Medicine (St Vincent's) - Research Publications
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ItemHair transplantation in mice: Challenges and solutions(WILEY-BLACKWELL, 2016-07)Hair follicle cells contribute to wound healing, skin circulation, and skin diseases including skin cancer, and hair transplantation is a useful technique to study the participation of hair follicle cells in skin homeostasis and wound healing. Although hair follicle transplantation is a well-established human hair-restoration procedure, follicular transplantation techniques in animals have a number of shortcomings and have not been well described or optimized. To facilitate the study of follicular stem and progenitor cells and their interaction with surrounding skin, we have established a new murine transplantation model, similar to follicular unit transplantation in humans. Vibrissae from GFP transgenic mice were harvested, flip-side microdissected, and implanted individually into needle hole incisions in the back skin of immune-deficient nude mice. Grafts were evaluated histologically and the growth of transplanted vibrissae was observed. Transplanted follicles cycled spontaneously and newly formed hair shafts emerged from the skin after 2 weeks. Ninety percent of grafted vibrissae produced a hair shaft at 6 weeks. After pluck-induced follicle cycling, growth rates were equivalent to ungrafted vibrissae. Transplanted vibrissae with GFP-positive cells were easily identified in histological sections. We established a follicular vibrissa transplantation method that recapitulates human follicular unit transplantation. This method has several advantages over current protocols for animal hair transplantation. The method requires no suturing and minimizes the damage to donor follicles and recipient skin. Vibrissae are easier to microdissect and transplant than pelage follicles and, once transplanted, are readily distinguished from host pelage hair. This facilitates measurement of hair growth. Flip-side hair follicle microdissection precisely separates donor follicular tissue from interfollicular tissue and donor cells remain confined to hair follicles. This makes it possible to differentiate migration of hair follicle cells from interfollicular epidermis in lineage tracing wound experiments using genetically labeled donor follicles.
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ItemTreatment of alopecia areata: An Australian expert consensus statement(WILEY, 2019-05)Alopecia areata (AA) severity varies from a single small patch to complete loss of scalp hair, body hair, eyelashes and eyebrows. While 40% of all affected individuals only ever get one patch and will achieve a spontaneous complete durable remission within 6 months, 27% will develop additional patches but still achieve complete durable remission within 12 months and 33% will develop chronic AA. Without systemic treatment, 55% of individuals with chronic AA will have persistent multifocal relapsing and remitting disease, 30% will ultimately develop alopecia totalis and 15% will develop alopecia universalis. The unpredictable course and psychological distress attributable to AA contributes to the illness associated with AA. Numerous topical, intralesional and systemic agents are currently used to treat AA; however, there is a paucity of data evaluating their use, effectiveness and tolerability. Topical therapy, including topical glucocorticosteroids, minoxidil and immunotherapy, can be used in cases of limited disease. There are no universally agreed indications for initiating systemic treatment for AA. Possible indications for systemic treatment include rapid hair loss, extensive disease (≥50% hair loss), chronic disease, severe distress or a combination of these factors. Currently available systemic treatments include glucocorticosteroids, methotrexate, ciclosporin, azathioprine, dapsone, mycophenolate mofetil, tacrolimus and sulfasalazine. The optimal treatment algorithm has not yet been described. The purpose of this consensus statement is to outline a treatment algorithm for AA, including the indications for systemic treatment, appropriate choice of systemic treatment, satisfactory outcome measures and when to discontinue successful or unsuccessful treatment.
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ItemNo Preview AvailableA Global eDelphi Exercise to Identify Core Domains and Domain Items for the Development of a Global Registry of Alopecia Areata Disease Severity and Treatment Safety (GRASS)(AMER MEDICAL ASSOC, 2021-04)IMPORTANCE: A recent expert consensus exercise emphasized the importance of developing a global network of patient registries for alopecia areata to redress the paucity of comparable, real-world data regarding the effectiveness and safety of existing and emerging therapies for alopecia areata. OBJECTIVE: To generate core domains and domain items for a global network of alopecia areata patient registries. EVIDENCE REVIEW: Sixty-six participants, representing physicians, patient organizations, scientists, the pharmaceutical industry, and pharmacoeconomic experts, participated in a 3-round eDelphi process, culminating in a face-to-face meeting at the World Congress of Dermatology, Milan, Italy, June 14, 2019. FINDINGS: Ninety-two core data items, across 25 domains, achieved consensus agreement. Twenty further noncore items were retained to facilitate data harmonization in centers that wish to record them. Broad representation across multiple stakeholder groups was sought; however, the opinion of physicians was overrepresented. CONCLUSIONS AND RELEVANCE: This study identifies the domains and domain items required to develop a global network of alopecia areata registries. These domains will facilitate a standardized approach that will enable the recording of a comprehensive, comparable data set required to oversee the introduction of new therapies and harness real-world evidence from existing therapies at a time when the alopecia areata treatment paradigm is being radically and positively disrupted. Reuse of similar, existing frameworks in atopic dermatitis, produced by the Treatment of Atopic Eczema (TREAT) Registry Taskforce, increases the potential to reuse existing resources, creates opportunities for comparison of data across dermatology subspecialty disease areas, and supports the concept of data harmonization.
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ItemAndrogenetic alopecia: new insights into the pathogenesis and mechanism of hair loss.(F1000 Research Ltd, 2015)The hair follicle is a complete mini-organ that lends itself as a model for investigation of a variety of complex biological phenomena, including stem cell biology, organ regeneration and cloning. The arrector pili muscle inserts into the hair follicle at the level of the bulge- the epithelial stem cell niche. The arrector pili muscle has been previously thought to be merely a bystander and not to have an active role in hair disease. Computer generated 3D reconstructions of the arrector pili muscle have helped explain why women with androgenetic alopecia (AGA) experience diffuse hair loss rather than the patterned baldness seen in men. Loss of attachment between the bulge stem cell population and the arrector pili muscle also explains why miniaturization is irreversible in AGA but not alopecia areata. A new model for the progression of AGA is presented.
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ItemEpidermal Cells Expressing Putative Cell Markers in Nonglabrous Skin Existing in Direct Proximity with the Distal End of the Arrector Pili Muscle(HINDAWI LTD, 2016)Inconsistent with the view that epidermal stem cells reside randomly spread along the basal layer of the epidermal rete ridges, we found that epidermal cells expressing stem cell markers in nonglabrous skin exist in direct connection with the distal end of the arrector pili muscle. The epidermal cells that express stem cell markers consist of a subpopulation of basal keratinocytes located in a niche at the lowermost portion of the rete ridges at the distal arrector pili muscle attachment site. Keratinocytes in the epidermal stem cell niche express K15, MCSP, and α6 integrin. α5 integrin marks the distal end of the APM colocalized with basal keratinocytes expressing stem cell markers located in a well-protected and nourished environment at the lowermost point of the epidermis; these cells are hypothesized to participate directly in epidermal renewal and homeostasis and also indirectly in wound healing through communication with the hair follicle bulge epithelial stem cell population through the APM. Our findings, plus a reevaluation of the literature, support the hierarchical model of interfollicular epidermal stem cell units of Fitzpatrick. This new view provides insights into epidermal control and the possible involvement of epidermal stem cells in nonmelanoma skin carcinogenesis.
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