Calcific Aortic Valve Disease: Cellular Origins of Valve Calcification

Calcific aortic valve disease is the most common indication for surgical valve replacement in the world.1 For years this disease was thought to be a passive degenerative phenomenon. Understanding of the cellular mechanisms of this valve lesion will present new cellular therapeutic options to slow disease progression. In this study by Egan et al,2 they identify for the first time in human calcifying aortic valves a population of circulating osteogenic precursor cells (COP) in calcified human aortic valves. Their finding of these CD45+ OCN+ COP cells in areas of calcification and not in the unaffected calcified tissues provides another level of evidence that mesenchymal derived cell populations are responsible for the development of osteogensis in the calcified aortic valve. Specifically, the study demonstrated that these cells were localized to areas of confirmed endochondral ossification and bone formation. Within the regions of interest there were areas of mature bone with the characteristic architecture including osteocytes and bone lining cells. However, within the limits of the study there was no consistent involvement of the valve leaflet layers as the areas of endochondral ossification …