Formalin-fixed paraffin-embedded tissue

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A formalin-fixed paraffin-embedded tissue (English, formalin-fixed paraffin-embedded tissue or formaldehyde-fixed paraffin-embedded tissue , FFPE tissue) is a biochemical term for formalin- fixed and then paraffin- embedded tissue .

properties

The fixation of tissues with formalin and the subsequent embedding in paraffin is one of the most common methods of preserving and stabilizing biological tissues before a microsection and a histological examination under a microscope . Many clinical samples are stored as FFPE-treated samples. In subsequent genetic analyzes of the sample, the FFPE changes in the sample must be reversed, e.g. B. for an extraction and a subsequent analysis of the DNA or RNA by DNA sequencing or by microarray for purposes of personalized medicine or for purposes of proteomics . Therefore, various extraction and renaturation methods have been developed in order to be able to use FFPE preparations for other diagnostic procedures even after years. Methods of antigen unmasking are used , among other things .

Proteins

For immunostaining , the paraffin in FFPE tissues is extracted with xylene . With an ascending alcoholic series , the tissue is hydrophilized with several solutions of increasing concentrations of ethanol in xylene and later ethanol in water , so that the immunostaining can then take place with aqueous solutions. When extracting proteins, FFPE tissues are usually heated to 100 ° C before extraction.

Nucleic acids

When extracting DNA or RNA, the xylene extraction of the paraffin is often not necessary. Typical damage to nucleic acids after formaldehyde fixation is deamination of cytosine to uracil , which leads to C → T mutations after amplification via polymerase chain reaction (PCR) and sequencing , as well as single-strand breaks which shorten the length of the amplified products. Therefore, the nucleic acids extracted from FFPE tissues are occasionally treated with the enzymes uracil-N-glycosylase and a DNA ligase prior to a PCR in order to achieve partial DNA repair .

history

Antigen unmasking for the use of FFPE tissues in immunostaining was first carried out in 1991 using metal ion solutions and heating with microwaves to 100 ° C.

literature

Individual evidence

  1. ^ OJ Gustafsson, G. Arentz, P. Hoffmann: Proteomic developments in the analysis of formalin-fixed tissue. In: Biochimica et Biophysica Acta . [Electronic publication before printing] October 2014, ISSN  0006-3002 , doi: 10.1016 / j.bbapap.2014.10.003 , PMID 25315853 .
  2. ↑ L. Giusti, A. Lucacchini: Proteomic studies of formalin-fixed paraffin-embedded tissues. In: Expert review of proteomics. Volume 10, Number 2, April 2013, ISSN  1744-8387 , pp. 165-177, doi: 10.1586 / epr.13.3 , PMID 23573783 .
  3. ^ R. Klopfleisch, AT Weiss, AD Gruber: Excavation of a buried treasure - DNA, mRNA, miRNA and protein analysis in formalin fixed, paraffin embedded tissues. In: Histology and histopathology. Volume 26, Number 6, June 2011, ISSN  1699-5848 , pp. 797-810, PMID 21472693 .
  4. ^ JA Fairley, K. Gilmour, K. Walsh: Making the most of pathological specimens: molecular diagnosis in formalin-fixed, paraffin embedded tissue. In: Current drug targets. Volume 13, Number 12, November 2012, ISSN  1873-5592 , pp. 1475-1487, PMID 22974391 .
  5. ^ A b S. R. Shi, Y. Shi, CR Taylor: Antigen retrieval immunohistochemistry: review and future prospects in research and diagnosis over two decades. In: The journal of histochemistry and cytochemistry: official journal of the Histochemistry Society. Volume 59, number 1, January 2011, ISSN  1551-5044 , pp. 13-32, doi: 10.1369 / jhc.2010.957191 , PMID 21339172 , PMC 3201121 (free full text).
  6. ^ Gudrun Lang: Histotechnology. Springer-Verlag, 2013. ISBN 978-3-7091-1190-1 . Chapter 8.3.2.3 Reagents.
  7. ↑ SR Shi, ME Key, KL Kalra: Antigen retrieval in formalin-fixed, paraffin-embedded tissues: an enhancement method for immunohistochemical staining based on microwave oven heating of tissue sections. In: The journal of histochemistry and cytochemistry: official journal of the Histochemistry Society. Volume 39, Number 6, June 1991, ISSN  0022-1554 , pp. 741-748, PMID 1709656 .