Collection, Storage, Retrieval and Distribution of Biological Materials for Research

Validation of PON1 enzyme activity assays for longitudinal studies

BACKGROUND

Paraoxonase (PON1) enzymatic activity assays are used to characterize sensitivity to organophosphates and oxidative stress. Length of sample storage, temperature and other factors may influence variability of PON1 measurements, especially in longitudinal studies.

METHODS

Effects of assay temperature, storage duration up to 7 y (-80 degrees C), freeze-thaw cycles, the type of specimen (serum or heparinized plasma) and assay variability were evaluated for 4 PON1 substrate-specific assays using samples from two pediatric cohorts and laboratory volunteers.

RESULTS

Intra- and inter-assay variation, as well as inter-laboratory variability for PON1 activities were <10%. The effect of storage duration up to 2 y was minimal. However, after 7 y, arylesterase, paraoxonase, and chlorpyrifos-oxonase activities decreased more noticeably. Similarly, while freeze-thaw cycles did not affect the PON1 activities in samples stored <2 y, this factor was more significant after 7 y for arylesterase. Assay temperature and specimen type also influenced PON1 measurements.

CONCLUSIONS

Sources of technical variability of PON1 activity assays, including storage duration, freeze-thaw, and temperature should be monitored and minimized through study design, quality control procedures and statistical methods, especially in longitudinal studies where specimens may be stored for years prior to analysis.

[Biological safety in the storage and transport of biological specimens from patients with respiratory diseases used in research settings]

Major advances in genomics and proteomics have prompted the creation of biological specimen collections and biobanks for use in biomedical research. These specimen collections and the wealth of data they generate will allow longitudinal studies to be conducted and subproducts such as DNA or RNA to be obtained. They may even be used in future studies. To ensure specimen integrity, from the outset it is necessary to define procedures for sampling, transport and storage, the subproducts to be obtained, and the end purpose, as well as to address biosafety issues and arrange for suitable equipment monitoring. Strict control of these conditions will confer added value on the specimens, as quality and traceability would be assured. This article aims to provide a general overview of the recommendations concerning biological safety, transport, and storage of biological specimens for biomedical research into respiratory diseases in accordance with current legislation.

Influence of evolution in tumor biobanking on the interpretation of translational research

PURPOSE

Translational cancer research increasingly relies on human tissue biospecimens and this has coincided with a shift in tissue biobanking approach. Newer biobanks (post year 2000) deploy standard operating procedures to reduce variability around biospecimen collection. Because current translational research is based on pre-2000 and post-2000 era biospecimens, we consider whether the collection era may influence gene expression data.

DESIGN

We compared the range of breast tumor collection times from pre-2000 and post-2000 era biobanks and compared estrogen receptor (ER) protein expression with collection time. We then collected 10 breast tumor biospecimens under a standardized protocol and examined whether the expression of c-myc and ER was influenced by storage on ice < or = 24 hours.

RESULTS

The range of collection times achieved at a pre-2000 versus post-2000 era biobank differed. Thirty-two percent of biospecimens were cryopreserved within 30 minutes at the pre-2000 era biobank versus 76% at the post-2000 era biobank. Collection time and ER protein level was inversely correlated (r = -0.19, P = 0.025; n = 137). We observed a wide range in initial c-myc and ER mRNA levels (50- versus 130-fold). Although mRNA levels of both genes declined with increasing collection time, the rate of change differed because c-myc was significantly reduced after 24 hours (mean reduction to 79% of initial) versus ER (94% of initial).

CONCLUSION

The overall shift in biobanking around the year 2000 is reflected in the ranges of collection times associated with pre-2000 and post-2000 era biobanks. Because collection time can differentially alter gene expression, the biospecimen collection era should be considered in gene expression studies.

Biobanking for better healthcare

Translational cancer research is highly dependent of large series of cases including high quality samples and their associated data. Comprehensive Cancer Centers should be involved in networks to enable large-scale multi-center research projects between the centers [Ringborg, U., de Valeriola, D., van Harten, W., Llombart-Bosch, A., Lombardo, C., Nilsson, K., Philip, T., Pierotti, M.A., Riegman, P., Saghatchian, M., Storme, G., Tursz, T., Verellen, D, 2008. Improvement of European translational cancer research. Collaboration between comprehensive cancer centers. Tumori 94, 143-146.]. Combating cancer knows many frontiers. Research is needed for prevention as well as better care for those who have acquired the disease. This implies that human samples for cancer research need to be sourced from distinct forms of biobanking. An easier access to these samples for the scientific community is considered as the main bottleneck for research for health, and biobanks are the most adequate site to try to resolve this issue [Ozols, R.F., Herbst, R.S., Colson, Y.L., Gralow, J., Bonner, J., Curran Jr., W.J., Eisenberg, B.L., Ganz, P.A., Kramer, B.S., Kris, M.G., Markman, M., Mayer, R.J., Raghavan, D., Reaman, G.H., Sawaya, R., Schilsky, R.L., Schuchter, L.M., Sweetenham, J.W., Vahdat, L.T., Winn, R.J., and the American Society of Clinical Oncology, 2007. Clinical cancer advances 2006: major research advances in cancer treatment, prevention, and screening: a report from the American Society of Clinical Oncology. J. Clin. Oncol. 25, 146-162.]. However, biobanks should not be considered a static activity. On the contrary, biobanking is a young discipline [Morente, M.M., Fernandez, P.L., de Alava, E. Biobanking: old activity or young discipline? Semin. Diagn. Pathol., in press.], which need continuously evolve according to the permanent development of new techniques and new scientific goals. To accomplish current requirements of the scientific community biobanks need to face some essential challenges including an appropriate design, harmonized and more suitable procedures, and sustainability, all of them in the framework of their ethic, legal and social dimensions. This review therefore presents an overview on these issues, based on the works and discussions of the Marble Arch International Working Group on Biobanking for Biomedical Research, integrated by experts in biobanking from five continents.

Evaluation of Freeze Thaw Cycles on stored plasma in the Biobank of the Norwegian Mother and Child Cohort Study

BACKGROUND: In many cohort studies, biological specimens are being stored without specific plans for analyses. In the Norwegian Mother and Child Cohort Study biological specimens (DNA, plasma, and whole blood) are stored on 96-well plates and as a result may undergo multiple freeze-thaw cycles. METHODS: To explore the impact of multiple freeze-thaw cycles on chemical constituents, we conducted a quality control study using pooled EDTA-plasma. Over a two-year period, samples stored at -80 degrees C were subjected up to 100 freeze-thaw cycles. Specimens were analyzed in triplicate for sodium, cholesterol, triglycerides, vitamin E, aspartate aminotransferase (AST), and free fatty acids. We assessed the percent change of analyte concentration from the values for the first freeze-thaw cycle, because this is the baseline for all stored specimens. RESULTS: With the exception of free fatty acids, there was little change over the first 10 freeze-thaw cycles. A majority of analytes showed no significant changes until 30 freeze-thaw cycles. After 30 freeze-thaw cycles, the largest percent change was observed for free fatty acids (+32%), AST (+21%), and triglycerides (-19%). CONCLUSIONS: Human plasma can go through several freeze-thaw cycles before analysis without influencing sample integrity for the selected analytes.