Engineering blood cells to fool filtration organsCari Cooney | March 04, 2022
The human body is equipped to filter out things that are not needed to sustain life. Lungs, kidneys and livers are major organs that act as filters to unwanted intruders. Unfortunately, the human body also filters out things that are needed. Lifesaving medications found in chemotherapy or drugs for multiple sclerosis are also considered “foreign” by these filtration systems. In some situations, less than 10% of the medications are allowed to continue their path through the body.
Having substantial quantities of drugs removed by the body before serving their purpose is a major issue scientists are looking to remedy. Higher dosages can bring negative side effects. A strategy of focus is to get the medication to its targeted location and bypass the organs that want to cast it out before its time.
"Many drug delivery vehicles fail to reach the right location in the body, and the main reason is because our bodies have this really nice filtering system. So many of them end up in the liver, the kidney or the spleen," said Minkyu Kim, assistant professor of materials science and engineering and biomedical engineering at the University of Arizona. "If we can overcome this by developing new drug delivery vehicles, it will be a significant advance."
Masquerading medicine to fool the body
With the help of a $600,000 award from CAREER (National Science Foundation award), Kim is hoping to construct a plan to combine materials science with synthetic biology and mechanics to develop a better way for drugs to enter the human body and bypass filtration systems.
What is the best way to get medicine past filtration security to where it needs to be? Disguise it. Kim is creating a microparticle vehicle that mimics red blood cells. Consisting of a protein and lipid-based casing with hemoglobin, it transports oxygen through the body. Kim is replacing the hemoglobin with medication. The system is fooled and the drugs get to their designated location.
"A red blood cell is about 7 micrometers in diameter, and they go through microcapillaries, which are a lot smaller than that," said Kim, who is also a member of the BIO5 Institute. "The cytoskeleton of a red blood cell is made up of a well-ordered structure of proteins. When it needs to move through a small space, that structure can be extended by protein unfolding, but once the stresses are removed, the original structure returns. A red blood cell can do this a thousand times and continue to show the same mechanical behavior."
Red blood cells are incredibly effective at moving through the body and reaching small spaces. However, using real blood for the vehicle poses a lot of issues; it would require human donation and storage space. A synthetic vehicle would be ideal because it could be a baseline to carry a variety of medical treatments throughout the body, regardless of blood type.