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RNAlater® FAQs
Preserving
RNA Before Isolation
Appropriate storage of cells or tissue samples
prior to RNA isolation is critical for preservation of intact
RNA within those samples. RNAlater is
an aqueous solution designed specifically to maintain RNA integrity
during storage of fresh tissue and cell samples. Here are some
commonly asked questions regarding RNAlater:
1) How do I use RNAlater to store
my tissue/cell sample?
• For fresh tissue, simply cut
samples to a maximum thickness of 0.5 cm in any one dimension
and submerge in 5 volumes of RNAlater.
• Cultured cells should be pelleted,
resuspended in a small volume of PBS, then mixed with 5-10
volumes of RNAlater.
• Once in RNAlater, samples
can be stored for up to 1 day at 37°C, 1 week at 25°C,
1 month or more at 4°C, and long-term at -20°C or -80°.
2) Does storing samples in RNAlater have
advantages over freezing samples on dry ice or in liquid
nitrogen?
Using samples that were stored in RNAlater is
much easier than using frozen samples. Frozen samples must be ground to a powder
and then the frozen powder must be transferred to a tube for homogenization.
This procedure is laborious, messy, risks loss of sample, and perhaps most
importantly, may lead to sample thawing, which can compromise RNA integrity.
Samples stored in RNAlater are protected from RNases as long as the
tissue remains in the solution, and they can typically be disrupted using the
simpler methods appropriate for freshly collected samples (grinding in liquid
nitrogen is only required for extremely hard or tough tissues such as bone
or tumor tissue). Thus, in addition to making sample disruption easier, storage
in RNAlater eliminates the risks of sample loss and mess due to transferring
or thawing frozen powdered tissue.
3) Has RNAlater been tested with
my tissue or with blood samples?
RNAlater has been successfully tested with many
different tissues, (including brain, heart, kidney, liver, skeletal muscle,
fat, lung) and cell types (E. coli, Drosophila, cultured mammalian cells,
and some plant cells). RNAlater can also be used to store anticoagulated
whole blood or the white blood cell fraction of whole blood. Ambion's RiboPure™-Blood
RNA Isolation Kit incorporates RNAlater and provides instructions on
how best to use RNAlater with blood.
4) Which downstream applications can
be used with tissue stored in RNAlater?
Tissue stored in RNAlater is
compatible with all commonly used RNA isolation methods, including
single reagent isolation products like Trizol®,
and all of Ambion's RNA isolation kits. It is also possible
to extract both genomic DNA and total protein from samples
stored in RNAlater. RNAlater will denature proteins,
so it is only compatible with routine protein analyses such
as Western blotting and 2D gel electrophoresis that do not
require native protein [protocols].
Note: RNAlater is not recommended for use
with tissues that will be sectioned using a cryostat.
5) How can I ship my sample in RNAlater?
Samples in RNAlater can safely
be shipped on wet ice for several days. For longer shipping
times use dry ice.
6) Can I add RNAlater to samples
that are already frozen?
• A different product, RNAlater®-ICE,
is used with samples that are already frozen. RNAlater-ICE
transitions tissue from a frozen to a non-frozen state. The
frozen tissue is simply placed in RNAlater-ICE and left
at -20°C overnight. Treated tissues can then be used
directly in standard homogenization and isolation protocols
and processed like fresh tissue.
• RNAlater and RNAlater-ICE
provide flexibility for sample collection and storage, and
help ensure that high quality RNA is preserved in samples.
Both are available in a variety of convenient sizes.
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