Quality Control Program for Fresh Frozen Tissue and Its Results of Chonbuk National University Hospital National Biobank of Korea

BACKGROUND: Molecular tools for tissue profiling generally require collection of fresh frozen tissues (FFT) as sources of high-quality DNA and RNA. Nowadays, researchers carry out large-scale, multi-center studies and they request inter-institutional minimal intrinsic bias, some fundamental similarities, and the same standardized and validated procedures. METHODS: This study reports standardized quality control procedure for fresh frozen tissue of the National Biobank of Korea. RESULTS: The main procedures for quality control for FFT are as follows: records related to sample collection such as labeling of samples, transport temperature, lag time from excision of tissue to freezing, and sample size were reviewed for all fresh frozen samples. The stability of RNA and DNA in fresh frozen tissue was evaluated for 3% of collected samples and purity was assessed (ratio of the absorbance at 260 and 280 nm) as was integrity (agarose gel electrophoresis). Stained hematoxylin and eosin sections were reviewed by a pathologist to confirm the diagnosis and to assess how representative the frozen sample was. CONCLUSIONS: We introduced that the quality-control criteria for fresh frozen tissue of the NBK. We expect that this study contributes to standardization of collection, storage, and quality control of fresh frozen tissue.

Effects of Delay in the Snap Freezing of Colorectal Cancer Tissues on the Quality of DNA and RNA

PURPOSE: The success of basic molecular research using biospecimens strongly depends on the quality of the specimen. In this study, we evaluated the effects of delayed freezing time on the stability of DNA and RNA in fresh frozen tissue from patients with colorectal cancer. METHODS: Tissues were frozen at 10, 30, 60, and 90 minutes after extirpation of colorectal cancer in 20 cases. Absorbance ratio of 260 to 280 nm (A(260)/A(280)) and agarose gel electrophoresis were evaluated. In addition, the RNA integrity number (RIN) was assayed for the analysis of the RNA integrity. RESULTS: Regardless of delayed freezing time, all DNA and RNA samples revealed A(260)/A(280) ratios of more than 1.9, and all DNA samples showed a discrete, high-molecular-weight band on agarose gel electrophoresis. The RINs were 7.53 +/- 2.04, 6.70 +/- 1.88, 6.47 +/- 2.58, and 4.22 +/- 2.34 at 10, 30, 60, and 90 minutes, respectively. Though the concentration of RNA was not affected by delayed freezing, the RNA integrity was decreased with increasing delayed freezing time. CONCLUSION: According to the RIN results, we recommend that the collection of colorectal cancer tissue should be done within 10 minutes for studies requiring RNA of high quality and within 30 minutes for usual RNA studies.