Glycosaminoglycans (GAGs) are major components of cartilage extracellular matrix (ECM), which play an important role in tissue homeostasis not only by providing mechanical load resistance, but also as signaling mediators of key cellular processes such as adhesion, migration, proliferation and differentiation. Specific GAG types as well as their disaccharide sulfation patterns can be predictive of the tissue maturation level but also of disease states such as osteoarthritis. In this work, we used a highly sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method to perform a comparative study in terms of temporal changes in GAG and disaccharide composition between tissues generated from human bone marrow- and synovial-derived mesenchymal stem/stromal cells (hBMSC/hSMSC) after chondrogenic differentiation under normoxic (21% O₂) and hypoxic (5% O₂) micromass cultures. The chondrogenic differentiation of hBMSC/hSMSC cultured under different oxygen tensions was assessed through aggregate size measurement, chondrogenic gene expression analysis and histological/immunofluorescence staining in comparison to human chondrocytes. For all the studied conditions, the compositional analysis demonstrated a notable increase in the average relative percentage of chondroitin sulfate (CS), the main GAG in cartilage composition, throughout MSC chondrogenic differentiation. Additionally, hypoxic culture conditions resulted in significantly different average GAG and CS disaccharide percentage compositions compared to the normoxic ones. However, such effect was considerably more evident for hBMSC-derived chondrogenic aggregates. In summary, the GAG profiles described here may provide new insights for the prediction of cartilage tissue differentiation/disease states and to characterize the quality of MSC-generated chondrocytes obtained under different oxygen tension culture conditions.

中文翻译：

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常氧和缺氧条件下人骨髓/滑膜来源的间充质干/基质细胞软骨分化过程中的糖胺聚糖重塑。

糖胺聚糖 (GAG) 是软骨细胞外基质 (ECM) 的主要成分，它不仅通过提供机械负荷阻力，而且作为关键细胞过程（如粘附、迁移、增殖和分化）的信号传导介质，在组织稳态中发挥重要作用。特定的 GAG 类型及其二糖硫酸化模式可以预测组织成熟水平，也可以预测骨关节炎等疾病状态。在这项工作中，我们使用高灵敏度液相色谱-串联质谱 (LC-MS/MS) 方法对人骨髓和滑膜衍生的组织之间的 GAG 和二糖组成的时间变化进行了比较研究常氧 (21% O) 下软骨分化后的间充质干/基质细胞 (hBMSC/hSMSC)₂ ) 和缺氧 (5% O ₂) 微量培养。与人软骨细胞相比，通过聚集体大小测量、软骨基因表达分析和组织学/免疫荧光染色评估了在不同氧张力下培养的 hBMSC/hSMSC 的软骨分化。对于所有研究条件，成分分析表明，在整个 MSC 软骨形成分化过程中，硫酸软骨素 (CS)（软骨成分中的主要 GAG）的平均相对百分比显着增加。此外，与常氧条件相比，低氧培养条件导致平均 GAG 和 CS 二糖百分比组成显着不同。然而，对于 hBMSC 衍生的软骨形成聚集体，这种效果更为明显。总之，