Leni and Peter W. May Department of Orthopaedics, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
Department of Chemical Engineering, The Cooper Union for the Advancement of Science and Art, New York, NY, USA.
Cartilage. 2022 Jul-Sep;13(3):19476035221113959. doi: 10.1177/19476035221113959.
Intervertebral disk degeneration is a prevalent postoperative complication after discectomy, underscoring the need to develop preventative and bioactive treatment strategies that decelerate degeneration and seal annulus fibrosus (AF) defects. Human mesenchymal stem cell-derived exosomes (MSC-Exos) hold promise for cell-free bioactive repair; however, their ability to promote AF repair is poorly understood. The objective of this study was to evaluate the ability of MSC-Exos to promote endogenous AF repair processes and integrate MSC-Exos within a biomaterial delivery system.
We characterize biophysical and biochemical properties of normoxic (Nx) and hypoxic (Hx) preconditioned MSC-Exos from young, healthy donors and examine their effects on AF cell proliferation, migration, and gene expression. We then integrate a poly(lactic--glycolic acid) microsphere (PLGA µSphere) delivery platform within an interpenetrating network hydrogel to facilitate sustained MSC-Exo delivery.
Hx MSC-Exos led to a more robust response in AF cell proliferation and migration than Nx MSC-Exos and was selected for a downstream protection experiment. Hx MSC-Exos maintained a healthy AF cell phenotype under a TNFα challenge and attenuated catabolic responses. In all functional assays, AF cell responses were more sensitive to Hx MSC-Exos than Nx MSC-Exos. PLGA µSpheres released MSC-Exos over a clinically relevant timescale without affecting hydrogel modulus or pH upon initial embedment and µSphere degradation.
This MSC-Exo treatment strategy may offer benefits of stem cell therapy without the need for exogenous stem cell transplantation by stimulating cell proliferation, promoting cell migration, and protecting cells from the degenerative proinflammatory microenvironment.
椎间盘退变是椎间盘切除术后一种普遍的术后并发症，这凸显了开发预防和生物活性治疗策略的必要性，以减缓退变并封闭纤维环（AF）缺陷。人骨髓间充质干细胞衍生的外泌体（MSC-Exos）在无细胞生物活性修复方面具有应用前景；然而，其促进 AF 修复的能力尚未被充分了解。本研究旨在评估 MSC-Exos 促进内源性 AF 修复过程的能力，并将 MSC-Exos 整合到生物材料递送系统中。
我们对来自年轻健康供体的常氧（Nx）和低氧（Hx）预处理 MSC-Exos 的生物物理和生化特性进行了表征，并研究了它们对 AF 细胞增殖、迁移和基因表达的影响。然后，我们将聚乳酸-羟基乙酸共聚物（PLGA）微球（µSphere）递送平台整合到互穿网络水凝胶中，以促进 MSC-Exo 的持续递送。
与 Nx MSC-Exos 相比，Hx MSC-Exos 导致 AF 细胞增殖和迁移的反应更为强烈，并被选为下游保护实验的研究对象。Hx MSC-Exos 在 TNFα 挑战下维持了健康的 AF 细胞表型，并减轻了分解代谢反应。在所有功能测定中，AF 细胞对 Hx MSC-Exos 的反应比对 Nx MSC-Exos 的反应更为敏感。PLGA µSphere 在临床上相关的时间范围内释放 MSC-Exos，而在初始嵌入和 µSphere 降解时不会影响水凝胶的模量或 pH。
这种 MSC-Exo 治疗策略可能通过刺激细胞增殖、促进细胞迁移以及保护细胞免受退行性炎症微环境的影响，提供无需外源性干细胞移植的干细胞治疗的益处。
