A review of room temperature storage of biospecimen tissue and nucleic acids for anatomic pathology laboratories and biorepositories.

Frozen biospecimens are crucial for translational research and contain well preserved nucleic acids and protein. However, the risk for catastrophic freezer failure as well as space, cost, and environmental concerns argue for evaluating long-term room temperature storage alternatives. Formalin-fixed paraffin embedded (FFPE) tissues have great value but their use is limited by cross-linking and fragmentation of nucleic acids, as well as loss of enzymatic activity. Stabilization solutions can now robustly preserve fresh tissue for up to 7 days at room temperature. For longer term storage, commercial vendors of chemical matrices claim real time stability of nucleic acids of over 2 years and their accelerated aging studies to date suggest stability for 12 years for RNA and 60 years for DNA. However, anatomic pathology biorepositories store mostly frozen tissue rather than nucleic acids. Small quantities of tissue can be directly placed on some chemical matrices to stabilize DNA, however RNA and proteins are not preserved. Current lyophilization approaches can preserve histomorphology, DNA, RNA, and proteins though RNA shows moderate degradation after 1–2 years. Formalin free fixatives show improved but varying abilities to preserve nucleic acids and face validation as well as cost barriers in replacing FFPE specimens. The paraffin embedding process can degrade RNA. Development of robust long-term room temperature biospecimen tissue storage technology can potentially reduce costs for the biomedical community in the face of growing targeted therapy needs and decreasing budgets.