A human hair follicle (pink) surrounded by sensory nerve endings (green) -Photo: Science Alert
The research team, led by scientists at Imperial College London (ICL) in the UK, used RNA sequencing to discover cells in a part of the hair follicle, called the outer root sheath. The proportion of touch-sensitive receptors (ORs) is higher than that of equivalent cells in the skin.
It was previously thought that only nerve endings located in the skin and around hair follicles could transmit sensation.
The research team created a culture of human hair follicle cells along with sensory nerves in the laboratory.
When hair follicle cells are mechanically stimulated, the sensory nerves next to them also become active, indicating that this sense of touch has been registered.
Furthermore, experiments revealed that the neurotransmitters serotonin and histamine are being released by ORS cells as a way of transmitting signals to surrounding cells via small vesicles.
Bioengineer Claire Higgins, of ICL University, said: “This is a surprising discovery, because we still don’t know why hair follicle cells have this role in processing light touch.”
This research was published in Science Advances Journal.
Notably, from this hair follicle study, the experiments were repeated using skin cells instead of hair follicle cells. As a result, the neurotransmitter histamine is released, which suggests something unique about the function of ORS cells.
Histamine is a neurotransmitter involved in local immune responses that plays an important role in many inflammatory skin diseases, including eczema.
“Our study highlights a new role for skin cells in histamine release, with potential applications for the treatment of eczema,” said study author Higgins.
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