American scientists have found that the same types of cells that cause goosebumps, responsible for controlling hair growth. The study is published in the journal Cell.
Traditionally, the appearance of the tingling on the skin helps animals to protect themselves from the cold. However, this reflex is inherent in all mammals, even those who do not have thick hair, including humans.
Biologists from Harvard University in USA in conjunction with their Taiwanese colleagues found that the muscle that is Contracting initiate the formation of tingling, connect the sympathetic nerve with stem cells of the hair follicle. That is, each time the emergence of “goose skin” stimulates the growth of new hair.
The authors have studied on mice, the interaction of different cells in response to changes in the external environment.
“We were interested in understanding how the behavior of stem cells is regulated by external stimuli. Leather is on the border between our body and the outside world and has lots of stem cells, surrounded by various other types of cells — presented in a press release, Harvard University, the head of studies I-Chie Hsu (Ya-Chieh Hsu), associate Professor of stem cell and regenerative biology. — In this study, we found interesting two-component system that regulates behavior of stem cells in accordance with the temperature changes of the external environment”.
Relationship between sympathetic nerve and the tiny smooth muscle in the skin tissue are well known. When the body feels cold, the sympathetic neurons to send nerve signal, the muscle responds by Contracting and forcing the hair to stand on end.
However, in the study of the skin using electron microscopy, the researchers found that the sympathetic nerve is not only related to muscle, but also forms a direct link with the stem cells of the hair follicle. In fact, nerve fibers are wrapped around the stem cells of the hair follicle as a ribbon.
“At the ultrastructural level, we saw the interaction of nerve and stem cell. We were surprised to find that the nerve cells form synaptopathies structure from epithelial stem cells, which are usually not targeted to neurons,” says Hsu.
A detailed study confirmed that neural activity constantly maintains stem cells in a state ready to regenerate. In the case of strong cooling the nerve is activated at a higher level, and released more neurotransmitters, which leads to a rapid activation of stem cells, regeneration of the hair follicle and the growth of new hair.
When the researchers removed the muscle connected to the hair follicle, the sympathetic nerve became involved, and the neural link with the stem cells of the hair follicle has been lost.
Through these experiments, the researchers identified two-component system, which regulates the stem cells of the hair follicle. Nerve is a signal component that activates stem cells via neurotransmitters, while muscle is a structural component, directly connecting nerve fibers with stem cells of the hair follicle.
Moreover, the authors found that the signal comes from the hair follicle. It secretes protein, which activates smooth muscle associated with the sympathetic nerve. After that, the reverse interaction — the nerve runs through the muscle stem cells of the hair follicle, triggering the growth of new hair.
In the future, the researchers plan to continue to study the impact of the environment on stem skin cells, for example, in the rebuilding and healing of wounds.