Clarity and Immunofluorescence on Mouse Brain Tissue

MRI-Based and Histologically Verified 3D Modeling of Spatial Distribution of Intra-Arterially Transplanted Cells in Rat Brain

Visualization of transplanted stem cells in the brain is an important issue in the study of the mechanisms of their therapeutic action. MRI allowing visualization of single transplanted cells previously labeled with superparamagnetic iron oxide particles is among the most informative methods of non-invasive intravital imaging. Verification of MRI data using pathomorphological examination at the microscopic level helps to avoid errors in data interpretation. However, making serial sections of the whole brain and searching for transplanted cells under the microscope is laborious and time-consuming. We have developed a method for 3D modeling of the distribution of transplanted cells in the brain allowing navigating through various brain structures and identifying the areas of accumulation of transplanted cells, which significantly increases the efficiency and reduces the time of histological examination.

Chemical Sectioning for Immunofluorescence Imaging

Immunofluorescence (IF) is a powerful investigative tool in biological research and medical diagnosis, whereas conventional imaging methods are always conflict between speed, contrast/resolution, and specimen volume. Chemical sectioning (CS) is an effective method to overcome the conflict, which works by chemically manipulating the off/on state of fluorescent materials and turning on only the extremely superficial surface fluorescence of tissues to realize the sectioning capacity of wide-field imaging. However, the current mechanism of CS is only applicable to samples labeled with pH-sensitive fluorescent proteins and still cannot fulfill samples immunolabeled with frequently used commercial fluorescent dyes. Here, immunofluorescence chemical sectioning (IF-CS) is described to present an off/on mechanism for Alexa dyes by complexation reactions, allowing CS imaging of IF labeled tissues. IF-CS enables IF freeing from out-of-focus interference in wide-field imaging and satisfying with multicolor imaging. IF-CS demonstrates the utility of the 3D submicron-resolution imaging of large immunolabeled tissues on the wide-field block-face system. IF-CS may remarkably facilitate systematic studies of refined subcellular architectures of endogenous proteins in intact biological systems.