Instituto Murciano de Investigación Biosanitaria (IMIB)
A sustainable alternative to deep-freezing for serum preservation.
Objective
To compare the quality and functionality of serum samples stabilized and stored at room temperature vs. those frozen at -80°C in the context of a prospective biobank sample collection. The quality of freeze-dried samples was compared to frozen samples to demonstrate their usefulness in the study of serum from general population donors.
Materials and Methods
Samples used for the study
40 Serum samples
Procedure
The collected samples were evaluated according to the QA and subsequently divided into 5 parts: 1 for initial control, 2 for freeze-drying and 2 for freezing at 80°C. Aliquots of 500 µL were lyophilised immediately after collection and at the same time as freezing. All freeze-dried samples, were stored at room temperature.
Lyophilized samples were compared to frozen samples using defined quality criteria to demonstrate their utility in the study of serum from general population donors.
Samples were evaluated at three different times: first, fresh, immediately after collection to perform an initial quality control (QC) corresponding to time 0; then, after one month of lyophilized or frozen storage (time: 1 month); and finally, they will be evaluated after six months of storage under the same conditions (time: 6 months).
Quality Assurance
Ceruloplasmin Colorimeter Assay
Protease Activity Assay
An activity assay was performed to check the state of degradation of both ceruloplasmin and proteases in serum samples. These assays will confirm whether the protein is damaged after lyophilization and freezing at different storage times.
Results
When compared with fresh measurements, both frozen and freeze-dried serum samples stored for 1 month showed reduced ceruloplasmin activity (left). However, this reduction was more pronounced in freeze-dried samples (50,6% activity vs 78% activity) (right).
Regarding protease activity, both frozen and freeze-dried serum samples stored for 1 month showed a minor reduction when compared with the results obtained prior storage (left). Nevertheless, this reduction was almost identical between both types of storage, showing slightly lower values in the frozen samples (83,5% activity vs 87,8% activity) (right).
Conclusion
300K Plasma and Serum Stabilization Solution offers an innovative solution for RT Storage of serum samples becoming a real alternative to ultra-low temperature freezing for the detection of specific metabolites
- Further studies are needed to ensure the use of these technology for all kinds of metabolites.
- Freeze-dried serum samples are suitable for colorimetric activity assays.
- Results from the next time point will provide a more robust information about the protective effect of both types of storage.
