Are stem cells using injuries as practice for future healing?
Researchers at the Massachusetts Institute of Technology and Brigham and Women's Hospital say it is possible.
Stem cells, the cells on which all of the body's tissues are built, have long been considered "blank slates" by researchers. But, recent studies have shown that these cells could possibly keep a memory of previous injuries, illnesses and inflammation to improve how they function in the future.
"Stem cells are the cells responsible for repairing damage from injuries or illness," said Dr. Bill Johnson, a Dallas, Texas, stem cell physician.
Stem cells lay dormant in the organs and tissues of the body until alerted by the immune system to wake up and start working. Once awakened, they begin to regenerate without limit until affected tissues are restored.
Some stem cells can differentiate into different types of tissue, which makes them exceptional for treating a wide range of health conditions.
"The ability to differentiate themselves makes them unique," Johnson said.
So, why do researchers think that stem cells work to hone their healing power? Studies regarding stem cell behavior in the gut, airway and on the skin show that these cells are working to improve healing time every time they are called for repair.
Additionally, some researchers also believe that stem cells can take in information about their environment and be responsive to what is going on around them.
As part of this ability, stem cells may divide to generate new cells, or they may kill themselves off if they sense their environment is "unsafe." The ability to respond to the environment shows how dynamic these cells are, but if they respond the wrong way, it could mean inflammation, chronic illness or allergies.
To test their theory about cell memory, researchers at MIT investigated why some people have chronic and severe allergies to dust, pollen and other allergens.
In most people, allergens trigger responses such as sneezing, sinus congestion, coughing or other similar symptoms, and in most cases, these symptoms resolve with medication. But, in almost 12 percent of the population, these allergens trigger severe reactions and the development of nasal polyps.
The MIT researchers used genetic sequencing to track stem cell activity and follow the behaviors of the genes in the cells when they were exposed to allergens.
To do so, they collected 60,000 cells from the nasal cavities of 20 participants who suffered from chronic inflammatory sinusitis. After collecting the cells, they compared them to cells taken from a control group of individuals without chronic sinusitis.
After comparing the two groups of cells, the researchers then sequenced the cells from the test group to identify their active genes.
The most active genes in the test group cells were those known to cause allergic inflammation. Two of the active genes, interleukin 4 (IL-4) and interleukin 13 (IL-13), play a role in how cells communicate.
Researchers believe this activity could send the immune system the signal to kick into gear and increase inflammation.
The overactivity of the cells was also evident in cells grown in a lab and exposed to the original allergen.
This gives researchers enough evidence to theorize that stem cells possibly transfer information of previous exposure to newly created stem cells. This is also enough to hypothesize that stem cells could be leaving an impression about past healing on those new cells, too.
Although the researchers believe that stem cells could share experiences with new cells, they are not sure how they do it. One theory is that healing injuries change cell DNA, and that these changes affect cell behavior.
Quanta Magazine. Stem Cells Remember Tissues' Past Injuries. 12 November 2018.