Extraction of high quality RNA from cells and tissue for gene expression analyses using real-time PCR or microarray methodologies is often problematic due to RNase contamination of samples and reagents. RNAlater from Ambion, Inc. offers a simple and convenient means to avoid frustrating RNA degradation within precious irreplaceable experimental samples. RNAlater is an aqueous, non-toxic tissue and cell storage reagent that permeates cells and stabilizes intracellular RNA in unfrozen samples. RNAlater preserves the quantity and quality of RNA in cells and tissues for up to 24 hr. at 37C, 1 week at 25C, and over 30 days at 4C. RNAlater treated samples can also be transferred to -20C or -80C for long-term storage.
We have been using RNAlater routinely over the last two years in our microarray studies of gene expression in PBMC’s and intestinal lymphoid tissue. We have found that cryopreservation of cells and tissue from blood samples and biopsies invariably results in degradation and reduction in the quality of RNA present in the sample, and that use of RNAlater has virtually eliminated these problems. PBMC’s are immersed in RNAlater immediately following isolation and tissue samples are placed directly into RNAlater containing microfuge tubes before flash freezing and storage at -80C. Although our comparisons have shown that the total amount of RNA isolated is reduced slightly (by ~10%) from the total obtained in samples without RNAlater, the improvement in RNA quality and downstream data more than compensates for the loss.
In summary, we have found RNAlater to be an extremely valuable asset in our ongoing microarray and Real-time PCR studies, and now require all other labs that send us material for microarray processing and analysis to use RNAlater during sample acquisition. Thus, we highly recommend the use of RNAlater for anyone working with RNA, especially those who require short or long-term archival storage of samples before they are processed for analyses.
Michael George, Ph.D.
Dept. of Medical Microbiology and Immunology
University of California, Davis