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Updated: Dec 9, 2025
En Face Endocardial Cushion Preparation for Planar Morphogenesis Analysis in Mouse Embryos
Published on: July 27, 2022
Fsp1 cardiac embryonic expression delineates atrioventricular endocardial cushion, coronary venous and lymphatic
Sara Cano-Ballesteros1,2, Paul Palmquist-Gomes1,2, Ernesto Marín-Sedeño1,2
1Department of Animal Biology, Faculty of Sciences, Instituto Malagueño de Biomedicina (IBIMA), University of Málaga, Málaga, Spain.
Insights
Fibroblast Specific Protein 1 (Fsp1) is found in cardiac vascular cells, including endocardium and specific endothelial cells. This study maps its expression during heart development, suggesting roles in valve formation and patterning.
Area of Science:
- Cardiovascular Biology
- Developmental Biology
- Cell Biology
Background:
- Fibroblast Specific Protein 1 (Fsp1), also known as S100A4 or Metastatin, is primarily recognized as a fibroblast marker.
- Emerging evidence indicates Fsp1 expression in non-fibroblast cell types, including a subset of endothelial cells.
- A comprehensive understanding of Fsp1's spatio-temporal expression within cardiac vascular cells is lacking.
Purpose of the Study:
- To systematically investigate the expression pattern of Fsp1 in the developing and postnatal cardiac vasculature and endocardium.
- To elucidate the role of Fsp1 in cardiac valve development and morphogenesis.
Main Methods:
- Utilized a transgenic Fsp1-GFP murine line to track Fsp1 expression.
- Analyzed Fsp1 localization in the developing and postnatal cardiac endocardium and vasculature.
Main Results:
- Fsp1 expression was observed in the endocardium and mesenchyme of atrioventricular valve primordia.
- Fsp1 is present in specific coronary venous and lymphatic endothelial cells.
- Expression in cardiac venous and lymphatic endothelium becomes restricted to valve leaflets during development.
Conclusions:
- Fsp1 is expressed in key cardiac cell populations involved in heart development.
- Fsp1 may play a significant role in the development of atrioventricular valves.
- Fsp1 is implicated in the patterning and morphogenesis of cardiac venous and lymphatic vessel valves.
Abstract:
Fsp1 (a.k.a S100A4 or Metastatin) is an intracellular and secreted protein widely regarded as a fibroblast marker. Recent studies have nonetheless shown that Fsp1 is also expressed by other cell types, including small subsets of endothelial cells. Since no detailed and systematic description of Fsp1 spatio-temporal expression pattern in cardiac vascular cells is available in the literature, we have used a transgenic murine line (Fsp1-GFP) to study Fsp1 expression in the developing and postnatal cardiac vasculature and endocardium. Our work shows that Fsp1 is expressed in the endocardium and mesenchyme of atrioventricular valve primordia, as well as in some coronary venous and lymphatic endothelial cells. Fsp1 expression in cardiac venous and lymphatic endothelium is progressively restricted to the leaflets of cardiac venous and lymphatic valves. Our results suggest that Fsp1 could play a role in the development of atrioventricular valves and participate in the patterning and morphogenesis of cardiac venous and lymphatic vessel valves.
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