Expression of beta-catenin, p63 and CD34 in hair follicles during the course of androgenetic alopecia

p63 immunoexpression in hair follicles of normal and alopecia X-affected skin of Pomeranian dogs

BACKGROUND

Alopecia X in Pomeranians is caused by a hair cycle deregulation, associated with downregulation of key regulatory genes of the Wnt and Shh pathways, and stem-cell markers. However, the pathogenesis remains unclear. p63 is an important transcription factor correlated with the aforementioned hair cycle modulating genes.

HYPOTHESIS/OBJECTIVES

The aim of this study was to highlight possible changes of p63 immunohistochemical expression within the hair follicles in canine alopecia X compared with normal skin.

ANIMALS

Skin biopsies from 19 alopecia X-affected and six control Pomeranians were analysed.

MATERIALS AND METHODS

Serial histological sections of skin biopsies harbouring anagen, telogen and kenogen hair follicles were immunohistochemically evaluated for differences in p63 expression in the affected and control samples.

RESULTS

Dogs with alopecia X had a significantly decreased immunoexpression of p63 in telogen and kenogen hair follicles.

CONCLUSIONS AND CLINICAL RELEVANCE

The decrease of p63 immunoexpression observed in canine alopecia X suggests an involvement of p63 in hair cycle.

p63: a crucial player in epithelial stemness regulation

Epithelial tissue homeostasis is closely associated with the self-renewal and differentiation behaviors of epithelial stem cells (ESCs). p63, a well-known marker of ESCs, is an indispensable factor for their biological activities during epithelial development. The diversity of p63 isoforms expressed in distinct tissues allows this transcription factor to have a wide array of effects. p63 coordinates the transcription of genes involved in cell survival, stem cell self-renewal, migration, differentiation, and epithelial-to-mesenchymal transition. Through the regulation of these biological processes, p63 contributes to, not only normal epithelial development, but also epithelium-derived cancer pathogenesis. In this review, we provide an overview of the role of p63 in epithelial stemness regulation, including self-renewal, differentiation, proliferation, and senescence. We describe the differential expression of TAp63 and ΔNp63 isoforms and their distinct functional activities in normal epithelial tissues and in epithelium-derived tumors. Furthermore, we summarize the signaling cascades modulating the TAp63 and ΔNp63 isoforms as well as their downstream pathways in stemness regulation.

Stem cell therapy as a novel therapeutic intervention for resistant cases of alopecia areata and androgenetic alopecia

BACKGROUND

Management of alopecia areata (AA) and androgenetic alopecia (AGA) is often challenging as patients may be resistant to currently available modalities of treatment. The use of stem cells may be a novel option for resistant cases.

OBJECTIVE

To evaluate the safety and efficacy of the use of autologous bone marrow derived mononuclear cells (including stem cells) as compared to follicular stems cells for the management of resistant cases of AA and AGA.

METHODS

This study included 40 patients (20 AA patients and 20 AGA patients), all patients were treated with a single session of intradermal injection of autologous stem cells (SCs) therapy. They were divided into four groups according to the applied modality [either autologous bone marrow derived mononuclear cells (bone marrow mononuclear cells [BMMCs] or autologous follicular stem cells [FSC]).

RESULTS

Six months after stem cell therapy (SCT) injection, there was a significant improvement, confirmed by immunostaining and digital dermoscopy. The mean improvement in all groups was "very good". There was no significant difference between both methods in either type of alopecia. No serious adverse events were reported.

CONCLUSION

Autologous BMMCs and FSC seem to be a safe tolerable and effective treatment for the management of both resistant AA and AGA.

Hedgehog signaling maintains hair follicle stem cell phenotype in young and aged human skin

Skin hair follicles (HF) contain bulge stem cells (SC) that regenerate HFs during hair cycles, and repair skin epithelia following injury. As natural aging is associated with decreased skin repair capacity in humans, we have investigated the impact of age on human scalp HF bulge cell number and function. Here, we isolated human bulge cells, characterized as CD200+/KRT15+/KRT19+ cells of the HF, by dissection-combined CD200 selection in young and aged human skin. Targeted transcriptional profiling indicates that KRT15, KRT19, Dkk3, Dkk4, Tcf3, S100A4, Gas1, EGFR and CTGF/CCN2 are also preferentially expressed by human bulge cells, compared to differentiated HF keratinocytes (KC). Our results demonstrate that aging does not alter expression or localization of these HF SC markers. In addition, we could not detect significant differences in HF density or bulge cell number between young and aged human scalp skin. Interestingly, hedgehog (Hh) signaling is activated in human bulge cells in vivo, and down-regulated in differentiated HF KCs, both in young and aged skin. In addition, activation of Hh signaling by lentivirus-mediated overexpression of transcription factor Gli1 induces transcription of HF SC markers KRT15, KRT19, and Gas1, in cultured KCs. Together with previously reported knock-out mouse results, these data suggest a role for Hh signaling in maintaining bulge cell phenotype in young and aged human skin.