Cat. No. / ID: 765512
The fixation and stabilization method preserves tissue morphology and the integrity of nucleic acids without destructive crosslinking and degradation found in formalin-fixed tissues (see figure " Preservation of tissue morphology").
When fixed tissue is stored in PAXgene Tissue STABILIZER, the nucleic acids, proteins, and morphology of the tissue sample are stable for up to 7 days at room temperature (15–25°C) or for up to 4 weeks at 2–8°C. Tissue samples can even be stored in the PAXgene Tissue STABILIZER for longer periods at –20°C (–15°C to –30°C) or –80°C (–65°C to –90°C) without negative effects on the morphology of the tissue or the integrity of the nucleic acids.
Specifications for storage conditions in PAXgene Tissue STABILIZER were determined using animal tissues.
The methods for tissue fixation currently used in traditional histology are of limited use for molecular analysis. Fixatives that contain formaldehyde crosslink biomolecules and modify nucleic acids and proteins. Such crosslinks lead to nucleic acid degradation during tissue fixation, storage, and processing. Since they cannot be removed completely, the resulting chemical modifications can cause inhibition in downstream applications, such as quantitative PCR or RT-PCR. To enable both molecular and traditional pathology testing from the same specimen, a method is needed to stabilize molecular content and preserve morphology.
To meet this need, PreAnalytiX has developed the PAXgene Tissue System. The system consists of a fixation reagent (PAXgene Tissue FIX), a stabilization reagent (PAXgene Tissue STABILIZER), prefilled containers for tissue collection, storage, and transportation, and kits for purification of RNA, DNA, or total RNA, including miRNA. In addition, supplementary protocols for protein purification and other applications are available in the 'Resources' section of this page or at www.preanalytix.com.
PAXgene Tissue reagents in prefilled containers and PAXgene Tissue Kits provide a complete preanalytical solution for collection, fixation, and stabilization of tissue, and purification of high-quality nucleic acids for molecular research analysis.
The PAXgene Tissue STABILIZER stabilization reagent contains alcohol and other stabilization agents.
It is strongly advised to follow the recommendations for preparing sample material provided in the corresponding Protocol Sheet to ensure reliable results.
Plasma: It is recommended to perform plasma separation immediately after blood collection when using EDTA as anticoagulant to prevent the release of genomic DNA into the plasma fraction.
Urine: Because circulating cell-free DNA in non-stabilized urine samples is rapidly degraded after sample collection due to high nuclease activity, eluates may contain no DNA or exhibit low DNA concentration. Therefore, it is recommended to stabilize urine samples. Even when using stabilized urine, it is recommended to perform a centrifugation step immediately after stabilization to prevent the release of genomic DNA from cells. Alternatively, non-stabilized urine samples can be processed immediately after collection and centrifugation using ATL pretreatment and automated DNA extraction as described in the corresponding Protocol Sheet.
Yes, human tissue samples treated with the PAXgene Tissue System were successfully used for Fluorescence in situ hybridization (FISH) and Chromogenic in situ hybridization (CISH). However, specimens treated with the PAXgene Tissue System are more sensitive to enzyme digestion compared to formalin-fixed samples. Enzyme digestion and other pretreatment steps may need to be optimized.
Human tissue samples treated with the PAXgene Tissue System were successfully used for periodic acid schiff (PAS), resorcin fuchsin, sirius red, and Gomori staining (Kap et al., PLoS ONE 6(11): e27704). However, to achieve the same staining intensities with both PFPE and formalin-fixed, paraffin-embedded (FFPE) samples, it may be necessary to adjust incubation times.
PFPE tissue blocks can be stored at 2–25°C for short-term storage or transport. However, biomolecules within paraffin blocks will undergo slow chemical degradation. To better preserve morphology and biomolecule integrity within the paraffin-embedded tissue, store PFPE blocks at–30°C to –15°C. For the latest results on long-term storage of PFPE and formalin-fixed, paraffin-embedded (FFPE) tissue, see poster RT-PCR Performance of RNA Obtained from Archived FFPE and PFPE Blocks of Tissue under the Product Resources tab.
Yes. Comparable morphology was observed in adjacent pieces from a tissue sample fixed either with neutral-buffered formalin or with the PAXgene Tissue System for a variety of human and animal tissue (Gündisch et al., Virchows Arch. 2014 Aug; Kap et al., PLoS ONE 6(11): e27704). Examples are provided in the Tissue Atlas at www.preanalytix.com. PAXgene Tissue treated specimens have a tendency to be more eosinophilic. If an identical staining pattern to formalin-fixed samples is required, the incubation time in eosin should be reduced.
RNA yield depends on several parameters, such as tissue type, time from resection until fixation, fixation time (ideally 2 to 4 hours), processing protocol used and age and storage conditions of the PFPE block.
In a study with PFPE tissue sections (area: 100 mm²; thickness: 10 µm) median RNA yield from rat liver was 4.2 µg (n=58), from kidney 2.2 µg (n=58), from spleen 4.7 µg (n=58), from intestine 4.7 µg (n=58) and from lung 0.9 µg (n=58) (see Technical Note "Yield, purity, and integrity of RNA purified from PAXgene Tissue fixed, paraffin-embedded (PFPE) rat tissue" under the Product Resources tab).
The PAXgene Tissue DNA, RNA, and miRNA Kits are based on proven QIAGEN technologies. Nucleic acids isolated with these kits are generally of high purity.
On average, measurements of the A260/A280 ratio for DNA purified with the PAXgene Tissue DNA Kit are >1.7, and ratios for RNA and miRNA purified with the PAXgene Tissue RNA or miRNA Kits are both >1.8.
For examples of RNA purity see Technical Note "Yield, purity, and integrity of RNA purified from PAXgene Tissue fixed, paraffin-embedded (PFPE) rat tissue" under the Product Resources tab.
Yes. All processors commonly used for formalin-fixed samples can be used to produce PAXgene Tissue fixed, paraffin-embedded (PFPE) blocks of tissue. However, when processing PAXgene Tissue-treated specimens, do not use reagents contaminated with formalin. Residual formalin can lead to significant reduction of nucleic acid yield and integrity from PFPE tissue samples (see Technical Note “Influence of formalin contamination during processing of PAXgene Tissue fixed, paraffin-embedded tissue (PFPE) on RNA yield, integrity, and performance in quantitative RT-PCR”). Therefore, always use separate batches of reagents (alcohol, xylene, or xylene substitutes) for processing PAXgene Tissue fixed and formalin-fixed samples.
Fixation is performed within a standard tissue cassette. The maximum sample size is 4 x 15 x 15 mm, so that the sample fits in the cassette without requiring physical pressure to close the lid. The cassette should leave no marks or grid impressions on the tissue.