ECFCs demonstrate robust proliferative capacity. A, Phase contrast image of ECFCs colony after 14 days in culture. 5× objective. Scale bar: 50 μm. B, Fluorescence image of ECFCs stained with CD31-FITC (endothelial cells marker) indicated by arrowheads and Hoechst 33258 (nuclear dye) marked as N. The photographs were taken with green and blue filters, respectively, and then superimposed and processed as a gray scale images in Adobe Photoshop. 20× objective. Scale bar: 10 μm. C, ECFC growth chart: cells were passaged every 4–6 days for 4 weeks. Data were extrapolated assuming seeding one million cells on day one and further growing all of the cells. Mean values are plotted on the graph (n = 2). X-axis – days, Y-axis – calculated number of cells (in billions, log10 scale).