Dynamic changes of nonepithelial thymic stroma during thymus organogenesis

The thymic stroma provides the microenvironment for T cell lineage commitment, development, maturation, and repertoire selection. While the thymic epithelial cell (TEC) compartment is relatively well characterised, a comparably detailed analysis of the non-TEC stromal compartment including the endothelial cells and fibroblasts is currently lacking. Here, we probe the composition of thymic mesenchymal cells and their dynamic change during thymus organogenesis. Using a single cell transcriptomic approach, we identify previously unappreciated heterogeneity within the non-TEC stromal compartment and demonstrate dynamic shifts within non-TEC stromal cell populations over thymic development. We then use a compound heterozygous model (Tbx1+/-Crkl+/-) for 22q11.2DS syndrome to show that significant reductions of multiple mesenchymal subpopulations associated with functional defects and accelerated aging are associated with the thymic hypoplasia observed in this condition. Thus, we provided a comprehensive picture of non-TEC thymic stromal development and their functional defects in a disease model of thymic hypoplasia. Thymic stromal cells - 10X gene expression: non-TEC thymic stroma over development (n=8) and thymic stroma wild-type vs. Tbx1+/-Crkl+/- mice (n=6); RNA-seq wild-type thymic stroma mice胸腺基质为T细胞谱系定型、发育、成熟及T细胞受体库选择提供专属微环境。尽管胸腺上皮细胞（thymic epithelial cell, TEC）的特征已得到相对充分的解析，但目前仍缺乏对包括内皮细胞与成纤维细胞在内的非TEC基质区域的同等细致分析。本研究探究了胸腺间充质细胞的组成及其在胸腺器官发生过程中的动态变化。借助单细胞转录组学方法，我们在非TEC基质区域中鉴定出此前未被认知的细胞异质性，并证实胸腺发育进程中，非TEC基质细胞群存在动态转变。随后，我们采用针对22q11.2缺失综合征（22q11.2DS syndrome）的复合杂合模型（Tbx1+/-Crkl+/-）开展实验，结果显示该病症中观察到的胸腺发育不全，与多种间充质亚群的显著减少、细胞功能缺陷及衰老加速密切相关。综上，本研究全面阐明了非TEC胸腺基质的发育过程，并揭示了胸腺发育不全疾病模型中其功能缺陷。本数据集相关信息如下：胸腺基质细胞的10X基因表达谱，涵盖发育阶段的非TEC胸腺基质样本（n=8）以及野生型与Tbx1+/-Crkl+/-小鼠的胸腺基质样本（n=6）；同时包含野生型小鼠胸腺基质的RNA-seq数据