In vivo monitoring of tumor initiation
and relapse
capacity of CR-CSCs #21 after in vitro pretreatment
with MHT using TR-Cubes or TR-DOXO nanoplatforms. (a) Scheme of the in vivo experiment steps. CR-CSC #21 cells subjected to
administration of TR-DOXO or TR-Cubes with or without the MHT exposure
(182 kHz for three cycles of MHT of 30 min each) were injected subcutaneously
on the flank of NMRI nude mice (1 × 106 live cells
per animal). A follow-up of the animals was prolonged up to 8 months.
A tumor of 2 cm in at least one of its side marked the end point of
the experiment.(b) Percentage of tumor-free animals over time (8 months
of experiment). * **p < 0.001 control vs TR-DOXO
+ MHT and ***p < 0.001 TR-DOXO vs TR-DOXO + MHT
for days 120, 155, and 180, respectively; ANOVA and Tukey post hoc
test. (c) Tumor growth curves (tumor volume: mm3) for animals
injected with CR-CSC #21 cells (control, not treated) or cells previously
treated with TR-Cubes + MHT, TR-DOXO, or free DOXO or TR-DOXO + MHT
cells. ANOVA and Dunn post hoc test. Statistical analysis shows statistical
differences, ***p < 0.001, on the experimental
groups: control vs TR-DOXO + MHT, TR-Cubes + MHT vs TR-DOXO + MHT,
DOXO vs TR-DOXO + MHT, and TR-DOXO vs TR- DOXO + MHT for days 45,
60, 75, 90, 105, and 120, respectively. (d) Kaplan–Meier survival
plot showing the difference in tumor suppression and improved survival
between the TR-DOXO + MHT and the other groups studied up to 8 months;
*p = 0.030; p value is calculated
with the log-rank test. (e) Weight graphs of animals in control (no
treated), DOXO, TR-DOXO, TR-Cubes + MHT, and TR-DOXO + MHT groups
showing no weight loss for the 8 months of experiment. For graphs
in panels (b), (c), (d), and (e), data shown are mean ± SD, with n = 6 of two independent experiments.