For the first time, biophysicists have measured the mechanical properties of red blood cells as they squeeze through tiny channels, mimicking the conditions they experience in the body's capillaries. The findings, published in the journal Nature Physics, could help scientists better understand and treat diseases that affect red blood cell function, such as sickle cell anemia and malaria.

Red blood cells are doughnut-shaped cells that carry oxygen from the lungs to the rest of the body. They are about 7 micrometers in diameter, and they can deform significantly as they flow through narrow blood vessels. This deformability is essential for red blood cells to be able to deliver oxygen to all of the body's tissues.

In the new study, researchers used a microfluidic device to measure the mechanical properties of red blood cells as they flowed through channels that were just a few micrometers wide. The device allowed the researchers to control the size of the channels and the flow rate of the red blood cells, and to measure the force required to squeeze the cells through the channels.

The researchers found that red blood cells are much more deformable than previously thought. They were able to squeeze through channels that were only about half their diameter without rupturing. This deformability is due to the cell's unique structure, which consists of a flexible membrane and a semi-liquid interior.

The researchers also found that red blood cells become stiffer as they flow through narrower channels. This stiffening is due to the increased stretching of the cell membrane. The researchers believe that this stiffening may be important for preventing red blood cells from rupturing as they flow through narrow capillaries.

The new findings could help scientists better understand and treat diseases that affect red blood cell function. For example, in sickle cell anemia, a genetic mutation causes red blood cells to become sickle-shaped and less deformable. This can lead to blockages in blood vessels and pain, tissue damage, and organ failure. The new findings could help scientists develop new treatments for sickle cell anemia that target the mechanical properties of red blood cells.

The findings could also help scientists develop new ways to deliver drugs to specific tissues. For example, drugs could be encapsulated in red blood cells and then targeted to specific tissues by controlling the size of the channels through which the red blood cells flow.

The new study provides a new understanding of the mechanical properties of red blood cells and could lead to new treatments for diseases that affect red blood cell function.