Expression of Coxsackievirus and Adenovirus Receptor Separates Hematopoietic and Cardiac Progenitor Cells in Fetal Liver Kinase 1‐Expressing Mesoderm

In developing embryos or in vitro differentiation cultures using pluripotent stem cells (PSCs), such as embryonic stem cells and induced pluripotent stem cells, fetal liver kinase 1 (Flk1)‐expressing mesodermal cells are thought to be a heterogeneous population that includes hematopoietic progenitors, endothelial progenitors, and cardiac progenitors. However, information on cell surface markers for separating these progenitors in Flk1+ cells is currently limited. In the present study, we show that distinct types of progenitor cells in Flk1+ cells could be separated according to the expression of coxsackievirus and adenovirus receptor (CAR, also known as CXADR), a tight junction component molecule. We found that mouse and human PSC‐ and mouse embryo‐derived Flk1+ cells could be subdivided into Flk1+CAR+ cells and Flk1+CAR− cells. The progenitor cells with cardiac potential were almost entirely restricted to Flk1+CAR+ cells, and Flk1+CAR− cells efficiently differentiated into hematopoietic cells. Endothelial differentiation potential was observed in both populations. Furthermore, from the expression of CAR, Flk1, and platelet‐derived growth factor receptor‐α (PDGFRα), Flk1+ cells could be separated into three populations (Flk1+PDGFRα−CAR− cells, Flk1+PDGFRα−CAR+ cells, and Flk1+PDGFRα+CAR+ cells). Flk1+PDGFRα+ cells and Flk1+PDGFRα− cells have been reported as cardiac and hematopoietic progenitor cells, respectively. We identified a novel population (Flk1+PDGFRα−CAR+ cells) with the potential to differentiate into not only hematopoietic cells and endothelial cells but also cardiomyocytes. Our findings indicate that CAR would be a novel and prominent marker for separating PSC‐ and embryo‐derived Flk1+ mesodermal cells with distinct differentiation potentials. Distinct progenitor types in fetal liver kinase 1‐positive (Flk1+) cells were separated by the expression of coxsackievirus and adenovirus receptor (CAR), a tight junction component molecule. A novel population with the potential to differentiate into hematopoietic cells, endothelial cells, and cardiomyocytes was identified. Our findings indicate that CAR would be a novel and prominent marker for separating pluripotent stem cell‐ and embryo‐derived Flk1+ mesodermal cells with distinct differentiation potentials.