Multi-modal analysis of the four AD mouse strains studies in this cross-sectional [¹⁸F]-florbetaben PET study.

<p>Upper images represent group averaged sagittal PET slices, normalised to the cerebellum and overlayed on an MRI mouse atlas [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0116678#pone.0116678.ref039" target="_blank">39</a>]. Dots indicate corresponding assessments of SUVR_CTX/CBL in individual mice. Dashed lines express the estimated time dependent progression in PS2APP (red; five months: N = 5; eight months: N = 7; 10 months: N = 6; 12 months: N = 2; 16 months: N = 6, 19 months: N = 6), G384A (green; five months: N = 2; 16 months: N = 1) and APP/PS1dE9 (purple; 12 months: N = 2; 24 months: N = 2) mice, fitted with a polynomial function (for the purposes of illustration). Longitudinal progression in APPswe mice is indicated by a continuous blue line. Lower images depict representative <i>ex vivo</i> autoradiography results; autoradiography of APP/PS1dE9 mice and young G384A mice was performed <i>in vitro</i>. WT level expresses the mean SUVR_CTX/CBL of pooled WT mice (N = 22).</p

Amyloid-PET and <i>ex vivo</i> autoradiography in PS2APP mice before and after PVEC.

<p><b>(A)</b> Comparison of uncorrected [¹⁸F]-florbetaben PET images (upper row), corresponding <i>ex vivo</i> autoradiography (mid row) and PVE-corrected PET (lower row) of representative PS2APP mice at 8, 12 and 19 months of age. Sagittal PET images captured 1.6 mm left of the midline were scaled to cerebellum and overlain on a 3T MRI mouse template [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0116678#pone.0116678.ref013" target="_blank">13</a>]. PVEC was performed with a 10 region mask (four cerebral and six extracerebral VOIs). <b>(B)</b> Error-(%) (±SD) of uncorrected (black bar) and PVE-corrected (blue bar) data versus <i>ex vivo</i> autoradiography are shown for the whole group of PS2APP mice.</p

Cross-Sectional Comparison of Small Animal [¹⁸F]-Florbetaben Amyloid-PET between Transgenic AD Mouse Models

<div><p>We aimed to compare [¹⁸F]-florbetaben PET imaging in four transgenic mouse strains modelling Alzheimer’s disease (AD), with the main focus on APPswe/PS2 mice and C57Bl/6 mice serving as controls (WT). A consistent PET protocol (N = 82 PET scans) was used, with cortical standardized uptake value ratio (SUVR) relative to cerebellum as the endpoint. We correlated methoxy-X04 staining of β-amyloid with PET results, and undertook <i>ex vivo</i> autoradiography for further validation of a partial volume effect correction (PVEC) of PET data. The SUVR in APPswe/PS2 increased from 0.95±0.04 at five months (N = 5) and 1.04±0.03 (p<0.05) at eight months (N = 7) to 1.07±0.04 (p<0.005) at ten months (N = 6), 1.28±0.06 (p<0.001) at 16 months (N = 6) and 1.39±0.09 (p<0.001) at 19 months (N = 6). SUVR was 0.95±0.03 in WT mice of all ages (N = 22). In APPswe/PS1G384A mice, the SUVR was 0.93/0.98 at five months (N = 2) and 1.11 at 16 months (N = 1). In APPswe/PS1dE9 mice, the SUVR declined from 0.96/0.96 at 12 months (N = 2) to 0.91/0.92 at 24 months (N = 2), due to β-amyloid plaques in cerebellum. PVEC reduced the discrepancy between SUVR-PET and autoradiography from −22% to +2% and increased the differences between young and aged transgenic animals. SUVR and plaque load correlated highly between strains for uncorrected (R = 0.94, p<0.001) and PVE-corrected (R = 0.95, p<0.001) data. We find that APPswe/PS2 mice may be optimal for longitudinal amyloid-PET monitoring in planned interventions studies.</p></div

Comparison of uncorrected (A) and PVE-corrected (B) SUVR_CTX/CBL of the entire dataset.

<p>Dots indicate corresponding assessments of SUVR_CTX/CBL in individual mice. Dashed lines express the estimated time dependent progression in PS2APP (red; five months: N = 5; eight months: N = 7; 10 months: N = 6; 12 months: N = 2; 16 months: N = 6, 19 months: N = 6), G384A (green; five months: N = 2; 16 months: N = 1) and APP/PS1dE9 (purple; 12 months: N = 2; 24 months: N = 2) mice, fitted with a polynomial function (for the purposes of illustration). Longitudinal progression in APPswe mice is indicated by a continuous blue line. P-values for one-way ANOVA (incl. post hoc Tukey) testing of PS2APP and APPswe mice versus youngest littermates were as indicated: * p < 0.05; ** p < 0.005; *** p < 0.001.</p

α_vß₃-integrin/CD31 fluorescent double stainings.

<p>A— α_vß₃-integrin; B—CD31; C—overlay of A and B. Fluorescent double stainings demonstrated a significant coexpression (C) of α_vß₃-integrin and the endothelial receptor CD31 and therefore confirmed the predominantly endothelial expression of α_vß₃-integrin in the investigated tumor model. No relevant tumor cell α_vß₃-integrin expression was detected.</p

Study setup.

<p>After the ⁶⁸Ga-TRAP-(RGD)₃-PET/CT baseline scan (day 0), animals of the imaging cohort were treated daily with either bevacizumab (therapy group) or a volume-equivalent placebo solution (control group) for 6 days. ⁶⁸Ga-TRAP-(RGD)₃-PET/CT follow-up scan was performed on day 7. Animals of the immunohistochemistry cohort were randomized to a therapy and a control group and treated analogously to the imaging cohort with either bevacizumab (therapy group) or placebo (control group) for 6 days. On day 7, the animals of the immunohistochemistry cohort were sacrificed and the tumors were explanted in order to undergo immunohistochemical workup with regard to α_vß₃-integrin expression, microvascular density (CD31), proliferation (Ki-67), and apoptosis (TUNEL).</p

Quantitative immunohistochemical parameters for the therapy and control group.

<p>Note the significant (p = 0.03) suppression of α_vß₃-integrin expression in the bevacizumab-treated group (A). Also note the significantly (p<0.01) lower microvascular density (CD31, B), proliferation (Ki-67, C), as well as the significantly (p = 0.002) higher apoptosis (TUNEL, D) in the therapy compared to the control group.</p

Representative tumor sections of the therapy and the control group.

<p>Note the lower α_vß₃-integrin expression (A vs. B), microvascular density (CD31, C vs. D), proliferation (Ki-67, E vs. F) and the higher apoptosis (TUNEL, G vs. H) in the therapy compared to the control group</p

Quantitative analysis of the autoradiography blocking experiments.

<p>Quantitative analysis of the autoradiography blocking experiments.</p

VOI selection.

<p>Images in coronal reconstruction. A: unenhanced CT (tumor indicated by asterisk); B: unenhanced CT with tumor (green, asterisk) and muscle (violet, arrow) VOIs; C: fused PET and CT data sets; D: fused PET and CT data sets with tumor (pink, asterisk) and muscle (violet, arrow) VOIs. Tumor and muscle VOIs selected on the unenhanced CT (B) were superimposed on the PET data sets (D) to allow for a quantification of the PET signal. Note that tumor regions with significant signal spillover from the urinary bladder were excluded from the quantitative analysis (D).</p