A new study by American scientists from the University of Illinois shows that stem cell proliferation is directly controlled by the autonomic nervous system.
Somatic stem cells constantly renew the tissues and organs in the body, such as the skin and intestinal mucosa. They have a strong undisclosed potential for neuroscientists at the University of Illinois
“If we could find a way to target and control stem cell proliferation in the body, there could be potential medical benefits, including turning off the proliferation of cancer stem cells or inducing proliferation of somatic stem cells where we want to grow tissue”, – says Elizabeth Davis, doctoral researcher and lead author of a study that demonstrates, for the first time, that stem cell proliferation is directly controlled by the autonomic nervous system (ANS).
Features of the influence of the autonomic nervous system on the cells
ANS regulates the physiological functions of the body without the participation of consciousness (autonomously), for example, such processes as breathing, blood flow, digestion, and so on. Its two main networks of nerve fibers extend from the brain throughout the body, innervating almost every organ.
ANS neurons release chemicals called neurotransmitters (or neuromediators) that act on target cells directly or indirectly.
When neurotransmitters bind to receptors in the cell membranes, they elicit a direct response within the cell. However, changes in cells can also occur when the transmitters initiates general state of inflammation or when bleeding occurs – processes mediated by the ANS.
Is the new method of stem cell regulation close?
Before the Davis study, published in Physiological Reports, scientists had guessed that ANS was involved in stem cell proliferation, but did not know for sure whether this relationship was direct or indirect. If this relationship were direct, this could have serious consequences for the medical treatment of certain diseases.
“If you wanted to change the regeneration potential of an organ, for example, you wouldn’t have to stimulate or suppress the activity of those neurons. Instead, you could just figure out what neurotransmitters are controlling proliferation and then get that chemical to those stem cells with targeted drug delivery”, – says Megan Dailey, assistant professor and co-author on the paper.
To determine the type of ANS connection, researchers concentrated on stem cells in the intestinal lining, or epithelium, in mice. They found not only that the stem cells did have receptors for the neurotransmitters of the ANS, but also that neurotransmitters changed the behavior of the cells – just what they would expect to see for a direct relationship.
“We knew that nerves of the ANS came into close contact with cells of the intestinal epithelium, including stem cells, but we didn’t know if the neurotransmitters were able to bind to the stem cells. When we isolated the stem cells and found there were actually ANS neurotransmitter receptors, we found that missing piece”, – Davis says.
To demonstrate that stem cell behavior changes as a result of ANS stimulation, the researchers cultured intestinal epithelial cells in the lab and exposed them to high concentrations of two neurotransmitters: norepinephrine and acetylcholine.
Norepinephrine – the main neurotransmitter of the sympathetic nervous system is the precursor of adrenaline. It takes part in the implementation of ANS “fight or flight” branch in stressful situations.
Acetylcholine is produced by the parasympathetic nervous system and is responsible for resting functions, including reducing respiratory rate, slowing heartbeat, secreting gastric enzymes, or “rest and digest” branch.
“When we simulated activation of either of those systems, we saw a decrease in stem cell proliferation”, – Dailey says.
Dailey believes that the body may avoid the expenditure of energy to create new cells when the fight or flight system is active. She believes that instead of this, energy is needed for a quick retreat in dangerous stressful situations.
Peak moments of rest and digest may not be the best for making new cells, either, because when food is coming in, cellular processes related to digestion can create free radicals that can damage new cells.
Although studies have been conducted on the intestinal epithelium, Davis and Dailey believe that ANS is directly controlling stem cell proliferation in other parts of the body.
They recently published another article in the American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, expanding the boundaries of the study area, using information from various studies.
“In neuroscience, people don’t see the ANS as flashy or exciting, but these nerves are reaching so many cells in the body, including stem cells”, – Davis says. “Why would those nerves communicate with stem cells if they weren’t doing anything? What if there’s this big, exciting idea that we could use the nervous system to control stem cells?”
“The ANS isn’t controlled by itself – it’s controlled by the brain and the central nervous system. We think the brain is controlling the regeneration of all these tissues through the ANS. But that brings up a bigger picture. For individuals under severe depression or PTSD, for example, you see degeneration of some of their organs. It could be some sort of stress-related effect through the ANS decreasing the regenerative potential of the organs. Based on our findings, it looks like there could be a direct effect”.