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

Pre-treatment with non-labeled Df-Bz-JRF/AβN/25 only partially blocks [89Zr]-Df-Bz-JRF/AβN/25 uptake in APPPS1–21 mice. APPPS1–21 mice were treated with 400 μg of non-labeled Df-Bz-JRF/AβN/25 2 h prior to injection of [89Zr]-Df-Bz-JRF/AβN/25. Brain retention was assessed at 4 days pi. Graph (A) depicts VOI analysis of the μPET imaging, data is presented as mean + SD. Graph (B) shows voxel-wise analysis, data is presented as the % of each brain region that was significantly changed (decrease). Image (C) is statistical T-maps depicting regions of significantly reduced tracer retention in pre-treated versus untreated APPPS1–21 mice. Radioactivity was measured ex vivo by (D) γ–counting and (E) autoradiography. Data is presented as the average ± SD. Student’s t-test, ∗∗∗p < 0.001, ∗∗p < 0.01.
© Copyright Policy
Related In: Results  -  Collection

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

Figure 5: Pre-treatment with non-labeled Df-Bz-JRF/AβN/25 only partially blocks [89Zr]-Df-Bz-JRF/AβN/25 uptake in APPPS1–21 mice. APPPS1–21 mice were treated with 400 μg of non-labeled Df-Bz-JRF/AβN/25 2 h prior to injection of [89Zr]-Df-Bz-JRF/AβN/25. Brain retention was assessed at 4 days pi. Graph (A) depicts VOI analysis of the μPET imaging, data is presented as mean + SD. Graph (B) shows voxel-wise analysis, data is presented as the % of each brain region that was significantly changed (decrease). Image (C) is statistical T-maps depicting regions of significantly reduced tracer retention in pre-treated versus untreated APPPS1–21 mice. Radioactivity was measured ex vivo by (D) γ–counting and (E) autoradiography. Data is presented as the average ± SD. Student’s t-test, ∗∗∗p < 0.001, ∗∗p < 0.01.

Mentions: Lastly, we conducted a competitive blocking study (Figure 5). Pre-administration of 400 μg unlabeled Df-Bz-JRF/AβN/25 to APPPS1–21 mice did not alter blood or organ retention of [89Zr]-Df-Bz-JRF/AβN/25 (Supplementary Table S3). VOI analysis of the μPET imaging data showed significantly reduced [89Zr]-Df-Bz-JRF/AβN/25 retention in pre-treated APPPS1–21 mice in the brain stem (p = 0.0008), hypothalamus (p = 0.0023), and amygdala (0.0048), when compared to un-treated APPPS1–21 at the same 4 days pi time point (Figure 5A). With voxel-wise analysis we similarly showed the greatest significant decreases between pre-treated and untreated APPPS1–21 mice in these regions and additionally demonstrated appreciable differences in the cerebellum (23.5%) and midbrain (20.8%) (Figures 5B,C). With ex vivo measures, pre-treatment non-significantly reduced brain retention in APPPS1–21 mice by 18 and 3.17% as measured by γ-counting and autoradiography, respectively, (Figures 5D,E). Immunohistochemistry confirmed the same regional pattern of staining for mice with or without pre-treatment.


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)

Pre-treatment with non-labeled Df-Bz-JRF/AβN/25 only partially blocks [89Zr]-Df-Bz-JRF/AβN/25 uptake in APPPS1–21 mice. APPPS1–21 mice were treated with 400 μg of non-labeled Df-Bz-JRF/AβN/25 2 h prior to injection of [89Zr]-Df-Bz-JRF/AβN/25. Brain retention was assessed at 4 days pi. Graph (A) depicts VOI analysis of the μPET imaging, data is presented as mean + SD. Graph (B) shows voxel-wise analysis, data is presented as the % of each brain region that was significantly changed (decrease). Image (C) is statistical T-maps depicting regions of significantly reduced tracer retention in pre-treated versus untreated APPPS1–21 mice. Radioactivity was measured ex vivo by (D) γ–counting and (E) autoradiography. Data is presented as the average ± SD. Student’s t-test, ∗∗∗p < 0.001, ∗∗p < 0.01.
© Copyright Policy
Related In: Results  -  Collection

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

Figure 5: Pre-treatment with non-labeled Df-Bz-JRF/AβN/25 only partially blocks [89Zr]-Df-Bz-JRF/AβN/25 uptake in APPPS1–21 mice. APPPS1–21 mice were treated with 400 μg of non-labeled Df-Bz-JRF/AβN/25 2 h prior to injection of [89Zr]-Df-Bz-JRF/AβN/25. Brain retention was assessed at 4 days pi. Graph (A) depicts VOI analysis of the μPET imaging, data is presented as mean + SD. Graph (B) shows voxel-wise analysis, data is presented as the % of each brain region that was significantly changed (decrease). Image (C) is statistical T-maps depicting regions of significantly reduced tracer retention in pre-treated versus untreated APPPS1–21 mice. Radioactivity was measured ex vivo by (D) γ–counting and (E) autoradiography. Data is presented as the average ± SD. Student’s t-test, ∗∗∗p < 0.001, ∗∗p < 0.01.
Mentions: Lastly, we conducted a competitive blocking study (Figure 5). Pre-administration of 400 μg unlabeled Df-Bz-JRF/AβN/25 to APPPS1–21 mice did not alter blood or organ retention of [89Zr]-Df-Bz-JRF/AβN/25 (Supplementary Table S3). VOI analysis of the μPET imaging data showed significantly reduced [89Zr]-Df-Bz-JRF/AβN/25 retention in pre-treated APPPS1–21 mice in the brain stem (p = 0.0008), hypothalamus (p = 0.0023), and amygdala (0.0048), when compared to un-treated APPPS1–21 at the same 4 days pi time point (Figure 5A). With voxel-wise analysis we similarly showed the greatest significant decreases between pre-treated and untreated APPPS1–21 mice in these regions and additionally demonstrated appreciable differences in the cerebellum (23.5%) and midbrain (20.8%) (Figures 5B,C). With ex vivo measures, pre-treatment non-significantly reduced brain retention in APPPS1–21 mice by 18 and 3.17% as measured by γ-counting and autoradiography, respectively, (Figures 5D,E). Immunohistochemistry confirmed the same regional pattern of staining for mice with or without pre-treatment.

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