Quality Control of RNA Extracted from PAXgene Blood RNA Tubes After Different Storage Periods

Background: The PAXgene Blood RNA tube is used to protect RNA of whole blood, and the stability of RNA in this tube has already been reported. However, there are few reports on the quality of RNA from long-term preservation of these tubes. Materials and Methods: Our biobank conducted quality control of RNA extracted from the tubes after varying storage periods. A total of 300 blood samples of renal disease patients were randomly selected at each time point (from 1 month to 7 years). Results: Median RNA yields were 3.46 (2.65-4.87) mu g, 4.34 (3.20-5.87) mu g, 4.77 (2.88-6.29) mu g, 4.19 (2.65-6.26) mu g, 3.85 (2.43-6.13) mu g, and 3.21 (1.85-6.61) mu g at 1 month, 1, 2, 3, 6, and 7 years, respectively. There were no significant differences in RNA yields among all the storage periods. A(260/280) ratios were 2.02 +/- 0.04, 2.05 +/- 0.04, 2.05 +/- 0.04, 2.08 +/- 0.03, 2.12 +/- 0.10, and 2.11 +/- 0.05, all of which were >= 1.8. However, A(260/280) of the samples stored for 6 and 7 years had a rising trend, compared with the other time points (p < 0.05). Median RNA integrity number (RIN) values were 8.4 (7.6-9.1), 8.3 (7.7-8.9), 8.3 (7.8-8.8), 8.5 (8.3-8.9), 7.6 (7.1-8.1), and 7.9 (7.2-8.3) at each time point. Lower RIN values were found at 6 and 7 years compared with the other storage periods (p < 0.05). The rates of RIN values >= 7.0 were 92%, 84%, 96%, 92%, 86%, and 84%, which exhibited no differences across all the storage periods. In addition, the yields and RIN values of RNA from samples with blood clots were significantly lower than those without (p < 0.001). Conclusions: The quantity and quality of RNA extracted from PAXgene Blood RNA tubes are stable throughout cryopreservation for 7 years.