In a Nature Neuroscience report posted online yesterday, Japanese researchers at the RIKEN Center for Developmental Biology show how they’ve grabbed a ball tossed by Stanford psychiatrist/ neuroscientist/bioengineer Karl Deisseroth, MD, PhD, and run with it.
In April, Deisseroth’s team announcedan amazing new method for transforming biological tissues (in this case, the brain of a rat) into, essentially, a transparent 3-D replica of itself replete with all its cells and even the proteins that sit on their surfaces. The breakthrough was achieved by using a chemical mixture to dissolve away the fatty materials that, while critical to the function of cells and tissues, is also largely responsible for their lack of transparency.
Getting transparent tissue samples via that method, dubbed CLARITY, required a couple of weeks and some pretty nasty chemicals. But it worked. And by doing so, it meant that scientists would for the first time be able to study, in exquisite detail, an intact tissue sample or even an entire organ without having to first slice it into dozens or hundreds of razor-thin sections, with all the distortion such mechanical manipulation wreaks and without the benefit of being able to view, say, intact nerve tracts. It was a big deal.
But innovation is contagious (and no true scientist would have it any other way). And now, with the latest discovery, no more noxious chemicals! You just toss a tissue sample into a jar of fruit juice (okay, technically “an aqueous fructose solution”) for a few days, and out comes your see-through sample. …
a team of neuroscientists at the RIKEN institute in Japan have created a liquid, primarily fashioned out of fructose sugar, that turns flesh transparent. This aqueous solution, called SeeDB, has been successfully used by the researchers to make mouse embryos and brains transparent without damaging any of the fine structures within the samples. The researchers were then able to visualize the entire neuronal circuitry of a mouse brain on a whole-brain scale, without having to first cut it into slices — an important first for neuroscience.