Figure 2.

LITT increases BBB and BTB permeability in vivo. (A) Representative white light and fluorescence images of mouse brains harvested on the indicated days after intravenous fluorescein injection (n = 3 for each condition). LITT was performed in the right somatosensory cortex. Control = unmanipulated brain. Scale bar = 5 mm. (B) Animals treated as in A were assessed for tissue fluorescein uptake (normalized to control brains) on indicated post-LITT days. Control = 1 (dotted line). Data represent mean ± SEM. Laser increased BBB permeability compared to control (n = 3 for each condition, ANOVA, *P < .05, **P < .01, ***P < .001). (C) Relative BBB permeability was measured as in B on post-laser day 3 in indicated brain regions. LITT increased BBB permeability in the treated forebrain hemisphere, but not in the cerebellum (CBL) of the same brain or sham treatment (insertion of optical fiber) (n = 3 for each condition, ANOVA, *P < .01). (D) Animals treated with laser were injected intravenously with 10 kDa dextran on post-LITT day 30, and brains processed for immunofluorescence on free-floating 50 µm sections to assess dextran penetration. Representative images are shown (n = 3 for each condition). Scale bar = 50 µm. (E) Brain permeability of 10 kDa dextran was quantified by the mean pixel intensity of fluorescence divided by area (µm²). Data represent mean ± SEM (n = 3 for each condition, unpaired t-test, *P < .01). (F) Animals were orthotopically implanted with GL261 tumor cells, and laser treatment to the tumor performed 7 days later. Relative BTB permeability (normalized to control brain) was assessed by quantification of tissue fluorescein uptake on indicated post-LITT days. Control = 1 (dotted line). LITT increased BTB permeability compared to control (n = 3 for each condition, ANOVA, *P < .01, **P < .001). (G) Relative BTB permeability was measured as in (F) on post-laser day 3 following LITT (treated) or sham treatment. The normal brain represents a contralateral forebrain hemisphere with no tumor and not treated with laser. Laser treatment increased BBB permeability in the tumor-bearing hemisphere compared to sham treatment and contralateral hemisphere (n = 3 for each condition, ANOVA, *P < .001).