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Cardiac Fibroblasts regulate myocardium and coronary vasculature development via the collagen signaling pathway
Yiting Deng1, Yuanhang He2,1, Juan Xu1
1Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15201, USA.
Insights
Cardiac fibroblasts regulate heart development by influencing cardiomyocytes and vascular endothelial cells. Collagen signaling from fibroblasts is crucial for myocardium and vasculature formation, with fibroblast ablation causing defects.
Area of Science:
- Cardiovascular Biology
- Developmental Biology
- Cellular Interactions
Background:
- The heart comprises fibroblasts (FB), cardiomyocytes (CM), and vascular endothelial cells (Vas_EC), but their developmental interactions are poorly understood.
- Existing research lacks detailed insight into the spatial and molecular relationships between these key cardiac cell types during development.
Purpose of the Study:
- To investigate the anatomical and molecular interactions between cardiac fibroblasts, cardiomyocytes, and vascular endothelial cells during heart development.
- To determine the role of fibroblasts and their secreted molecules, particularly collagen, in regulating cardiac development and function.
Main Methods:
- RNA staining for fibroblast (Col1a1), cardiomyocyte (Actn2), and vascular endothelial cell (Cdh5) marker genes at different developmental stages.
- Single-cell mRNA sequencing (scRNA-seq) to analyze gene expression profiles and identify signaling pathways.
- Fibroblast ablation using a Pdgfra-CreER controlled diphtheria toxin A (DTA) system at embryonic and neonatal stages.
Main Results:
- Cardiac fibroblasts were found to interact directly with cardiomyocytes and vascular endothelial cells, with collagen identified as a key signaling molecule.
- Fibroblast ablation disrupted myocardium and vasculature development, leading to embryonic heart defects and molecular alterations in ventricular cardiomyocytes and vascular endothelial cells.
- Neonatal fibroblast ablation showed stage-dependent effects, with short-term ablation reducing collagen and vascular endothelial cell density, while long-term ablation appeared compensated.
Conclusions:
- Fibroblasts play a critical role in regulating cardiac myocardium and vasculature development.
- The collagen signaling pathway is essential for fibroblast-mediated regulation of cardiac development.
- Fibroblast ablation studies highlight their importance, with potential for compensatory mechanisms in response to perturbation.
Abstract:
The fibroblast (FB), cardiomyocyte (CM), and vascular endothelial cell (Vas_EC) are the three major cell types in the heart, yet their relationships during development are largely unexplored. To address this gap, we employed RNA staining of the FB marker gene Col1a1 together with the CM marker gene Actn2 and the Vas_EC marker gene Cdh5 at different stages. This approach enabled us to discern the anatomical pattern of cardiac FBs and identify approximately one EC and four CMs directly interacting with each FB. Molecularly, through the analysis of single-cell mRNA sequencing (scRNA-seq) data, we unveiled collagen as the top signaling molecule derived from FBs influencing CM and Vas_EC development. Subsequently, we used a Pdgfra-CreER controlled diphtheria toxin A (DTA) system to ablate the FBs at different stages. We found that the ablation of FBs disrupted myocardium and vasculature development and led to embryonic heart defects. Using scRNA-seq, we further profiled the ablated hearts and identified molecular defects in their ventricular CMs and Vas_ECs compared to control hearts. Moreover, we identified a reduction of collagen in the ablated hearts and predicted collagen as the major signaling pathway regulating the differentially expressed genes in the ablated ventricular CMs. Finally, we performed both short-term and long-term fibroblast ablation at the neonatal stage. We found that short-term ablation caused a reduction in collagen and Vas_EC density, while long-term ablation may induce compensatory collagen expression without causing heart function reduction. In summary, our study has identified the function of fibroblasts in regulating myocardium and vasculature development and implicated an important role for the collagen pathway in this process.
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