In vivo and In vitro cartilage differentiation from embryonic epicardial progenitor cells

The presence of cartilage tissue in embryonic and adult hearts of various vertebrate species is a well-recorded fact. However, while the embryonic neural crest has been historically considered as the main source of cardiac cartilage, recently reported results on the wide connective potential of epicardial lineage cells suggest they could also differentiate into chondrocytes. During heart embryogenesis, the epicardial epithelium forms over the originally bare myocardial surface from epicardial progenitor (proepicardial) cells to then give rise to a large population of mesenchymal Epicardial-Derived Cells (EPDCs) that will crucially contribute to the building, growth, and maturation of the ventricle and atrioventricular cardiac structures. In this work, we describe the formation of cardiac cartilage clusters from proepicardial cells, both in vivo and in vitro. Our findings report, for the first time, cartilage formation from epicardial progenitor cells in the embryonic heart, and strongly support the concept of proepicardial cells as multipotent connective progenitors. These results are relevant to our understanding of cardiac cell complexity and responses to pathologic stimuli.Universidad de Málaga (UMA18-FEDERJA-146). Campus de Excelencia Internacional Andalucía Tech; Ministerio de Educación (FPU18/05219); Ministerio de Ciencias (RTI2018-095410-B-I00); ISCIII-RETICs (RD16/0011/0030); Consejería de Salud y Familias, Junta de Andalucía (PIER-0084-2019) Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Unravelling the mechanisms regulating embryonic epicardial cell proliferation.

Epicardial development is a highly complex process that relies on the precise coordination of cell proliferation and differentiation. The epicardium originates from an extracardiac cluster of cells, the proepicardium, which initially migrates to the myocardium and then massively expands to form the epicardial epithelial layer. Finally, some epicardial epithelial cells transform into mesenchymal cells via Epithelial-to-Mesenchymal Transition (EMT), and progressively invade the myocardial walls. The regulatory signals that govern epicardial cell proliferation remain largely unknown. To unveil the molecular signals involved in controlling epicardial cell proliferation, we examined the proliferation status of epicardial cells at different embryonic stages, and performed an RNA-seq analysis to identify candidate signalling pathways operating within the proepicardium. Then, we conducted in vivo and in vitro research to carefully dissect epicardial proliferation. Our results show that both canonical and non-canonical Wnt signals are involved in the regulation of epicardial proliferation during embryonic development.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. FPU19/05219 Ministerio de Ciencia: PID2021-122626-OB-100 y JIN2020-119430RJ-10

Understanding the Adult Mammalian Heart at Single-Cell RNA-Seq Resolution

During the last decade, extensive efforts have been made to comprehend cardiac cell genetic and functional diversity. Such knowledge allows for the definition of the cardiac cellular interactome as a reasonable strategy to increase our understanding of the normal and pathologic heart. Previous experimental approaches including cell lineage tracing, flow cytometry, and bulk RNA-Seq have often tackled the analysis of cardiac cell diversity as based on the assumption that cell types can be identified by the expression of a single gene. More recently, however, the emergence of single-cell RNA-Seq technology has led us to explore the diversity of individual cells, enabling the cardiovascular research community to redefine cardiac cell subpopulations and identify relevant ones, and even novel cell types, through their cell-specific transcriptomic signatures in an unbiased manner. These findings are changing our understanding of cell composition and in consequence the identification of potential therapeutic targets for different cardiac diseases. In this review, we provide an overview of the continuously changing cardiac cellular landscape, traveling from the pre-single-cell RNA-Seq times to the single cell-RNA-Seq revolution, and discuss the utilities and limitations of this technology.This work was supported by funds from the Spanish Ministry of Science, Innovation and Universities (RTI2018-095410-B I00); University of Málaga (UMA18-FEDERJA-146), and Carlos III Institute of Health (RD16/0011/0030). EM-S was supported by funds from the Spanish Ministry of Science, Innovation and Universities FPU fellowship (FPU18/05219). AR-V was supported by funds from University of Málaga (Incorporación de doctores from the I Plan Propio de Incorporación de Doctores, 2020)Ye

In Vivo and In Vitro Cartilage Differentiation from Embryonic Epicardial Progenitor Cells

The presence of cartilage tissue in the embryonic and adult hearts of different vertebrate species is a well-recorded fact. However, while the embryonic neural crest has been historically considered as the main source of cardiac cartilage, recently reported results on the wide connective potential of epicardial lineage cells suggest they could also differentiate into chondrocytes. In this work, we describe the formation of cardiac cartilage clusters from proepicardial cells, both in vivo and in vitro. Our findings report, for the first time, cartilage formation from epicardial progenitor cells, and strongly support the concept of proepicardial cells as multipotent connective progenitors. These results are relevant to our understanding of cardiac cell complexity and the responses of cardiac connective tissues to pathologic stimuli