Single-cell analysis uncovers fibroblast heterogeneity and criteria for fibroblast and mural cell identification and discrimination

TLDR

Mesenchymal cells such as fibroblasts and vascular mural cells are biologically important, yet organ‑specific heterogeneity among them has not been thoroughly characterized. The study compares single‑cell transcriptional profiles of fibroblasts and vascular mural cells in four mouse muscular organs. The authors performed single‑cell RNA‑seq on fibroblasts and mural cells from heart, skeletal muscle, intestine, and bladder. They identified distinct gene signatures that separate fibroblasts from mural cells, revealed extensive inter‑ and intra‑organ fibroblast heterogeneity driven by extracellular matrix genes, mapped subtypes to specific anatomical locations, and laid a foundation for understanding their physiological and pathological roles.

Abstract

Abstract Many important cell types in adult vertebrates have a mesenchymal origin, including fibroblasts and vascular mural cells. Although their biological importance is undisputed, the level of mesenchymal cell heterogeneity within and between organs, while appreciated, has not been analyzed in detail. Here, we compare single-cell transcriptional profiles of fibroblasts and vascular mural cells across four murine muscular organs: heart, skeletal muscle, intestine and bladder. We reveal gene expression signatures that demarcate fibroblasts from mural cells and provide molecular signatures for cell subtype identification. We observe striking inter- and intra-organ heterogeneity amongst the fibroblasts, primarily reflecting differences in the expression of extracellular matrix components. Fibroblast subtypes localize to discrete anatomical positions offering novel predictions about physiological function(s) and regulatory signaling circuits. Our data shed new light on the diversity of poorly defined classes of cells and provide a foundation for improved understanding of their roles in physiological and pathological processes.