Imaging-based quantification of leukemia initiating cell frequencies. a

<p>Imaging visualizes dependence of leukemic growth on both time and cell numbers; experiment shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0052798#pone-0052798-g002" target="_blank">Figure 2b</a> was followed up over time in all groups injected with the different cell numbers; depicted is the quantification of imaging as mean of each group +/− SEM; <b>b</b> Imaging enables convenient determination of CSC frequencies; ALL-54 cells were freshly isolated from a mouse spleen, seeded at 10⁶ cells/ml and stimulated in vitro with PBS or TRAIL (1 µg/ml). After 48 hours, cells were serially diluted based on the cell concentration seeded at the beginning of the experiment and injected into groups of 2–3 mice. After 8 weeks, mice were imaged and analyzed for leukemic engraftment (defined using signals of legs only, identically as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0052798#pone-0052798-g003" target="_blank">Figure 3D</a>; engraftment is indicated with a star); frequency of leukemia initiating cells was calculated out of engraftment rates using Poisson statistics. In all mice, mid-abdominal signals are unspecific.