The interference of cold ischemia time in the quality of total RNA from frozen tumor samples

Abstract

Tumor Banks were created to organize the collection, storage and distribution of biological samples from oncological patients, facilitating its use in cancer research. To ensure the quality of the samples from our bank, we implemented standard operating procedures international. In order to evaluate the influence of cold ischemia time (time between surgical removal of the specimen and the snap freezing of the sample) on the quality of the samples (evaluated by measurement integrity of their RNA), collected during 10 months two tumor samples from each donor, one with up to 30 min of cold ischemia and other with exact 45 min, totaling 100 different donors and 200 samples, 40 from each of the following organs: breast, thyroid, stomach, lung and colorectum. We extracted total RNA from the samples and with the aid of a Bioanalyser, evaluate their quality, comparing it with cold ischemia times in different organs. Among the samples up to 30 min and the samples with exact 45 min, we respectively found 63 (64.3 %) and 36 (36 %) with intact RNA, 11 (11.2 %) and 17 (17 %) partially degraded and 24 (24.5 %) and 47 (47 %) degraded (p < 0.001). Thyroid and colorectal samples were more sensitive to variations in cold ischemia time (p = 0.006 and p = 0.03, respectively). Stomach and lungs were less sensitive (p = 0.919 and p = 0.384, respectively). We concluded that the cold ischemia time up to 30 min was more efficient to maintain the integrity of RNA in most samples, and that RNA degradation varied according to the different topographies.