What’s new in Hair – July/August 2018 | Dr. Annika Vogt
FGF signalling controls the specification of hair placode-derived SOX9 positive progenitors to Merkel cells
Nat Commun. 2018 Jun 13;9(1):2333. doi: 10.1038/s41467-018-04399-y. Erratum in: Nat Commun. 2018 Jul 17;9(1):2854
Nguyen MB, Cohen I, Kumar V, Xu Z, Bar C, Dauber-Decker KL, Tsai PC, Marangoni P, Klein OD, Hsu YC, Chen T, Mikkola ML, Ezhkova E.
The hair follicle is a known reservoir for many different progenitor cell populations. Apart from this, the close connection between ectodermal and neural tissue development is widely recognized. This work by Nguyen et al., however, provides completely new insights in the field of Merkel cell research. The authors characterize the capacity of SOX9-positive cells, known to give rise to hair follicle stem cells, to form Merkel cells; not under the regulation of SOX9, but via FGF2-mediated epithelial signaling. Their results significantly contribute to our molecular understanding of how the formation of different precursor cell types is orchestrated. Moreover, they shed new light on sensory nervous system development in skin, and could significantly boost Merkel cell research.
The Mesenchymal Niche of the Hair Follicle Induces Regeneration by Releasing Primed Progenitors from Inhibitory Effects of Quiescent Stem Cells
Cell Rep. 2018 Jul 24;24(4):909-921.e3. doi: 10.1016/j.celrep.2018.06.084.
Avigad Laron E, Aamar E, Enshell-Seijffers D.
This work is focusing on the regulation of the mesenchymal niche of the hair follicle and on how the dermal papilla orchestrates the proliferation of the epithelial compartments during the hair cycle. Avigad Laron et al. explain the hair cycle as a result of disinhibition of primed progenitors in the bulge and regulated Shh signaling activity. The work is especially intriguing as it illustrates the dynamic interplay between the dermal papilla and the proliferating epithelium and provides evidence for spatial and timely regulation as well as signaling cross-talk with the Wnt pathway.
Arch Dermatol Res. 2018 Aug 18. doi: 10.1007/s00403-018-1853-5. [Epub ahead of print]
Guttman-Yassky E, Nia JK, Hashim PW, Mansouri Y, Alia E, Taliercio M, Desai PN, Lebwohl MG.
The hypothesis that interleukin-17 could be a promising target for alopecia areata therapy, is compelling. In this double-blinded, randomized prospective pilot study in which 11 subjects were treated with either secukinumab (n = 7) or placebo (n = 4) subcutaneously at weeks 0, 1, 2, 3, 4 and every 4 weeks thereafter until (inclusive of) week 20, however, the authors found a striking lack of response. In the secukinumab group, for example, one (14.3%) subject had some hair regrowth, one (14.3%) subject had worsening hair loss, and five (71.4%) subjects had no change in response to treatment. Even in consideration of the low number of individuals, the results indicate that the role of interleukin 17 in alopecia areata is complex and maybe not the essential pathogenic event sufficient to provide a therapeutic target of general relevance for larger patient populations. Nevertheless, the exploration as to whether certain subgroups may benefit from interleukin-17 targeting remains an interesting topic.
For a detailed review of IL-17 in alopecia areata, see also:
IL-17 inhibition: is it the long-awaited savior for alopecia areata?
Arch Dermatol Res. 2018 Jul;310(5):383-390. doi: 10.1007/s00403-018-1823-y. Epub 2018 Mar 1. Review.
Ramot Y, Marzani B, Pinto D, Sorbellini E, Rinaldi F.
Permanent Chemotherapy-Induced Alopecia in Patients with Breast Cancer: A 3-Year Prospective Cohort Study.
Oncologist. 2018 Aug 17. pii: the oncologist.2018-0184. doi: 10.1634/theoncologist.2018-0184. [Epub ahead of print]
Kang D, Kim IR, Choi EK, Im YH, Park YH, Ahn JS, Lee JE, Nam SJ, Lee HK, Park JH, Lee DY, Lacouture ME, Guallar E, Cho J.
In a study on 61 individuals with postoperative diagnosis of stage I-III breast cancer undergoing breast cancer chemotherapy, the authors found that up to 42% of patients had permanent alopecia with incomplete hair growth 3 years after treatment. At this 3-year follow-up study, hair thinning was the most common problem reported by study participants (75.0%), followed by reduced hair volume (53.9%), hair loss (34.6%), and gray hair (34.6%). Given that chemotherapy-associated hair loss is widely recognized as transient phenomenon, these data are not only highly relevant for appropriate consultation of the patients by oncologists, but also by the trichologists who are often important contact persons for affected individuals. They demonstrate that chemotherapy-induced alopecia is an under-reported adverse event and underline the great value which preventive and therapeutic strategies would have for affected individuals.
Evaluating the Efficacy of Different Platelet-Rich Plasma Regimens for Management of Androgenetic Alopecia: A Single-Center, Blinded, Randomized Clinical Trial
Dermatol Surg. 2018 Sep;44(9):1191-1200. doi: 10.1097/DSS.0000000000001567.
Hausauer AK, Jones DH.
Platelet-rich plasma (PRP) is receiving increasing attention as a treatment option for androgenetic alopecia (AGA), but a major challenge is the lack of standardized procedures and administration protocols. Herein, Hausauer and Jones compared the efficacy, safety and patient satisfaction of two PRP injection protocols in a prospective, randomized, single-blinded trial among 40 patients with moderate AGA.
Over a time period of 6 months they found indications for more profound effects after three monthly injections followed by a booster after another three months compared to two sessions every three months. The variability of parameters was quite high, and not all parameters showed significant changes among the groups, but the effort undertaken to help understand the surplus value and to standardize those newly emerging therapies, should be acknowledged, and further research in such direction should be encouraged.
J Optom. 2018 Jul 14. pii: S1888-4296(18)30048-7. doi: 10.1016/j.optom.2018.05.003. [Epub ahead of print]
Aumond S, Bitton E.
Aumond and E. Bitton provide a wonderful comprehensive overview on the biology of eyelashes, a type of hair follicle less well studied but of essential importance for patients. The authors not only explain the biology and cycling, but also the research methods and a variety of eyelash disorders. The review is concise, extremely well structured and nicely illustrated. Even practical guidelines for clinical assessment are provided. Taken together, this review article is recommendable for basic scientists, clinical researchers as well as for clinicians.