RNA is a tool used in many fields, from molecular and cellular biology to medicine and nanotechnology. For most of these uses, the integrity of RNA is required and must be maintained during storage. Even though freezing is currently the storage method of choice, the increasing number of samples to be stored and the costly use of a cold chain have highlighted the need for room temperature preservation methods. Here, we report a new room temperature technology that consists in drying RNA samples in the presence of a stabilizer in stainless steel minicapsules. These air-and water-tight capsules isolate RNA from the atmosphere and maintain an anhydrous and anoxic environment. Through the evaluation of RNA integrity over time at room temperature or 90 1C, we identified atmospheric humidity as a major deleterious factor. The degradation rate dependence in temperature fitted an Arrhenius model, with an activation energy of 28.5 kcal/mol and an extrapolated room temperature degradation rate of 3.2 10 À13 /nt/s (95% confidence interval: 2.3-4.2/nt/s). In these conditions, it is expected that an RNA molecule will be subjected to 0.7-1.3 cut every 1000 nucleotides per century. In addition, we showed that stored RNA is compatible for further analyses, such as reverse transcription-quantitative PCR. No significant change in the C q values was observed over a simulated period of several decades. At last, our data are consistent with a sequence-independent degradation rate of RNA in the solid state.

Conventional storage of blood-derived fractions relies on cold. However, lately, ambient temperature preservation has been evaluated by several independent institutions that see economic and logistic advantages in getting rid of the cold chain. Here we validated a novel procedure for ambient temperature preservation of DNA in white blood cell and buffy coat lysates based on the confinement of the desiccated biospecimens under anoxic and anhydrous atmosphere in original hermetic minicapsules. For this validation we stored encapsulated samples either at ambient temperature or at several elevated temperatures to accelerate aging. We found that DNA extracted from stored samples was of good quality with a yield of extraction as expected. Degradation rates were estimated from the average fragment size of denatured DNA run on agarose gels and from qPCR reactions. At ambient temperature, these rates were too low to be measured but the degradation rate dependence on temperature followed Arrhenius’ law, making it possible to extrapolate degradation rates at 25°C. According to these values, the DNA stored in the encapsulated blood products would remain larger than 20 kb after one century at ambient temperature. At last, qPCR experiments demonstrated the compatibility of extracted DNA with routine DNA downstream analyses. Altogether, these results showed that this novel storage method provides an adequate environment for ambient temperature long term storage of high molecular weight DNA in dehydrated lysates of white blood cells and buffy coats.

No abstract