Objectives The heterogeneity of meniscus cells and the mechanism of meniscus degeneration is not well understood. Here, single-cell RNA sequencing (scRNA-seq) was used to identify various meniscus cell subsets and investigate the mechanism of meniscus degeneration. Methods scRNA-seq was used to identify cell subsets and their gene signatures in healthy human and degenerated meniscus cells to determine their differentiation relationships and characterise the diversity within specific cell types. Colony-forming, multi-differentiation assays and a mice meniscus injury model were used to identify meniscus progenitor cells. We investigated the role of degenerated meniscus progenitor (DegP) cell clusters during meniscus degeneration using computational analysis and experimental verification. Results We identified seven clusters in healthy human meniscus, including five empirically defined populations and two novel populations. Pseudotime analysis showed endothelial cells and fibrochondrocyte progenitors (FCP) existed at the pseudospace trajectory start. Melanoma cell adhesion molecule ((MCAM)/CD146) was highly expressed in two clusters. CD146+ meniscus cells differentiated into osteoblasts and adipocytes and formed colonies. We identified changes in the proportions of degenerated meniscus cell clusters and found a cluster specific to degenerative meniscus with progenitor cell characteristics. The reconstruction of four progenitor cell clusters indicated that FCP differentiation into DegP was an aberrant process. Interleukin 1β stimulation in healthy human meniscus cells increased CD318+ cells, while TGFβ1 attenuated the increase in CD318+ cells in degenerated meniscus cells. Conclusions The identification of meniscus progenitor cells provided new insights into cell-based meniscus tissue engineering, demonstrating a novel mechanism of meniscus degeneration, which contributes to the development of a novel therapeutic strategy.

中文翻译：

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单细胞 RNA-seq 分析识别半月板祖细胞并揭示半月板退化的进展

目的 半月板细胞的异质性和半月板变性的机制尚不清楚。在这里，单细胞RNA测序（scRNA-seq）用于鉴定各种半月板细胞亚群并研究半月板变性的机制。方法 scRNA-seq 用于鉴定健康人和退化半月板细胞中的细胞亚群及其基因特征，以确定它们的分化关系并表征特定细胞类型内的多样性。集落形成、多分化试验和小鼠半月板损伤模型用于鉴定半月板祖细胞。我们使用计算分析和实验验证研究了退化的半月板祖细胞 (DegP) 细胞簇在半月板退化过程中的作用。结果我们在健康的人类半月板中发现了七个簇，包括五个凭经验定义的种群和两个新种群。伪时间分析显示在伪空间轨迹开始时存在内皮细胞和纤维软骨细胞祖细胞 (FCP)。黑色素瘤细胞粘附分子 ((MCAM)/CD146) 在两个簇中高度表达。CD146+ 半月板细胞分化为成骨细胞和脂肪细胞并形成集落。我们确定了退化的半月板细胞簇比例的变化，并发现了一个特定于具有祖细胞特征的退化半月板的簇。四个祖细胞簇的重建表明 FCP 分化为 DegP 是一个异常过程。健康人半月板细胞中的白细胞介素 1β 刺激增加了 CD318+ 细胞，而 TGFβ1 减弱了退化半月板细胞中 CD318+ 细胞的增加。