Old Banked Blood Grows Stiffer with Age: New Technique May Monitor Health of Donations

While banking blood is an important when it comes to saving lives, it turns out that storing it for too long may not be a good thing. Scientists have found that the longer blood is stored, the less it can carry oxygen into the tiny microcapillaries of the body.

About 14 million units of blood are banked annually in the U.S. The established "shelf life" for blood in these banks is 42 days. During this time, though, quite a few changes can happen to these blood cells; they can become damaged and rupture.

"Our results show some surprising facts: Even though the blood looks good on the surface, its functionality is degrading steadily with time," said Gabriel Popescu, the lead researcher, in a news release.

In order to see what degradation and changes were taking place, the scientists used a special optical technique called spatial light interference microscopy (SLIM). This method uses light in order to noninvasively measure cell mass and topology with nanoscale accuracy.

The scientists took time-lapse images of the cells in order to measure and chart the cell's properties. They measured the nanometer scale motions of the cell's membrane as well, which can reveal the cell's stiffness and function.

So what did they find? While many of the characteristics stay the same over time, like shape, mass and hemogoblin content, the membranes change. In fact, they become stiffer and less elastic as time goes by, which can prevent them from traveling through tiny capillaries.

"In microcirculations such as that in the brain, cells need to squeeze through very narrow capillaries to carry oxygen," said Basanta Bhaduri, lead author of the new paper. "If they are not deformable enough, the oxygen transport is impeded to that particular organ and major clinical problems may arise. This is the reason why new red blood cells are produced continuously by the bone marrow, such that no cells older than 100 days or so exist in our circulation."

The findings reveal that blood should possibly be tested before being given to a patient, especially if it's been stored for a long time. In addition, the SLIM imaging technique will give researchers a new tool to monitor blood in banks.

The findings are published in the journal Scientific Reports.