A bald statement — Current approaches to manipulate miniaturisation focus only on promoting hair growth

Abstract

Hair plays a large part in communication and society with its role changing through time and across cultures. Most people do not leave the house before combing their hair or shaving their beard and for many hair loss or irregular hair growth can have a significant impact on their psychological health. Somewhat unsurprisingly, according to GMR Data, today's global hair care industry is worth an estimated $87 Billion, with hair loss estimated at $2.8 Billion. Considering that no current hair loss-related products can completely reverse hair loss, it is reasonable to believe this market could expand significantly with the discovery of a comprehensive therapy. As such, a great deal of research focuses on overcoming hair loss, and in particular, a common form of hair loss known as androgenetic alopecia (AGA) or male pattern baldness. In AGA, hair follicles miniaturise in a large step change from a terminal to a vellus state. Within this viewpoint article, we discuss how influx and efflux of cells into and out from the dermal papilla (DP) can modulate DP size during the hair cycle. As DP size is positively correlated with the size of the hair fibre produced by a follicle, we argue here that therapies for treating AGA should be developed which can alter DP size, rather than just promote hair growth. We also discuss current therapeutics for AGA and emphasise the importance of using the right model systems to analyse miniaturisation.

PPAR‐γ signalling as a key mediator of human hair follicle physiology and pathology

“…Based on these findings, treatment with PPAR‐γ antagonists deserves to be explored for AGA management. Furthermore, possible effects of PPAR‐γ modulators on androgen activity can also be of benefit for the treatment of AGA …”

“…Furthermore, possible effects of PPAR-γ modulators on androgen activity can also be of benefit for the treatment of AGA. [110] The effects of PPAR-γ signalling on androgen synthesis, together with the known catagen-inducing properties of PPAR-γ agonists, can also be utilized for the treatment of androgen-dependent unwanted male-pattern hair growth in females (hirsutism). Indeed, reportedly, systemic rosiglitazone (2 or 4 mg/day) showed reduced hair growth and overall cosmetic improvement in hirsutism, accompanied by a reduction in androstenedione and serum-free testosterone levels.…”

New developments in hair research

“…[41] Pantelireis and Higgins argue that therapies for treating hair loss should be developed which can alter dermal papilla size, rather than just promote hair growth. [42] Bak et al show Boehmite promotes the β-catenin pathway and increases expression of vascular endothelial growth factor (VEGF), both associated with increasing dermal papilla and overall hair follicle size in previous studies. Might Boehmite and/or other treatments with similar effects facilitate dermal papilla regeneration?…”

“…Perhaps, it may yet find a new role via its apparent cell growth and inflammatory modulating properties . Pantelireis and Higgins argue that therapies for treating hair loss should be developed which can alter dermal papilla size, rather than just promote hair growth . Bak et al show Boehmite promotes the β‐catenin pathway and increases expression of vascular endothelial growth factor (VEGF), both associated with increasing dermal papilla and overall hair follicle size in previous studies.…”

27TH Fondation René Touraine Annual SCIENTIFIC MEETING 2019

“…In one of these loci The availability of new tools that greatly expand our methodological repertoire in human hair research, which has so long been overshadowed by the unparalleled (and often spectacular) insights that can be won via a mouse genomic approach and in vivo-imaging in mice, is expected to also stimulate and embolden experimental approaches taken in human hair research, beyond human HF organ culture [19] and scalp skin or HF xenotransplants on immunocompromised mice. [70][71][72] Instead, the vellus HFs among these "survivors" are waiting to be retransformed, for example by effective pharmacotherapy that promotes the immigration of inductive fibroblasts into the dermal papilla [73,74] of vellus HFs so as to re-transform these into large, pigmented terminal HFs. (There is as yet no conclusive evidence that the implantation of tissue-engineered HFs promotes this retransformation process in their vicinity).…”