Comparison of two techniques for a comprehensive gut histopathological analysis: Swiss Roll versus Intestine Strips

Improved Preservation of Mouse Intestinal Tissue Using a Formalin/Acetic Acid Fixative and Quantitative Histological Analysis Using QuPath

The architecture and morphology of the intestinal tissue from mice or other small animals are difficult to preserve for histological and molecular analysis due to the fragile nature of this tissue. The intestinal mucosa consists of villi and crypts lined with epithelial cells. In between the epithelial folds extends the lamina propria, a loose connective tissue that contains blood and lymph vessels, fibroblasts, and immune cells. Underneath the mucosa are two layers of contractile smooth muscle and nerves. The tissue experiences significant changes during fixation, which can impair the reliability of histologic analysis. Poor-quality histologic sections are not suitable for quantitative image-based tissue analysis. This article offers a new fixative composed of neutral buffered formalin (NBF) and acetic acid, called FA. This fixative significantly improved the histology of mouse intestinal tissue compared to traditional NBF and enabled precise, reproducible histologic molecular analyses using QuPath software. Algorithmic training of QuPath allows for automated segmentation of intestinal compartments, which can be further interrogated for cellular composition and disease-related changes. © 2024 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol: Improved preservation of mouse intestinal tissue using a formalin/acetic acid fixative Support Protocol: Quantitative tissue analysis using QuPath.

ROCKETS - a novel one-for-all toolbox for light sheet microscopy in drug discovery

Advancing novel immunotherapy strategies requires refined tools in preclinical research to thoroughly assess drug targets, biodistribution, safety, and efficacy. Light sheet fluorescence microscopy (LSFM) offers unprecedented fast volumetric ex vivo imaging of large tissue samples in high resolution. Yet, to date laborious and unstandardized tissue processing procedures have limited throughput and broader applications in immunological research. Therefore, we developed a simple and harmonized protocol for processing, clearing and imaging of all mouse organs and even entire mouse bodies. Applying this Rapid Optical Clearing Kit for Enhanced Tissue Scanning (ROCKETS) in combination with LSFM allowed us to comprehensively study the in vivo biodistribution of an antibody targeting Epithelial Cell Adhesion Molecule (EpCAM) in 3D. Quantitative high-resolution scans of whole organs did not only reveal known EpCAM expression patterns but, importantly, uncovered several new EpCAM-binding sites. We identified gustatory papillae of the tongue, choroid plexi in the brain and duodenal papillae as previously unanticipated locations of high EpCAM expression. Subsequently, we confirmed high EpCAM expression also in human tongue and duodenal specimens. Choroid plexi and duodenal papillae may be considered as particularly sensitive sites due to their importance for liquor production or as critical junctions draining bile and digestive pancreatic enzymes into the small bowel, respectively. These newly gained insights appear highly relevant for clinical translation of EpCAM-addressing immunotherapies. Thus, ROCKETS in combination with LSFM may help to set new standards for preclinical evaluation of immunotherapeutic strategies. In conclusion, we propose ROCKETS as an ideal platform for a broader application of LSFM in immunological research optimally suited for quantitative co-localization studies of immunotherapeutic drugs and defined cell populations in the microanatomical context of organs or even whole mice.

Multimodal Imaging Mass Spectrometry of Murine Gastrointestinal Tract with Retained Luminal Content

The gastrointestinal tract, including luminal content, harbors a complex mixture of microorganisms, host dietary content, and immune factors. Existing imaging approaches remove luminal content and only visualize small regions of the GI tract. Here, we demonstrate a workflow for multimodal imaging using matrix-assisted laser desorption/ionization imaging mass spectrometry, autofluorescence, and bright field microscopy for mapping intestinal tissue and luminal content. Results comparing tissue and luminal content in control murine tissue show both unique molecular and elemental distributions and abundances using multimodal protein, lipid, and elemental imaging. For instance, lipid PC(42:1) is 2× higher intensity in luminal content than tissue, while PC(32:0) is 80× higher intensity in tissue. Additionally, some ions such as the protein at m/z 3443 and the element manganese are only detected in luminal content, while the protein at m/z 8564 was only detected in tissue and phosphorus had 2× higher abundance in tissue. These data highlight the robust molecular information that can be gained from the gastrointestinal tract with the inclusion of luminal content.

Histopathological evaluation of amino acid capped silver nanoconjugates in albino mice

Various molecules may modify the surface chemistry of commonly used nanomaterials (NMs), resulting in the synthesis of novel and safer NMs. The current study was delineated to evaluate the in vivo toxicity profiling of the silver nanoconjugates (AgNCs) conjugated with different amino acids. The L-glycine capped-AgNCs exhibited toxicity and caused tissue damage, while L-cystine- and L-tyrosine-capped AgNCs showed protective effects against cadmium-induced toxicity. L-cystine-capped AgNCs performed well as compared to other amino-acid AgNCs. The level of serum creatinine, alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase and blood urea increased (p < 0.05) in G2, G3 and G5 in comparison to G1 (control group), while an increase in bilirubin for G2 was statistically non-significant (p > 0.05). The ALT and AST elevated (p < 0.05) in G4; however, other serological parameters in G4 and G6 did not show any noticeable change in their values. Histological analysis showed disturbed and deformed cellular structures in liver and kidney tissues of G2, G3 and G5. However, G4 and G6 samples demonstrated minute changes in comparison to G1. It is concluded that L-cystine- and L-tyrosine-capped AgNCs exhibited protective effects and should be tested further for developing safer nanoconjugates for biomedical uses.