Some changes in red blood cells that occur within current 42-day use guidelines may not be apparent to the human eye, but offer a new way to measure the amount of oxygen that the cells can carry
At the University of Illinois (UI), researchers have developed a new method to assess the freshness and clinical effectiveness of whole blood. As these findings are validated, pathologists and clinical laboratory scientists who manage hospital blood banks may need to establish new guidelines for the use of such blood products.
Researchers at the UI campus in Urbana-Champaign stated that their findings indicate that blood stored in the laboratory or at the community blood bank may not be as fresh as it appears. They also said that the longer blood is stored, the less effective it can be in carrying oxygen into the body’s tiny microcapillaries, according to a news release issued by the UI.
Researchers Question Changes in Shelved Blood and Its Effects
A paper describing the study and its findings was published in Nature’s Scientific Reports. The researchers wanted to determine quantitative changes in red blood cells over time. They also wanted to assess what effects old blood might have on patients.
“Stored red blood cells undergo numerous biochemical, structural, and functional changes, referred to as storage lesion,” wrote the authors in the study, which was published in Nature’s Scientific Reports. “How much these changes impede the ability of erythrocytes to perform their function and, as result, impact clinical outcomes in transfusion patients is unknown.”
Food and Drug Administration (FDA) standards allow donated blood to be kept for 42 days. More than 14 million units of blood are reportedly collected annually in the United States and almost 13.9 million units of red blood cells are given to 4.8 million U.S. patients.
The Illinois-based researchers are not the only ones to question the date stamp on stored blood. Surgeons who treat patients needing transfusions after open-heart surgeries and other major procedures have inquired about the effectiveness of stored blood.
“Surgeons have always been concerned about the risk of using old stored blood and whether it will increase the patient’s chance of developing blood clots or other complications,” reported Medical Daily in an article on the UI study.
Novel Imaging Method to Measure Cell Membrane of Red Blood Cells
Indeed, within the 42-day time horizon, blood cells get damaged or rupture over time, the study noted. These changes are not so obvious to the naked eye.
”Even though the blood looks good on the surface, its functionality is degrading steadily over time,” observed lead researcher Gabriel Popescu, Ph.D. He is a UI Professor of Electrical and Computer Engineering and part of the Beckman Institute for Advanced Science and Technology research Team.
Changes to cells in fresh blood became apparent when researchers used an optical technique dubbed SLIM—short for Spatial Light Interference Microscopy. SLIM combines microscopy with interferometry to measure nanoscale fluctuations in red blood cell membrane, Popescu explained in an interview with MedicalResearch.com.
In the published study, the research team used the SLIM technology in the following ways:
- Took time-lapse images of cells;
- Measured and charted cell properties; and,
- Noted nanometer scale motions of cell membrane, which is indicative of cell stiffness and function.
SLIM was created during 2011 in Popescu’s Quantitative Light Imaging Laboratory. It is capable of revealing intrinsic contrast of cell structures and produces topographic accuracy comparable to atomic-force microscopy, according to the Popescu’s Quantitative Light Imaging Laboratory website.
Findings Reveal Blood Cells Worsen Over Time; Function Stalls
The study found blood cells retain shape, mass, and their hemoglobin content. But the data also showed their membranes stiffen, which can decrease functionality of the blood cells.
“This is important because the blood cells need to be flexible enough to travel through tiny capillaries and permeable enough for oxygen to pass through,” noted the university press release on the study.
“We found that the (nanoscale) fluctuations, known to be due to thermal or Brownian motion, decrease with blood storage time,” Popescu told MedicalReseach.com. “These results indicate that the deformability of the cells degrades with time. It means that blood functionality is lower the longer the blood is stored.”
Implications for Physicians and Hematologists
As to the implications of this study, researchers anticipate physicians turning to the data when decisions must be made about when to give red blood cell transfusions to patients with anemia. Popescu believes the test can be part of hematologists’ assays menu, MedicalResearch.com reported.
The researchers said that SLIM is adaptable to clinical settings. They note how just a few extra components are needed to transform conventional white-light microscopes to tools for conducting SLIM and checking blood’s freshness.
The UI study is another example of how researchers are taking unrelated technology—in this case the optical technique called SLIM—and applying it for diagnostic purposes to human specimens. Pathologists and laboratory administrators are advised to stay tuned as additional studies will build on these findings.
For laboratory administrators who pay close attention to quality and cost of blood products, the study raises at least two important issues. First, researchers at UI are offering a new idea for how to evaluate a unit of fresh blood prior to transfusion. This could be a major step forward for patient safety.
Second, their solution comes with a cost. The researchers’ recommendations could lead to blood inventory with shorter shelf life than current standards allow. This may cause the cost of blood to rise, putting even more strain on budgets of medical laboratories, where blood products are already a pricey line item.
—By Donna Marie Pocius