One representative experiment showing the ability of isolated cells to organize into tubular structures.

<p>(<b>A</b>) P1 cells were prepared from 4 consecutive fractions of cells isolated either on the intimal or the adventitial side of the same aorta (phase contrast images). Cells were amplified to test their performance in an <i>in vitro</i> angiogenesis assay. Resulting P2 cells were plated in 48-well plates coated with Matrigel. After 18h tubular structures had formed. Micrographs of the resulting network are shown (4x magnification). The EC-enriched fractions with the cobblestone appearance on plastic are those able to form tubes on Matrigel. In this example, the typical capillary-like structures were observed with IECs of fraction 1 and AECs from fraction 2. (<b>B</b>) Graphs showing the number of polygons or branching points, formed by IECs and AECs selected as the most EC-enriched fractions isolated from 11 different patients. AECsamples displayed more polygons (p = 0.0269) and more branching points (0.0039) than IEC ones. On the right panel, representative phase contrast micrographs showing the network formed by the selected (highest EC-enrichment) IEC and AEC fractions from patient 16, on Matrigel.