Xerra: High resolution and quantification for neuroscientists
Cryo-Fluorescence Tomography (CFT) is a powerful imaging tool for neuroscience. CFT can be used to study the physiology, anatomy, and molecular biology of the brain. In addition, neurodegenerative diseases and other pathologies that affect different regions of the brain and neurological pathways can also be visualized with CFT. CFT can help elucidate anatomy, disease etiology and progression via fluorescence visualization. The 3D CFT maps of fluorescence reporters can aid in visualization of cell tracking, drug delivery, and pharmacodynamics in the brain.
Mouse Brain images 1 to 12 hours after injection of a Cy7 conjugated therapeutic.
Delivery of antisense (ASOs) labeled with Cy7 are evaluated in mouse brains.
PDT – new, exciting, trending
Photodynamic therapy (PDT) is a new technique based on simple biology. Levels of Protoporphyrin IX (PPIX), a blood protein, are high in malignant gliomas and meningioma (types of brain and brain/spinal cord tumors, respectively). PPIX is made from Aminolevulinic acid (ALA). When you flood the brain with ALA, a lot of PPIX is produced. Exposing PPIX to light of a particular wavelength excites it – making it give off by-products (reactive oxygen species) that can be quantified and traced. This is PDT. PDT is an exciting and trending technique because it can be used to treat cancer and guide brain surgery to remove tumors.
High-resolution localization and quantification of ALA in the mouse
CFT takes PDT to the next level
CFT takes PPIX visualization to the next level. As shown in this experiment where an immunocompromised mouse was injected with ALA and a normal mouse with saline. The mice were later exposed to UV LED light (394-410 nm). Conventional microscopy (middle panel) shows that there’s more fluorescence in the ALA mouse. But the resolution is poor and there’s no quantification organ-specific localization. The mice were then observed using CFT. Mice were preserved, sliced, imaged and images were processed. 3D reconstructions precisely show the localization (skin, salivary glands, thymus), quantity of PPIX in the tumor (left panel) vs. control (right panel). The color bar sets the scale, necessary for precise quantification, which is one of the advantages of CFT.
CFT, a powerful tool in PK studies
Cryo-Fluorescence Tomography (CFT) allows for high-resolution visual feedback, a powerful tool in pharmacokinetics studies, researchers can precisely track the movement of dyes and molecules through the body. Data can be used for the whole animal or segmented to view individual regions or organs. Data can be viewed as an image/3D rendering over time and quantified as a time course plot.
Quantify and trace drug movement in one step
In this experiment, a fluorescent tracer, Cy7 conjugated therapeutic, was injected into a murine model. Their brains were collected at different time points. Using CFT, the brains were sliced, imaged and processed. 3D reconstructions showed the movement of the tracer across the brain from 1 hour to 12 hours (top panel). Tracer concentration was quantified across time and in different regions of the brains. Using CFT, a drug’s pharmacokinetics can be visualized, quantified and traced in real-time.
Visualization and Quantification of Therapeutics in the brain
IT-injected agent distribution is imaged at a mesoscopic scale at multiple time points. Co-registered white light data can be used with atlases to provide regions for subsequent analysis.