Ambion’s RNAlater is a proprietary, solution-based product for storing tissue samples that will subsequently be used for RNA extraction.
The most common procedure for preserving tissue for the extraction of RNA is to freeze the tissue sample in liquid nitrogen. One of the main disadvantages of the liquid nitrogen method is that it requires a source of liquid nitrogen and, as a consequence, is associated with the significant hazards of handling the liquid nitrogen. Furthermore, the tissue has to be kept frozen until it is homogenized in the commonly used guanidinium thiocyanate solution to prevent release of cellular RNAses and subsequent degradation of cellular RNA. In contrast, RNAlater is a non-toxic solution that is stable at room temperature and simply requires the immersion of the tissue in five to ten volumes of solution.
Depending on the time frame that the researcher wishes to isolate the RNA, the tissue can be stored at either 4C for a month or so or at –20C indefinitely without noticeable loss of RNA integrity. Although Ambion claims that the RNA integrity is good for 1 day when tissues are stored in RNAlater at 37C and one week when stored at room temperature (25C) it is doubtful that any researcher would store RNA at these temperatures. In our experience, we usually dissect tissues and isolate RNA at the time of tissue removal or store tissue samples at –20C in five volumes of the RNAlater solution. Using this protocol we have not seen a significant loss of RNA integrity (as assessed by ethidium bromide-stained 28S and 18S ribosomal bands on denaturing gels) in the tissues we commonly work with i.e. mammary gland, kidney, liver and salivary gland. Furthermore, we have successfully utilized the isolated RNA for both RT-PCR and northern blot analyses with excellent results.
With the introduction of RNAlater, the researcher is now able to store tissue samples without significant loss of RNA integrity. RNAlater is stable at room temperature, is affordable and offers the convenience of not having to deal with the hazards of liquid nitrogen.
Johnathan Shillingford, Ph.D.
Research Associate
Department of Cell Biology
Lerner Research Institute