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RNA aptamer probes as optical imaging agents for the detection of amyloid plaques.

Farrar CT, William CM, Hudry E, Hashimoto T, Hyman BT - PLoS ONE (2014)

Bottom Line: We examined the possibility of developing highly specific and sensitive optical imaging agents using aptamer technology.Dot blots of synthetic Aβ aggregates provide further evidence that β55 binds both fibrillar and non-fibrillar Aβ.The high binding affinity, the ease of probe development, and the ability to incorporate multiple and multimodal imaging reporters suggest that RNA aptamers may have complementary and perhaps advantageous properties compared to conventional optical imaging probes and reporters.

View Article: PubMed Central - PubMed

Affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts, United States of America.

ABSTRACT
Optical imaging using multiphoton microscopy and whole body near infrared imaging has become a routine part of biomedical research. However, optical imaging methods rely on the availability of either small molecule reporters or genetically encoded fluorescent proteins, which are challenging and time consuming to develop. While directly labeled antibodies can also be used as imaging agents, antibodies are species specific, can typically not be tagged with multiple fluorescent reporters without interfering with target binding, and are bioactive, almost always eliciting a biological response and thereby influencing the process that is being studied. We examined the possibility of developing highly specific and sensitive optical imaging agents using aptamer technology. We developed a fluorescently tagged anti-Aβ RNA aptamer, β55, which binds amyloid plaques in both ex vivo human Alzheimer's disease brain tissue and in vivo APP/PS1 transgenic mice. Diffuse β55 positive halos, attributed to oligomeric Aβ, were observed surrounding the methoxy-XO4 positive plaque cores. Dot blots of synthetic Aβ aggregates provide further evidence that β55 binds both fibrillar and non-fibrillar Aβ. The high binding affinity, the ease of probe development, and the ability to incorporate multiple and multimodal imaging reporters suggest that RNA aptamers may have complementary and perhaps advantageous properties compared to conventional optical imaging probes and reporters.

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Related in: MedlinePlus

β55 Staining of Amyloid Plaques in Ex Vivo Human AD Brain Tissue.Merged red and green channel confocal images of frozen-section human AD brain tissue stained with biotinylated β55 (a) and β55rc (b). β55 positive plaques (green) were clearly visible, while only a few very faint β55rc positive plaques were observed. Background auto-fluorescence, observed in both red and green channels, is shown in yellow. (c) Fluorescence images of human AD brain tissue costained with biotinylated-β55 (red) and Thioflavin-S (green). β55 colocalized with Thioflavin-S positive plaques. (Scale bars: 50 µm).
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pone-0089901-g002: β55 Staining of Amyloid Plaques in Ex Vivo Human AD Brain Tissue.Merged red and green channel confocal images of frozen-section human AD brain tissue stained with biotinylated β55 (a) and β55rc (b). β55 positive plaques (green) were clearly visible, while only a few very faint β55rc positive plaques were observed. Background auto-fluorescence, observed in both red and green channels, is shown in yellow. (c) Fluorescence images of human AD brain tissue costained with biotinylated-β55 (red) and Thioflavin-S (green). β55 colocalized with Thioflavin-S positive plaques. (Scale bars: 50 µm).

Mentions: The ability of the β55 aptamer to stain amyloid plaques was demonstrated by staining frozen-section brain tissue from AD subjects with biotinylated β55 and β55rc aptamers. While plaques were clearly visible with the β55 aptamer (Figure 2a), only a few very faint β55rc positive plaques were observed (Figure 2b). A tissue section co-stained with β55 and Thioflavin-S showed good colocalization of β55 and Thioflavin-S for amyloid plaques (Figure 2c).


RNA aptamer probes as optical imaging agents for the detection of amyloid plaques.

Farrar CT, William CM, Hudry E, Hashimoto T, Hyman BT - PLoS ONE (2014)

β55 Staining of Amyloid Plaques in Ex Vivo Human AD Brain Tissue.Merged red and green channel confocal images of frozen-section human AD brain tissue stained with biotinylated β55 (a) and β55rc (b). β55 positive plaques (green) were clearly visible, while only a few very faint β55rc positive plaques were observed. Background auto-fluorescence, observed in both red and green channels, is shown in yellow. (c) Fluorescence images of human AD brain tissue costained with biotinylated-β55 (red) and Thioflavin-S (green). β55 colocalized with Thioflavin-S positive plaques. (Scale bars: 50 µm).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3935954&req=5

pone-0089901-g002: β55 Staining of Amyloid Plaques in Ex Vivo Human AD Brain Tissue.Merged red and green channel confocal images of frozen-section human AD brain tissue stained with biotinylated β55 (a) and β55rc (b). β55 positive plaques (green) were clearly visible, while only a few very faint β55rc positive plaques were observed. Background auto-fluorescence, observed in both red and green channels, is shown in yellow. (c) Fluorescence images of human AD brain tissue costained with biotinylated-β55 (red) and Thioflavin-S (green). β55 colocalized with Thioflavin-S positive plaques. (Scale bars: 50 µm).
Mentions: The ability of the β55 aptamer to stain amyloid plaques was demonstrated by staining frozen-section brain tissue from AD subjects with biotinylated β55 and β55rc aptamers. While plaques were clearly visible with the β55 aptamer (Figure 2a), only a few very faint β55rc positive plaques were observed (Figure 2b). A tissue section co-stained with β55 and Thioflavin-S showed good colocalization of β55 and Thioflavin-S for amyloid plaques (Figure 2c).

Bottom Line: We examined the possibility of developing highly specific and sensitive optical imaging agents using aptamer technology.Dot blots of synthetic Aβ aggregates provide further evidence that β55 binds both fibrillar and non-fibrillar Aβ.The high binding affinity, the ease of probe development, and the ability to incorporate multiple and multimodal imaging reporters suggest that RNA aptamers may have complementary and perhaps advantageous properties compared to conventional optical imaging probes and reporters.

View Article: PubMed Central - PubMed

Affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts, United States of America.

ABSTRACT
Optical imaging using multiphoton microscopy and whole body near infrared imaging has become a routine part of biomedical research. However, optical imaging methods rely on the availability of either small molecule reporters or genetically encoded fluorescent proteins, which are challenging and time consuming to develop. While directly labeled antibodies can also be used as imaging agents, antibodies are species specific, can typically not be tagged with multiple fluorescent reporters without interfering with target binding, and are bioactive, almost always eliciting a biological response and thereby influencing the process that is being studied. We examined the possibility of developing highly specific and sensitive optical imaging agents using aptamer technology. We developed a fluorescently tagged anti-Aβ RNA aptamer, β55, which binds amyloid plaques in both ex vivo human Alzheimer's disease brain tissue and in vivo APP/PS1 transgenic mice. Diffuse β55 positive halos, attributed to oligomeric Aβ, were observed surrounding the methoxy-XO4 positive plaque cores. Dot blots of synthetic Aβ aggregates provide further evidence that β55 binds both fibrillar and non-fibrillar Aβ. The high binding affinity, the ease of probe development, and the ability to incorporate multiple and multimodal imaging reporters suggest that RNA aptamers may have complementary and perhaps advantageous properties compared to conventional optical imaging probes and reporters.

Show MeSH
Related in: MedlinePlus