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Platelet-rich plasma (PRP) therapy has been considered as a promising treatment for androgenetic alopecia (AGA). The aim of the study was comparative evaluation of the clinical efficacy of PRP-therapy, minoxidil, and their combination in the treatment of men with AGA and to evaluate the effects of PRP on the proliferation of hair follicle (HF) cells in skin biopsy. Materials and Methods: The study involved 69 men who were divided into 3 groups who received PRP therapy, minoxidil, and their combination. The clinical efficacy of the therapy was evaluated by the dynamics of morphometric of hairs. To assess cell proliferation antibodies to β-catenin, CD34, Ki67, and to Dkk-1 were used. Results. PRP treatment was more effective than minoxidil therapy (p = 0.005). Complex therapy turned out to be more effective than minoxidil monotherapy (p < 0.0001) and PRP monotherapy (p = 0.007). After applying PRP the absolute and relative values of the β-catenin and CD34 expression area increased; an increase in Ki67+ index was also significant. Conclusions: PRP can be considered as a treatment option for AGA. Combined PRP and minoxidil use seems promising for the treatment of AGA. PRP increase in the proliferative activity of HF cells and improves hair morphology in patients with AGA.

Functional mechanoelectrical transduction (MET) channels of cochlear hair cells require the presence of transmembrane channel-like protein isoforms TMC1 or TMC2. We show that TMCs are required for normal stereociliary bundle development and distinctively influence channel properties. TMC1-dependent channels have larger single-channel conductance and in outer hair cells (OHCs) support a tonotopic apex-to-base conductance gradient. Each MET channel complex exhibits multiple conductance states in ~50 pS increments, basal MET channels having more large-conductance levels. Using mice expressing fluorescently tagged TMCs, we show a three-fold increase in number of TMC1 molecules per stereocilium tip from cochlear apex to base, mirroring the channel conductance gradient in OHCs. Single-molecule photobleaching indicates the number of TMC1 molecules per MET complex changes from ~8 at the apex to ~20 at base. The results suggest there are varying numbers of channels per MET complex, each requiring multiple TMC1 molecules, and together operating in a coordinated or cooperative manner. Mechanoelectrical transduction channel (MET) current found in stereocilia of hair cells matures over the first postnatal week. Here the authors look at the contribution of transmembrane channel-like protein 1 and 2 (TMC1 and TMC2) to MET current during development of tonotopic gradients.

The main hypothesis of this study in older adults is that repeated walks in a forest but not an urban environment for one month lead to reduced chronic stress compared to the previous month without any intervention. This was achieved by the measurement of cumulative cortisol concentrations in hair. Older adults of both sexes ( n  = 54; 71 ± 6.2 years) participated in a randomised, parallel-group trial. They were randomly assigned to a forest or an urban walking group. They completed two 40-minute walking sessions per week over one month. Hair samples and morning, as well as afternoon salivary samples, were collected at baseline and following one month of walking interventions. A significant reduction in cumulative hair cortisol was observed during the month of repeated forest but not urban walking compared to the previous month, indicating decreased chronic stress. Salivary cortisol concentrations decreased in the forest group only. No differences in salivary alpha-amylase activity were noticed. Walking activities had no negative impact on the diurnal rhythmicity of stress markers. Quality of life measures showed improvements in emotional well-being in the forest group. A negative correlation was found between hair cortisol and certain quality of life dimensions in urban but not forest groups. Repeated forest walks affect objective measures of chronic stress in older adults, evidenced by lower cumulative hair cortisol concentrations and improved emotional well-being. These findings encourage incorporating forest-based interventions into mental health programs for older adults aimed at enhancing well-being, stress coping, and cognitive functions.

Tissues and cells in organism are continuously exposed to complex mechanical cues from the environment. Mechanical stimulations affect cell proliferation, differentiation, and migration, as well as determining tissue homeostasis and repair. By using a specially designed skin-stretching device, we discover that hair stem cells proliferate in response to stretch and hair regeneration occurs only when applying proper strain for an appropriate duration. A counterbalance between WNT and BMP-2 and the subsequent two-step mechanism are identified through molecular and genetic analyses. Macrophages are first recruited by chemokines produced by stretch and polarized to M2 phenotype. Growth factors such as HGF and IGF-1, released by M2 macrophages, then activate stem cells and facilitate hair regeneration. A hierarchical control system is revealed, from mechanical and chemical signals to cell behaviors and tissue responses, elucidating avenues of regenerative medicine and disease control by demonstrating the potential to manipulate cellular processes through simple mechanical stimulation. Mechanical stimulation is known to affect cell proliferation, differentiation, and regeneration. Here, the authors demonstrate that stretching mouse skin recruits macrophages and polarizes them into M2 cells that facilitate hair regeneration through the release of growth factors, including HGF and IGF-1

Hair follicle development and hair growth are regulated by multiple factors and multiple signalling pathways. The hair follicle, as an important skin appendage, is the basis for hair growth, and it has the functions of safeguarding the body, perceiving the environment and regulating body temperature. Hair growth undergoes a regular hair cycle, including anagen, catagen and telogen. A small amount of physiological shedding of hair occurs under normal conditions, always in a dynamic equilibrium. Hair loss occurs when the skin or hair follicles are stimulated by oxidative stress, inflammation or hormonal disorders that disrupt the homeostasis of the hair follicles. Numerous researches have indicated that oxidative stress is an important factor causing hair loss. Here, we summarize the signalling pathways and intervention mechanisms by which oxidative stress affects hair follicle development and hair growth, discuss existing treatments for hair loss via the antioxidant pathway and provide our own insights. In addition, we collate antioxidant natural products promoting hair growth in recent years and discuss the limitations and perspectives of current hair loss prevention and treatment.

Maintenance of tissue homeostasis is dependent on the communication between stem cells and supporting cells in the same niche. Regulatory T cells (Treg cells) are emerging as a critical component of the stem-cell niche for supporting their differentiation. How Treg cells sense dynamic signals in this microenvironment and communicate with stem cells is mostly unknown. In the present study, by using hair follicles (HFs) to study Treg cell–stem cell crosstalk, we show an unrecognized function of the steroid hormone glucocorticoid in instructing skin-resident Treg cells to facilitate HF stem-cell (HFSC) activation and HF regeneration. Ablation of the glucocorticoid receptor (GR) in Treg cells blocks hair regeneration without affecting immune homeostasis. Mechanistically, GR and Foxp3 cooperate in Treg cells to induce transforming growth factor β3 (TGF-β3), which activates Smad2/3 in HFSCs and facilitates HFSC proliferation. The present study identifies crosstalk between Treg cells and HFSCs mediated by the GR–TGF-β3 axis, highlighting a possible means of manipulating Treg cells to support tissue regeneration.Skin Treg cell crosstalk with hair-follicle stem cells (HFSCs) can control hair regrowth. Here the authors show that glucocorticoid receptor signaling in skin Treg cells induces TGF-β3, which in turn facilitates HFSC proliferation.

The functional aspect of scalp hair is not only to protect from solar radiation and heat/cold exposure but also to contribute to one’s appearance and personality. Progressive hair loss has a cosmetic and social impact. Hair undergoes three stages of hair cycle: the anagen, catagen, and telogen phases. Through cyclical loss and new-hair growth, the number of hairs remains relatively constant. A variety of factors, such as hormones, nutritional status, and exposure to radiations, environmental toxicants, and medications, may affect hair growth. Androgens are the most important of these factors that cause androgenic alopecia. Other forms of hair loss include immunogenic hair loss, that is, alopecia areata. Although a number of therapies, such as finasteride and minoxidil, are approved medications, and a few others (e.g., tofacitinib) are in progress, a wide variety of structurally diverse classes of phytochemicals, including those present in ginseng, have demonstrated hair growth-promoting effects in a large number of preclinical studies. The purpose of this review is to focus on the potential of ginseng and its metabolites on the prevention of hair loss and its underlying mechanisms.

Understanding the underlying mechanisms regulating hair regeneration is crucial, especially given the increasing demand for effective drugs to treat hair loss, which remain not fully elucidated. In the present study, we found that lipid metabolism was attenuated in the scalp tissues of patients with androgenetic alopecia. Lipid supplementation in the culture medium upregulated hair growth-related genes and promoted the proliferation of human dermal papilla cells (DPCs). By using RNA-sequencing analysis and HIF-1α knockdown in DPCs, we found that HIF-1α is a potential candidate that governs lipid-reinforced upregulation of trichogenic genes. Finally, we assessed the hair growth-promoting effects of lipids using in vitro hair follicle organoids and found that lipids accelerated the elongation of hair-shaft-like structures. Our results highlight the importance of lipids in promoting hair growth through HIF-1 signaling, suggesting that this may be a promising target for the treatment of hair loss.

Dermal papilla cells (DPCs) are located at the bottom of the hair follicle and play a critical role in hair growth, shape, and cycle. Epidermal growth factor receptor (EGFR) and Wnt/β-catenin signaling pathways are essential in promoting keratinocyte activation as well as hair follicle formation in DPCs. Piperonylic acid is a small molecule that induces EGFR activation in keratinocytes. However, the effects of piperonylic acid on DPCs in regard to the stimulation of hair growth have not been studied. In the present study, piperonylic acid was shown to activate the Wnt/β-catenin signaling pathway in addition to the EGFR signaling pathway in DPCs. Piperonylic acid suppressed DKK1 expression, which presumably promoted the accumulation of β-catenin in the nucleus. In addition, piperonylic acid promoted cyclin D upregulation and cell growth and increased the expression of alkaline phosphatase (ALP), a DPC marker. In a clinical study, the group that applied a formulation containing piperonylic acid had a significantly higher number of hairs per unit area than the placebo group. These results identify piperonylic acid as a promising new candidate for hair loss treatment.

We have investigated the expression of 52 of the 54 keratins in beard hair medulla. We found that not only 12 hair keratins but, unexpectedly, also 12 epithelial keratins are potentially expressed in medulla cells. The latter comprise keratins also present in outer- and inner-root sheaths and in the companion layer. Keratins K5, K14, K17, K25, K27, K28, and K75 define a “pre-medulla,” composed of cells apposed to the upper dermal papilla. Besides K6, K16, K7, K19, and K80, all pre-medullary epithelial keratins continue to be expressed in the medulla proper, along with the 12 hair keratins. Besides this unique feature of cellular keratin co-expression, the keratin pattern itself is highly variable in individual medulla cells. Remarkably, both epithelial and hair keratins behave highly promiscuously with regard to heterodimer- and IF formation, which also includes keratin chain interactions in IF bundles. We also identified cortex cells within the medullary column. These exhibit all the properties of genuine cortex cells, including a particular type of keratin heterogeneity of their compact IF bundles. In both keratin expression profile and keratin number, medulla cells are distinct from all other cells of the hair follicle or from any other epithelium.