-
Nature Reviews. Disease Primers Mar 2017Alopecia areata is an autoimmune disorder characterized by transient, non-scarring hair loss and preservation of the hair follicle. Hair loss can take many forms ranging... (Review)
Review
Alopecia areata is an autoimmune disorder characterized by transient, non-scarring hair loss and preservation of the hair follicle. Hair loss can take many forms ranging from loss in well-defined patches to diffuse or total hair loss, which can affect all hair-bearing sites. Patchy alopecia areata affecting the scalp is the most common type. Alopecia areata affects nearly 2% of the general population at some point during their lifetime. Skin biopsies of affected skin show a lymphocytic infiltrate in and around the bulb or the lower part of the hair follicle in the anagen (hair growth) phase. A breakdown of immune privilege of the hair follicle is thought to be an important driver of alopecia areata. Genetic studies in patients and mouse models have shown that alopecia areata is a complex, polygenic disease. Several genetic susceptibility loci were identified to be associated with signalling pathways that are important to hair follicle cycling and development. Alopecia areata is usually diagnosed based on clinical manifestations, but dermoscopy and histopathology can be helpful. Alopecia areata is difficult to manage medically, but recent advances in understanding the molecular mechanisms have revealed new treatments and the possibility of remission in the near future.
Topics: Alopecia Areata; Environmental Exposure; Hair; Hair Follicle; Humans; Microbiota; Scalp; Stress, Psychological
PubMed: 28300084
DOI: 10.1038/nrdp.2017.11 -
Drug Design, Development and Therapy 2019Minoxidil was first introduced as an antihypertensive medication and the discovery of its common adverse event, hypertrichosis, led to the development of a topical... (Review)
Review
Minoxidil was first introduced as an antihypertensive medication and the discovery of its common adverse event, hypertrichosis, led to the development of a topical formulation for promoting hair growth. To date, topical minoxidil is the mainstay treatment for androgenetic alopecia and is used as an off-label treatment for other hair loss conditions. Despite its widespread application, the exact mechanism of action of minoxidil is still not fully understood. In this article, we aim to review and update current information on the pharmacology, mechanism of action, clinical efficacy, and adverse events of topical minoxidil.
Topics: Animals; Antihypertensive Agents; Hair; Humans; Hypertrichosis; Minoxidil; Molecular Structure; Sulfotransferases
PubMed: 31496654
DOI: 10.2147/DDDT.S214907 -
The Journal of Investigative... Dec 2007Shiny hair with a smooth texture and clean-cut ends or tapered tips is generally perceived to be healthy. Hair texture and shine relate to hair surface properties,... (Review)
Review
Shiny hair with a smooth texture and clean-cut ends or tapered tips is generally perceived to be healthy. Hair texture and shine relate to hair surface properties, whereas the integrity of hair ends relates to the hair cortex. Hair can be straight, wavy or curly, blonde, black, brown, red, gray white, and its natural variations are important to our identity. Manipulation of the normal structure of the hair shaft is epidemic and dictated by culture, fashion, and above all, celebrity. Although cosmetic procedures are intrinsically safe, there is potential for damage to the hair. Loss of lustre, frizz, split ends, and other hair problems are particularly prevalent among people who repeatedly alter the natural style of their hair or among people with hair that is intrinsically weak. This may be due to individual or racial variation or less commonly an inherited structural abnormality in hair fiber formation. Hair health is also affected by common afflictions of the scalp as well as age-related phenomena such as graying and androgenetic alopecia. Hair products that improve the structural integrity of hair fibers and increase tensile strength are available, as are products that increase hair volume, reduce frizz, improve hair manageability, and stimulate new hair growth.
Topics: Eicosanoic Acids; Female; Hair; Hair Diseases; Hair Preparations; Humans; Hygiene
PubMed: 18004288
DOI: 10.1038/sj.jidsymp.5650046 -
Cells May 2019The use of stem cells has been reported to improve hair regrowth in several therapeutic strategies, including reversing the pathological mechanisms, that contribute to... (Review)
Review
Advances in Regenerative Stem Cell Therapy in Androgenic Alopecia and Hair Loss: Wnt pathway, Growth-Factor, and Mesenchymal Stem Cell Signaling Impact Analysis on Cell Growth and Hair Follicle Development.
The use of stem cells has been reported to improve hair regrowth in several therapeutic strategies, including reversing the pathological mechanisms, that contribute to hair loss, regeneration of hair follicles, or creating hair using the tissue-engineering approach. Although various promising stem cell approaches are progressing via pre-clinical models to clinical trials, intraoperative stem cell treatments with a one-step procedure offer a quicker result by incorporating an autologous cell source without manipulation, which may be injected by surgeons through a well-established clinical practice. Many authors have concentrated on adipose-derived stromal vascular cells due to their ability to separate into numerous cell genealogies, platelet-rich plasma for its ability to enhance cell multiplication and neo-angiogenesis, as well as human follicle mesenchymal stem cells. In this paper, the significant improvements in intraoperative stem cell approaches, from in vivo models to clinical investigations, are reviewed. The potential regenerative instruments and functions of various cell populaces in the hair regrowth process are discussed. The addition of Wnt signaling in dermal papilla cells is considered a key factor in stimulating hair growth. Mesenchymal stem cell-derived signaling and growth factors obtained by platelets influence hair growth through cellular proliferation to prolong the anagen phase (FGF-7), induce cell growth (ERK activation), stimulate hair follicle development (β-catenin), and suppress apoptotic cues (Bcl-2 release and Akt activation).
Topics: Adipocytes; Adipose Tissue; Adult; Alopecia; Hair; Hair Follicle; Humans; Intercellular Signaling Peptides and Proteins; Mesenchymal Stem Cells; Platelet-Rich Plasma; Regenerative Medicine; Stem Cell Transplantation; Stem Cells; Tissue Engineering; Wnt Signaling Pathway
PubMed: 31100937
DOI: 10.3390/cells8050466 -
Physiological Reviews Jan 2001Nearly 50 years ago, Chase published a review of hair cycling in which he detailed hair growth in the mouse and integrated hair biology with the biology of his day. In... (Review)
Review
Nearly 50 years ago, Chase published a review of hair cycling in which he detailed hair growth in the mouse and integrated hair biology with the biology of his day. In this review we have used Chase as our model and tried to put the adult hair follicle growth cycle in perspective. We have tried to sketch the adult hair follicle cycle, as we know it today and what needs to be known. Above all, we hope that this work will serve as an introduction to basic biologists who are looking for a defined biological system that illustrates many of the challenges of modern biology: cell differentiation, epithelial-mesenchymal interactions, stem cell biology, pattern formation, apoptosis, cell and organ growth cycles, and pigmentation. The most important theme in studying the cycling hair follicle is that the follicle is a regenerating system. By traversing the phases of the cycle (growth, regression, resting, shedding, then growth again), the follicle demonstrates the unusual ability to completely regenerate itself. The basis for this regeneration rests in the unique follicular epithelial and mesenchymal components and their interactions. Recently, some of the molecular signals making up these interactions have been defined. They involve gene families also found in other regenerating systems such as fibroblast growth factor, transforming growth factor-beta, Wnt pathway, Sonic hedgehog, neurotrophins, and homeobox. For the immediate future, our challenge is to define the molecular basis for hair follicle growth control, to regenerate a mature hair follicle in vitro from defined populations, and to offer real solutions to our patients' problems.
Topics: Animals; Apoptosis; Body Patterning; Cell Differentiation; Cell Lineage; Cell Movement; Epithelial Cells; Growth Substances; Hair; Hair Follicle; Humans; In Vitro Techniques; Mesoderm; Mice; Morphogenesis; Periodicity; Skin; Stem Cells
PubMed: 11152763
DOI: 10.1152/physrev.2001.81.1.449 -
Indian Journal of Dermatology,... 2018Androgenetic alopecia is the most common form of progressive hair loss in humans. A genetic predisposition and hormonal status are considered as major risk factors for... (Review)
Review
Androgenetic alopecia is the most common form of progressive hair loss in humans. A genetic predisposition and hormonal status are considered as major risk factors for this condition. Several recent advances in molecular biology and genetics have increased our understanding of the mechanisms of hair loss in androgenetic alopecia. We review these advances and examine the trends in the genetic and molecular aspects of androgenetic alopecia.
Topics: Alopecia; Epigenesis, Genetic; Finasteride; Genetic Predisposition to Disease; Genome-Wide Association Study; Hair; Hair Follicle; Humans; Minoxidil; Receptors, Androgen
PubMed: 29595184
DOI: 10.4103/ijdvl.IJDVL_262_17 -
International Journal of Molecular... Sep 2018The 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.... (Review)
Review
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.
Topics: Alopecia; Animals; Hair; Hair Follicle; Humans; Panax; Phytotherapy; Plant Preparations; Signal Transduction
PubMed: 30208587
DOI: 10.3390/ijms19092703 -
BMB Reports Jan 2023Hair follicles in the skin undergo cyclic rounds of regeneration, degeneration, and rest throughout life. Stem cells residing in hair follicles play a pivotal role in... (Review)
Review
Hair follicles in the skin undergo cyclic rounds of regeneration, degeneration, and rest throughout life. Stem cells residing in hair follicles play a pivotal role in maintaining tissue homeostasis and hair growth cycles. Research on hair follicle aging and age-related hair loss has demonstrated that a decline in hair follicle stem cell (HFSC) activity with aging can decrease the regeneration capacity of hair follicles. This review summarizes our understanding of how age-associated HFSC intrinsic and extrinsic mechanisms can induce HFSC aging and hair loss. In addition, we discuss approaches developed to attenuate ageassociated changes in HFSCs and their niches, thereby promoting hair regrowth. [BMB Reports 2023; 56(1): 2-9].
Topics: Humans; Hair Follicle; Hair; Aging; Alopecia; Stem Cells
PubMed: 36379515
DOI: 10.5483/BMBRep.2022-0183 -
Current Cardiology Reports Aug 2019This review focuses on the concentration of cortisol in human hair as a biomarker of chronic stress in cardiovascular disease (CVD). We outline the cardiovascular... (Review)
Review
PURPOSE OF REVIEW
This review focuses on the concentration of cortisol in human hair as a biomarker of chronic stress in cardiovascular disease (CVD). We outline the cardiovascular consequences of cortisol excess and provide a comprehensive overview of recent studies investigating the relationship of hair cortisol with CVD. In addition, clinical implications and limitations of the evidence are discussed, together with directions for future research.
RECENT FINDINGS
Hair cortisol may be a reliable biomarker of chronic stress since it provides quantification of total cortisol secreted into hair over several weeks. A growing body of evidence suggests that elevated hair cortisol levels are associated with both the incidence of CVD and poorer recovery and treatment outcomes. Moreover, increased hair cortisol concentration has been linked with established cardiometabolic risk factors for CVD including high blood pressure, diabetes, and adiposity. Hair cortisol is a promising biomarker of chronic cortisol excess which may contribute to both the pathogenesis and prognosis of CVD. However, the current evidence relies on small-scale cross-sectional studies. Further research adopting longitudinal designs across larger samples of CVD patients and healthy participants is required to inform the development of novel evidence-based interventions.
Topics: Biomarkers; Cardiovascular Diseases; Chronic Disease; Hair; Humans; Hydrocortisone; Saliva; Stress, Physiological; Stress, Psychological
PubMed: 31471749
DOI: 10.1007/s11886-019-1208-7 -
Cell Stem Cell Mar 2020Skin homeostasis is orchestrated by dozens of cell types that together direct stem cell renewal, lineage commitment, and differentiation. Here, we use single-cell RNA...
Skin homeostasis is orchestrated by dozens of cell types that together direct stem cell renewal, lineage commitment, and differentiation. Here, we use single-cell RNA sequencing and single-molecule RNA FISH to provide a systematic molecular atlas of full-thickness skin, determining gene expression profiles and spatial locations that define 56 cell types and states during hair growth and rest. These findings reveal how the outer root sheath (ORS) and inner hair follicle layers coordinate hair production. We found that the ORS is composed of two intermingling but transcriptionally distinct cell types with differing capacities for interactions with stromal cell types. Inner layer cells branch from transcriptionally uncommitted progenitors, and each lineage differentiation passes through an intermediate state. We also provide an online tool to explore this comprehensive skin cell atlas, including epithelial and stromal cells such as fibroblasts, vascular, and immune cells, to spur further discoveries in skin biology.
Topics: Animals; Cell Differentiation; Hair; Hair Follicle; Mice; Skin
PubMed: 32109378
DOI: 10.1016/j.stem.2020.01.012