Brilliant Dye Provides High-Resolution, 3D Views of the Cerebral Vascular System

To obtain very high-resolution, three-dimensional (3D) images of the cerebral vascular system, French researchers are evaluating a new dye that fluoresces in the near infrared and can pass through the skin.

The Lem-PHEA chromophore new dye technology has been developed by a team from the laboratoire de chimie at the Centre National de la Recherche Scientifique [CNRS]/ENS de Lyon/Université Claude Bernard Lyon 1 (France). Conducted in collaboration with researchers from the Institut des Neurosciences (Université Joseph Fourier-Grenoble /CEA/Inserm /CHU; France) and the Laboratoire Chimie et Interdisciplinarité: Synthèse, Analyse, Modélisation (CNRS/Université de Nantes; France), this project’s findings were published online April 29, 2013, in the journal Chemical Science. The technology creates significant ways to better visualize the brain and better determine how it functions.

Different cerebral imaging techniques, such as two-photon microscopy or magnetic resonance imaging (MRI), contribute to a better understanding of how the healthy or diseased brain works. One of their basic characteristics is their spatial resolution, meaning, the level of the smallest details visualized by each technique. Typically, for MRI, this resolution is limited to several millimeters, which does not make it possible to capture images such as the new dye can obtain, with a resolution on the order of a micrometer.

To obtain such images of the vascular system of a mouse brain, it is necessary to use a fluorescent dye that combines several characteristics: luminescence in the near infrared, biologic media solubility, low cost, nontoxicity and suitable for 3D imaging (two-photon absorption). The researchers have developed the new product, Lem-PHEA, which combines these very properties and is easy to synthesize.

When injected into the blood vessels of a mouse, it has revealed details of the rodent’s vascular system with never before actualized precision, due to a considerably enhanced fluorescence compared to standard dyes (such as rhodamine-B and cyanine derivatives). With Lem-PHEA, the researchers have obtained more contrasted images (in terms of brilliance) than with these conventional dyes. Finally, the dye is easily eliminated by the kidneys and no toxic residues have been found in the liver. These new findings pave the way for a better understanding of the working of the brain, according to the researchers.

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Université Claude Bernard Lyon 1
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Université de Nantes