Effects of ex vivo ischemia time and delayed processing on quality of specimens in tissue biobank

The RNA quality of tissue biobank is crucial for translational research; however, the effects of the ex vivo ischemia time on RNA integrity and expression of genes related to hypoxia, stress, apoptosis and autophagy remains elusive. A total of 18 carcinoma tissues were stored at room temperature for 15 min, 30 min, 1, 2, 4, 8 and 24 h. The integrity and purity of isolated RNA were analyzed. Furthermore, the gene expression of mTOR, hypoxia‑inducible factor 1α, phosphatidylinositol 4,5‑bisphosphate 3‑kinase catalytic subunit β isoform (PI3KCB), threonine kinase 1 (AKT1), NF‑κB, protein kinase AMP‑activated catalytic subunit α1 (AMPKα1), caspase 8 (CASP8), unc‑51 like autophagy activating kinase 1 and Fas cell surface death receptor were analyzed using reverse transcription‑quantitative PCR. The results demonstrated that RNA integrity numbers (RINs) remained stable in carcinoma tissues following ex vivo ischemia for 2 h at room temperature and that degradation began at 4 h (P<0.001). Additionally, the expression of PI3KCB, AKT1, AMPKα1 and CASP8 decreased at time points 8‑24 h following ex vivo ischemia and delayed processing (P<0.001). In conclusion, >2 h of ex vivo ischemia and delayed processing induced RNA degradation and RIN, and the gene expressions of PI3KCB, AKT, AMPKα1 and CASP8 may be considered as markers to evaluate tissue quality at the gene expression level, providing a method for the standard processing and assessment of tissue specimen.