By Randolph Fillmore
David Graham, Ph.D., believes blood sampling collection can become EASIER, more standardized, and enable greater access and accuracy.
Graham, associate professor and the director of the Johns Hopkins All Children’s Molecular Determinants Core, heads a team of researchers and technicians who apply advanced technologies to gain a better understanding of biological processes at the molecular level. In addition to his own research, his team serves other researchers by providing their analytical services and technical expertise.
Graham and his interdisciplinary team have been working to develop a blood sampling kit that includes a simple card to stabilize dried blood spot (DBS) samples. The blood samples, blotted and dried on filter paper, can replace blood sampling that uses large volumes of blood drawn into tubes. He and his colleagues believe this method of getting and preserving blood samples is more convenient, preserves samples better than long-term freezing and provides both better preservation and better analytical results.
The concept of dried blood sampling has been around for decades, but recent advances in science and technology have made DBS practical for broader use. Graham and his colleagues have been carrying out a variety of research projects to better demonstrate the potential of DBS.
One of the most innovative aspects of the card type used in this study, and the beauty in its function, is that it separates plasma from the rest of the blood cells at collection. Graham expects that DBS technology can one day replace the centrifuge, that ubiquitous rotating laboratory machine that applies centrifugal force to separate fluids of different densities. They have been used for more than a century in industry and medicine.
A Study to Improve Newborn Screening Using DBS
A recent study carried out by Graham and a team of researchers from Johns Hopkins All Children’s and their colleagues at the Johns Hopkins University School of Medicine in Baltimore, used DBS and some advanced technologies to screen newborns to establish normal ranges for metabolism measures and, in doing so, to discover potential future health problems for the infants based on the data they derive from DBS analysis.
Their recent study, titled “Defining the Healthy Infant Metabolome: Liquid Chromatography Tandem-Mass Spectrometry Analysis of Dried Blood Spot Extracts from the Prospective Research on Early Determinants of Illness and Children’s Health Trajectories Birth Cohort Study,” was published in the Journal of Pediatrics.
The study’s objectives were to develop and describe a standardized procedure for infant DBS collection, storage and analysis that would be suitable for broad use.
According to the study’s lead author William Schleif, M.S., M.T., manager of the Johns Hopkins All Children’s pediatric biorepository, the study found a reference range for 32 analytes, or biomarkers, from the healthy newborns that fit the suitability criteria for consideration into expanded newborn screening if future studies indicate these analytes — also known as biomarkers — are important in differentiating between healthy newborns and those with underlying metabolic disorders.
“Using this approach, we had hoped to find values for a large array of analytes, which are substances found in blood samples that can be identified and measured using sophisticated technologies,” explains Graham.
One technology the researchers employed was mass spectrometry, which can identify metabolites, substances formed by the body’s metabolic processes. They also used liquid chromatography, a technique in analytical chemistry used to separate, identify and quantify each component in a sample, Graham says.
DBS Fits Nicely with The Goals of PREDICT
According to Neil Goldenberg, M.D., Ph.D., associate dean for clinical and translational research and director of the Johns Hopkins All Children's Institute for Clinical and Translational Research, one of the strengths of the DBS project was its interdisciplinary nature.
“The project involved key contributions from biospecimen science, metabolics, cohort study design and execution, and analytics,” notes Goldenberg.
The study was also part of an on-going, large-scale project called “Prospective Research on the Early Determinants of Child Health Trajectory,” or PREDICT, initiated in 2014. PREDICT was designed to follow groups of infants and young children in an effort to discover factors influencing child development and health. According to one of the DBS study’s co-authors, Sara Johnson, Ph.D., M.P.H, an associate professor of pediatrics at the Johns Hopkins University School of Medicine in Baltimore, PREDICT offers an opportunity to better understand why some children develop chronic conditions, such as obesity, or are slower to hit their developmental milestones, and find the risk factors that differentiate them from the children who do not experience these health or developmental problems.
In analyzing 30 DBS samples, the researchers identified 134 biomarkers in healthy newborns that could be valuable for identifying metabolic disorders and molecular markers that may show early indications of child health and disease. Of the 134 biomarkers, 32 were defined in a quantitative manner that is required for future clinical use.
One of PREDICT’s study leaders, Raquel Hernandez, M.D., M.P.H, director of the Center for Health Equity Research at Johns Hopkins All Children's Hospital and an assistant professor of pediatrics in the Johns Hopkins University School of Medicine, was also a co-author on the DBS study. She focuses on prevention and management of childhood obesity and identifying factors that enhance obesity prevention and treatment efforts.
“Although these values are not validated for clinical use at this time, they do provide a useful foundation and range for future research studies to continue exploring clinical correlations of these biomarkers,” adds Hernandez, who helped design the cohort study.
Prioritizing Biomedical Sample Quality
Schleif manages the on-site Johns Hopkins All Children’s Pediatric Biorepository where biomedical samples are stored. He noted that among the important aspects of the study was the relationship between what happens between sample collection and sample use in research, known as the preanalytical phase. A number of environmental factors can work against the viability of biomedical samples, and it is imperative to have high quality samples when conducting research. Schleif said that researchers must have representative biomedical samples and his team’s work is focused on assuring sample quality and availability.
“Our biorepository is built around clinical integration and focuses on maximizing the scientific value of samples in research,” explains Schleif, who helps implement a diverse portfolio of clinical and investigator-initiated studies into the hospital setting.
He noted that the DBS sampling method used in the study mitigates some of the pre-analytical issues seen with conventional DBS samples and may support adoption of more sensitive testing strategies in newborn screening.
The Future Impact of DBS
For Graham, the success of the study enhances the future of DBS and drying card technology. It also opens new doors for improving health care.
“We know that we can work with those small volumes of blood from dry blood spot cards,” Graham says. “I imagine a day when low-cost blood testing will be available to everyone and help expand access to the best health care.”