For people at risk of a heart attack or stroke, the common preventative treatment is to take aspirin or another blood-thinning medicine. With these medicines, though, can come unwanted side-effects, like ulcers. Now two physicists have come up with a mechanical treatment that might offer an alternative to the traditional medicinal one.
Blood, like the motor oil in a car’s engine, has an ideal viscosity, or thickness, that keeps the body’s circulatory system running smoothly. When a person’s blood is too viscous (too thick and sticky) his or her blood vessels build up more plaque leading to a greater risk of heart attack. Finding a way to decrease the blood’s viscosity, by taking aspirin for example, reduces those risks. The problem with aspirin, though, is that it may cause as much harm as it does help.
Rongjia Tao, chair of the Department of Physics at Temple University, and his former student have found a mechanical alternative to aspirin to thin highly viscous blood.
“It’s quite simple,” Tao said of the technique. He uses a magnetic field to rearrange a person’s red blood cells, streamlining blood that is too thick. A magnetic field of 1.3 Tesla (about the same as an MRI – magnetic resonance imaging - machine) applied to blood for about one minute can reduce its viscosity by 20 to 30 percent.
It works because red blood cells contain iron. “Iron responds to magnetic fields very well,” said Tao’s former student, Ke “Colin” Huang who is now a medical physics resident in the Department of Radiation Oncology at the University of Michigan.
Huang and Tao tested the technique on human blood samples acquired from Temple University. Once a sample arrived at the lab, it was kept refrigerated until the experiment started. Then, a water bath brought the sample up to human temperature. A huge magnet, weighing near a thousand pounds, created a magnetic field that was applied to the sample with the magnetic field pointed in the blood flow direction.
When applied, the magnetic field polarizes the red blood cells causing them to link together in short chains. Because the field is aligned to the blood flow direction, the chains also form in the same direction, streamlining the movement of the blood. Additionally, because the chains are larger than the single blood cells, they tend to flow down the center of the tube reducing the friction against the walls of the blood vessels. The combined effects reduce the viscosity of the blood, helping it to flow more freely.
[This series of images shows (a) red blood cells randomly distributed before the magnetic field is applied, (b) the formation of short red blood cell chains after a magnetic field was applied for one minute and (c) the formation of long red blood cell chains after a magnetic field was applied for 12 minutes. Photo credit: R. Tao and K. Huang, PRE.]
After a lab sample was exposed to the magnetic field for anywhere from one to twelve minutes Tao and Huang compared the blood’s post-test viscosity to its original value. Multiple experiments showed a reduction in blood viscosity thanks to the magnetic field. The blood samples do, however, slowly return to their original viscosities after a few hours, but the process, the researchers said, is repeatable.
Unlike the magnets found on a refrigerator door, the magnet used in this technique is not a permanent magnet but instead a coil. Electrical current going through the coil turns it into an electromagnet capable of producing a very high magnetic field. The same coil-type magnet is found in MRI machines which use magnetic fields to image the inside of the body.
Just like in an MRI, the magnet Tao and Huang used does not have the ionizing radiation, like that found in CT scans, which can be harmful to the body. The technique also does not interfere with the normal oxygen delivery and waste removal function of the red blood cells, the researchers said, and is not dependent on blood type.
Tao is still doing research on the technique and hopes that clinical trials will soon follow. Tao and Huang’s research will appear in Physical Review E.