Fig. 1

Flow cytometry analysis of freshly dissociated and frozen tumor samples. a Left panels viability of fresh (upper) or freeze/thawed (lower) tumor cells was assessed using the non-permeant fluorescent DNA marker 7-ADD. The gate shows the percentage of living cells. Right panels percentage of dead cells observed after thawing 15 TNBCs. b Leucocytes and non-immune cells (mainly tumor cells) within the dissociated tumor cell population were analyzed by flow cytometry after staining with an anti-CD45 mAb. The percentage of CD45+ (leukocytes) and CD45− (tumor cells) before and after freezing is depicted. Statistical differences were evaluated using the Mann–Whitney U test. c Two examples of fresh and freeze/thawed dissociated tumor cells. Expression of CD44 and CD24 by CD45− tumor cells was evaluated. d Comparison of the proportion of CD45− tumor cells showing CD24 and CD44 before and after the freeze/thaw process. P values were calculated using a paired Student’s t test (n = 15). Density plot showing the percentage of living tumor cells expressing CD24 and CD44 before and after cryopreservation