Background: Biobanks process, store, and supply biological materials for research. Preanalytical factors, especially storage time and temperature, must be controlled and standardized at all stages when handling biospecimen samples, especially because the literature reports highly contradictory optimal parameters. As large-sample studies are required to better understand the influence of time and temperature on cryopreserved samples' quality for genomic research, this study evaluated the integrity and quality of cryopreserved samples stored for up to 9 years at the biobank of Barretos Cancer Hospital, one of the largest biobanks in Latin America. Methods: We randomly selected 447 samples with tumor tissue paired with buffy coat or peripheral blood mononuclear cells (PBMCs) that were stored from 2008 to 2016. The genetic material quality was evaluated based on RNA integrity (RIN) and DNA integrity (DIN) ≥7, which indicated undegraded samples, and compared with storage time, which means that for DNA storage time, samples <8.1 and ≥8.1 years and for RNA <4.5 and ≥4.5 were used. Results: A total of 190 tumor tissues were eligible for DNA and RNA extraction. Those stored for 8 years had lower DIN (68%) than those stored for a shorter period (92%). A similar pattern, based on storage time (<8.1 and ≥8.1 years), was observed in the buffy coat (74% and 95%, respectively) and PBMCs (54% and 96%, respectively). For RNA extracted from tumor tissues, we observed lower RIN in samples stored for 4.5 years (17%) than in samples stored for a shorter period (45%). Buffy coat and PBMC samples stored at -30°C exhibited greater degradation (26%) than those stored at -80°C (1%). The DIN (p = 0.15) and RNA (p = 0.18) were unrelated to topography type. Conclusion: The temperature, particularly cryopreservation methodology, and storage time were the main factors that affected nucleic acid integrity, especially RNA, during cryopreservation of biospecimens.
Keywords: biobank; biospecimens; nucleic acid integrity; quality control; storage time.