For decades it has been common practice among pathologists to take a tissue biopsy from a cancer patient's tumor, fix it in formaldehyde (also known as formalin), and then dry the fixed tissue and insert it into a paraffin wax block.
This preparation allows formalin-fixed, paraffin-embedded (FFPE) specimens to be cut into thin sections which can be mounted on slides and subjected to techniques such as immunohistochemistry for further analysis of protein expression, cell morphology, etc.
This method also renders samples suitable for long-term storage under ambient conditions. To get more information about the paraffin-embedded tissue visit www.geneticistinc.com/blog/paraffin-embedded-tissue-what-is-it
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As a result, clinics and research institutes around the world have accumulated a large repository of FFPE samples combined with relevant patient data. This repository has proved invaluable to researchers wishing to conduct large-scale analyzes to elucidate the molecular mechanisms of cancer.
While the FFPE biobanking network provides cancer researchers with an important resource, it is not easy to obtain adequate yields of adequate quality DNA and RNA from these samples for downstream analysis.
Fixation causes fragmentation of nucleic acids, formation of cross-links between nucleic acids and proteins, and recognition of nucleotide changes which together prevent further analysis.
Various nucleic acid purification methods have been developed especially for FFPE samples, which provide suitable results for applications such as PCR and NGS to overcome this obstacle.