High-Resolution Transcriptomic Profiling of the Heart During Chronic Stress Reveals Cellular Drivers of Cardiac Fibrosis and Hypertrophy

Abstract

Background: Cardiac fibrosis is a key antecedent to many types of cardiac dysfunction including heart failure. Physiological factors leading to cardiac fibrosis have been recognized for decades. However, the specific cellular and molecular mediators that drive cardiac fibrosis, and the relative effect of disparate cell populations on cardiac fibrosis, remain unclear. Methods: We developed a novel cardiac single-cell transcriptomic strategy to characterize the cardiac cellulome, the network of cells that forms the heart. This method was used to profile the cardiac cellular ecosystem in response to 2 weeks of continuous administration of angiotensin II, a profibrotic stimulus that drives pathological cardiac remodeling. Results: Our analysis provides a comprehensive map of the cardiac cellular landscape uncovering multiple cell populations that contribute to pathological remodeling of the extracellular matrix of the heart. Two phenotypically distinct fibroblast populations, Fibroblast- Cilp and Fibroblast- Thbs4 , emerged after induction of tissue stress to promote fibrosis in the absence of smooth muscle actin–expressing myofibroblasts, a key profibrotic cell population. After angiotensin II treatment, Fibroblast- Cilp develops as the most abundant fibroblast subpopulation and the predominant fibrogenic cell type. Mapping intercellular communication networks within the heart, we identified key intercellular trophic relationships and shifts in cellular communication after angiotensin II treatment that promote the development of a profibrotic cellular microenvironment. Furthermore, the cellular responses to angiotensin II and the relative abundance of fibrogenic cells were sexually dimorphic. Conclusions: These results offer a valuable resource for exploring the cardiac cellular landscape in health and after chronic cardiovascular stress. These data provide insights into the cellular and molecular mechanisms that promote pathological remodeling of the mammalian heart, highlighting early transcriptional changes that precede chronic cardiac fibrosis.

Cross-tissue single-cell transcriptomics reveals organizing principles of fibroblasts in health and disease

“…3a,c,d). Enrichment of genes including Cilp, Chad and Wif1 indicate that this cluster also contains cells approximating matrifibrocytes 55 and Fibroblast- Thbs4 and - Clip 56 , three cell states which have been identified as ECM producing and modifying cell states in the context of cardiac fibrosis.…”

“…i. Thbs4+ fibroblasts from human RA ("Lining" 54 ) and cardiac hypertrophy 56 . f. Universal fibroblasts pancreatic cancer ("iCAF" 13 ), RA ("Human RA F5" 7 ), pulmonary fibrosis ("Has1+ fibroblast" 59 ) and ulcerative colitis ("S4" 45 ).…”

Ex uno, plures–From One Tissue to Many Cells: A Review of Single-Cell Transcriptomics in Cardiovascular Biology

“…Other studies have used snRNAseq to sample CMs, and they either used total snRNAseq [ 110 ] or a combination of snRNAseq and scRNAseq [ 111 ] to sequence interstitial cells and CMs in pathological contexts. The first study [ 110 ] sequenced nuclei from all cardiac cell types isolated from sham or MI murine hearts 5 days post-surgery.…”

“…They observed no de novo CM differentiation from interstitial cells, but a small population of differentiated CM appeared to re-enter the cell cycle. The second study [ 111 ] analyzed CM nuclei and interstitial cells in a murine model of hypertension, which was induced with 2-weeks AngII infusion, comparing control and treated mice of both sexes. The analysis revealed the transcriptomic signature of activated fibroblasts responsible for the perivascular and interstitial fibrosis as well as gene expression differences based on biological sex evident in almost all cell types, particularly in fibroblasts.…”

Diastolic Dysfunction in a Pre-clinical Model of Diabetes Is Associated With Changes in the Cardiac Non-myocyte Cellular Composition

“…Cardiac non-myocytes-comprised of endothelial cells (ECs), resident mesenchymal cells (RMCs) and leukocytes-outnumber myocytes, and are critical for maintaining homeostasis of the heart [10,11]. While a number of recent studies have provided valuable new insight into the disparate roles of non-myocytes in cardiac homeostasis [10,12] and pathological remodelling [13][14][15], the cellular dynamics of non-myocytes during development of diabetes-induced heart failure remains unexplored. Using a recently published murine model of diabetesinduced cardiomyopathy [16], this study aimed to determine the difference in cardiac non-myocyte cellular proportions compared to non-diabetic mice.…”