Researchers who draw on the serum bank note that the wealth of longitudinal data from DoDSR enables cutting-edge research. Take, for example, several projects that are searching for biomarkers of post-traumatic stress disorder. By matching up pre- and post-deployment DNA from individuals who developed PTSD and also comparing the genetic material with DNA from a control population, researchers are hoping to discern clues about when and how PTSD becomes apparent at a genetic level, impacting the DNA building blocks via DNA methylation and perhaps the silencing of certain genes. Related work is also focusing on microRNA—a small, noncoding RNA molecule—that helps regulate numerous biological processes and serves as a fingerprint for disease development.
Meanwhile, other researchers are studying serum to garner clues about links between traumatic brain injury (TBI) and DNA methylation among individuals who served in Iraq and Afghanistan, gleaning information from samples on 150 service members with mild to severe TBI, along with 50 control subjects. Because individuals—both on and off the battlefield—can suffer from mild TBI and not know it, identifying a biomarker could help speed up clinical care, says study investigator Jennifer Rusiecki, an epidemiologist at Uniformed Services University of the Health Sciences in Bethesda, Md.
Without the serum available through DoDSR and its accompanying information, some of this work would likely be impossible. “I’m not aware of other banks that have this data,” Rusiecki says. All told, almost 75 publications have depended on data gleaned from the samples in these freezers. Still more projects have drawn on them but did not make it into print. And because the repository’s stated purpose is health surveillance, the samples would not be chucked even if all the studies were halted, DoDSR’s Rubertone says.
The military has instituted safeguards to prevent misuse of the serum reserve. All studies conducted with DoDSR serums are required to have a military co-investigator, a policy DoD put in place to help ensure that the serum is being used for military-relevant purposes. Researchers must also receive approval from their home institutions’ institutional review boards, groups that ensure investigators will guard patients’ confidentiality and adhere to ethical research principles.
Unfortunately, despite the scale of the military repository, blood serum has its limits as a medical resource. For research and health surveillance, the serum can only tell you so much, says Capt. Kevin Russell, the director of the Armed Forces Health Surveillance Center that oversees DoDSR. Because the serum samples are not linked to very specific exposure information—such as exactly where a service member was stationed or what he or she encountered while deployed—they only stand in as a surrogate for exposure. At the moment DoD is exploring whether other materials—urine, throat cultures, blood clots—or perhaps new technologies could enhance their repository. Nevertheless, it would be “unlikely” that Defense would get rid of its serum reserve or stop adding new samples, Russell says. And so four freezers remain empty, waiting.