Functional Complexity of Hair Follicle Stem Cell Niche and Therapeutic Targeting of Niche Dysfunction for Hair Regeneration

This study found that lymphatic vessels in mice are important for hair follicle development and organization, as their depletion blocks hair growth.

This review discusses the mechanisms behind alopecia areata and primary cicatricial alopecia and reports no new clinical results, aiming to guide the development of targeted treatments.

This study found that mechanical skin stretching can stimulate hair stem cell proliferation and hair regeneration by activating a complex pathway involving WNT, BMP-2, and M2 macrophages.

This study found that Oncostatin M, via JAK-STAT5 signaling, keeps hair follicle stem cells inactive, and its removal leads to hair growth initiation in mice.

This study suggests that damaged anagen hair follicles have the capability to repair themselves and resume growth by mobilizing extra-bulge epithelial cells, particularly after injuries like chemotherapy and radiotherapy.

This consensus statement outlines a treatment algorithm for alopecia areata, discussing when to consider systemic treatment and how to assess outcomes, without providing new clinical results.

In this study, the researchers found that treatment with the JAK inhibitor tofacitinib in alopecia areata patients may reduce clonal CD8+ T cell expansions but does not eliminate them entirely, which could contribute to disease relapse.

This study found that Hoxc gene expression can reprogram mesenchymal dermal papilla cells, enhance epithelial stem cell regenerative potential, and promote region-specific hair follicle regeneration through Wnt signaling.

In this review, the researchers reported that JAK inhibitors, originally approved by the FDA for other uses, have shown effectiveness in reversing hair loss in patients with moderate to severe alopecia areata, based on current preclinical and clinical studies.

This study found that light stimulation of intrinsically photosensitive retinal ganglion cells in the eyes can activate hair follicle stem cells through a neural circuit involving the sympathetic nervous system.

In this randomized, double-blind trial, researchers observed that low-level laser therapy led to significantly greater hair regrowth on treated areas compared to a sham treatment in patients with androgenetic alopecia over 24 weeks, suggesting it as a potentially effective and safe option.

This review discusses the unique features of dermal white adipose tissue, its interaction with hair follicles, and its role in skin physiology, reporting no new experimental findings.

This review discusses the role of immune privilege collapse in the pathogenesis of alopecia areata, emphasizing the potential for therapeutic manipulation of hair bulb immune privilege to offer new treatment options, and reports no new results.

This article reviews current and emerging treatments for alopecia areata, including Janus kinase inhibitors, highlighting variability in clinical outcomes and the lack of sustained remission.

This article reviews the epidemiology, clinical evaluation, and pathogenesis of alopecia areata and highlights recent advancements, but it does not report new clinical findings.

PPAR-γ agonists like pioglitazone may help manage lichen planopilaris but don't fully reverse scarring.

This study observed that mTORC1 signaling is activated and crucial for hair follicle regeneration and hair growth in irradiated mice, facilitating recovery within 96 hours without significant hair loss.

This study reports that hair follicles can mobilize ectopic progenitors for regeneration to repair damage from ionizing radiation. Augmenting WNT signaling enhanced this regenerative process and prevented radiation- and chemotherapy-induced hair loss, highlighting a potential approach to manage alopecia during cancer treatment.

This study identified overexpression of certain immune-related genes and underexpression of genes in specific signaling pathways in premature androgenetic alopecia, suggesting potential new therapeutic targets.

This study found that micro-niches within hair follicles create heterogeneity among stem cells and transit-amplifying cells, leading to specialized progenitors that control tissue morphogenesis and regeneration.

This study shows that macrophage-induced TNF signaling can activate hair follicle stem cells and promote new hair follicle formation after wounding by regulating AKT/β-catenin pathways.

This study suggests that stress-induced premature senescence of dermal papilla cells may contribute to hair follicle aging by impairing critical epithelial-mesenchymal interactions and promoting inflammatory cytokine production.

This study found that Sonic Hedgehog secreted by hair follicle transit-amplifying cells is essential for dermal adipogenesis and hair follicle growth by acting on adipocyte precursors.

This study explored the effectiveness of the oral JAK1/2 inhibitor ruxolitinib in treating patients with moderate-to-severe alopecia areata, building on prior success with JAK inhibitors in mice, but results are not reported in this abstract.

This review examines the immunological aspects of alopecia areata, focusing on genetic, neuroimmunological, and immune privilege factors, but does not report new clinical findings.

In this study, oral tofacitinib treatment led to significant hair regrowth and changes in skin and blood biomarkers in a patient with alopecia areata.

This research found that Foxc1 transcription factor and COL17A1 are critical in regulating quiescence and hair thinning in hair follicle stem cells, with aging-related DNA damage leading to hair loss.

This study observed that applying JAK-STAT pathway inhibitors to mouse and human skin led to rapid hair growth by inducing the anagen phase of hair follicles.

This review discusses how macro-environmental factors such as intradermal adipose tissue and sex hormones influence hair and feather stem cell niches, suggesting environmental targets for regenerative medicine, but reports no new clinical results.

This study found that patterned hair plucking in mice triggers a collective regeneration response in nearby unplucked hair follicles via a quorum sensing mechanism involving immune signaling.

In this study, the researchers found that the effectiveness of a 1,550-nm fractional laser in promoting hair growth in mice depends on the specific combination of beam energy and density, with inappropriate settings potentially causing ulcers or hair follicle injury.

This study found that mTOR signaling plays a crucial role in activating hair follicle stem cells by balancing BMP-mediated repression, essential for hair regeneration.

This study found that red light accelerated the transition from the resting to growth phase in hair follicles faster than green and blue light in mice, suggesting it may stimulate hair growth.

This study found that macrophages near hair follicles contribute to the activation of skin epithelial stem cells in mice, suggesting a novel role for macrophages in regulating hair growth.

This study identifies a bipotent stem cell in adult hair follicles that self-renews and contributes to dermal sheath and papilla cell populations, potentially aiding hair regrowth after injury, disease, or aging.

This study found that JAK inhibitors promote hair regrowth in both mice and human alopecia areata cases by blocking key immune pathways involved in disease development.

This narrative review examines the interactions between skin stem cells and their niches, finding new insights from advancements in genetic and imaging tools but reporting no new experimental results.

This study found that in mice, epidermal Wnt/β-catenin signaling influences adipocyte differentiation and hair growth, suggesting its critical role in synchronizing adipogenesis with the hair growth cycle.

This study reviews the significant prevalence of organic etiologies, especially vascular causes, in erectile dysfunction among men under 40 and emphasizes thorough evaluation and consideration of treatment options like exercise and PDE-5 inhibitors.

This study found that higher BMI was significantly associated with more severe hair loss in men with male-pattern and early-onset androgenetic alopecia.

This study found that immune privilege collapse in the hair follicle bulge and associated immune responses may contribute significantly to the pathogenesis of lichen planopilaris, suggesting a potential autoimmune basis for the disease.

This review discusses mesenchymal–epithelial interactions in hair follicle development and cycling, highlighting recent insights without reporting new experimental results.

This review discusses the roles of androgens and androgen receptors in skin-related disorders and suggests that targeting androgen receptors may be a more effective treatment strategy.

In this study, researchers showed that Wnt ligands secreted by hair follicle epithelium are crucial for hair follicle regeneration and may be significant for treating hair disorders like alopecia.

This study reports that hair regeneration in live mice involves spatially regulated stem cell divisions and requires mesenchymal interactions, observed in real-time using a novel non-invasive imaging method.

Alopecia Areata is an autoimmune condition causing hair loss with no cure and treatments that often don't work well.

The study reports that Fgf18 and Tgf-β2 signaling pathways in hair follicle stem cells have opposing effects on the timing of hair cycle transitions, influencing the shift from telogen to anagen phases.

This review describes minoxidil's hair regrowth mechanism and discusses dermatological applications, but reports no new clinical results, emphasizing the need for regular use and addressing allergic reactions.

This study identified TGF-β2 as a crucial signal in hair follicle stem cell regeneration, highlighting its role in counteracting BMP signaling to promote tissue regeneration.

IL-6 contributes to hair loss by shortening the growth phase and causing hair follicles to regress.

This study found that intradermal adipocyte lineage cells in mice are necessary and sufficient to activate follicular stem cells, highlighting their role in regulating skin stem cell activity.

This study found that Shh from neurons signals to Gli1-expressing cells in the hair follicle, cultivating a niche where these bulge cells can potentially transform into epidermal stem cells in wound healing.

This article discusses the pathogenesis and possible biological mechanisms of alopecia areata but reports no new clinical results.

This study found that in a population of hair follicles, regenerative cycling stages are regulated by both intrinsic and extrinsic signals, with WNT/BMP signaling mediating interactions among follicles for adaptability.

This review discusses how changes in hair and skin may indicate underlying vitamin deficiencies and emphasizes the need to identify populations at risk for these deficiencies; it reports no new results.

This study identified key genetic regions associated with alopecia areata, highlighting both acquired and innate immune involvement, with a novel link to the upregulation of ULBP ligands in autoimmune disease.

This study found that in mice, inactivating beta-catenin in the dermal papilla reduces hair follicle progenitor proliferation and disrupts the hair cycle.

This review discusses treatment options for alopecia areata and suggests tailored treatment plans, noting the challenges posed by spontaneous remission and limited high-quality clinical trials.

This study suggests that the action of minoxidil in stimulating hair growth likely occurs at the follicular dermal papilla, though it does not induce new follicle formation.

No treatment showed clear superiority for lichen planopilaris.

This article reviews lichen planopilaris, a chronic scarring alopecia, and explores recent treatment developments, but it reports no new clinical results.

This study found that balding dermal papilla cells show premature senescence and altered expression of stress and DNA damage markers, suggesting sensitivity to environmental stress in androgenetic alopecia.

The study found that bioengineered hair follicles work when using cells from the same species but have issues when combining human and mouse cells.

This review examines the interplay of genetics and neuroimmunology in alopecia areata, highlighting its potential to inform broader autoimmunity research, but reports no new findings.

The researchers reported that DHT-inducible DKK-1 may play a significant role in DHT-driven balding by inhibiting hair follicle cell growth and promoting apoptosis in androgenetic alopecia.

This study found that dutasteride increased scalp hair growth in men with male pattern hair loss, particularly at a 2.5 mg dose, and was more effective than finasteride over 24 weeks.

Male pattern baldness is largely genetic, linked to the androgen receptor gene, and may relate to certain health issues.

TGF-β1 from dermal papilla cells suppresses hair growth, and targeting it may help treat androgenetic alopecia.

This review discusses the diagnosis and treatment of hirsutism, emphasizing that a systematic evaluation can determine its cause, while combination therapy effectively manages the condition for most patients.

This study demonstrated that multipotent stem cells in adult mice whisker follicles migrate to produce whisker growth, and that this process requires precise control of stem cell trafficking.

This study suggests that the paradoxical effects of androgens on hair growth are due to differential gene expression in hair follicles, possibly established during embryogenesis.

This study observes the expression of mRNA for androgen receptor, 5α‐reductase, and 17β‐hydroxysteroid dehydrogenase in human dermal papilla cells.

This article discusses the biologic and psychosocial significance of hair, the current limitations in hair growth drugs, and anticipates future therapies based on advancing hair follicle research.

In male pattern hair loss, this study found that finasteride 1 mg daily significantly slowed hair loss and increased hair growth over two years compared to placebo.

This study found that dermal papilla cells from balding scalp hair follicles have significantly higher levels of androgen receptors than those from non-balding follicles, supporting their in vivo androgen response.

TGF-β receptors are crucial for hair follicle development.

This study found that dermal papilla cells from balding follicles exhibit distinct growth characteristics compared to non-balding cells, suggesting their potential as a model for understanding androgenetic alopecia.

This article reviews the biochemical properties of 5 alpha-reductase isoforms and highlights the limited dermatological use of inhibitors like finasteride, especially for type 1 isozyme-targeting agents, while suggesting further clinical exploration.

In this study, IL-6 expression in transgenic mice thickened the stratum corneum without causing increased epidermal proliferation or inflammation, suggesting it may enhance skin protection rather than directly induce inflammation.

In this randomized trial, topical minoxidil treatment resulted in cosmetically acceptable hair growth in 32% of men with hereditary male pattern baldness, with no serious side effects reported.

This study found that 32% of patients with hereditary male pattern baldness experienced cosmetically acceptable hair growth after applying topical minoxidil twice daily, with no serious side effects reported.

Minoxidil helped bald patient regrow hair.

Hair growth is cyclic and influenced mainly by local factors.