Zhu Qianqi, Tan Miaoying, Wang Chengniu, Chen Yufei, Wang Chenfei, Zhang Junqi, Gu Yijun, Guo Yuqi, Han Jianpeng, Li Lei, Jiang Rongrong, Fan Xudong, Xie Huimin, Wang Liang, Gu Zhifeng, Liu Dong, Shi Jianwu, Feng Xingmei
Department of Stomatology, Affiliated Hospital of Nantong University, Medical School of, Nantong University, Nantong, 226001, China.
Institute of Reproductive Medicine, Medical School of Nantong University, Nantong, 226001, China.
Cell Biosci. 2023 Jul 19;13(1):130. doi: 10.1186/s13578-023-01069-5.
The temporomandibular joint (TMJ) is a complex joint consisting of the condyle, the temporal articular surface, and the articular disc. Functions such as mastication, swallowing and articulation are accomplished by the movements of the TMJ. To date, the TMJ has been studied more extensively, but the types of TMJ cells, their differentiation, and their interrelationship during growth and development are still unclear and the study of the TMJ is limited. The aim of this study was to establish a molecular cellular atlas of the human embryonic temporomandibular joint condyle (TMJC) by single-cell RNA sequencing, which will contribute to understanding and solving clinical problems.
Human embryos at 3 and 4 months of age are an important stage of TMJC development. We performed a comprehensive transcriptome analysis of TMJC tissue from human embryos at 3 and 4 months of age using single-cell RNA sequencing. A total of 16,624 cells were captured and the gene expression profiles of 15 cell clusters in human embryonic TMJC were determined, including 14 known cell types and one previously unknown cell type, "transition state cells (TSCs)". Immunofluorescence assays confirmed that TSCs are not the same cell cluster as mesenchymal stem cells (MSCs). Pseudotime trajectory and RNA velocity analysis revealed that MSCs transformed into TSCs, which further differentiated into osteoblasts, hypertrophic chondrocytes and tenocytes. In addition, chondrocytes (CYTL1 + THBS1) from secondary cartilage were detected only in 4-month-old human embryonic TMJC.
Our study provides an atlas of differentiation stages of human embryonic TMJC tissue cells, which will contribute to an in-depth understanding of the pathophysiology of the TMJC tissue repair process and ultimately help to solve clinical problems.
颞下颌关节（TMJ）是一个复杂的关节，由髁突、颞骨关节面和关节盘组成。咀嚼、吞咽和发音等功能通过颞下颌关节的运动来完成。迄今为止，对颞下颌关节的研究较为广泛，但颞下颌关节细胞的类型、它们的分化以及在生长发育过程中的相互关系仍不明确，对颞下颌关节的研究有限。本研究的目的是通过单细胞RNA测序建立人类胚胎颞下颌关节髁突（TMJC）的分子细胞图谱，这将有助于理解和解决临床问题。
3个月和4个月大的人类胚胎是TMJC发育的重要阶段。我们使用单细胞RNA测序对3个月和4个月大的人类胚胎TMJC组织进行了全面的转录组分析。共捕获了16624个细胞，确定了人类胚胎TMJC中15个细胞簇的基因表达谱，包括14种已知细胞类型和一种以前未知的细胞类型，即“过渡态细胞（TSCs）”。免疫荧光分析证实TSCs与间充质干细胞（MSCs）不是同一细胞簇。伪时间轨迹和RNA速度分析显示，MSCs转化为TSCs，TSCs进一步分化为成骨细胞、肥大软骨细胞和肌腱细胞。此外，仅在4个月大的人类胚胎TMJC中检测到来自继发性软骨的软骨细胞（CYTL1+THBS1）。
我们的研究提供了人类胚胎TMJC组织细胞分化阶段的图谱，这将有助于深入了解TMJC组织修复过程的病理生理学，并最终有助于解决临床问题。
