What’s new in hair — February 2015 | Dr. Claire A. Higgins

Paracrine cross-talk between human hair follicle dermal papilla cells and microvascular endothelial cells

Exp Dermatol. 2015 Feb 18. doi: 10.1111/exd.12670.

In the past few years we have seen increasing evidence that the macroenvironment of the follicle can influence hair growth and cycling.  In this study, Bassino et al utilised an in vitro co-culture system, and were able to show that hair follicle dermal papilla cells could promote tubulogenesis of human microvascular endothelial cells, more efficiently that their interfollicular fibroblast counterparts.  Dermal papilla cells express high levels of VEGF and IGF1, which are both angiogenic factors, and may be playing a role in promoting tubulogenesis.  This paper reinforces the idea that there is two way communication between the follicle and its macroenvironment.

 

Human Hair as a Natural Sun Protection Agent: A Quantitative Study

Photochem Photobiol. 2015 Feb 16. doi: 10.1111/php.12433.

Overexposure to Solar UVA (320nm-400nm) is recognised as a causative factor for skin cancer.  The clinical observation that lesions are more common in bare areas of scalp has pointed towards hair as a photoprotective covering.  However, until now the photoprotective efficiency of hair has not been quantitated.  In this study, de Gálvez et al analysed hair samples of different colours and densities, and calculated the photoprotective efficiency of the different samples.  As perhaps expected, they found that increasing density of hair conferred a photoprotective effect.  However, more interesting was the observation that the presence of melanin in hair also elicited a photoprotective effect.  Significantly higher levels of UVA were transmitted across white hair compared to brown, red and blond hair, enabling them to calculate that only 550 pigmented hairs/cm2 would be required to confer the same level of photoprotection as 700 white hairs/cm2.

 

Restorative effect of hair follicular dermal cells on injured human hair follicles in a mouse model

Exp Dermatol. 2015 Mar;24(3):225-7. doi: 10.1111/exd.12625.

There are several research groups working on hair follicle induction.  While neogenesis of follicles would be desired in skin where there is a complete absence of follicles, for example in a skin graft, augmentation of existing follicles is a possible strategy in cases of androgenetic alopecia.  In this study, Yamao etal developed a humanised scalp mouse model, into which they grafted human hair follicles.  After integration of these follicles into the skin they damaged the bulb region, and at the same time injected in dermal papilla cells.  They went onto demonstrate that when the follicle regenerates, 33% of the cells in the new papilla structure are derived from the injected cells.  While the injected dermal papilla cells may have moved to the follicle in response to the injury, it still raises the possibility that dermal papilla cells may be useful for follicle augmentation in other circumstances.

 

Colocalization of vitiligo and alopecia areata presenting as poliosis

J Cutan Pathol. 2015 Feb;42(2):150-4. doi: 10.1111/cup.12437.

Vitiligo and alopecia areata are two autoimmune disorders that affect the skin and hair.  While vitiligo results in autoimmune destruction of melanocytes, alopecia areata results in inflammation induced hair loss.  Despite both being autoimmune disorders, cases of vitiligo and alopecia areata are rarely co-localised.  In this study, Walker et al describe a case of a 10 year old boy who presented with poliosis.  Upon taking a punch biopsy of the affected area, the authors were surprised to see a dense dermal infiltrate around hair follicles, and an absence of epidermal melanocytes, characteristics of both alopecia areata and vitiligo.  This suggests there may be more of an interplay between the pathogenic mechanisms in alopecia areata and vitiligo than previously anticipated.

 

Oxidative Stress-Associated Senescence in Dermal Papilla Cells of Men with Androgenetic Alopecia

J Invest Dermatol. 2015 Feb 3. doi: 10.1038/jid.2015.28.

The physiological concentration of oxygen in the dermis is normally relatively hypoxic (1-5%).  Therefore, isolation of dermal papilla cells from the skin, and culture in atmospheric oxygen conditions (21%) can result in ‘culture shock’ and oxidative stress.  In this paper, Upton et al demonstrate that hair follicle dermal papilla cells proliferate slower and senesce more quickly when grown in atmospheric oxygen conditions, compared to hypoxic conditions (2%).  They go on to show that Catalase, an indicator of oxidative stress, is much higher in balding dermal papilla cells, compared to occipital scalp papilla cells.  This suggests that balding dermal papillae are more sensitive to oxidative stress, and atmospheric oxygen conditions, than occipital scalp papillae.

 

Oral isotretinoin as the most effective treatment in folliculitis decalvans: a retrospective comparison of different treatment regimens in 28 patients

J Eur Acad Dermatol Venereol. 2015 Feb 24. doi: 10.1111/jdv.13052.

Folliculitis decalvans is inflammatory disorder of the scalp that results in scarring alopecia.  In the majority of cases the bacterium Staphylococcus aureus is found on the scalp, compared to an incidence of around 30% in the unaffected population.  In this study, Teitze et al evaluated the clinical course of treatment in 28 patients, comparing the efficiency of different regimes.  All patients were started on a topical treatment, which was successful in only 23% of cases.  The remaining 68% of patients were then enrolled on course of oral treatment, and required on average three different therapies before a remission could be achieved.  Of these therapies, the most successful was oral isotretinoin, which had a 90% remission rate in the 48% of patients who received it.  The authors found that with other therapies, especially antibiotic treatments, they saw relapsing disease with an increase in antibiotic-resistant bacteria in the scalp.  Antibiotics are often the first form of treatment for patients with Folliculitis decalvans, and the authors suggest that treatment regimens should be re-evaluated, to prevent against the development of antibiotic resistant S. aureus.

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