Spatial Gene Expression in the Adult Rat Patellar Tendon

Tendons are dense connective tissues with relatively few cells which makes studying the molecular profile of the tissue challenging. There is not a consensus on the spatial location of various cell types within a tendon, nor the accompanying transcriptional profile. In the present study, we used two male rat patellar tendon samples for sequencing-based spatial transcriptomics to determine the gene expression profile. We integrated our data with a single cell dataset to predict the cell type composition of the patellar tendon as a function of location within the tissue. The spatial location of the predicated cell types suggested that there were two populations of tendon fibroblasts, one located in the tendon midsubstance, while the other localized with red blood cells, pericytes, and immune cells to the tendon peripheral connective tissue. Of the highest expressed spatially variable genes, there were multiple genes with known function in tendon: Col1a1, Col1a2, Dcn, Fmod, Sparc, and Comp. Further, a novel spatially regulated gene (AABR07000398.1) with no known function was identified. The spatial gene expression of tendon associated genes (Scx, Thbs4, Tnmd, Can, Bgn, Lum, Adamts2, Lox, Ppib, Col2a1, Col3a1, Col6a2) was also visualized. Both patellar tendon samples had similar expression patterns for all these genes. This dataset provides new spatial insights into gene expression in a healthy tendon. tissue sections from two male rat patellar tendons

肌腱是细胞密度较低的致密结缔组织，这使得对该组织的分子特征开展研究颇具挑战。目前学界对于肌腱内各类细胞的空间定位及其伴随的转录特征尚未达成共识。本研究采用两份雄性大鼠髌腱组织切片作为样本，开展基于测序的空间转录组学（sequencing-based spatial transcriptomics）检测，以解析其基因表达特征。我们将本研究数据与单细胞数据集进行整合，以此预测髌腱内不同位置的细胞类型组成。预测得到的细胞类型空间分布结果显示，肌腱成纤维细胞存在两个亚群：一个亚群分布于肌腱主体区域，另一个亚群则与红细胞、周细胞及免疫细胞共同定位于肌腱外周结缔组织。在空间表达量差异最显著的基因中，存在多个已被证实与肌腱功能相关的基因，包括Col1a1、Col1a2、Dcn、Fmod、Sparc及Comp。此外，本研究还鉴定出一个全新的空间调控基因（AABR07000398.1），其功能尚未被探明。研究同时对一系列肌腱相关基因（Scx、Thbs4、Tnmd、Can、Bgn、Lum、Adamts2、Lox、Ppib、Col2a1、Col3a1、Col6a2）的空间表达模式进行了可视化展示。两份髌腱样本的上述基因表达模式均保持一致。本数据集为健康肌腱的基因表达空间分布特征提供了全新的研究视角。