New chemical reagent turns biological tissue transparent
By Ben Coxworth
September 2, 2011
Scientists are constantly looking for new and better ways of seeing through biological tissue, in order to see cells within it that have been marked with dyes, proteins or other substances. While recent research has involved using marking materials such as carbon nanotubes and firefly protein, scientists from Japan's RIKEN Brain Science Institute have taken a different approach - they've developed a chemical reagent that causes the tissue surrounding the marked cells to become transparent.
Known as Scale, the reagent was created by a team led by Dr. Atsushi Miyawaki. Already, they have used it to turn mouse brain tissue clear, in order to optically image the fluorescently-labeled cerebral cortex, hippocampus and white matter. They were able to see several millimeters into the tissue (keep in mind how small mouse brains are), allowing them "to visualize the axons connecting left and right hemispheres and blood vessels in the postnatal hippocampus in greater detail than ever before."
Not only did Scale turn the unmarked tissue transparent, but it also did not decrease the intensity of the fluorescent proteins that the RIKEN team used to mark cells.
While the experiments performed so far have mainly involved brain tissue samples, Miyawaki believes that it should work equally well on other organs, and ultimately in living subjects. "We are currently investigating another, milder candidate reagent which would allow us to study live tissue in the same way, at somewhat lower levels of transparency" he said. "This would open the door to experiments that have simply never been possible before."