Resin Tissue Microarrays: a Universal Format for Immunohistochemistry

Novel resin tissue array system reduces sample preparation time, labour and reagent costs in bone tissue histology

Resin histology plays an essential role in the analysis of hard tissues, such as bone and teeth, as well as in the context of metallic implant analysis. However, the techniques of resin embedding, followed by ground sectioning, are very costly due to significantly increased reagent cost and labour time when compared to the conventional paraffin histology approach. In the present study, a novel resin array system was developed to increase the affordability of a project analysing rat femur tissues containing metallic or polymeric implants. The resin array system enabled the simultaneous embedding of the femur samples in groups of eight samples compared to the conventional resin method where samples are processed individually. The ground sections produced with the resin array system allowed uniform ROI selection, ground section thickness, staining consistency, and histological analysis with Goldner's trichrome stain, offering a substantial opportunity for reproducible immunohistochemistry which is unable to be achieved when processing samples embedded individually. The application of this novel resin array system significantly reduced resource usage when compared to doing the same analysis on individual samples. A reduction of approximately 40% was achieved for both total labour time and total reagent cost through the use of the array system compared with individual embedding. This novel resin array system has widespread applicability to many bone, hard tissue, and metallic implant studies, offering substantial conservation of research funds and increased accessibility to advanced techniques for commercial partners due to more cost-effective sample preparation and more accurate, reproducible data.

Tissue microarrays - brief history, techniques and clinical future

Introduction and Aim: There is a growing need for better, cheaper and faster histopathological diagnostic. The authors reviewed the main steps of the efforts towards the improvement of the pre-analytical phase of tissue processing for histological examination. Results: Since their introduction decades ago tissue microarrays (TMAs) proved their value by increasing efficiency, standardization and accuracy of many histological techniques, such as histochemistry, histoenzymology, immunohistochemistry, in situ hybridization, etc. By allowing the simultaneous analysis and comparison of multiple different tissues on a single histology slide (up to 1000 individual samples), TMAs are also having a significant economic advantage (consumables and labor). From its first description until recent years, the TMA techniques have evolved steadily but slowly despite many attempts to adapt it for clinical diagnostics. In this paper, we are reviewing the main techniques of obtaining TMA blocks from the beginning to the present day, as well as recent developments that are expanding their scope into high accuracy/efficiency clinical diagnostics. Conclusions: Considering recent developments, we believe that the prospect of high-throughput histology might be achievable in the not-so-distant future.

The Demonstration of Immunohistochemical Biomarkers in Methyl Methacrylate-Embedded Plucked Human Hair Follicles

Plucked human hair follicles have been proposed as a potential surrogate for tumour tissue for measuring the effect of drugs on pharmacodynamic biomarkers in drug intervention studies. We describe a new technique of embedding plucked hair follicles in the acrylic resin, methyl methacrylate, and the immunohistochemical demonstration of six potential biomarkers (Ki67, EGFR, phospho-p27, phospho-histone H3, phospho-MAPK and phospho-Rb) in de-plasticised sections. The advantages of this technique over those that have been used in support of clinical drug trials, such as skin and tumour biopsies, whole blood and whole hair samples is discussed.

Overview on Techniques to Construct Tissue Arrays with Special Emphasis on Tissue Microarrays

With the advent of new histopathological staining techniques (histochemistry, immunohistochemistry, in situ hybridization) and the discovery of thousands of new genes, mRNA, and proteins by molecular biology, the need grew for a technique to compare many different cells or tissues on one slide in a cost effective manner and with the possibility to easily track the identity of each specimen: the tissue array (TA). Basically, a TA consists of at least two different specimens per slide. TAs differ in the kind of specimens, the number of specimens installed, the dimension of the specimens, the arrangement of the specimens, the embedding medium, the technique to prepare the specimens to be installed, and the technique to construct the TA itself. A TA can be constructed by arranging the tissue specimens in a mold and subsequently pouring the mold with the embedding medium of choice. In contrast, preformed so-called recipient blocks consisting of the embedding medium of choice have punched, drilled, or poured holes of different diameters and distances in which the cells or tissue biopsies will be deployed manually, semi-automatically, or automatically. The costs of constructing a TA differ from a few to thousands of Euros depending on the technique/equipment used. Remarkably high quality TAs can be also achieved by low cost techniques.

Analysis of protein biomarkers in human clinical tumor samples: critical aspects to success from tissue acquisition to analysis

There has been increased interest in the analysis of protein biomarkers in clinical tumor tissues in recent years. Tissue-based biomarker assays can add value and aid decision-making at all stages of drug development, as well as being developed for use as predictive biomarkers and for patient stratification and prognostication in the clinic. However, there must be an awareness of the legal and ethical issues related to the sourcing of human tissue samples. This article also discusses the limits of scope and critical aspects on the successful use of the following tissue-based methods: immunohistochemistry, tissue microarrays and automated image analysis. Future advances in standardization of tissue biobanking methods, immunohistochemistry and quantitative image analysis techniques are also discussed.

Resin technologies: construction and staining of resin TMA's

The traditional formaldehyde-fixed paraffin-embedded tissue, and therefore the tissue microarrays created from it, provide good morphology but with a compromised antigenicity when compared to frozen tissue. In contrast, while solving the issue of antigenicity, frozen tissue suffers from a lack of morphology. We have demonstrated that tissue microarrays constructed in glycol methacrylate resin, when combined with a cold acetone fixation step, have been able to combine the superior morphology of resin-embedded sections with the superior antigenicity of frozen tissue for prospectively collected material.

Tissue microarrays: an overview

Traditionally, screening for new markers involves using a slide from each of several different patients. A more efficient way is to have one slide that contains several minute specimens, one from each patient. These slides are prepared by transferring paraffin tissue cores from many "donor" blocks to one "recipient" block. Each slide cut from this recipient block is called a tissue microarray (TMA) slide. It can have various histological types of disease that need to be compared or can have the same histological type but different behavior (e.g., responders versus non-responders, etc.). TMAs are ideal for efficient screening of prospective biomarkers by a variety of different mechanisms including immunohistochemistry, fluorescence in situ hybridization of nucleic acids (FISH) and RNA in situ hybridization. Selection and number of cases from patient subsets in a given microarray slide is amenable to statistical modeling to enhance analysis of results. In addition, different microarrays can be constructed to answer different scientific questions. The microarrays can also be produced from retrospective paraffin blocks of well-characterized cases, with clinical follow-up. The TMA slides can be "whole-slide" imaged. This provides a mechanism to share results of experiments with other investigators. There are also ongoing efforts to generate software tools for automated analysis of TMA localization data. There has also been a significant body of work done to standardize data capture, thus facilitating subsequent exchange of information. The preferred current mechanism is to use an "XLM"-based data capture and transfer. There have also been efforts to create "frozen" TMAs. This has been attempted using "donor" frozen tissues embedded in OCT compound. These samples are then arrayed into a recipient OCT block. The presence of OCT can sporadically interfere with certain assays. However, it does provide a novel mechanism for high-throughput evaluation of frozen tissue, with corresponding visualization of tissue morphology.

TAMEE: data management and analysis for tissue microarrays

Background

With the introduction of tissue microarrays (TMAs) researchers can investigate gene and protein expression in tissues on a high-throughput scale. TMAs generate a wealth of data calling for extended, high level data management. Enhanced data analysis and systematic data management are required for traceability and reproducibility of experiments and provision of results in a timely and reliable fashion. Robust and scalable applications have to be utilized, which allow secure data access, manipulation and evaluation for researchers from different laboratories.

Results

TAMEE (Tissue Array Management and Evaluation Environment) is a web-based database application for the management and analysis of data resulting from the production and application of TMAs. It facilitates storage of production and experimental parameters, of images generated throughout the TMA workflow, and of results from core evaluation. Database content consistency is achieved using structured classifications of parameters. This allows the extraction of high quality results for subsequent biologically-relevant data analyses. Tissue cores in the images of stained tissue sections are automatically located and extracted and can be evaluated using a set of predefined analysis algorithms. Additional evaluation algorithms can be easily integrated into the application via a plug-in interface. Downstream analysis of results is facilitated via a flexible query generator.

Conclusion

We have developed an integrated system tailored to the specific needs of research projects using high density TMAs. It covers the complete workflow of TMA production, experimental use and subsequent analysis. The system is freely available for academic and non-profit institutions from .

An Agarose Matrix Facilitates Sectioning of Tissue Microarray Blocks

Tissue microarray (TMA) is a powerful, high-throughput technique for in situ investigation of biomarkers in many tissue samples in a paraffin block by immunohistochemistry or fluorescence in situ hybridization (FISH), and has rapidly become the standard in marker studies. One of the difficult steps in the procedure is the sectioning of array blocks and mounting of sections using special slides and/or adhesive-coated tape, which demands specific experience and is time-consuming. We report an arraying method that allows melting of the receiving paraffin block and subsequent sectioning like any ordinary paraffin-embedded tissue block. The major difference from the standard microarray technique is the use of an agarose matrix in the recipient block. The agarose matrix allows melting of the paraffin without disturbing the array, resulting in perfect integration of the tissue cores. The agarose-paraffin TMA blocks limit tissue core loss during cutting, mounting, or immunohistochemical or FISH staining and better maintains the array.