Maximizing DNA yield for epidemiologic studies: no more buffy coats?

Some molecular analyses require microgram quantities of DNA, yet many epidemiologic studies preserve only the buffy coat. In Frederick, Maryland, in 2010, we estimated DNA yields from 5 mL of whole blood and from equivalent amounts of all-cell-pellet (ACP) fraction, buffy coat, and residual blood cells from fresh blood (n = 10 volunteers) and from both fresh and frozen blood (n = 10). We extracted DNA with the QIAamp DNA Blood Midi Kit (Qiagen Sciences, Germantown, Maryland) for silica spin column capture and measured double-stranded DNA. Yields from frozen blood fractions were not statistically significantly different from those obtained from fresh fractions. ACP fractions yielded 80.6% (95% confidence interval: 66, 97) of the yield of frozen whole blood and 99.3% (95% confidence interval: 86, 100) of the yield of fresh blood. Frozen buffy coat and residual blood cells each yielded only half as much DNA as frozen ACP, and the yields were more variable. Assuming that DNA yield and quality from frozen ACP are stable, we recommend freezing plasma and ACP. Not only does ACP yield twice as much DNA as buffy coat but it is easier to process, and its yield is less variable from person to person. Long-term stability studies are needed. If one wishes to separate buffy coat before freezing, one should also save the residual blood cell fraction, which contains just as much DNA.

Custodianship as an ethical framework for biospecimen-based research.

Human biological specimens (biospecimens) are increasingly important for research that aims to advance human health. Yet, despite significant proliferation in specimen-based research and discoveries during the past decade, research remains challenged by the inequitable access to high-quality biospecimens that are collected under rigorous ethical standards. This is primarily caused by the complex level of control and ownership exerted by the myriad of stakeholders involved in the biospecimen research process. This article discusses the ethical model of custodianship as a framework for biospecimen-based research to promote fair research access and resolve issues of control and potential conflicts between biobanks, investigators, human research participants (human subjects), and sponsors. Custodianship is the caretaking obligation for biospecimens from initial collection to final dissemination of research findings. It endorses key practices and operating principles for responsible oversight of biospecimens collected for research. Embracing the custodial model would ensure transparency in research, fairness to human research participants, and shared accountability among all stakeholders involved in biospecimen-based research.