Modeling Human Hair Follicles: Lessons from Animal Models and Beyond

This study observed that incorporating human follicle dermal papilla cells into fibrin microgels increased cell viability and the formation of hair follicle structures in in vitro skin cultures compared to traditional dermal papilla spheroids, suggesting a promising approach for hair follicle regeneration therapies.

In this viewpoint, researchers discussed the possible role of the developmental origin of scalp dermis in influencing the specific pattern of hair follicle miniaturization seen in male pattern hair loss, noting that frontal follicles are more susceptible while occipital follicles remain largely terminal.

This study developed a biomimetic 3-D co-culture system that enhances the hair-inductive properties of human dermal papilla cell aggregates, potentially improving hair follicle tissue engineering.

This study found that incorporating hair follicle-primed spheroids into skin constructs showed potential for developing hair-bearing skin mimetics with follicle-forming abilities in vitro.

This study found that altering mechanical signals in mouse wounds, particularly through FAK inhibition, increased hair regeneration by modulating wound stiffness and gene expression linked to tissue regeneration.

This study reported that human induced pluripotent stem cell-derived skin organoids, used to model epidermolysis bullosa, have an epidermal-dermal junction largely lacking type VII collagen, which is important for skin structure.

This study found that in wound-induced hair neogenesis, African spiny mice and laboratory mice exhibit different morphogenetic field formation patterns related to tissue stiffness, suggesting evolutionary developmental biology advantages.

In this study, selective inhibition of JAK3 signaling effectively prevented and reversed alopecia areata in a mouse model, while JAK2 inhibitors did not restore hair growth.

This study found that conditioned medium from keratinocytes improved the hair-inductive properties of cultured dermal papilla cells, suggesting potential for enhancing hair follicle regeneration.

This study found that sympathetic nerves and arrector pili muscles form a niche that modulates hair follicle stem cell activity, revealing their role in hair follicle regeneration.

This study found that GDNF promotes hair formation and skin wound repair by enhancing the self-renewal and differentiation of bulge stem cells in mice.

Scientists created human skin with hair from stem cells, which could help treat hair loss and skin conditions.

The study suggests that a 3D culture system using the RAD16-I peptide scaffold can help restore the original phenotype of hair follicle dermal papilla cells and support their osteogenic and adipogenic differentiation.

This study demonstrates that incorporating human neopapilla into reconstructed human skin can initiate hair follicle morphogenesis by stimulating epidermal invagination and maintaining follicle-inductive properties in vitro.

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 developed an in vitro system to analyze human skin progenitor cells' ability to form hair peg-like structures, providing insights for engineering hair follicle organoids.

This study demonstrated that enhancing human skin constructs with hair follicles through engineered cell organization and vascularization improved hair growth in immunodeficient mice, suggesting potential advances for treating alopecia and chronic wounds.

This study found that activating the Sonic hedgehog pathway in scarring wounds can remodel the dermis to promote hair follicle regeneration, highlighting a potential new approach to enhance healing.

This study found that using 3D dermal papilla spheroid models enhances extracellular matrix production and hair follicle marker expression, providing insights into hair follicle biology and potential for drug screening.

This review evaluates dihydrotestosterone's role in androgenic alopecia and proposes a model suggesting that chronic scalp tension and inflammation contribute to hair follicle miniaturization, identifying fibrosis, calcification, and tension as treatment targets.

This article reviews different types of alopecia, their diagnosis, and treatment options available in a family physician's practice, but it reports no new research findings.

This study found that hair follicle patterning in development may arise from a combination of epidermal prepattern signals and mesenchymal self-organisation, with fibroblast growth factor and bone morphogenetic protein activities playing key roles.

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 found that while extracellular matrix components like hyaluronic acid promoted larger organoid formation, other matrix components hindered hair follicle germ assembly in an in vitro model.

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 article presents a comprehensive guide for classifying human hair follicle cycle stages in vivo using scalp xenografts on immunocompromised mice, offering valuable resources for researchers in the field.

This study found that composite skin constructs containing dermal papilla cells promoted better skin healing and hair regeneration in nude mice, highlighting their role in tissue-engineered skin for severe injuries.

This study found that Wnt signalling activates hair follicle fate in hair follicle stem cells by relieving TCF3/4–TLE-mediated repression, with β-catenin being crucial for this process.

This study found that altering cell culture conditions to form three-dimensional papilla spheroids can restore the ability of human dermal papilla cells to induce hair growth in adult skin.

This study demonstrated that cultured human dermal papilla cells can induce full hair follicle formation when combined with neonatal foreskin keratinocytes in a grafted dermal-epidermal construct on mice.

This study found that fibroblast growth factor 9, initially secreted by γδ T cells, plays a key role in modulating hair follicle regeneration in mice after skin wounds.

The researchers described a chip-based bioreactor platform for dynamic perfusion, which may enhance in vitro skin models by introducing mechanical shear stress and extending culture periods.

This study found that dermal Shh signaling regulates specific dermal papilla signatures essential for maintaining hair follicle development, suggesting that the Shh-Noggin signaling loop is crucial for hair morphogenesis.

In this mouse study, researchers found that dermal Wnt signaling/β-catenin activity is essential for fibroblast proliferation and initiating hair follicle formation by interacting with epidermal Wnt ligands.

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.

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.

COL17A1 is crucial for preventing hair graying and loss by supporting hair and pigment stem cells.

This study successfully recreated human hair follicles in vitro, which offers a potential advancement in hair regeneration and understanding the effects of drugs on hair follicles.

This study found that Acvr1b signaling is crucial for both hair follicle development and cycling in mice, with the genetic disruption leading to hair loss and a thickened epidermis.

This article discusses the challenges in hair follicle pigmentation research compared to epidermal melanocytes and highlights the limitations of relying on mouse models, but reports no new experimental findings.

This review discusses prolactin production and regulation in human skin and hair follicles, highlighting its potential broader implications but reports no new empirical results.

This study reports the development of the first rodent model for androgenetic alopecia, demonstrating that overexpression of androgen receptors in mice delays hair regeneration and can be used to test new treatments.

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.

This review discusses the shedding phase of the hair cycle, known as exogen, and reports no new findings while analyzing related processes like club fiber formation and release.

This review summarizes fundamental concepts and recent advancements in hair follicle biology, including insights from mouse models into broader molecular and cellular processes relevant to regeneration and development.

Hair follicles can regrow in wounded adult mouse skin using a process like embryo development.

This article discusses the influence of estrogens on hair follicle growth and metabolism, suggesting a significant role alongside androgens in hair growth control but reports no new clinical results.

This study found that bulge cells marked by CD200+ in human hair follicles show high colony-forming efficiency, suggesting successful enrichment of keratinocyte stem cells.

Genetic variation in the androgen receptor gene mainly causes early-onset hair loss, with maternal inheritance playing a key role.

This article reviews the mechanisms by which minoxidil stimulates hair growth and reports no new clinical findings.

This study found that BMP receptor IA is crucial for hair progenitor cell differentiation in mice, and its sequential inhibition and activation are necessary to generate a functioning hair shaft.

This paper discusses key mechanisms of androgen metabolism in androgenetic alopecia and reports the effectiveness of treatments like oral finasteride and topical minoxidil, highlighting the limited success rate due to factors like follicular inflammation.

This study found that specific genetic markers near the androgen receptor gene are significantly more common in men with male pattern baldness, suggesting a genetic component in its development.

In this study, researchers found that hair follicle stem cells in mice can generate both hair follicle and epidermis cells, highlighting their potential bipotency.

This study developed a follicular automaton model that simulates human hair cycle dynamics and can replicate hair pattern changes associated with diffuse or androgenetic alopecia.

This article reviews potential animal models for studying androgenetic alopecia and reports no new experimental results; the authors highlight the need for further development of rodent models.

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.

People with hair loss have more androgen receptors and enzymes in certain follicles, with men and women showing different patterns.