What is Chelex 100 Resin?
Chelex 100 Resin is a type of ion-exchange medium composed of styrene divinylbenzene copolymers. It is designed to bind polyvalent metal ions, making it useful in various biological and chemical applications, including histology.
How is Chelex 100 Resin Used in Histology?
In histology, Chelex 100 Resin is primarily used for the extraction of DNA from formalin-fixed, paraffin-embedded (FFPE) tissue samples. This process is crucial for downstream applications, such as polymerase chain reaction (PCR) and sequencing.
Why is DNA Extraction from FFPE Samples Important?
FFPE samples are commonly used in medical research and diagnostics because they preserve tissue morphology and enable long-term storage. However, the formalin fixation process can cause DNA crosslinking and degradation. Efficient DNA extraction, facilitated by Chelex 100 Resin, is essential for accurate molecular analyses.
Effective removal of metal ions that could inhibit PCR.
Simplification of the DNA extraction process, reducing the need for multiple purification steps.
Compatibility with a wide range of tissue types and conditions.
How Does Chelex 100 Resin Work?
Chelex 100 Resin works by chelating metal ions through its iminodiacetate functional groups. During the DNA extraction process, the resin binds to cations such as magnesium, calcium, and iron, which can interfere with PCR and other enzymatic reactions. This chelation helps to purify the DNA, making it suitable for downstream applications.
Deparaffinization of the tissue sample.
Adding a suspension of Chelex 100 Resin to the sample.
Incubating the mixture to allow the resin to bind metal ions.
Heating the sample to denature proteins and release DNA.
Centrifuging the mixture to separate the resin and other debris from the DNA-containing supernatant.
It may not completely remove all inhibitors, especially if the sample is heavily degraded or contaminated.
It can sometimes bind to DNA, resulting in lower yields.
It requires careful handling to avoid contamination and ensure reproducibility.
Proteinase K digestion followed by phenol-chloroform extraction.
Commercial DNA extraction kits designed specifically for FFPE samples.
Magnetic bead-based purification methods.
Each method has its own set of advantages and limitations, and the choice of method often depends on the specific requirements of the study.
Conclusion
Chelex 100 Resin is a valuable tool in histology for the efficient extraction of DNA from FFPE tissues. By binding metal ions, it helps to purify DNA and enhance the accuracy of downstream molecular analyses. Despite its limitations, it remains a widely used and effective method in the field of histology.
