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Nanoscope’s 3D Superresolution Reveals Alzheimer’s Source

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A superresolution nanoscope could enable 3D imaging of amyloid plaques — a characteristic feature of Alzheimer’s disease — with up to 10 times greater detail than conventional microscopes.

Researchers at Purdue University combined active shaping of point spread functions and adaptive optics to enable robust 3D single-molecule switching nanoscopy (SMSN) imaging within tissues. They used the technology to image through 30-μm-thick brain sections in a mouse model of Alzheimer’s disease. They were able to visualize and reconstruct the morphology and the nanoscale details of amyloid-β filaments.

The nanoscope demonstrated the ability to reconstruct the whole tissue, its cells, and cell constituents at a resolution six to 10× higher than traditional microscopes.

Superresolution 3D nanoscope, Purdue University.

Purdue researchers have taken 3D single-molecule superresolution images of the amyloid plaques associated with Alzheimer's disease in 30-µm-thick sections of the mouse's frontal cortex. Courtesy of Purdue University/Fenil Patel.



The use of adaptive optics compensates for aberrations that can occur when light travels through different parts of a cell or tissue structure at different speeds. To image brain tissue, researchers developed a technique that adjusts the mirrors in response to sample depths. The technique can compensate for aberration and also introduce aberration to maintain the position information carried by a molecule.

The limited resolution in traditional light microscopes and the natural thickness of brain tissue have made it challenging for researchers to clearly observe 3D morphology of amyloid plaques and the plaques’ interactions with other cells.


“Brain tissue is particularly challenging for single-molecule superresolution imaging because it is highly packed with extracellular and intracellular constituents, which distort and scatter light — our source of molecular information,"  said professor Fang Huang. "You can image deep into the tissue, but the image is blurry.”

Using genetically engineered mice, researchers developed plaques that are characteristic of Alzheimer's disease. Through 3D reconstructions, they observed that the amyloid plaques entangled surrounding tissue via small fibers that branch off waxy deposits.

“We can see now that this is where the damage to the brain occurs," said professor Gary Landreth. "The mouse gives us validation that we can apply this imaging technique to human tissue.”

Researchers have begun using the nanoscope to observe amyloid plaques and how they interact with other cells in human brain samples. The team hopes that the technology can be used to help further understanding of neurological diseases, such as Parkinson’s, MS, and Alzheimer’s.

“While strictly a research tool for the foreseeable future, this technology has allowed us to see how the plaques are assembled and remodeled during the disease process," Landreth said. "It gives insight into the biological causes of the disease, so that we can see if we can stop the formation of these damaging structures in the brain.” 

The research was published in Nature Methods (doi:10.1038/s41592-018-0053-8). 


Researchers discuss how a new imaging technique could reveal why Alzheimer's disease starts. Courtesy of Purdue University/Erin Easterling.

 


Published: July 2018
Glossary
adaptive optics
Adaptive optics (AO) is a technology used to improve the performance of optical systems by reducing the effects of atmospheric distortions. The Earth's atmosphere can cause light passing through it to experience distortions, resulting in image blurring and degradation in various optical applications, such as astronomical observations, laser communications, and imaging systems. Adaptive optics systems actively adjust the optical elements in real-time to compensate for these distortions. Key...
optogenetics
A discipline that combines optics and genetics to enable the use of light to stimulate and control cells in living tissue, typically neurons, which have been genetically modified to respond to light. Only the cells that have been modified to include light-sensitive proteins will be under control of the light. The ability to selectively target cells gives researchers precise control. Using light to control the excitation, inhibition and signaling pathways of specific cells or groups of...
nano
An SI prefix meaning one billionth (10-9). Nano can also be used to indicate the study of atoms, molecules and other structures and particles on the nanometer scale. Nano-optics (also referred to as nanophotonics), for example, is the study of how light and light-matter interactions behave on the nanometer scale. See nanophotonics.
Research & TechnologyAmericaseducationfluorescence imagingsuperresolution imagingImagingMicroscopyOpticsadaptive opticsmirrorsdeformable mirrorsoptogeneticsBiophotonicsnanonanoscopemedicalAlzheimersneuronal imagingPurdue UniversityGary Landreth3D imagingsingle-molecule switching nanoscopyBioScan

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