Biobanking organizations may use a range of different methods to preserve biological samples including cryopreservation, fixation and paraffin-embedding and FTA cards.
Biobanking Samples by Cryopreservation
Cryopreservation remains the gold standard for long-term biobanking because this method maintains the integrity and biological function of cells and tissues. However, cryopreservation requires significant infrastructure, resources and space. Moreover, cryopreservation can damage cellular structure.
Biobanking Samples by Fixation
A commonly used biobanking alternative to cryopreservation is to fix samples in formalin and embed them in paraffin blocks. Paraffin-embedded samples can be biobanked at room temperature and therefore, this method is more cost effective than cryopreservation. Paraffin-embedding also preserves the structure of the sample. However, formalin fixation fragments nucleic acids and crosslinks proteins. Current laboratory techniques cannot recover undamaged DNA, RNA or protein from formalin-fixed paraffin-embedded samples.
Biobanking Sample by FTA Cards
FTA cards are another method to biobank nucleic acids from cell samples at room temperature. FTA cards are made of a specialized filter paper containing reagents that lyse cells to liberate nucleic acids then capture and stabilize nucleic acids within the card. The manufacturer states that the cards can be biobanked at room temperature if preserving DNA, but should be frozen to preserve RNA. Several studies have shown that DNA biobanked on FTA cards at room temperature is stable for at least a year1. In contrast, DNA degraded when biobanked for 16 years on room temperature FTA cards. RNA is stable on room temperature FTA cards for up to 5 months and at -20°C for at least one year.
DNA recovered from FTA cards has been successfully used in many different molecular tests showing similar results to DNA isolated from fresh cell suspensions. DNA from FTA cards has also been shown to have similar 260/280 ratios to DNA from frozen samples, indicating that FTA cards can maintain DNA quality and integrity. However, the amount of DNA that can be extracted from FTA cards is 10 times lower than the amount of DNA that can be extracted from frozen samples.
Conclusion
FTA cards offer a cost-effective, space-saving method to collect and biobank nucleic acids from cell samples. The cards are easy to ship and so offer a convenient method to share samples with collaborators. However, FTA cards only work with cell samples, not with tissue samples. The amount of DNA and RNA that can be recovered from FTA cards is low but the nucleic acid quality is comparable to that of cryopreserved samples. Therefore, FTA cards could be a useful method to biobank DNA and RNA from blood samples and other cell samples, particularly for samples that have already undergone initial testing and may otherwise be discarded due to space and cost constraints.
Reference
- Da Cunha Santos, G. FTA Cards for Preservation of Nucleic Acids for Molecular Assays. Arch Pathol Lab Med. 2018
