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Background: Depletion or permanent quiescence of the hair follicle stem cell (HFSC) pool underlies pathogenesis in androgenetic alopecia (AGA). Reactivation of quiescent HFSCs is considered an efficient treatment strategy for hair loss. The retinoic acid (RA) is critical to ensure stem cell homeostasis and function. However, little is known about whether RA regulates HFSC homeostasis. We aimed to investigate the impact of RA on HFSC homeostasis and the underlying mechanisms, in order to provide new potential targets for medical therapies of AGA. Methods: Microdissected hair follicles from the occipital and frontal scalp in AGA were obtained for RNA sequencing analysis and test. The C57BL/6 mice model in telogen was established to investigate the effect of exogenous RA. Miniaturized hair follicles from frontal scalp were incubated with or without RA in hair follicle organ culture to test the effects on hair shaft elongation, hair cycling and HFSC activities. A strategy to characterize the effect of RA on HFSC in primary culture was developed to identify novel mechanisms that control HFSC activation. A clinical study was performed to test the efficacy of RA treatment in AGA patients. Results: RA signalling was inhibited in the course of AGA pathogenesis along with HFSC dysfunction. Hair regeneration was retarded in AGA miniaturized hair follicles with RA deficiency, but they tended to recover after treatment with RA. In addition, RA treatment during the telogen phase facilitated HFSC anagen entry and accelerated hair growth. Mechanistically, RA promoted hair growth by stimulating stem cells via Wnt/β‐catenin signalling and accelerating the transition from a dormant to an activated state. Furthermore, a clinical study suggested that RA has obvious advantages in the early intervention of AGA by reactivating HFSCs. Conclusions: Our study provides insights into the reactivation of HFSCs in AGA and provides potential targets for medical therapies. [ABSTRACT FROM AUTHOR]

Background: Recipient area scalp necrosis is considered a potential complication of hair transplantation, but has rarely been reported. A small number of patients have developed scalp necrosis after hair transplantation with the widely used Follicular unit excision (FUE) technique. There are no guidelines to prevent and manage this complication. The aim of this study was to provide an insight into the pathogenesis, prevention, and management of scalp necrosis following hair transplantation. Methods: From 2012 to 2021, among more than 10 000 patients who underwent hair transplantation, only three developed scalp necrosis in our clinical experience, besides, one patient transferred to our hospital because of scalp necrosis after undergoing hair transplantation. According to the disease etiology and patients' symptom, a combination of wound management and antimicrobial therapy was employed. This study was approved by the institutional ethics committee of Nanfang Hospital. Results: Of the four patients, three received timely treatment and had a good prognosis. Necrosis became confined and healed within 2–3 weeks. Grafts in the lesion area partially survived. In case 4, due to improper treatment at the early stage, the lesion developed extensively and deeply, which not only delayed wound healing, but also resulted in complete loss of grafts. Conclusion: Preoperative prophylaxis, timely diagnosis, and immediate treatment of scalp necrosis can prevent serious complications and reduce morbidity after hair transplantation. [ABSTRACT FROM AUTHOR]

Androgenetic alopecia (AGA) is the most common pattern of hair loss resulting from the effects of androgen on hair follicles. MicroRNAs (miRs) serve imperative roles in the regulation of many biological processes of hair follicles. However, the exact molecular mechanism of AGA remains to be elucidated. In the present study, we found miR‐122, which is mainly recognized as a tumor suppressor, was highly overexpressed in the bulb of balding hair follicles in comparison with nonbalding ones in AGA. Moreover, miR‐122 induces apoptosis of human dermal papilla cells (hDPCs) with miR‐122 mimics in vitro, and the expression of insulin‐like growth factor 1 receptor (IGF1R) in hDPCs was reduced following upregulation of miR‐122. Mechanistically, dual‐luciferase reporter assay confirmed that miR‐122 directly targeted the 3′‐untranslated region of IGF1R. These findings suggested that upregulation of miR‐122 induces apoptosis, potentially via the repression of IGF1R in hDPCs of AGA, providing a novel insight into the potential pathological mechanism of miR‐122 in AGA DPCs. [ABSTRACT FROM AUTHOR]

Androgenetic alopecia is the most common form of hair loss disorder. The features of this process are shortening of the anagen phase in hair cycling and progressive miniaturization of the hair follicle. However, the mechanisms in androgenetic alopecia are still unclear, and the treatment methods are also limited. Therefore, further study on the pathogenesis and new therapies for androgenetic alopecia are urgently needed. In this study, we found that endogenous autophagy was severely impaired, accompanied by increased apoptosis in early catagen‐like miniaturized hair follicles from the balding scalps of androgenetic alopecia patients. Moreover, inhibition of autophagy using 3‐methyladenine could induce apoptosis, premature hair follicle regression and slow down the hair growth in organ‐cultured hair follicles. Taken together, these results suggest that impairment of autophagy could be a potential mechanism in androgenetic alopecia. [ABSTRACT FROM AUTHOR]

Background: Hair transplantation is the gold standard method for the treatment of alopecia. Recently, demand for the surgery has increased rapidly. However, high demands also require more professional training for the surgeons. With the maturing of hairline design skills, parietal whorl design has become the next challenge and no appropriate training models have yet been reported. Aims: To present an innovative, simple, and appropriate training model for designing the scalp parietal whorl. Methods: Outward divergent arc curves were drawn from the navel of an orange. Recipient sites were created with 23G needles or 1.0‐mm knives or 1.0‐mm blades according to the outward divergent arc curves, then hair shafts were transplanted using forceps. Results: Different densities of hair shafts were transplanted. Transplantation of 10‐20 follicular units (FU)/cm2 was too sparse, 30 FU/cm2 achieved a good appearance, but 40‐50 FU/cm2 was better. Through practicing on the model, excellent results of parietal whorl transplantation on patients can be achieved. Conclusions: This new model can perfectly suit the lines and direction of the parietal whorl and also present different density transplantation practicing. We provide a training method for new surgeons as well as a rehearsal opportunity for previously trained doctors. [ABSTRACT FROM AUTHOR]