Researchers at the RIKEN Brain Science Institute in Japan have developed a new technique for creating transparent tissue that can be used to illuminate 3D brain anatomy at very high resolutions. Published in Nature Neuroscience, the work showcases the new technology and its practical importance in clinical science by showing how it has given new insights into Alzheimer's disease plaques.
"The usefulness of optical clearing techniques can be measured by their ability to gather accurate 3D structural information that cannot be readily achieved through traditional 2D methods," explains lead scientist Atsushi Miyawaki. "Here, we achieved this goal using a new procedure, and collected data that may resolve several current issues regarding the pathology of Alzheimer's disease. While Superman's x-ray vision is only the stuff of comics, our method, called ScaleS, is a real and practical way to see through brain and body tissue."
In recent years, generating see-through tissue--a process called optical clearing--has become a goal for many researchers in life sciences because of its potential to reveal complex structural details of our bodies, organs, and cells--both healthy and diseased--when combined with advanced microscopy imaging techniques. Previous methods were limited because the transparency process itself can damage the structures under study.
The original recipe reported by the Miyawaki team in 2011--termed Scale--was an aqueous solution based on urea that suffered from this same problem. The research team spent 5 years improving the effectiveness of the original recipe to overcome this critical challenge, and the result is ScaleS, a new technique with many practical applications.
"The key ingredient of our new formula is sorbitol, a common sugar alcohol," reveals Miyawaki. "By combining sorbitol in the right proportion with urea, we could create transparent brains with minimal tissue damage, that can handle both florescent and immunohistochemical labeling techniques, and is even effective in older animals."
The new technique creates transparent brain samples that can be stored in ScaleS solution for more than a year without damage. Internal structures maintain their original shape and brains are firm enough to permit the micron-thick slicing necessary for more detailed analyses.
"The real challenge with optical clearing is at the microscopic level," said Miyawaki, "In addition to allowing tissue to be viewable by light microscopy, a practical solution must also ensure accurate tissue preservation for effective electron microscopy."
On these tests, ScaleS passed with flying colors providing an optimal combination of cleared tissue and fluorescent signals, and Miyawaki believes that the quality and preservation of cellular structures viewed by electron microscopy is unparalleled.
The team has devised several variations of the Scale technique that can be used together. By combining ScaleS with AbScale--a variation for immunolabeling--and ChemScale--a variation for fluorescent chemical compounds--they generated multi-color high-resolution 3D images of amyloid beta plaques in older mice from a genetic mouse model of Alzheimer's disease developed at the RIKEN BSI by Takaomi Saido team.
After showing how ScaleS treatment can preserve tissue, the researchers put the technique to practical use by visualizing in 3D the mysterious "diffuse" plaques seen in the postmortem brains of Alzheimer's disease patients that are typically undetectable using 2D imaging. Contrary to current assumptions, the diffuse plaques proved not to be isolated, but showed extensive association with microglia --mobile cells that surround and protect neurons.
Another example of ScaleS's practical application came from examining the 3D positions of active microglial cells and amyloid beta plaques. While some scientists suggest that active microglial cells are located near plaques, a detailed 3D reconstruction and analysis using ScaleS clearing showed that association with active microglial cells occurs early in plaque development, but not in later stages of the disease after the plaques have accumulated.
"Clearing tissue with ScaleS followed by 3D microscopy has clear advantages over 2D stereology or immunohistochemistry," states Miyawaki. "Our technique will be useful not only for visualizing plaques in Alzheimer's disease, but also for examining normal neural circuits and pinpointing structural changes that characterize other brain diseases."
Hama H et al. (2015) ScaleS: An Optical Clearing Palette for Biological Imaging. Nature Neuroscience, doi: 10.1038/nn.4107.
Adam Phillips | EurekAlert!
Turning carbon dioxide into liquid fuel
06.08.2020 | DOE/Argonne National Laboratory
Tellurium makes the difference
06.08.2020 | Friedrich-Schiller-Universität Jena
Scientists at the Fraunhofer Institute for Laser Technology ILT have come up with a striking new addition to contact stamping technologies in the ERDF research project ScanCut. In collaboration with industry partners from North Rhine-Westphalia, the Aachen-based team of researchers developed a hybrid manufacturing process for the laser cutting of thin-walled metal strips. This new process makes it possible to fabricate even the tiniest details of contact parts in an eco-friendly, high-precision and efficient manner.
Plug connectors are tiny and, at first glance, unremarkable – yet modern vehicles would be unable to function without them. Several thousand plug connectors...
An international research team has found a new approach that may be able to reduce bone loss in osteoporosis and maintain bone health.
Osteoporosis is the most common age-related bone disease which affects hundreds of millions of individuals worldwide. It is estimated that one in three women...
Traditional single-cell sequencing methods help to reveal insights about cellular differences and functions - but they do this with static snapshots only...
“Core-shell” clusters pave the way for new efficient nanomaterials that make catalysts, magnetic and laser sensors or measuring devices for detecting electromagnetic radiation more efficient.
Whether in innovative high-tech materials, more powerful computer chips, pharmaceuticals or in the field of renewable energies, nanoparticles – smallest...
An international research team with Prof. Cornelia Denz from the Institute of Applied Physics at the University of Münster develop for the first time light fields using caustics that do not change during propagation. With the new method, the physicists cleverly exploit light structures that can be seen in rainbows or when light is transmitted through drinking glasses.
Modern applications as high resolution microsopy or micro- or nanoscale material processing require customized laser beams that do not change during...
23.07.2020 | Event News
21.07.2020 | Event News
07.07.2020 | Event News
06.08.2020 | Earth Sciences
06.08.2020 | Power and Electrical Engineering
06.08.2020 | Life Sciences