Long-term storage of endocrine tissues at - 80°C does not adversely affect RNA quality or overall histomorphology.
Author(s): Andreasson A, Kiss NB, Juhlin CC, Höög A
Publication: Biopreserv Biobank, 2013, Vol. 11, Page 366-70
PubMed ID: 24475321 PubMed Review Paper? No
Purpose of Paper
The paper investigated the effects of long-term storage of normal and tumor endocrine tissue at -80°C on RNA quality and tissue morphology.
Conclusion of Paper
RNA quality, determined by RNA integrity number (RIN), was not affected by up to 27 years of storage at -80°C when all specimens were combined. However, correlations between storage duration and RIN were significant among individual specimen types, as a strong negative correlation was observed among paraganglioma (PGL) specimens (ρ= -0.739; P=0.0025) and a weak positive correlation was observed among pheochromocytoma (PCC) specimens (ρ = 0.367; P=0.0005). Lower RIN values were observed among anaplastic thyroid cancers (mean RIN 5.3) but may have been influenced by necrosis and fibrosis caused by radio- and chemotherapies administered prior to surgical procurement. Tissue composition and morphological quality were not affected by storage duration and no correlation between tissue morphology and RIN values was observed.
Studies
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Study Purpose
The study investigated the effects of long-term storage of normal and tumor tissue specimens from adrenal and thyroid glands at -80° C on RNA quality and tissue morphology on normal and tumor tissue specimens from adrenal and thyroid glands. A total of 153 specimens comprised of 86 pheochromocytomas (PCC), 14 paragangliomas (PGL), 25 adrenocortical cancers (ACC), 11 anaplastic thyroid cancers (ATC), and 17 cases with normal adrenal gland tissue (nADR) were collected from surgical patients, snap-frozen in liquid nitrogen and stored at -80° C from 1986 – 2011, a 27-year period. RNA was extracted from each specimen and RNA quality was determined by RNA Integrity Number (RIN) using a bioanalyzer. A small piece of tissue from 86% of the specimens were fixed in neutral-buffered 4% formaldehyde, H&E stained, and examined independently by two pathologists for tumor or normal cell content, cytological and structural appearance, and graded for morphological quality as “excellent”, “acceptable” or “bad”.
Summary of Findings:
RIN values were not significantly correlated with storage time when all tissue specimens were considered (P = 0.36). Slightly higher RIN values were observed in specimens collected in the first decade of the collection period, which the authors note may be explained by shorter delays in specimen processing as a result of closer proximity of the processing site to the operating room. The duration of frozen storage and RIN were not correlated among nADR, ACC, or ATC specimens (P= 0.1619, P=0.7474 and P= 0.1619, respectively). However, a strong negative correlation (ρ = -0.739; p=0.0025) and a weak positive correlation (ρ =0.367; p=0.0005) were observed among PGL and PCC specimens, respectively, for storage duration and RIN. Lower RIN values were observed among anaplastic thyroid cancers (mean RIN 5.3) but may have been influenced by necrosis and fibrosis caused by radio- and chemotherapies administered prior to surgical procurement. Morphological representativeness (defined as tumor or normal cell content of more than 70%) was determined in 88% of the cases and tissue morphology was designated as ‘‘excellent’’ or ‘‘acceptable’’ in all cases. The authors state that no correlation between the quality of tissue morphology and RIN was observed but data was not provided.
Biospecimens
Preservative Types
- Formalin
- Frozen
Diagnoses:
- Neoplastic - Carcinoma
- Normal
Platform:
Analyte Technology Platform RNA Automated electrophoresis/Bioanalyzer Morphology H-and-E microscopy Pre-analytical Factors:
Classification Pre-analytical Factor Value(s) Storage Storage duration 2 - 27 years
Preaquisition Diagnosis/ patient condition Normal
Pheochromocytoma
Paraganglioma
Adrenocortical cancer
Anaplastic thyroid cancer