Millions of people donate blood every year, saving countless lives. After the blood donation is completed, the plasma and white blood cells will be separated, and the remaining red blood cell suspension is the most commonly used blood transfusion product in clinical practice. In most countries, it can be stored in liquid form under low temperature conditions for up to 42 days.
However, red blood cells gradually undergo structural changes during the cold storage process, the cell membrane becomes fragile, and various harmful metabolites accumulate, causing blood quality to decline. Therefore, red blood cells are usually considered no longer suitable for transfusion after six weeks. What's even more troublesome is that even under the same storage conditions and time, the red blood cells of different blood donors "age" at different rates. Their quality attenuation is affected by many factors such as the donor's metabolic status, lifestyle, weight, gender, and age, and varies greatly. These individual differences are often difficult to identify in hospitals and blood centers in a timely manner. The key reason is the lack of a blood quality testing method that is fast and cheap and can be used in front-line clinical practice before transfusion.
Researchers at the University of Colorado Boulder and the University of Colorado Anschutz Medical Center recently developed a compact, low-cost and easy-to-use new detection device, hoping to provide a solution to the above problems. The team envisions that in the future, this device can be made into a "chip" the size of a coin, which can be directly inserted into a smartphone and provide test results in about two minutes through the phone's camera and supporting application, enabling instant bedside assessment.
The working principle of this chip is based on acoustic microfluidic technology. Electrodes are arranged on the surface of the chip. When current passes through, surface acoustic waves similar to sound waves are generated on the uppermost layer, which act on a small drop of blood placed on the surface of the chip. Under the action of acoustic waves, red blood cells will vibrate and gradually heat up until the cells rupture, which is equivalent to a "miniature stress test" on red blood cells: the faster they rupture, the more fragile the red blood cells are and the worse the overall quality of the blood.
In the experiment, the researchers tested blood samples from multiple healthy blood donors every week during a 42-day storage period. The results show that as the storage time is extended, some donors' red blood cells will rupture at lower temperatures and earlier time points, and the quality will have significantly declined before reaching the official "expiration date." This shows that relying solely on a uniform shelf life is not enough to accurately reflect the true status of each bag of blood at a specific point in time.
To confirm whether acoustic vibrations were essential, the team also tried to observe the thermal rupture of red blood cells through precise temperature control alone, and compared them between different donors and different time points. The study found that heating alone cannot effectively distinguish the differences in red blood cell properties between donors without superimposing acoustic vibrations. However, after adding acoustic vibrations, these differences can be clearly displayed.
The researchers note that this technique shows that red blood cell quality is affected by both storage duration and individual biological differences. Once lower-quality blood bags can be identified before transfusion, hospitals can prioritize using them as quickly as possible, thereby improving blood resource utilization and providing better treatment assurance for patients. At the same time, this type of testing is also expected to help doctors predict how the recipient's red blood cells will perform in the body after transfusion, thereby optimizing blood transfusion decisions.
Currently, there is still a lot of work to be done before this method is widely deployed in hospitals, including further verification, engineering improvements, and integration with existing blood transfusion processes. In the future, the research team hopes to expand the application on this basis, use the same technical route to detect multiple factors that affect blood cells or specific protein levels in the blood, and develop more point-of-care diagnostic tools. The relevant research paper has been published in the latest issue of the journal "Lab on a Chip", and the research brief was released by the University of Colorado Boulder.