In today’s clinical and translational research, blood is one of most common biospecimens being used. Although the highest DNA yield and quality is achieved by purifying genomic DNA from freshly harvested material, regretfully most of our precious samples cannot be processed straight away. That´s why sample management is so crucial right from the very start. Did you know that by choosing the wrong treatment, storage buffer or temperature it can cause varying degrees of DNA degradation? This can lead, in the worst case scenario, to no PCR amplification products.
It might be hard to imagine, but up until the last decade the procurement of biospecimens in general was a grey area with only “best guess” approaches based on observations (1–2). In order to produce more evidence-based best practices rather than relying too much on empirical observations, organizations like the International Society for Biological and Environmental Repositories and the National Cancer Institute started to draft best practices for collection and storage of human biospecimens like blood (3–4).
Additionally, QIAGEN’s recently-completed 16-year DNA stability study shows the impact of storage buffer and temperature conditions. For this study, DNA from 24 peripheral blood samples was purified using the QIAamp DNA Blood Mini Kit. DNA was either eluted in water or with Buffer AE supplied with the kit, which contains 10 mM Tris·Cl and 0.5 mM EDTA, pH 9.0.
The study showed that DNA samples remained intact when stored in Buffer AE at 2–8ºC or –20ºC or in water at –20ºC, but were degraded to varying degrees when stored in water at 2–8ºC.
The DNA degradation may have been caused due to acid hydrolysis at pH 5–6, since water is unbuffered. Buffer AE protected DNA throughout the 16 years of storage, not only buffering against low pH with Tris, but also inhibiting nucleases with EDTA.
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- 1. Vaught, J.B., Henderson, M.K. and Compton, C.C. (2012) Biospecimens and biorepositories: from afterthought to science. Cancer Epidemiol Biomarkers Prev. 21, 253. Link
- 2. Shabihkhani, M et al. (2014) The procurement, storage and quality assurance of frozen blood and tissue biospecimens in pathology, biorepository, and biobank settings. Clin. Biochem. 47, 258. Link
- 3. Campbell, L.D. et al. (2012) Development of the ISBER Best Practices for Repositories: Collection, Storage, Retrieval and Distribution of Biological Materials for Research. Biopreserv. and Biobank. 10, 232. Link
- 4. National Cancer Institute Best Practices for Biospecimen Resources. (2016) Link