How do hair follicles get their start?

Researchers have discovered how hair follicles emerge from seemingly uniform skin cells during embryonic development.

The discovery could lead to strategies for regenerating lost hair follicles in adults.

To gain insight into early hair follicle development, the researchers combined the study of genetically engineered mouse models with single-cell RNA methods to examine the molecular and cellular events that occur prior to visible evidence of hair follicle formation—a process that was nearly impossible to decode by conventional methods.

Using this combined approach, the researchers were able to predict and validate key molecular changes that occur within a subpopulation of dermal progenitor cells as they differentiate and mature into cells uniquely capable of inducing hair follicles. The scientists found that these dermal progenitor cells can be found spatially within a specific reservoir just peripheral to the forming hair follicle.

“The hair follicles you have as an adult are the ones you were born with…”

In their study, they identified a cell signaling pathway that controls this differentiation process and the induction of hair follicles. By modulating this signal in mice, they were able to regulate hair follicle size during the early skin development.

Although several questions remain, the findings give researchers clues that they can use to potentially stimulate skin to regenerate hair follicles that have been lost, says senior author Peggy Myung, assistant professor of dermatology at Yale University.

“The hair follicles you have as an adult are the ones you were born with, and hair follicles that are lost by injury or inflammation generally cannot be recovered,” she says.

But with this study, Myung says, she and her team now have a molecular handle to begin to determine the signals that can instruct adult skin cells to regenerate what was lost. It also provides a paradigm to discover how other appendages that follow similar mechanisms of development, such as teeth, first emerge and grow, she says.

The research appears in the journal Developmental Cell.

Source: Yale University