Comparison of frozen and RNALater solid tissue storage methods for use in RNA expression microarrays.

Department of Pathology, Brigham and Women's Hospital, Boston, MA, USA.
BMC Genomics (Impact Factor: 4.4). 11/2004; 5:88. DOI: 10.1186/1471-2164-5-88
Source: PubMed

ABSTRACT Primary human tissues are an invaluable widely used tool for discovery of gene expression patterns which characterize disease states. Tissue processing methods remain unstandardized, leading to unanswered concerns of how to best store collected tissues and maintain reproducibility between laboratories. We subdivided uterine myometrial tissue specimens and stored split aliquots using the most common tissue processing methods (fresh, frozen, RNALater) before comparing quantitative RNA expression profiles on the Affymetrix U133 human expression array. Split samples and inclusion of duplicates within each processing group allowed us to undertake a formal genome-wide analysis comparing the magnitude of result variation contributed by sample source (different patients), processing protocol (fresh vs. frozen vs. 24 or 72 hours RNALater), and random background (duplicates). The dataset was randomly permuted to define a baseline pattern of ANOVA test statistic values against which the observed results could be interpreted.
14,639 of 22,283 genes were expressed in at least one sample. Patient subjects provided the greatest sources of variation in the mixed model ANOVA, with replicates and processing method the least. The magnitude of variation conferred by processing method (24 hours RNALater vs 72 hours RNALater vs. fresh vs frozen) was similar to the variability seen within replicates. Subset analysis of the test statistic according to gene functional class showed that the frequency of "outlier" ANOVA results within each functional class is overall no greater than expected by chance.
Ambient storage of tissues for 24 or 72 hours in RNALater did not contribute any systematic shift in quantitative RNA expression results relative to the alternatives of fresh or frozen tissue. This nontoxic preservative enables decentralized tissue collection for expression array analysis without a requirement for specialized equipment.

  • [Show abstract] [Hide abstract]
    ABSTRACT: Formalin-fixed tissue has been a mainstay of clinical pathology laboratories, but formalin alters many biomolecules, including nucleic acids and proteins. Meanwhile, frozen tissues contain better-preserved biomolecules, but tissue morphology is affected, limiting their diagnostic utility. Molecular fixatives promise to bridge this gap by simultaneously preserving morphology and biomolecules, enabling clinical diagnosis and molecular analyses on the same specimen. While previous reports have broadly evaluated the use of molecular fixative in various human tissues, we present here the first detailed assessment of the applicability of molecular fixative to both routine histopathological diagnosis and molecular analysis of cervical tissues. Ten specimens excised via the Loop Electrosurgical Excision Procedure, which removes conical tissue samples from the cervix, were cut into alternating pieces preserved in either formalin or molecular fixative. Cervical specimens preserved in molecular fixative were easily interpretable, despite featuring more eosinophilic cytoplasm and more recognizable chromatin texture than formalin-fixed specimens. Immunohistochemical staining patterns of p16 and Ki-67 were similar between fixatives, although Ki-67 staining was stronger in the molecular fixative specimens. The RNA of molecular fixative specimens from seven cases representing various dysplasia grades was assessed for utility in expression microarray analysis. Cluster analysis and scatter plots of duplicate samples suggest that data of sufficient quality can be obtained from as little as 50ng of RNA from molecular fixative samples. Taken together, our results show that molecular fixative may be a more versatile substitute for formalin, simultaneously preserving tissue morphology for clinical diagnosis and biomolecules for immunohistochemistry and gene expression analysis.
    Experimental and Molecular Pathology 01/2014; · 2.13 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Abstract Introduction: Hereditary transthyretin amyloidosis (ATTR) is a genetic disease caused by a point mutation in the TTR gene that causes the liver to produce an unstable TTR protein. The most effective treatment has been liver transplantation in order to replace the variant TTR producing liver with one that produces only wild-type TTR. ATTR amyloidosis patients' livers are reused for liver sick patients, i.e. the Domino procedure. However, recent findings have demonstrated that ATTR amyloidosis can develop in the recipients within 7-8 years. The aim of this study was to elucidate how the genetic profile of the liver is affected by the disease, and how amyloid deposits affect target tissue. Methods: Gene expression analysis was used to unravel the genetic profiles of Swedish ATTR V30M patients and controls. Biopsies from adipose tissue and liver were examined. Results and Conclusions: ATTR amyloid patients' gene expression profile of the main source organ, the liver, differed markedly from that of the controls, whereas the target organs' gene expression profiles were not markedly altered in the ATTR amyloid patients compared to those of the controls. An impaired ER/protein folding pathway might suggest ER overload due to mutated TTR protein.
    Amyloid: the international journal of experimental and clinical investigation: the official journal of the International Society of Amyloidosis 03/2014; · 2.12 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Biological materials collected in harsh environments such as archaeological excavations, at crime scenes, after mass disasters, in museums, or non-invasively in the field constitute a highly valuable source of genetic information. However, poor quality and limited quantity of the DNA extracted from these samples can be extremely challenging during further analyses. Here we have reviewed how degradation, decomposition, and contamination can affect DNA analysis, and how correct sample collection and storage methods will ensure the best possible conditions for further genetic analysis. Furthermore, highly efficient protocols for collection, decontamination, and extraction of DNA from minute amounts of biological material are presented.
    Biopreservation and Biobanking 02/2014; 12(1):17-22. · 1.50 Impact Factor

Full-text (2 Sources)

Available from
May 22, 2014