Gastruloids as an in vitro model of Cardiopharyngeal Mesoderm specification into skeletal and cardiac muscle lineages

Cardiopharyngeal mesoderm (CPM) contributes to the formation of the heart and head muscles. These muscles are both affected in rare congenital disorders including velocardiofacial syndrome or cardiofaciocutaneous syndrome. While the mechanisms governing CPM specification remain relatively unknown, there is a lack of an in vitro platform that would allow the differentiation of both head and heart muscles. Develop embryonic organoids from mouse embryonic stem cells (mESC), also called gastruloids, to form and specify CPM toward the cardiac and muscle lineages. Use in vitro 3D culture to develop and characterize embryonic organoid. By using single-cell RNAseq, and high-resolution imaging of single molecule FISH experiments, we confirm that the CPM is established in gastruloids, with a kinetic of gene expression that is similar to the mouse embryo. We identify different subpopulations of cardiomyocytes and skeletal muscles most likely corresponding to the different cardiac chambers and head and trunk skeletal muscles. These findings unveil the potential of mESCs-derived gastruloids to undergo CPM specification in both head and heart lineages, allowing the investigation of the mechanisms of CPM specification in development and how this could be affected in congenital disorders.