Microscopy Aids Single-Cell, Whole-Body Imaging

A microscopy and imaging technique could make tissue and potentially whole organisms transparent.

A team at the Riken Quantitative Biology Center and the University of Tokyo developed the method — CUBIC (Clear, Unobstructed Brain Imaging Cocktails and Computational Analysis) — which combines fluorescent microscopy with tissue decolorization to obtain extremely detailed images of the interior of individual organs and entire organisms, and ultimately image them at extremely precise, single-cell resolution.

It could offer a better understanding of the human body, as well as autoimmune and psychiatric diseases.

Mouse kidneys, liver, and pancreas imaged after treatment with a variety of protocols: a saline solution, Scale, SeeDB, CUBIC, and CB-Perfusion. Courtesy of Riken.

The technique, which the researchers have used to image whole brains in the past via comprehensive chemical screening, was used in conjunction with light-sheet fluorescent microscopy (this involves taking slices of tissues without having to cut into them) to obtain 3-D images of infant and adult mouse brains, hearts, lungs, kidneys and livers; in all cases, the researchers were able to get clear tissues.

Specifically examined were the pancreases of diabetic and non-diabetic mice. The researchers said they found clear differences in the isles of Langerhans, which are the structures in the pancreas that produce insulin.

“We were very surprised that the entire body of infant and adult mice could be made nearly transparent by a direct transcardial CUBIC perfusion coupled with a two-week clearing protocol,” said Kazuki Tainaka, a researcher with Riken. “It allowed us to see cellular networks inside tissues, which is one of the fundamental challenges in biology and medicine.”

While organs contain many molecular subunits, one in particular, heme, is present in most tissues of the body and blocks light, according to the researchers. However, they have discovered that aminoalcohols included in the CUBIC reagent could elude the heme, thus making other organs dramatically more transparent.

“This new method could be used for 3-D pathology, anatomical studies and immunohistochemistry of entire organisms,” said Hiroki Ueda, a researcher with Riken, adding that it could be used to study how embryos develop or how cancer and autoimmune diseases develop at the cellular level. “It could lead to the achievement of one of our great dreams, organism-level systems biology based on whole-body imaging at single-cell resolution.”

The study is ongoing, as the researchers work to improve their microscopy method to allow rapid imaging of whole bodies of adult mice or larger samples such as human brains.

For more information, visit www.riken.jp.