What is Tissue Microarray: an informative overview?

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What is tissue microarray?

Tissue MicroarrayTissue microarray is a recent diagnostic tool in the world of pathology. In this kind of technology, one can be able to do a detailed analysis of whether one antigen has expressed itself across a sample of tissues or cells. This tissue microarray is done in a single experiment, therefore it is an evolution from the traditional way of diagnosing and testing one sample of tissue or cell at a time. Tissue Microarray therefore, is used to simultaneously analyze whether protein antigens are present in several individual tissue samples that are presented on a slide.

The composition of tissue microarray includes cores that are about 0.6mm in diameter that are extracted from the areas of interest in tissues that are paraffin-embedded. In most cases, hollow needles are normally used to get these tissue cores. The hollow needles used are ones with the required diameters that will then be inserted into the blocks of paraffin. These tissue cores are then moved to spaces in the block of the recipient paraffin that are in an array pattern that is precisely spaced. It is after this extraction and placement process that some of the parts of the array block are cut using a microtome and mounted on a microscope slide for analysis. The analysis is done using a variety of methods or staining techniques like TUNEL analysis, cDNA hybridization, IHC and many others.

What is tissue microarray then? Tissue microarray is one of the most practical and one of the best tools that helps in the molecular analysis of tissues. It is useful in the diagnosis of some of the cancerous cells and tissues. Below is a brief insight on what is tissue microarray, every aspect of tissue microarray construction, what are some of tissue microarray’s advantages and its limitations.

What is tissue microarray and some of the advantages of tissue microarray?

Tissue microarray has a number of advantages over the ordinary methods. Some of the proven benefits of tissue microarray include:

Utilization of a scarce resource.
The common size of one histologic section is normally about 3-5mm in thickness depending on the pathologist or the technician who is submitting it. The histologic sections can then be cut after use, into about 50-100 more sections. This is dependent on the skill and care of the lab technician who is handling the sections. Therefore, the advantage is that, on an average scale, each block can be able to give results for at least 100 assays. This technically means that is the same histologic section is to be used in tissue microarray formation, then it could be optimized to about 200-300 times. This is dependent on how big the tumor is in the original block. The tissue microarrays can then be sectioned in order to utilize the number of sections derived from a single array. This tissue microarray technique can therefore be used to maximize on the otherwise limited tissue resource.

It saves time through simultaneous analysis of a huge number of samples.
Tissue microarray allows for a very high acquisition of data. This saves on a lot of time that would have been used to analyze the numerous individual specimens. For example, if one tissue microarray block perhaps contains 1000 cores and is divided 200 times. This will make it possible for the analysis of 200,000 individual specimens. Therefore, tissue microarray is advantageous because it saves time, which is otherwise a limited resource.

Tissue microarray allows for uniformity in conducted experiments.
Tissue microarray allows for experimental uniformity in the sense that, using such a technique, all individual samples of cells or tissues are given the same treatment. Tissue microarrays are also open to a wide variety of techniques that included is to chemical and immunologic stains, in situ hybridization and also micro-dissection of tissues. Each of these techniques may produce varying results. Tissue microarray makes it possible for the entire specimen samples to be analyzed using a single slide. Therefore, factors that might produce varying results like temperature during testing, the retrieving of the antigen process, the concentration of the reagent to be used and other variables, will be totally standard for the whole tissue specimen to be used in tissue microarray. This therefore is an advantage of tissue microarray as it allows for uniformity.

Tissue microarray allows for decreased assay volume and costs.
Tissue microarray is very efficient due to the fact that the reagent used is minimal compared to the other methods used to analyze a specimen. This also means that less laboratory technicians might actually be needed to perform the tissue microarray analysis. This saves a lot of time and money as well as some of the reagents used are very costly.

It helps to conserve the original block of tissue.
On a number of occasions, there might be need to return the original block of tissue to the donating source, which could be a patient or institution. In such cases, tissue microarray may be performed without having to destroy the original specimen.

What are the disadvantages of tissue microarray?
Just like there are two sides of every coin, there have been some criticisms about the tissue microarray technique. One of the glaring disadvantages of using tissue microarray technique is that the extracted samples might not be an accurate representation of the entire tumor. This might be true for cancers that are heterogeneous like prostate cancer. Nevertheless, there have been great experimental studies that have actually proven the concordance between the sample tissue and the rest of the tumor the tissue is derived from. The studies conducted that the sample tissue was comparable to the whole of the tumor in almost 95% of the cases.

In a nutshell, we have explained what is tissue microarray and seen that tissue microarray is one of the proven tools that is not only practical but also very effective in helping to diagnose and identify the prognostic markers in human cancer. The results it yields are very accurate in almost 97% of the cases. There is therefore a huge possibility that tissue microarray will soon be the technique used in every type of research involving the cells and tissues. This will be a great achievement in the medical industry. Here’s a great resource to learn more on the topic of tissue microarrays.