In view of the inspiriting results from the above experiments about glioblastoma cells,
in vivo experiments with 6 mice in each group were conducted to further evaluate the apoptosis-inducing effect of DA-azaBDP-NPs combined with 808 nm NIR laser (
Fig. 5). All animal experiments were approved by the Animal Experimental Ethics Committee of China medical university. Firstly, the mice were injected with a dose of 5 × 10
5 GL261 mouse glioblastoma cells intracerebrally by a stereotaxic technique [
65]. After 21 days, they were randomly grouped into four groups, and each group was received with different treatments, as follows: mice without treatment (group Control); mice with irradiation of 808 nm NIR laser (group Light); mice with the injection of DA-azaBDP-NPs
via the tail vein (group NPs); mice with the combination of laser irradiation and DA-azaBDP-NPs injection (group Light+NPs). To evaluate the intracranial tumor size from four groups, HE staining was performed to assess overall morphology of mouse brains. The results from HE staining showed that compared with group Control, the tumor size in the sole light and sole NPs groups was no significant differences (
Fig. 5a). However, the tumor size in the group Light+NPs decreased obviously compared the other three groups (
Fig. 5a). Cellular proliferation and apoptosis may acted as the main characters during the tumor growth [
66,
67]. Ki67 was a cellular proliferation marker and positively correlated with the malignant degree of glioblastoma [
68]. The proliferation of tumor cells can be examined by immunohistochemistry staining against Ki67. Immunohistochemistry results revealed the expression level of Ki67 in the area of intracranial tumors from group Light+NPs was lower than group Light or group NPs, suggesting the combination of laser irradiation and DA-azaBDP-NPs injection could inhibit the cellular proliferation of glioblastoma (
Fig. 5b). In the other hand, the TdT-mediated dUTP nick-end labeling (TUNEL) staining was used to measure the apoptosis level of intracranial glioblastoma from each group [
69]. The apoptotic cells were stained with TUNEL (Red), while nucleus stained with DAPI (blue). Similar to the
in vitro result, the combination of laser irradiation and DA-azaBDP-NPs injection could promote the apoptosis of glioblastoma on the basis of red fluorescent expression (
Fig. 5c). LC3 is the essential autophagy protein and represents the activity of autophagy [
70]. In our immunofluorescence experiments, autophagic tumor cells were stained with LC3 (Green), while nucleus stained with DAPI (blue). Immunofluorescence assay demonstrated that the autophagic level of mouse glioblastoma cells from group Light+NPs was upregulated compared with the other three groups according to the fluorescent expression from LC3 (
Fig. 5d). These results clearly confirmed the good tumor-inhibition capability with promoting the apoptosis and autophagy level of glioblastoma cells by the DA-azaBDP-NPs under NIR irradiation.