Researchers from the University of Southern California have described some of the factors that determine when hair grows, when it stops growing and when it falls out.
Krzysztof Kobielak, Eve Kandyba and colleagues focused on stem cells located in hair follicles (hfSCs), which can regenerate hair follicles as well as skin.
These hfSCs are governed by the signalling pathways BMP and Wnt - which are groups of molecules that work together to
control cell functions, including the cycles of hair growth.
The research focuses on how the gene Wnt7b activates hair growth. Without Wnt7b, hair is much shorter, scientists said.
The research identified a complex network of genes including the Wnt and BMP signalling pathways controlling the cycles of hair growth.
Reduced BMP signalling and increased Wnt signalling activate hair growth. The inverse increased BMP signalling and decreased Wnt signalling keeps the hfSCs in a resting state, scientists said.
Further research clarified the workings of the BMP signalling pathway by examining the function of two key proteins, called Smad1 and Smad5.
These proteins transmit the signals necessary for regulating hair stem cells during new growth.
"Collectively, these new discoveries advance basic science and, more importantly, might translate into novel therapeutics for various human diseases," said Kobielak.
"Since BMP signalling has a key regulatory role in maintaining the stability of different types of adult stem cell populations, the implication for future therapies might be potentially much broader than baldness and could include skin regeneration for burn patients and skin cancer," Kobielak said.
The findings were published in the journals Stem Cells and the Proceedings of the National Academy of Sciences (PNAS).