Grey hair is caused by the absence of a certain protein in hair progenitor cells, scientists from the University of Texas Southwestern Medical Center have discovered.
The findings, published in Genes & Development, show that KROX20 cells are responsible for the development of hair shafts.
These precursor or progenitor cells then produce a protein called stem cell factor (SCF), which is essential for hair pigmentation.
Testing on mouse models, scientists explored what happened when they deleted the SCF gene in the hair progenitor cells – the animals’ hair turned grey, then white with age.
Furthermore, when the scientists deleted the KROX20 cells, it caused hair to stop growing completely and the mice became bald.
Described as a ‘serendipitous’ discovery, the scientists led by Dr Le were initially studying Neurofibromatosis Type 1 – a genetic disease that causes tumours to grow on nerves.
The researchers are now planning to try to find out if the KROX20 cells and SCF gene stop working properly as humans age.
It is already established that stem cells are involved in hair creation and that SCF is important for pigmentation, however, until now scientists have not been able to explain what happens when SCF moves down to the base or bulb of follicles and which cells in the follicles produce SCF.
The University of Texas scientists were able to show that if cells with functioning KROX20 and SCF are present, they move up from the bulb, interact with pigment-producing melanocyte cells and grow into coloured hairs.
