Turning 30 signifies the advent of middle age and brings with it a host of physiological changes such as slowing metabolism and bone density loss. The more obvious and irksome changes, however, are aesthetic ones like the development of wrinkles and loss of hair pigmentation aka greying. Greying occurs due to the loss of the cells that produce hair pigments, known as melanocytes. Dyeing hair only serves as a way of masking grey hair and does not affect the actual process in any way.
The human hair cycle consists of an anagen phase, during which hair grows continuously at a rate of 1cm per month and can last 3-5years on the scalp producing hair that can grow to length of 36 to 60cm. At the end of the anagen phase, hair growth stops for three months. At the end of the telogen (resting) phase, the hair is shed and the follicle remains empty until the anagen cycle restarts. Pigment production also follows this rhythmic cycle and turns on and off in tune with the hair cycle. When pigment cells turn off at the end of one hair cycle and fail to turn back on with the onset of the next, hair becomes grey.
If greying of hair has to be prevented, scientists knew they would need to either prolong the life of the melanocytes in the hair bulb – by protecting them from injury – or expand the melanocyte stem cell reservoir in the upper or top region of the hair follicle so they continue to replace lost pigment cells.
The R&D department of the cosmetic giant, L’Oreal, decided to tackle this problem at its roots and find a way to slow the process of greying down.
Melanocytes are present in large numbers in the bulb of the hair follicle. They produce melanin and transfer the pigment to keratinocytes, cells that produce strands of hair. The upper region of the hair follicle contains a reservoir of melanocytes that are normally inactive, but are cyclically activated to replace dead melanocytes. Coloured strands of hair contain high levels of active and inactive melanocytes, while grey hair has reduced levels of these components.
Three main enzymes tightly control melanin production: tyrosinase, TRP-1 and TRP-2. One of the functions of TRP-2 is to protect the DNA of melanocytes from the damage caused by molecules that induce oxidative stress, thus preventing their death. TRP-2 is also not expressed in grey hair follicles.
Researchers at L’Oreal have developed a chemical agent that mimics the activity of TRP-2, thereby promoting melanocyte survival and decelerating the process of greying. The company claims that this agent can be formulated as a gel or a shampoo that can be directly applied on the scalp as a gel or ingested orally in the form of a pill. While these formulations are currently not on the market, a patent has been granted to L’Oreal and product trials are currently under way. “Ideally you would take it for your whole life, but realistically we’d encourage people to start using it before their hair goes grey because we don’t think it can reverse the process once it has started. We have a watertight proof of concept, and we think it will have a market among men as well as women,“ said Bruno Bernard, a researcher at L’Oreal, in a statement to the Daily Mail, UK.