Three-dimensional model system of valvulogenesis.

Valvular defects are among the most common and deleterious of all cardiac malformations. The early cardiac cushions are located in the atrioventricular (AV) canal of the embryonic heart. These cushions contain cells that are the primordia of the cardiac valves and membranous septa. Significant progress has been made in delineating the molecular mechanisms that regulate the early steps of cushion formation; however, little is known about how these cushions differentiate into valve leaflets. Here, a new three-dimensional collagen tube culturing system was tested for its ability to sustain the development and maturation of the AV cushion anlagen. We report that AV cushion tissues grown within the collagen tube scaffold recapitulate aspects of AV valve development both at the molecular and morphological levels. Furthermore, our results indicate that valve leaflet formation in the tube model is dependent on the presence of cardiac myocytes.