Hair Biology Workshop

A review by Gill Westgate

Development of new products that change hair, whether it’s condition, shape, colour, density, growth or removal brings together several disparate science disciplines working together to generate novel consumer desirable product benefits and effective solutions to consumers hair concerns.

The diversity of hair types globally and the inevitable changes that occur over a lifetime such as hair damage, thinning and greying demands a constant stream of innovation. Add to this the complexity of the claims and regulatory environment, means there is the need for significant scientific and consumer understanding to generate appropriate claims. Increasingly the reality check of delivering a true benefit; both measurable and perceivable, needs to be adopted by product developers, whether these be of new formulations, active ingredients and increasingly new devices that influence fibre, follicle or both. The need to provide education by top experts in the fundamentals of follicle biology and hair fibre modification was recognised during a two-day course „Follicle to Fibre, Principles to Practice“ hosted by the proDERM Academy on 16 and 17 June 2015.

Hair follicle biology has grown as a research discipline very dramatically since the early 1980’s driven initially by the serendipitous arrival of an effective topical hair growth product on the market in the form of products containing the drug minoxidil, and more recently by the recognition that the hair follicle contains a vital stem cell reservoir important not only for continuous hair regeneration but also to supply vital regenerative cells for skin repair and wound healing.

Hair follicle anatomy is well described, however, recent research has focused on identifying the biomarkers and signalling molecules that characterise the stem cell regions, the pigmentary unit as well as in the individual cell lineages that arise in the hair bulb to form the various root sheaths and hair fibre. Hair grows in continuous cycles of activity (anagen) and rest (telogen) and disruption in this cycle generates the changes that consumers are often concerned about. Presentations from Dr Gill Westgate and Professor Desmond Tobin explained how the latest research is introducing themes such as the importance of the dermal environment in the control of the hair cycle, the hair induction properties of the dermal papilla and the intriguing biology of the hair follicle melanocyte.

Perhaps of greatest interest are changes that happen with age. Consumers are seeking a wide range of solutions to cope with hair aging and Dr Fraser Bell explained how product developers need to understand the physiology of hair aging and how this translates into changing hair properties. Consumer perception of hair being  ‚weak‘, ‚brittle‘, ‚dry‘, ‚limp‘ connects the physiologically driven changes with external factors such as humidity, heat and chemicals in aging hair. Loss of hair density (thinning), thickness (diameter) and greying are all recognised to increase with age, however, research suggests that pattern hair loss and the transition from thick terminal to fine vellus hairs in males is much more likely to be linked to genetic factors than in females, which leaves open the question of what might be responsible for the typical thinning on the crown experienced by many women? Stem cell research may reveal some clues to this question, however, Dr Westgate explained that while stem cell numbers remain constant during aging, fewer progenitor cells may be derived from these stem cells that are needed to continue to produce new terminal hair follicles and some scientists now believe that the influence of the dermis surrounding the hair follicle might be important in supporting healthy hair growth.

Hair traits are clearly genetic. Professor Tobin described how red hair (with pale skin and freckles) is strongly genetic and is linked to polymorphic variation in the melanocortin receptor gene, MCR1 arising during evolution as human populations migrated away from the cradle of civilisation several 10’s of thousands of years ago. Now MCR1 is the single most useful gene to be able to predict appearance! Greying of hair is also strongly heritable and although research has not yet identified the major genetic (or perhaps epigenetic) factors responsible for greying, Prof Tobin described how unpigmented hair follicles retain ‘dormant’ melanocytes that can be cultured and then induced to make melanin in vitro. However, with age, these hair follicle melanocytes are less able to cope with oxidative stress, which is likely to contribute to the lessening of hair colour and the appearance of grey hair. Melanin type and transfer into the pre-cortical cells that form the hair fibre is what gives hair its natural colour and Prof Tobin described how recent research in his labs at the University of Bradford has revealed new insights into the mechanisms involved.

The shape of the hair fibre, especially traits including curly hair, is clearly genetic. Indeed Dr Gill Westgate described how curly hair is known to have developed twice in evolution, both in Central Africa and in Melanesia suggesting strong environmental drivers have been in force to create a scalp hair type that helps dissipate sweat and heat from the scalp. Research shows that curl really does seem to be formed at the hair root with curved follicles setting up the curly fibre structure and several genes have been described that predict curly or straight hair.

The chemical composition of hair is remarkably constant between different hair types and ethnicities and perhaps the area of most recent research interest is the lipids in the hair fibre. Although only a small component by percentage, hair lipids contribute to the surface properties of the hair fibre, appear to differ in distribution in curly and straight hair and sebum components have been described as present within the fibre and making a contribution to hair beauty attributes such as shine and smoothness.  Of course hair straightening and curling technologies have been used to ’shape‘ hair since the 19th century and Dr Jonathan Wood described the molecular basis of the major types of shaping technology, from water set through to permanent straightening using strong redox reactions. One of the more recent popular innovations, the Brazilian hair straightening treatment, has undergone rapid development driven by the need to remove formaldehyde for safety reasons. Glyoxylic acid is now used to help maintain straightened hair.

Although hair is a biological material, it is highly resilient to moderate physical and chemical treatment. Heat treatments for hair shaping are now commonplace yet the effects of heat on the fine structure of the hair shaft have only recently been well characterised. Dr Crisan Popescu demonstrated that hair actually ‚melts‘ at above 230oC and undergoes molecular transition removing its natural strength and high heat on wet hair causes even more damage actually denaturing the keratin protein. Such investigations under idealised conditions enable the relationships between temperature and tensile strength to be investigated; but the take home message is that heating devices are damaging if not used properly.

While hair growth remains the aspiration of many; safe, longer lasting hair removal is also an as yet unmet need for many consumers. Dr Marijke van Vlimmeren reviewed the many hair removal methods and showed that more recently photo-epilation has emerged with home use light-based devices becoming a rapid growth category. Dr Vlimmeren also showed the importance of understanding hair follicle physiology in the development of effective photo-epilation devices and described a new ex vivo human skin model in which the effects of a range light parameters on transitioning hair follicles from anagen to catagen was tested that was able to improve consumer product design and predict clinical efficacy.

The foregoing reveals that knowledge of follicle biology and its physiological impacts on the hair fibre is becoming much more essential in new product innovation within the hair category. The Workshop concluded on a note of realism when Dr Chris Gummer led participants down the tricky road to making claims that imply product action at the level of the follicle. Nuanced terminology such as ‚grows more hair, ‚maintains hair‘ and ‚reduces hair loss/fall‘ all require the accurate counting of hairs (terminal/vellus or both) or measuring hair volume (number plus density) or separating broken vs naturally shed hairs. Similarly, hair removal claims of temporary and permanent apply to the different types of hair removal technology; photo-epilation, for example, would satisfy the criterion of permanent hair removal if the site remains hair free for 12 months. Understanding the rhythms of the hair cycle and how these vary with the body site location are important factors in arriving at such claims.

After 1 ½ days of lectures, the participants were led through the laboratories of proDERM where Stephan Bielfeldt and Marianne Brandt demonstrated the methods for claims substantiation of „anti dandruff efficacy“ and „hair growth efficacy“. Corresponding imaging techniques and onscreen evaluations were shown and could be tested live by the participants of the workshop. In addition, the inclusion criterion of hair loss for the mentioned hair growth studies was practically shown by some invited male and female patients, presenting mild to moderate degrees of hair loss. A presentation of the biophysical hair laboratory at proDERM rounded up the tour, showing many in vitro methods like „anti-frizz“, „hair volume“, „repeated grooming“, „tensile test“ and „combing forces“ that are typically used for screening a number of hair care formulations as well as for claim substantiation.

The overwhelmingly positive feedback of the 35 international participants is a good motivation for repeating this workshop in the following years.