Poster Presentation 50th International Society for the Study of the Lumbar Spine Annual Meeting 2024

简介 间充质干细胞（MSC）在治疗椎间盘退变方面显示出巨大的潜力，但大多数 MSC 在椎间盘内移植后很快就会死亡。细胞焦亡是一种新的细胞死亡形式，由于椎间盘中积聚的活性氧（ROS）受到刺激，可能与间充质干细胞死亡有关。目前，块状水凝胶是提高组织中 MSC 存活率的常用解决方案，但块状水凝胶的微小空隙和紧密结构阻碍了细胞归巢和细胞因子响应性细胞迁移。微凝胶是细胞表面生物相容性材料的外壳，可以保留对组织 ECM 的敏感性和迁移能力。在本研究中，我们用微凝胶封装个体间充质干细胞，以提高治疗椎间盘退变的疗效。

方法采用层层（LbL）自组装方法，通过沉积交替的带相反电荷的生物相容材料层来制造MSC。通过扫描电子显微镜（SEM）、流式细胞术和荧光共聚焦显微镜等检测微凝胶的包裹情况。为了评价微凝胶的细胞保护作用，我们利用免疫印迹、免疫荧光和免疫印迹分析了氧化应激下包被和未包被的MSC的存活和焦亡激活情况。细胞存活染色等。在椎间盘退变的针刺大鼠模型中检查微凝胶包被的间充质干细胞的治疗效果。

结果微凝胶封装有效保护单个MSC而不影响其结构或功能。微凝胶保持了细胞的完整性、独立性，并保留了细胞增殖、迁移和分化的能力。微凝胶增强了氧化应激条件下的细胞存活率，表明其具有细胞保护作用。微凝胶涂层减轻了线粒体DNA渗漏引起的焦亡，表明微凝胶通过在氧化应激下保持线粒体稳态来减轻焦亡。在针刺诱导的椎间盘退变模型中，我们证明微凝胶封装增强了 MSC 在退变椎间盘中的保留，增强了 MSC 抑制焦亡的能力，并提高了缓解椎间盘退变的治疗效果。

讨论细胞焦亡与退变椎间盘中移植的 MSC 的死亡有关。微凝胶涂层能够减轻氧化应激下的细胞焦亡，提高 MSC 治疗椎间盘退变的疗效。研究结果表明，抑制焦亡可能是提高 MSC 治疗椎间盘退变疗效的潜在策略。

Introduction Mesenchymal stem cells (MSCs) show great potential in treating intervertebral disc degeneration, but most MSCs die soon after intradiscal transplantation. Pyroptosis is a new form of cell death that may be related to mesenchymal stem cell death due to stimulation of reactive oxygen species (ROS) accumulated in the intervertebral disc. Currently, bulk hydrogels are a common solution to improve MSC survival in tissues, but the tiny voids and tight structure of bulk hydrogels hinder cell homing and cytokine-responsive cell migration. Microgels are shells of biocompatible materials on cell surfaces that retain sensitivity to tissue ECM and migration capabilities. In this study, we used microgels to encapsulate individual mesenchymal stem cells to improve the efficacy of treating intervertebral disc degeneration.

Methods A layer-by-layer (LbL) self-assembly method was used to fabricate MSCs by depositing alternating layers of oppositely charged biocompatible materials. The encapsulation of microgels was detected by scanning electron microscopy (SEM), flow cytometry, and fluorescence confocal microscopy. To evaluate the cytoprotective effect of microgels, we analyzed the survival and pyroptosis activation of coated and uncoated MSCs under oxidative stress using immunoblotting, immunofluorescence, and immunoblotting. Cell survival staining, etc. The therapeutic efficacy of microgel-coated mesenchymal stem cells was examined in an acupuncture rat model of intervertebral disc degeneration.

Results Microgel encapsulation effectively protected individual MSCs without affecting their structure or function. Microgels maintain cell integrity, independence, and retain the ability of cells to proliferate, migrate, and differentiate. The microgel enhanced cell survival under oxidative stress conditions, suggesting a cytoprotective effect. Microgel coating alleviated pyroptosis induced by mitochondrial DNA leakage, suggesting that microgels mitigate pyroptosis by maintaining mitochondrial homeostasis under oxidative stress. In an acupuncture-induced disc degeneration model, we demonstrated that microgel encapsulation enhanced the retention of MSCs in degenerated discs, enhanced the ability of MSCs to inhibit pyroptosis, and improved the therapeutic effect of alleviating disc degeneration.

Discussion Pyroptosis is associated with death of transplanted MSCs in degenerating discs. Microgel coating can reduce cell pyroptosis under oxidative stress and improve the efficacy of MSC in treating intervertebral disc degeneration. The findings suggest that inhibiting pyroptosis may be a potential strategy to improve the efficacy of MSCs in the treatment of intervertebral disc degeneration.