It is critical to determine the best method for storing tissue. When researchers request tissue from our biobank, we must ensure that we are providing them with the highest quality tissue possible. Therefore, the biobank at Windber Research Institute (WRI) is constantly designing and performing experiments to determine how the tissue collected from the many donors is impacted by pre-analytical variables and how these “uncontrollable” factors could impact the derivatives of the tissue such as DNA, RNA and Protein.
Pre analytical variables may be represented by the following 1) Physiology of the human research participant 2) Specimen collection practices 3) Specimen handling practices before downstream testing (NCI Best practices, 2014; http://biospecimens.cancer.gov/bestpractices/to/bcpsrd.asp). There are other variables that could potentially affect tissue quality, for example, it is believed that “minor” aspects such as sample storage vessels (snap cap and screw lid, non-sterile, sterile or RNase/DNase free tubes) could impact tissue quality (Pfaendner 2006). Additionally, tubes can be made out of different plastics which can result in adherence of biomolecules to the vessel walls or leaching of plastic components into the sample (McDonald et al., 2008). This makes it important to ensure that samples are stored in appropriate tubes that will maintain tissue quality over time and at specific storage conditions (Smith 2011). Additionally, the storage temperature of tissue and nucleic acids is very critical (Andreasson et al. 2013). Normally, samples intended for long term storage are stored in liquid nitrogen vapor tanks at -190 degrees Celsius and samples intended for short term storage are stored in -80 degree Celsius freezers (Karisson and Toner 1996). However, not all biobanks have the ability to store in liquid nitrogen vapor and as such utilize mechanical freezers at -80 degree Celsius. It is essential for biobankers to know which types of samples can be stored at which temperature and for what length of time (Hubel, Spindler and Skubitz 2014). These are the many areas awaiting evidence based data to support biobank storage protocols. Biospecimen Science Research is the umbrella whereby these issues are being addressed and in the future, this science should provide more evidence based data to allow biobanks fully understand all that impacts tissue quality. Since biobanks have their individual interest in what they store, what these tissue samples are used for and for how long they will be stored, these evidence based studies will have to meet a variety of needs.
Interestingly, studies have shown that the concentration of the RNA stored could have an impact on the integrity of the RNA over time (Olivieri et al. 2014). In their study Olivieri et. al, showed the effects of storing RNA at high concentrations (250ng/µL) and low concentration (25ng/µL). They found that after 8 months of storage, RNA stored at high concentrations preserved its integrity while RNA stored at low concentrations showed significant degradation. Therefore, while low concentrations of RNA may be acceptable for immediate analysis, storage for a few months may not be suitable. These kinds of results are a clear indication of the complex issues that biobanks face when working to maintain tissue integrity and provide quality DNA, RNA and Protein for downstream analysis.
Proper storage of tissue and nucleic acids can greatly affect experiments and their outcome (Yang and Chang 2012). If tissue is not stored correctly, valuable proteins can be degraded (Auer et al. 2014). Additionally, degradation of RNA and/or DNA can affect critical analyses such as gene expression (Shane, Kohlmeyer & Hunter 2010). Biobanks need to be on top of these issues either by designing internal experiments that provide data for the design of evidence based Standard Operating Procedures (SOPs) or keeping abreast with research results in the area of Biospecimen Science as the source of new information/findings that will drive biobanking SOPs. The International Society for Biological and Environmental Repositories (ISBER http://www.isber.org/) and the Biorepository and Biospecimen Research Branch of the NCI (BBRB http://biospecimens.cancer.gov/default.asp) remain great resources for biobanks to tap into for current ideas and information that will enable them maintain the desired standards that will drive biobanking for quality tissue.
Andreasson, A., Kiss, NB., Juhlin, CC and Höög, A (2013). Long-Term Storage of Endocrine Tissues at -80oC Does Not Adversely Affect RNA Quality or Overall Histomorphology. Biopres. & Biobanking, 10.1089/bio.2013.0038
Auer, H., Mobley, J., Ayers, L., Bowen, J., Chuaqui, R., Johnson, L., … Ramirez, N. (2014). The effects of frozen tissue storage conditions on the integrity of RNA and protein. Biotechnic & Histochemistry : Official Publication of the Biological Stain Commission, 89(7), 518–528. http://doi.org/10.3109/10520295.2014.904927
Hubel, A., Spindler, A and Skubitz, A (2014). Storage of Human Biospecimens: Selection of the Optimal Storage Temperature. Biopres. & Biobanking, 10.1089/bio.2013.0084
Karlsson, JOM and Toner, M (1996). Long-term storage of tissues by cryopreservation: critical issues. Biomaterials, 17(3): 243-256.
McDonald, GR et al., (2008). Bioactive contaminants leach from disposable laboratory plasticware. Science, 322(5903):917
Olivieri, EHR., Franco, LA., Pereira, RG., Mota, LDC., Campos, AH and Carraro, DM (2014). Biobanking Practice: RNA Storage at Low Concentrations Affects Integrity. Biopres. & Biobanking, 10.1089/bio.2013.0056
Pfaendner, R (2006). How will additives shape the future of plastics? Polymer Degrad. Stabil. 91:2249-2256.
Shane, M. L., Kohlmeyer, M., Hunter, T., and Tighe, S. (2010). RT-qPCR Analysis of Degraded RNA using Five Different Pre-Amplification Methods. Journal of Biomolecular Techniques : JBT, 21(3 Suppl), S45.
Smith, C (2011). Selecting the Right Tubes or Plates for Your Research. Life Science Articles, http://www.biocompare.com
Yang, T-H and Chang, P-L (2012). Determination of RNA degradation by capillary electrophoresis with cyan light-emitted diode-influences fluorescence. J. of Chromatogr. A, http://dx.doi.org/10.1016/j.chroma.2012.03.070