Interchangeable potential varies among mesothelial cell populations in the embryo

Abstract

Mesothelium is an epithelial sheet that covers coelomic organs and is involved in development of the vascular system. In the developing heart, the proepicardium (PE), migrates over the heart forming the epicardium, and undergoes epithelial‐mesenchymal transition (EMT) to contribute cells to the coronary blood vessels. The gut mesothelium also serves as a major source of vascular smooth muscle cells for the gut tube in development. We hypothesize that heart and gut mesothelial cell populations possess an interchangeable potential in coelomic organs. First, we characterized avian mesothelial cells using histological and molecular techniques to determine the cell types present at time of transplant. In addition, mesothelial cells were cultured to investigate the differentiative properties the mesothelial isolates. To test the interchangeable potential of mesothelial cells, we used the chick‐quail chimera system, transplanting quail PE and epicardial cells into the peritoneal cavity of a chick embryo and quail gut mesothelial cells into chick pericardial cavities. Our findings have revealed that all mesothelia have the potential to migrate into organs in the analogous coelomic cavity. However, PE and epicardial cells did not incorporate into the endogenous gut mesothelium and retained epithelial characteristics. Alternatively, gut mesothelial cells incorporated into the endogenous epicardium and contributed vascular smooth muscle cells, fibroblasts, and myofibroblasts to the heart. Taken together, our current data suggest a limited developmental potential between heart and gut mesothelial cell populations.