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Preservation of pathological tissue specimens by freeze-drying for immunohistochemical staining and various molecular
S Matsuo1, T Sugiyama, T Okuyama
1Department of Pathology, Kobe University School of Medicine, Japan.
Abstract:
Conditions of preserving DNA, RNA and protein in pathological specimens are of great importance as degradation of such macromolecules would critically affect results of molecular biological analysis. The feasibility of freeze-drying as a means of preserving pathological tissue samples for molecular analysis has previously been shown. In the present study, further tests on long-term storage conditions and analyses of freeze-dried samples by polymerase chain reaction (PCR), reverse transcriptase (RT)-PCR, western blotting and immunohistochemistry are reported. Rat chromosomal DNA of freeze-dried samples stored for 4 years showed slight degradation while RNA degradation was more prominently seen at an earlier stage of storage. However, these 4 year DNA and RNA samples were still able to serve as a template for some PCR and RT-PCR analyses, respectively. Overexpression of c-erbB-2 and p53 protein was demonstrated by western blotting and immunohistochemical staining using freeze-dried human breast cancer tissues. Although macromolecules in freeze-dried samples degrade to some extent during the preservation period, they should still be of value for certain molecular biological analyses and morphological examination; hence, providing more convenient and inexpensive ways of pathological tissue storage.
Insights
Freeze-drying pathological tissues preserves macromolecules like DNA and RNA for molecular analysis. While some degradation occurs over time, freeze-dried samples remain valuable for PCR, RT-PCR, and protein analysis, offering a convenient storage method.
Area of Science:
- Pathology
- Molecular Biology
- Biochemistry
Background:
- Preserving macromolecules like DNA, RNA, and proteins in pathological specimens is crucial for accurate molecular analysis.
- Degradation of these molecules significantly impacts analytical outcomes.
- Freeze-drying has shown potential for preserving pathological tissue samples for molecular analysis.
Purpose of the Study:
- To evaluate long-term storage conditions for freeze-dried pathological samples.
- To assess the integrity of DNA, RNA, and proteins in freeze-dried tissues over time.
- To determine the suitability of freeze-dried samples for various molecular analyses.
Main Methods:
- Freeze-drying of pathological tissue samples.
- Long-term storage of samples under various conditions.
- Analysis of DNA and RNA using polymerase chain reaction (PCR) and reverse transcriptase (RT-PCR).
- Analysis of proteins using western blotting and immunohistochemistry.
Main Results:
- Rat chromosomal DNA showed slight degradation after 4 years of storage, while RNA degradation was more pronounced earlier.
- Despite degradation, DNA and RNA from 4-year-old samples were still usable as templates for some PCR and RT-PCR analyses.
- Overexpression of c-erbB-2 and p53 proteins was successfully demonstrated in freeze-dried human breast cancer tissues using western blotting and immunohistochemistry.
Conclusions:
- Freeze-dried pathological samples undergo some macromolecular degradation during storage.
- These samples remain valuable for specific molecular biological analyses and morphological examination.
- Freeze-drying offers a more convenient and cost-effective method for pathological tissue storage.