Immunohistochemistry (IHC) Facility

Immunohistochemistry (IHC) is a powerful technique used in pathology and molecular biology to identify and visualize specific proteins within tissue samples. This method utilizes antibodies that selectively bind to specific antigens within tissue sections, which are then visualized using either a fluorophore or a coloured substrate. By identifying stained proteins and their respective locations, IHC helps in understanding the types of cells present and their roles within the tissue.

The IHC process can be divided into three main stages: sample preparation, staining, and imaging.

1. Equipment involved in sample processing:

The following equipment is used for processing tissues and preparing high-quality slides for imaging and analysis. The general workflow is as follows: after the grossing of samples, tissues are fixed and dried without damaging their ultrastructure in an automated tissue processor, then embedded in paraffin wax to form blocks. These blocks are sectioned using a microtome. Following sectioning, staining and imaging are performed. Additionally, a cryostat is available for cutting fresh, unfixed tissue at -20°C for further staining and imaging.

1. Tissue Processor (STP 120): The STP 120 tissue processor is designed to process biological specimens from chemical fixation to wax infiltration. It features a unique design that uses programmable centrifugal force to enhance the agitation process typical of carousel processors. The processor offers both immediate and delayed-start processing modes for flexibility. Cassette baskets rotate clockwise and counterclockwise within reagent containers to improve processing efficiency. The system is customizable, with adjustable spin speeds and programmable immersion times to accommodate a variety of specimen types. The microprocessor can store up to ten processing programs, saving time in setup. The basket holds up to 120 cassettes for processing at a time.
2. Embedding (Thermo Scientific HistoStar): The Embedding Module includes a base mold storage compartment, wax reservoir, tissue storage tank, wax dispenser, and Para Trimmer. The wax is maintained at 60°C to remain molten. After processing, tissue sections are placed in a cassette compatible with a microtome. In a steel mold, a small amount of molten wax is added, followed by the cassette containing the tissue section, then more wax is added to fully embed the tissue. The steel mold is placed on a cold pad to solidify the wax. Once solidified, the tissue block is demolded and ready for sectioning.
3. Microtome HM 340E: The HM340E is an in vitro diagnostic device designed to take precision sections of tissue specimens, including paraffin-embedded samples. It is commonly used in medical and pharmaceutical laboratories for preparing tissue for examination. The microtome can cut sections ranging from 0.5 µm to 100 µm. To protect both the knife and the specimen, the instrument retracts the specimen after each cut. If desired, the retraction function can be disabled. A trimming function allows for fine adjustments in section thickness, ranging from 5 µm to 500 µm, facilitating optimal preparation for the first cuts.
4. Cryostat (HM 525NX): The HM 525NX cryostat is a high-performance, ergonomically designed device with a modular stainless steel cooling chamber. A cryostat is used to prepare thin slices (sections) of frozen specimens, particularly biological tissues. It is an essential tool in histology, pathology, and related fields, enabling precise examination of tissue structure, enzymes, or proteins. The cryostat maintains the tissue at temperatures as low as -20°C to -30°C, preserving cellular integrity and preventing ice crystal formation that can damage the tissue.
5. Equipment for imaging and analysis:

Fully Automated Computerized Archival System: This high-performance microscopy-based or camera-based automatic slide scanner system is designed for imaging animal tissue and supports standard microscopy glass slides. It can accommodate both brightfield and fluorescence samples, equipped with dedicated cameras. The system is integrated with user-friendly software and a web-based database for image sharing, annotations, and analysis. It facilitates the imaging and analysis of both animal and human tissue samples, allowing multiple users to collaborate and interpret the results.