Abstract：
Osteochondral regeneration remains formidable challenges despite significant advances in microsurgery. Herein, an acellular trilayer cryogel (TC) with injectability, tunable pore sizes (80-200 µm), and appropriate compressive modulus (10.8 kPa) is manufactured from self-healable hydrogel under different gelling times through Schiff reaction between chitosan and difunctionalized polyurethane (DFPU). Bioactive molecules (Y27632 and dexamethasone) are respectively loaded in the top and bottom layers to form the Y27632/dexamethasone-loaded trilayer cryogel (Y/DEX-TC). Mesenchymal stem cells (MSCs) seeded in Y/DEX-TC proliferated ≈350% in vitro and underwent chondrogenesis or osteogenesis in response to the respective release of Y or DEX in 14 days. Acupuncture is administered to animals in an attempt to modulate the innate regulatory system and mobilize endogenous MSCs for osteochondral defect regeneration. In vivo rabbit experiments using Y/DEX-TC combined with acupuncture successfully regulate SDF-1 and TGF-β1 levels, which possibly cause MSC migration toward Y/DEX-TC. The synergistic effect of cryogel and acupuncture on immunomodulation is verified with a ≈7.3-fold enhancement of the M2-/M1-macrophage population ratio by treatment of Y/DEX-TC combining acupuncture, significantly greater than ≈1.5-fold increase by acupuncture or ≈2.2-fold increase by Y/DEX-TC alone. This novel strategy using acellular drug-loaded cryogel and accessible acupuncture shows promise in treating osteochondral defects of joint damage.
摘要：
尽管显微外科取得了重大进展，但骨软骨再生仍然面临巨大挑战。在这里，具有可注射性的无细胞三层冷冻凝胶（TC），可调孔径（80-200µm），通过壳聚糖和双官能化聚氨酯（DFPU）之间的希夫反应，在不同的胶凝时间下由可自愈合的水凝胶制成适当的压缩模量（10.8kPa）。将生物活性分子(Y27632和地塞米松)分别装载在顶层和底层中以形成装载Y27632/地塞米松的三层冷冻凝胶(Y/DEX-TC)。接种在Y/DEX-TC中的间充质干细胞（MSC）在体外增殖约350％，并在14天内响应Y或DEX的各自释放而发生软骨形成或成骨。向动物施用针刺以试图调节先天调节系统并动员内源性MSC用于骨软骨缺损再生。兔体内实验采用Y/DEX-TC联合针刺成功调节SDF-1和TGF-β1水平,这可能导致MSC向Y/DEX-TC迁移。通过Y/DEX-TC联合针刺治疗，证实了冷冻凝胶和针刺对免疫调节的协同作用，M2-/M1-巨噬细胞群比率增加了约7.3倍，显着大于针刺增加约1.5倍或Y/DEX-TC单独增加约2.2倍。这种使用无细胞载药冷冻凝胶和可及的针灸的新策略在治疗关节损伤的骨软骨缺损方面显示出希望。
