Limits...
In Vivo Amyloid-β Imaging in the APPPS1-21 Transgenic Mouse Model with a (89)Zr-Labeled Monoclonal Antibody.

Waldron AM, Fissers J, Van Eetveldt A, Van Broeck B, Mercken M, Pemberton DJ, Van Der Veken P, Augustyns K, Joossens J, Stroobants S, Dedeurwaerdere S, Wyffels L, Staelens S - Front Aging Neurosci (2016)

Bottom Line: To confirm imaging specificity we also evaluated brain uptake of a non-amyloid targeting [(89)Zr]-labeled antibody (trastuzumab) as a negative control, additionally we performed a competitive blocking study with non-radiolabeled Df-Bz-JRF/AβN/25 and finally we assessed the possible confounding effects of blood retention.The low brain penetrance of the antibody in addition to non-specific binding prevented an accurate estimation of plaque burden.However, it should be noted that [(89)Zr]-Df-Bz-JRF/AβN/25 nevertheless demonstrated in vivo binding and strategies to increase brain penetrance would likely achieve better results.

View Article: PubMed Central - PubMed

Affiliation: Faculty of Medicine and Health Sciences, Molecular Imaging Center Antwerp, University of AntwerpAntwerp, Belgium; Translational Neurosciences, University of AntwerpAntwerp, Belgium.

ABSTRACT

Introduction: The accumulation of amyloid-β is a pathological hallmark of Alzheimer's disease and is a target for molecular imaging probes to aid in diagnosis and disease monitoring. This study evaluated the feasibility of using a radiolabeled monoclonal anti-amyloid-β antibody (JRF/AβN/25) to non-invasively assess amyloid-β burden in aged transgenic mice (APPPS1-21) with μPET imaging.

Methods: We investigated the antibody JRF/AβN/25 that binds to full-length Aβ. JRF/AβN/25 was radiolabeled with a [(89)Zr]-desferal chelate and intravenously injected into 12-13 month aged APPPS1-21 mice and their wild-type (WT) controls. Mice underwent in vivo μPET imaging at 2, 4, and 7 days post injection and were sacrificed at the end of each time point to assess brain penetrance, plaque labeling, biodistribution, and tracer stability. To confirm imaging specificity we also evaluated brain uptake of a non-amyloid targeting [(89)Zr]-labeled antibody (trastuzumab) as a negative control, additionally we performed a competitive blocking study with non-radiolabeled Df-Bz-JRF/AβN/25 and finally we assessed the possible confounding effects of blood retention.

Results: Voxel-wise analysis of μPET data demonstrated significant [(89)Zr]-Df-Bz-JRF/AβN/25 retention in APPPS1-21 mice at all time points investigated. With ex vivo measures of radioactivity, significantly higher retention of [(89)Zr]-Df-Bz-JRF/AβN/25 was found at 4 and 7 days pi in APPPS1-21 mice. Despite the observed genotypic differences, comparisons with immunohistochemistry revealed that in vivo plaque labeling was low. Furthermore, pre-treatment with Df-Bz-JRF/AβN/25 only partially blocked [(89)Zr]-Df-Bz-JRF/AβN/25 uptake indicative of a high contribution of non-specific binding.

Conclusion: Amyloid plaques were detected in vivo with a radiolabeled monoclonal anti-amyloid antibody. The low brain penetrance of the antibody in addition to non-specific binding prevented an accurate estimation of plaque burden. However, it should be noted that [(89)Zr]-Df-Bz-JRF/AβN/25 nevertheless demonstrated in vivo binding and strategies to increase brain penetrance would likely achieve better results.

No MeSH data available.


Related in: MedlinePlus

μPET imaging demonstrates increased brain uptake of [89Zr]-Df-Bz-JRF/AβN/25 in APPPS1–21 mice in comparison to WT. Mice were injected with 133 μg of [89Zr]-Df-Bz-JRF/AβN/25 and brain uptake was measured by μPET scanning and quantified as the %ID/g. The graphs show the VOI analysis of [89Zr]-Df-Bz-JRF/AβN/25 retention in WT and APPPS1–21 mice at (A) 2 days pi, (B) 4 days pi, and (C) 7 days pi. Significant genotype differences in retention were observed at 4 and 7 days pi. Data is presented as mean + SD. Student’s t-test, ∗∗∗p < 0.001, ∗∗p < 0.01, ∗p < 0.05.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4815004&req=5

Figure 1: μPET imaging demonstrates increased brain uptake of [89Zr]-Df-Bz-JRF/AβN/25 in APPPS1–21 mice in comparison to WT. Mice were injected with 133 μg of [89Zr]-Df-Bz-JRF/AβN/25 and brain uptake was measured by μPET scanning and quantified as the %ID/g. The graphs show the VOI analysis of [89Zr]-Df-Bz-JRF/AβN/25 retention in WT and APPPS1–21 mice at (A) 2 days pi, (B) 4 days pi, and (C) 7 days pi. Significant genotype differences in retention were observed at 4 and 7 days pi. Data is presented as mean + SD. Student’s t-test, ∗∗∗p < 0.001, ∗∗p < 0.01, ∗p < 0.05.

Mentions: Figure 1 displays the results from VOI analysis of the PET imaging. We used unpaired Student’s t-tests (corrected for multiple comparisons) to compare [89Zr]-Df-Bz-JRF/AβN/25 retention between brain regions with this analysis. At 2 days pi no clear differences were observed between WT and APPPS1–21 mice (Figure 1A). At 4 days pi, APPPS1–21 mice demonstrated increased [89Zr]-Df-Bz-JRF/AβN/25 retention in all brain regions investigated (Figure 1B). The most significant differences were found in the brain stem (p = 0.00015) followed by the midbrain (p = 0.0015) and thalamus (p = 0.0045). By 7 days pi significant differences remained only in the brain stem (p = 0.0021) and amygdala (p = 0.000057) (Figure 1C). With a more sensitive voxel-wise analysis (Figure 2A), significant differences in [89Zr]-Df-Bz-JRF/AβN/25 retention between genotypes was observed already at 2 days pi in the midbrain (16.3%) and brain stem (13%). By 4 days pi, significant voxels increased substantially in the brain stem (89%), midbrain (79.3%), amygdala (58.7%), hypothalamus (44.7%), and basal forebrain and septum (44%). While the percent of significant voxels in the whole brain remained relatively constant between 4 and 7 days pi (32.1 and 29.6%, respectively), regionally there were less significant voxels in the basal forebrain and septum (from 44% to 1.5%) and hypothalamus (44.7 to 1%) and an increase in the cerebellum (from 35.4 to 51.3%). Figure 2B illustrates the localization of significant voxels on an anatomical brain template.


In Vivo Amyloid-β Imaging in the APPPS1-21 Transgenic Mouse Model with a (89)Zr-Labeled Monoclonal Antibody.

Waldron AM, Fissers J, Van Eetveldt A, Van Broeck B, Mercken M, Pemberton DJ, Van Der Veken P, Augustyns K, Joossens J, Stroobants S, Dedeurwaerdere S, Wyffels L, Staelens S - Front Aging Neurosci (2016)

μPET imaging demonstrates increased brain uptake of [89Zr]-Df-Bz-JRF/AβN/25 in APPPS1–21 mice in comparison to WT. Mice were injected with 133 μg of [89Zr]-Df-Bz-JRF/AβN/25 and brain uptake was measured by μPET scanning and quantified as the %ID/g. The graphs show the VOI analysis of [89Zr]-Df-Bz-JRF/AβN/25 retention in WT and APPPS1–21 mice at (A) 2 days pi, (B) 4 days pi, and (C) 7 days pi. Significant genotype differences in retention were observed at 4 and 7 days pi. Data is presented as mean + SD. Student’s t-test, ∗∗∗p < 0.001, ∗∗p < 0.01, ∗p < 0.05.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4815004&req=5

Figure 1: μPET imaging demonstrates increased brain uptake of [89Zr]-Df-Bz-JRF/AβN/25 in APPPS1–21 mice in comparison to WT. Mice were injected with 133 μg of [89Zr]-Df-Bz-JRF/AβN/25 and brain uptake was measured by μPET scanning and quantified as the %ID/g. The graphs show the VOI analysis of [89Zr]-Df-Bz-JRF/AβN/25 retention in WT and APPPS1–21 mice at (A) 2 days pi, (B) 4 days pi, and (C) 7 days pi. Significant genotype differences in retention were observed at 4 and 7 days pi. Data is presented as mean + SD. Student’s t-test, ∗∗∗p < 0.001, ∗∗p < 0.01, ∗p < 0.05.
Mentions: Figure 1 displays the results from VOI analysis of the PET imaging. We used unpaired Student’s t-tests (corrected for multiple comparisons) to compare [89Zr]-Df-Bz-JRF/AβN/25 retention between brain regions with this analysis. At 2 days pi no clear differences were observed between WT and APPPS1–21 mice (Figure 1A). At 4 days pi, APPPS1–21 mice demonstrated increased [89Zr]-Df-Bz-JRF/AβN/25 retention in all brain regions investigated (Figure 1B). The most significant differences were found in the brain stem (p = 0.00015) followed by the midbrain (p = 0.0015) and thalamus (p = 0.0045). By 7 days pi significant differences remained only in the brain stem (p = 0.0021) and amygdala (p = 0.000057) (Figure 1C). With a more sensitive voxel-wise analysis (Figure 2A), significant differences in [89Zr]-Df-Bz-JRF/AβN/25 retention between genotypes was observed already at 2 days pi in the midbrain (16.3%) and brain stem (13%). By 4 days pi, significant voxels increased substantially in the brain stem (89%), midbrain (79.3%), amygdala (58.7%), hypothalamus (44.7%), and basal forebrain and septum (44%). While the percent of significant voxels in the whole brain remained relatively constant between 4 and 7 days pi (32.1 and 29.6%, respectively), regionally there were less significant voxels in the basal forebrain and septum (from 44% to 1.5%) and hypothalamus (44.7 to 1%) and an increase in the cerebellum (from 35.4 to 51.3%). Figure 2B illustrates the localization of significant voxels on an anatomical brain template.

Bottom Line: To confirm imaging specificity we also evaluated brain uptake of a non-amyloid targeting [(89)Zr]-labeled antibody (trastuzumab) as a negative control, additionally we performed a competitive blocking study with non-radiolabeled Df-Bz-JRF/AβN/25 and finally we assessed the possible confounding effects of blood retention.The low brain penetrance of the antibody in addition to non-specific binding prevented an accurate estimation of plaque burden.However, it should be noted that [(89)Zr]-Df-Bz-JRF/AβN/25 nevertheless demonstrated in vivo binding and strategies to increase brain penetrance would likely achieve better results.

View Article: PubMed Central - PubMed

Affiliation: Faculty of Medicine and Health Sciences, Molecular Imaging Center Antwerp, University of AntwerpAntwerp, Belgium; Translational Neurosciences, University of AntwerpAntwerp, Belgium.

ABSTRACT

Introduction: The accumulation of amyloid-β is a pathological hallmark of Alzheimer's disease and is a target for molecular imaging probes to aid in diagnosis and disease monitoring. This study evaluated the feasibility of using a radiolabeled monoclonal anti-amyloid-β antibody (JRF/AβN/25) to non-invasively assess amyloid-β burden in aged transgenic mice (APPPS1-21) with μPET imaging.

Methods: We investigated the antibody JRF/AβN/25 that binds to full-length Aβ. JRF/AβN/25 was radiolabeled with a [(89)Zr]-desferal chelate and intravenously injected into 12-13 month aged APPPS1-21 mice and their wild-type (WT) controls. Mice underwent in vivo μPET imaging at 2, 4, and 7 days post injection and were sacrificed at the end of each time point to assess brain penetrance, plaque labeling, biodistribution, and tracer stability. To confirm imaging specificity we also evaluated brain uptake of a non-amyloid targeting [(89)Zr]-labeled antibody (trastuzumab) as a negative control, additionally we performed a competitive blocking study with non-radiolabeled Df-Bz-JRF/AβN/25 and finally we assessed the possible confounding effects of blood retention.

Results: Voxel-wise analysis of μPET data demonstrated significant [(89)Zr]-Df-Bz-JRF/AβN/25 retention in APPPS1-21 mice at all time points investigated. With ex vivo measures of radioactivity, significantly higher retention of [(89)Zr]-Df-Bz-JRF/AβN/25 was found at 4 and 7 days pi in APPPS1-21 mice. Despite the observed genotypic differences, comparisons with immunohistochemistry revealed that in vivo plaque labeling was low. Furthermore, pre-treatment with Df-Bz-JRF/AβN/25 only partially blocked [(89)Zr]-Df-Bz-JRF/AβN/25 uptake indicative of a high contribution of non-specific binding.

Conclusion: Amyloid plaques were detected in vivo with a radiolabeled monoclonal anti-amyloid antibody. The low brain penetrance of the antibody in addition to non-specific binding prevented an accurate estimation of plaque burden. However, it should be noted that [(89)Zr]-Df-Bz-JRF/AβN/25 nevertheless demonstrated in vivo binding and strategies to increase brain penetrance would likely achieve better results.

No MeSH data available.


Related in: MedlinePlus