The refined technique optimizes the CLARITY concept so that it can be used to clear other organs besides the brain, and even whole organisms. By making clever use of an organism's own network of blood vessels, Gradinaru and her colleaguesincluding scientific researcher Bin Yang and postdoctoral scholar Jennifer Treweek, coauthors on the papercan quickly deliver the lipid-dissolving hydrogel and chemical solution throughout the body.
Gradinaru and her colleagues have dubbed this new technique PARS, or perfusion-assisted agent release in situ.
Once an organ or whole body has been made transparent, standard microscopy techniques can be used to easily look through a thick mass of tissue to view single cells that are genetically marked with fluorescent proteins. Even without such genetically introduced fluorescent proteins, however, the PARS technique can be used to deliver stains and dyes to individual cell types of interest. When whole-body clearing is not necessary the method works just as well on individual organs by using a technique called PACT, short for passive clarity technique.
To find out if stripping the lipids from cells also removes other potential molecules of interestsuch as proteins, DNA, and RNAGradinaru and her team collaborated with Long Cai, an assistant professor of chemistry at Caltech, and his lab. The two groups found that strands of RNA are indeed still present and can be detected with single-molecule resolution in the cells of the transparent organisms.
The Cell paper focuses on the use of PACT and PARS as research tools for studying disease and development in research organisms. However, Gradinaru and her UCLA collaborator Rajan Kulkarni, have already found a diagnostic medical application for the methods. Using the techniques on a biopsy from a human skin tumor, the researchers were able to view the d
|Contact: Deborah Williams-Hedges|
California Institute of Technology