<i>In vitro</i> life-span and senescence of ALL-MSCs as compared with HD-MSCs.

<p><i>In vitro</i> life-span of HD-MSCs (<b>A</b>) and ALL-MSCs at diagnosis (<b>B</b>), defined as number of passages before observation of senescence, from 10 representative donors and patients (#1–10). A large variability among HDs and patients was observed. (<b>C</b>): ß-Galactosidase staining of ALL-MSCs from patient #2 at passage (P) 18, isolated at day+0. Senescence of the cells is indicated by the positivity for the staining. <b>D and E:</b> cell cycle analysis performed by flow-cytometry on ALL-MSCs from patient #2 at early (P2) and late (P18) passages in culture. At P2 (D), the percentage of proliferating cells (in S phase) is 56.6%, whereas cells in G0/G1, G2 phase are 11.1 and 29.2%, respectively. The percentage of apoptotic cells in subG1 phase is 2%. At P18 (E), when cells become senescent, the percentage of proliferating cells decreases to 26.5%, whereas cells in G0/G1, G2 and subG1 phase are 57.5%, 2.6% and 12.3%, respectively.