The TMA technique was described for the first time in 1998 by the staff of J. Kononen, although something similar, the MTTB ("Multitumor (sausage) Tissue Block), had already been presented in 1986 by H. Battifora. TMA is the evolution of the MTTB method and uses a sampling system able to produce tissue samples of regular size and shape, which can be arranged more efficiently and with a higher density, according to a matrix scheme. The analysis can be performed y different techniques depending on whether we want to analyze at mRNA level rather than protein, the expression of the presence/absence of the product of a given gene.
The innovative technology of tissue microarray slides allows investigating in a simultaneous, efficient, and above all technically controlled method, numerous samples from patient tissues or animal models. Also used in many research areas and all branches of medicine from oncology to neurology.
With a "coring" system using a special hollow needle, small biopsies (cores) of the appropriate size (usually from 0.6 to 2mm), are taken from regions of interest in blocks of paraffin tissue (donor blocks) and then aligned, according to a matrix structure. With a microtome, several sections of the TMA block are cut, with which they are set up as many slides; 100/500 parts can be obtained from each block per array. The slides are then analyzed under a microscope using appropriate evaluation and investigation techniques (immunohistochemistry, immunofluorescence, in situ hybridization, FISH, histochemical staining).
Therefore, Tissue microarray slides also referred to as TMA slides, are a selection of tissue cores fabricated in a paraffin block and arranged in a precise array. Histological sections of the collection can be cut from the paraffin block, resulting in thin slices of paraffin-prepared tissue array, under a regular microscope, Slide-placed tissue microarrays are used to conduct a variety of tests on numerous tissue specimens contained on a single slide, allowing for high speed and precision in scientific experiments, for example, often use tissue microarrays slide to determine gene expression in normal and pathological tissues use the genetics to diagnose various diseases. Through this technology, complete management is obtained, starting from the paraffin block, of all the sample preparation procedures: from the automatic core drilling of the neighborhood to the cutting for the preparation of the sections, to the different immunostaining, to the acquisition and automatic reading of the slides.
Tissue microarray slides are ideally suited for the highly parallel analysis of antigens as well as for the assessment of newly identified disease-inducing genes. In a TMA with up to one hundred tissue samples on a slide, the staining effort is kept to a minimum with stable, consistent results. Tissue sections with a diameter of up to 3 mm provide sufficient area for morphological evaluation. TMA allows rapid localization of DNA or protein molecules in both standard and pathological human tissues.
Many different laboratories, mostly in biological and medical research, use tissue microarray slides to enhance the efficiency and precision with which they can perform various experiments on tissue samples. Immunohistochemistry, for example, is a procedure in which fluorescent agents are attached to exposed tissue samples a microarray of the antibody to specific antigens on the tissue specimens and researchers can bind this binding due to the fluorescent agent to identify species specific antibodies to bind specific antigens, so mandatory levels can provide a lot of information about the antigen contained in a given tissue sample different antigens can be healthy or pathological cells; Understanding the difference can allow for the accurate diagnosis of diseases and can even provide information that can be used to find remedies for various diseases.
A similar technique, commonly applied to tissue microarray slides, is called fluorescence in situ hybridization, or fish in FISH, fluorescent probes bind to specific parts of chromosomes and can be used to find information about an individual's genetic makeup For example, method can be used to identify genetic markers for various diseases, fish and immunohistochemistry methods commonly used to identify and treat cancer.
Tissue samples can be difficult to obtain in large quantities, and tissue microarray slides are usually some time to prepare, so researchers need to make sure their samples are intact and that the arrangement is made tissue correctly, for example, must be quickly processed to be processed in paraffin Disintegration Some researchers decide to pre-made tissue microarrays rather than producing their own mistakes while preparing their individual tissue microarray slides Another consideration to buying is the number of samples that can be placed on a single slide Several hundred tissue nuclei on a single slide but it can be challenging to keep track and be careful to experiment with many small samples.
Finally, the tissue microarray slides experiments allow the monitoring of gene behavior during a disease, changes in tumor tissues, the appearance of markers related to disease or toxicity prognostic factors, and gene polymorphisms, among many other applications.
The growing magnitude of information and the development of innovative techniques today provides the researchers with the powerful, flexible, non-toxic and high-performance tools. This extended scale, both in the quality and in the quality of the data obtained in microarray experiments, possess an additional question not only because of the volume of data that must be processed is very high, but also because many of the said data are obtained from way collateral, without a previous hypothesis to guide the experiment, or involve genes that today they do not have functionally assigned even for model organisms. The global information is neither good nor bad by itself; it is an instrument that, correctly used, will allow reaching a higher level of knowledge.
The evolution of this advanced technology over time led to a decrease in associated costs and infrastructure requirements, making it feasible today in pharmaceutical companies and the not clear future in specialized biomedical centers. The implementation of studies of gene behavior in the population will mark the way towards a personalized medicine where diagnostic strategies and treatment monitoring will be based on the evidence provided by microarray experiments.
In the latter case, the availability of retrospective clinical data will accelerate the identification of the existing correlations between the experimental data and the clinical reality and will allow the identification of specific expression profiles for a given type of pathology, the validation of potential targets therapeutic, analysis of diagnostic markers, prognostic and predictive response to therapy. The equipment for TMA will, therefore, be used as a "facility" for use on commission and to create "custom made TMA."If you want to read more on tissue microarray then read the following article titled, The Tissue Microarray: Tissue Analysis from Research to Treatment.