January 1, 1970 (Vol. , No. )
Gunnel Tybring, Ph.D. Karolinska Institute
These tips can help improve stored sample integrity and long-term stability of analytes.
Biobanks have become a hot area in recent years as many hospitals and research institutes build up large collections of biological samples from healthcare and population cohorts. Such biorepositories are becoming essential in medical research and provide a powerful tool in the identification of biomarkers for disease and development of new analytical methods for diagnostics. Retrospective sample analysis is helping scientists discover and understand why some people develop particular diseases.
However, archived samples may have been handled with various protocols for collection, processing, and storage that may have caused sample degradation and thus affect analytical findings. When collecting samples from participants over a long time period (expectations of 25+ years storage are not uncommon) secure storage and integrity of samples is of absolute importance. Here are 7 practical tips for maintaining your sample quality.
- Try to minimize the number of freeze-thaw cycles as multiple cycles degrade the sample quality. More and more data is being published that is showing the impact of freeze-thaw cycles on the analytes in blood, serum, and plasma samples.
- Most assays require very small volumes, thus the trend is to fractionate samples into multiple 50–200 μL fractions in single-use tubes in 96 or 384 microtube formats.
- Storage at -80°C or even lower temperatures <150 °C in vapor-phase liquid nitrogen is essential for the long-term stability and for preserving the activity in viable cells.
- Manual freezers often contain samples that must be pulled into room temp. for researchers to pick out the correct sample—this task is not only awkward and labor-intensive but the temperature variation also puts sample quality at risk. Automated sample recovery overcomes these issues by reducing the sample exposure to higher temperatures during withdrawal.
- Automation at -80°C is now possible and this technology enables rapid access to any sample in the frozen archive without disturbing all samples.
- The use of heat-sealed tubes, especially for large-scale repositories, can save space and offer high sample integrity at low temperatures versus screw caps.
- Effective sample and process documentation and tracking processes are essential. Recording any freeze-thaw cycles and effective data tracking of a samples’ use through barcoding can avoid variation in results caused by intravariability of samples.
Gunnel Tybring, Ph.D., senior advisor to the KI Biobank, department of medical epidemiology and biostatistics, Karolinska Institute.