL-1ra)表现出良好的生物相容性,良好的注射与组织保留，抑制脂多糖诱导的炎症反应和促进NPCs分泌ECM的协同作用。在体内,它们还显示出减少炎症反应的有益效果，保持椎间盘的高度和NP的含水量，只需注射一次，就能保持椎间盘结构的完整性。所有证明GelMA-CS-IL-1ra微球对于IVDD的微创治疗具有很大的希望。
