In Vitro Repair of the Wounded Porcine Mitral Valve

An organ culture of the anterior leaflet of the porcine mitral valve was developed and characterized in order to study the early events in the repair of small endocardial wounds. A linear superficial denuding endocardial injury was made with a nylon filament attached to a stereo tonearm. The repair process was studied by scanning and transmission electron microscopy over a 6-day period. By day 2 in culture, flattened endocardial cells at the wound edge extended processes out onto the wound edge. By 4 and 6 days, the wound was bridged over by spindle-shaped cells although gaps still remained between cells. In some areas, multilayering of cells beneath the surface was present. The results indicate that the initial events in in vitro endocardial repair involve both surface endocardial cells and interstitial cells.