Extraction and identification of endothelial cells and epithelial cells

The automated annotation “SingleR” package was used to further extract and identify the endothelial and epithelial cells, and was then modified according to the known cell markers of previous studies. Specifically, the following marker genes were used for extraction and identification of cell types, endothelial cells: VWF, CDH5, RAMP2 and CLDN5; epithelial cells: SPRR3, SFN, keratin genes (KRT5, KRT7, KRT8, KRT14, KRT17) and EPCAM. In addition, subclustering was performed for endothelial cells for more in‐depth investigation and better annotation of clusters according to the more specific markers.