Banked blood gets stiffer as time goes by

A new study has revealed that stored blood in blood banks gets stiffer and with time.

Using advanced optical techniques, the researchers from University of Illinois measured the stiffness of the membrane surrounding red blood cells over time. They found that, even though the cells retain their shape and hemoglobin content, the membranes get stiffer, which steadily decreases the cells' functionality.

It was found that it might look like fresh blood and flow like fresh blood, but the longer blood would be kept stored, the less it would carry oxygen into the tiny microcapillaries of the body.

The established "shelf life" for blood in blood banks has been 42 days. During that time, a lot of changes can happen to the blood cells, they could become damaged or rupture. But much of the blood keeps its shape and, by all appearances, looks like it did the day it was donated.

Researchers used a special optical technique called spatial light interference microscopy (SLIM), a method developed in electrical and computer engineering professor Gabriel Popescu's lab at Illinois in 2011. It uses light to noninvasively measure cell mass and topology with nanoscale accuracy. Through software and hardware advances, the SLIM system today acquires images almost 100 times faster than three years ago.

The measurements revealed the membranes become stiffer and less elastic as time goes by. This was important because the blood cells need to be flexible enough to travel through tiny capillaries and permeable enough for oxygen to pass through.

Krishna Tangella, U. of I professor of pathology, said that these results could have a wide variety of clinical applications like functional data from red blood cells would help physicians determine when to give red-cell transfusions for patients with anemia.

The study is published in the journal Scientific Reports.