Materiały źródłowe

• #1 An Overview of Alopecias

  https://pmc.ncbi.nlm.nih.gov/articles/PMC3935391/

  Hair loss is a topic of enormous public interest and understanding the pathophysiology and treatment of various alopecias will likely make a large impact on patients lives. […] Understanding the pathophysiology of the alopecias is critical for developing new hair loss treatments. […] Therefore, a better understanding of the pathogenesis and potential treatments of alopecia will be a welcome advancement. […] This article will cover the clinical presentations of major alopecias and delve into recent research regarding pathogenesis. […] Recent research has increased knowledge regarding AGA pathogenesis and raised possibilities for the development of new treatment. DHT is traditionally implicated in pattern hair loss, with dermal papilla cells (DP cells) hypothesized as the hormones target that sends signals to follicular epithelial cells.

• #2 Hair loss – Wikipedia

  https://en.wikipedia.org/wiki/Hair_loss

  Hair loss, also known as alopecia or baldness, refers to a loss of hair from part of the head or body. Typically at least the head is involved. The severity of hair loss can vary from a small area to the entire body. Inflammation or scarring is not usually present. Hair loss in some people causes psychological distress. […] The cause of male-pattern hair loss is a combination of genetics and male hormones; the cause of female pattern hair loss is unclear; the cause of alopecia areata is autoimmune; and the cause of telogen effluvium is typically a physically or psychologically stressful event. […] Male pattern hair loss is believed to be due to a combination of genetics and the male hormone dihydrotestosterone. The cause in female pattern hair loss remains unclear. […] Hair follicle growth occurs in cycles. Each cycle consists of a long growing phase (anagen), a short transitional phase (catagen) and a short resting phase (telogen). At the end of the resting phase, the hair falls out (exogen) and a new hair starts growing in the follicle, beginning the cycle again. […] A disruption of the growing phase causes abnormal loss of anagen hairs (anagen effluvium).

• #3 Hair loss – Wikipedia

  https://en.wikipedia.org/wiki/Hair_loss

  Hair loss, also known as alopecia or baldness, refers to a loss of hair from part of the head or body. Typically at least the head is involved. The severity of hair loss can vary from a small area to the entire body. Inflammation or scarring is not usually present. Hair loss in some people causes psychological distress. […] The cause of male-pattern hair loss is a combination of genetics and male hormones; the cause of female pattern hair loss is unclear; the cause of alopecia areata is autoimmune; and the cause of telogen effluvium is typically a physically or psychologically stressful event. […] Male pattern hair loss is believed to be due to a combination of genetics and the male hormone dihydrotestosterone. The cause in female pattern hair loss remains unclear. […] Hair follicle growth occurs in cycles. Each cycle consists of a long growing phase (anagen), a short transitional phase (catagen) and a short resting phase (telogen). At the end of the resting phase, the hair falls out (exogen) and a new hair starts growing in the follicle, beginning the cycle again. […] A disruption of the growing phase causes abnormal loss of anagen hairs (anagen effluvium).

• #4 Male Androgenetic Alopecia – Endotext – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK278957/

  Male androgenetic alopecia (MAA) is the most common form of hair loss in men, affecting 30-50% of men by age 50. […] The key pathophysiological features of MAA are alteration in hair cycle development, follicular miniaturization, and inflammation. […] In MAA, the anagen phase decreases with each cycle, while the length of telogen remains constant or is prolonged. Ultimately, anagen duration becomes so short that the growing hair fails to achieve sufficient length to reach the surface of the skin, leaving an empty follicular pore. Hair follicle miniaturization is the histological hallmark of androgenetic alopecia. […] The 3 key features of MAA are alteration of hair cycle dynamics, follicular miniaturization, and inflammation. […] In androgenetic alopecia, the duration of anagen decreases with each cycle, while the length of telogen remains constant or is prolonged; this results in a reduction of the anagen to telogen ratio.

• #5 Male Androgenetic Alopecia – Endotext – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK278957/

  Male androgenetic alopecia (MAA) is the most common form of hair loss in men, affecting 30-50% of men by age 50. […] The key pathophysiological features of MAA are alteration in hair cycle development, follicular miniaturization, and inflammation. […] In MAA, the anagen phase decreases with each cycle, while the length of telogen remains constant or is prolonged. Ultimately, anagen duration becomes so short that the growing hair fails to achieve sufficient length to reach the surface of the skin, leaving an empty follicular pore. Hair follicle miniaturization is the histological hallmark of androgenetic alopecia. […] The 3 key features of MAA are alteration of hair cycle dynamics, follicular miniaturization, and inflammation. […] In androgenetic alopecia, the duration of anagen decreases with each cycle, while the length of telogen remains constant or is prolonged; this results in a reduction of the anagen to telogen ratio.

• #6 Pathogenesis of hair loss – Primary Care Notebook

  https://primarycarenotebook.com/pages/dermatology/androgenetic-alopecia/pathogenesis-of-hair-loss

  The underlying abnormality in hair loss is the decrease in density of thick, pigmented terminal hair and increase in the density of short, fine, nonpigmented vellus hair (1). […] This is marked by several key features […] alteration in hair cycle dynamics […] the duration of anagen phase (growth phase of a hair follicle and controls hair length) is decreased and the duration of the telogen (resting) phase is increased […] this results in a reduction in the hairs in the anagen phase to hairs in the telogen phase ratio from around 12:1 to 5:1 […] since the duration of the anagen phase which controls the length of hair is decreased, each hair cycle causes shorter new anagen hair than its predecessor and with time, new anagen hair ultimately fails to reach the skin surface […] telogen hair is loosely attached to the follicle than anagen hairs which results in increased shedding

• #7 Recent Advances in Understanding of the Etiopathogenesis, Diagnosis, and Management of Hair Loss Diseases

  https://www.mdpi.com/2077-0383/12/9/3259

  Telogen effluvium (TE) is a hair loss condition typically manifesting an acute and diffuse hair loss caused by internal or external insults. Premature termination of the anagen (growing) phase of the hair cycle is the main pathomechanism of TE, which leads to excessive and diffuse loss of club hairs. […] Recent reviews of the scientific literature elucidated that TE represents the main pathomechanism of hair loss after COVID-19, and this was further supported by a recent histopathological analysis.

• #8 Pathogenesis of hair loss – Primary Care Notebook

  https://primarycarenotebook.com/pages/dermatology/androgenetic-alopecia/pathogenesis-of-hair-loss

  further more the latency period or the kenogen phase between telogen hair shedding and anagen regrowth is increased resulting in a reduction in the number of hairs present in the scalp (2) […] follicular miniaturization […] reduction in the diameter of the follicle with each successive hair-growth cycle, thus the large (terminal) follicles become miniaturized (vellus) follicles […] this makes hair more susceptible to falling out (2).

• #9

  https://journals.lww.com/cddr/fulltext/2022/06020/pathogenesis_of_androgenetic_alopecia.3.aspx

  The pathogenesis of androgenetic alopecia (AGA) is a complex interplay of genetic, hormonal, and environmental factors. […] In scalp follicles of susceptible individuals, androgens promote miniaturization of hair and shorten hair growth in the anagen stage, ultimately leading to AGA. […] The major circulating androgen, testosterone, is converted to the more potent androgen dihydrotestosterone by the enzyme 5-reductase (5R). […] Androgen receptors (ARs) and 5R are significantly more in balding scalp hair follicles than those from nonbalding follicles. […] The basic pathology of AGA is progressive miniaturization of the terminal hair follicles and eventual conversion of terminal hair to vellus hair. […] Although many mechanisms have been proposed, the actual mechanism of hair miniaturization has not yet been fully elucidated.

• #10 Male Androgenetic Alopecia – Endotext – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK278957/

  Male androgenetic alopecia (MAA) is the most common form of hair loss in men, affecting 30-50% of men by age 50. […] The key pathophysiological features of MAA are alteration in hair cycle development, follicular miniaturization, and inflammation. […] In MAA, the anagen phase decreases with each cycle, while the length of telogen remains constant or is prolonged. Ultimately, anagen duration becomes so short that the growing hair fails to achieve sufficient length to reach the surface of the skin, leaving an empty follicular pore. Hair follicle miniaturization is the histological hallmark of androgenetic alopecia. […] The 3 key features of MAA are alteration of hair cycle dynamics, follicular miniaturization, and inflammation. […] In androgenetic alopecia, the duration of anagen decreases with each cycle, while the length of telogen remains constant or is prolonged; this results in a reduction of the anagen to telogen ratio.

• #11 Pathogenesis of hair loss – Primary Care Notebook

  https://primarycarenotebook.com/pages/dermatology/androgenetic-alopecia/pathogenesis-of-hair-loss

  further more the latency period or the kenogen phase between telogen hair shedding and anagen regrowth is increased resulting in a reduction in the number of hairs present in the scalp (2) […] follicular miniaturization […] reduction in the diameter of the follicle with each successive hair-growth cycle, thus the large (terminal) follicles become miniaturized (vellus) follicles […] this makes hair more susceptible to falling out (2).

• #12

  https://journals.lww.com/cddr/fulltext/2022/06020/pathogenesis_of_androgenetic_alopecia.3.aspx

  The pathogenesis of AGA involves two main components: (a) Hair follicle miniaturization, and (b) changes to the hair cycle. […] The changes in hair cycle dynamics (shortening of anagen and an increase in telogen duration) are the most important component of the pathogenesis of AGA. […] Hair follicle miniaturization is the histological hallmark of AGA. […] The dermal papilla is principal in the maintenance and control of hair growth and is likely to be the target of androgen-mediated events leading to follicle miniaturization and alterations in hair cycle. […] The process of follicular miniaturization which occurs in AGA does not simultaneously affect all follicles within a FU and this leads to diffuse thinning of hair in the initial days of AGA. […] It is thought that the disruption of movement of cells between the dermal papilla and dermal sheath in AGA causes a loss of cells from the dermal sheath, and then, the dermal papilla that leads to hair follicle miniaturization. […] To summarize, the pathogenesis of AGA is a combination of genetic and hormonal factors leading to miniaturization of hair and shortening of anagen and an increase in telogen duration.

• #13 Androgenetic Alopecia: Practice Essentials, Background, Pathophysiology

  https://emedicine.medscape.com/article/1070167-overview

  Androgenetic alopecia is a genetically determined disorder and is progressive through the gradual conversion of terminal hairs into indeterminate hairs and finally to vellus hairs. Patients with androgenetic alopecia have a reduction in the terminal-to-vellus hair ratio, normally about 4:1. Following miniaturization of the follicles, fibrous tracts remain. Patients with this disorder usually have a typical patterned distribution of hair loss. […] In androgenetic alopecia, studies have indicated a self-renewal of the hair follicle via keratinocyte stem cells located at the area of the bulge of the hair follicle. In addition, a series of studies using mice has indicated that interfollicular keratinocyte stem cells could generate de novo hair follicles in adult mouse skin. These regenerated hair follicles cycled through stages of telogen to anagen. However, these transitions between bulge and epidermal keratinocytes have not been seen yet in human studies.

• #14 Male Androgenetic Alopecia – Endotext – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK278957/

  Hair follicle miniaturization is the histological hallmark of androgenetic alopecia. […] The mesenchyme-derived dermal papilla, located in the middle of the hair bulb at the follicle base, regulates many aspects of the epithelial follicle and determines the type of hair produced. […] The mechanism by which this decrease occurs is unexplained, and may be the result of either apoptotic cell death, decreased proliferation of keratinocytes, cell displacement with loss of cellular adhesion leading to dermal papilla fibroblasts dropping off into the dermis, or migration of dermal papilla cells into the dermal sheath associated with the outer root sheath of the hair follicle. […] In MAA tiny, pale hairs gradually replace large, pigmented ones. Androgens appear to reduce alopecia hair color by inhibiting dermal papilla stem cell factor (SCF) production, which is important in embryonic melanocyte migration and bulbar melanocyte pigmentation.

• #15

  https://journals.lww.com/cddr/fulltext/2022/06020/pathogenesis_of_androgenetic_alopecia.3.aspx

  The pathogenesis of AGA involves two main components: (a) Hair follicle miniaturization, and (b) changes to the hair cycle. […] The changes in hair cycle dynamics (shortening of anagen and an increase in telogen duration) are the most important component of the pathogenesis of AGA. […] Hair follicle miniaturization is the histological hallmark of AGA. […] The dermal papilla is principal in the maintenance and control of hair growth and is likely to be the target of androgen-mediated events leading to follicle miniaturization and alterations in hair cycle. […] The process of follicular miniaturization which occurs in AGA does not simultaneously affect all follicles within a FU and this leads to diffuse thinning of hair in the initial days of AGA. […] It is thought that the disruption of movement of cells between the dermal papilla and dermal sheath in AGA causes a loss of cells from the dermal sheath, and then, the dermal papilla that leads to hair follicle miniaturization. […] To summarize, the pathogenesis of AGA is a combination of genetic and hormonal factors leading to miniaturization of hair and shortening of anagen and an increase in telogen duration.

• #16 Androgenetic alopecia: new insights into the… | F1000Research

  https://f1000research.com/articles/4-585

  The hair follicle is a complete mini-organ that lends itself as a model for investigation of a variety of complex biological phenomena, including stem cell biology, organ regeneration and cloning. […] Loss of attachment between the bulge stem cell population and the arrector pili muscle also explains why miniaturization is irreversible in AGA but not alopecia areata. […] A new model for the progression of AGA is presented. […] Follicular miniaturization is the histological hallmark of AGA. […] This is because the process of follicular miniaturization which occurs in AGA does not simultaneously affect all follicles within a follicular unit (FU). […] Miniaturization occurs initially in the secondary follicles, leading to the reduction in hair density that precedes visible baldness.

• #17

  https://journals.lww.com/cddr/fulltext/2022/06020/pathogenesis_of_androgenetic_alopecia.3.aspx

  The pathogenesis of androgenetic alopecia (AGA) is a complex interplay of genetic, hormonal, and environmental factors. […] In scalp follicles of susceptible individuals, androgens promote miniaturization of hair and shorten hair growth in the anagen stage, ultimately leading to AGA. […] The major circulating androgen, testosterone, is converted to the more potent androgen dihydrotestosterone by the enzyme 5-reductase (5R). […] Androgen receptors (ARs) and 5R are significantly more in balding scalp hair follicles than those from nonbalding follicles. […] The basic pathology of AGA is progressive miniaturization of the terminal hair follicles and eventual conversion of terminal hair to vellus hair. […] Although many mechanisms have been proposed, the actual mechanism of hair miniaturization has not yet been fully elucidated.

• #18 Androgenetic alopecia: MedlinePlus GeneticsLock

  https://medlineplus.gov/genetics/condition/androgenetic-alopecia/

  Androgenetic alopecia is a common form of hair loss in both men and women. […] Researchers have determined that this form of hair loss, particularly in men, is related to hormones called androgens, specifically an androgen called dihydrotestosterone (DHT). […] Androgens help control this cycle. However, too much stimulation of hair follicles by androgens may lead to a shorter growth period, resulting in shorter and thinner strands of hair. The growth of new hair to replace strands that are shed is also delayed. Together, these changes lead to hair thinning or loss. […] Researchers suspect that variants (also called mutations) in several genes play a role in androgenetic alopecia. However, scientific studies have confirmed only that variations in one gene, the AR gene, are involved in this condition.

• #19 Male Androgenetic Alopecia – Endotext – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK278957/

  The observation that eunuchoidal patients with androgen-insensitivity syndrome and 5 alpha-reductase deficiency do not go bald suggests that MAA is induced by activation of follicular androgen receptors by DHT. […] Intrafollicular androgen over-activity may also be the result of local factors including an increased number of androgen receptors, functional polymorphisms of the androgen receptor, increased local production of DHT, and reduced local degradation of DHT. […] The 5 alpha reductase enzyme plays a central role through the intrafollicular conversion of testosterone to the more active metabolite DHT. DHT binds the androgen receptor with 5 times the avidity of testosterone and is more potent in its ability to cause downstream activation. […] Hair loss on the scalp progresses in an orderly and reproducible pattern, and is a function of factors intrinsic to each hair follicle. […] This intrinsic regulation is best demonstrated in hair transplantation experiments: occipital hairs maintain their resistance to MAA when transplanted to the vertex, and scalp hairs from the vertex transplanted to the forearm miniaturize at the same pace as hairs neighboring the donor site.

• #20 DHT: How It Causes Hair Loss and How to Slow It

  https://www.healthline.com/health/dht

  DHT is an androgen associated with the growth of body hair. However, it can also cause hair loss faster and earlier. […] Male pattern balding, also called androgenic alopecia, is one of the most common reasons that those with a penis lose hair as they get older. […] Sex hormones in the body are believed to be the most significant underlying factor behind male pattern hair loss. […] Dihydrotestosterone (DHT) is an androgen. An androgen is a sex hormone that contributes to the development of what are thought of as sex characteristics for people with a penis, such as body hair. But it can also make you lose your hair faster and earlier. […] Once its freely flowing through your bloodstream, DHT can then link to receptors on hair follicles in your scalp, causing them to shrink and become less capable of supporting a healthy head of hair.

• #21 Recent Advances in Understanding of the Etiopathogenesis, Diagnosis, and Management of Hair Loss Diseases

  https://www.mdpi.com/2077-0383/12/9/3259

  AGA is one of the common hair loss conditions characterized by the miniaturization of HFs in the frontal and parietal regions of the scalp predominantly affecting prime-aged male. The condition is with genetic predisposition, and the conversion of testosterone to dihydrotestosterone, a more active form, within the dermal papilla at the root of the HF by 5-α reductase has been shown to contribute to the etiopathology. In this condition, acceleration of the hair cycle has been conceived to account for hair follicular miniaturization and an increased ratio of kenogen HFs. The involvement of the prostaglandin pathway, Wnt/β-catenin pathway, mitochondrial activity, and oxidative stress has also been suggested. […] Unlike in AGA, the role of androgens in FPHL remains unclear, as the condition can be developed in individuals with normal androgen levels, and thus, the term “FPHL” is currently preferred over “female AGA.” Genetic predisposition may play a role in the development of FPHL in such individuals.

• #22 Pattern hair loss – Wikipedia

  https://en.wikipedia.org/wiki/Pattern_hair_loss

  Although it is generally accepted that male pattern baldness follows a pattern of autosomal dominant inheritance, more recent research has shown that approximately 80% of bald men have bald fathers. This is greater than would be expected if pattern balding were a purely autosomal trait, and may suggest that there is an important paternal route of inheritance, either through a Y-chromosome gene or a paternal imprinting effect. […] Androgens can interact with the Wnt signalling pathway to cause hair loss. The initial programming of pilosebaceous units of hair follicles begins in utero. The physiology is primarily androgenic, with dihydrotestosterone (DHT) being the major contributor at the dermal papillae. […] Men with premature androgenic alopecia tend to have lower than normal values of sex hormone-binding globulin (SHBG), follicle stimulating hormone (FSH), testosterone, and epitestosterone when compared to men without pattern hair loss.

• #23 An Updated Etiology of Hair Loss and the New Cosmeceutical Paradigm in Therapy: Clearing ‘the Big Eight Strikes’

  https://www.mdpi.com/2079-9284/10/4/106

  The cause of elevated TGF-β1 levels and how this relates to DHT is not known in full detail, except that the induction of TGF-β1 by DHT requires reactive oxygen species. […] In scarring alopecia, hair regrowth is permanently prevented due to damage around the hair bulge (rather than the bulb), which is the site of attachment of the erector pili muscle and the region of the epithelial stem cells. […] There are multiple classifications of scarring alopecia, but they generally fall into two major groups: (1) primary and (2) secondary cicatricial alopecia. […] The association of P. acnes overgrowth with miniaturized hair follicles from the scalps of candidates with AGA suggests a potential pathological contribution of P. acnes in the development of AGA. […] The most common symptom of hair loss disorders caused by psychological stress/trauma is telogen effluvium (TE), which occurs when the hair follicle terminates growth before the life of the follicle has been completed, i.e., premature telogen.

• #24 Genetic and molecular aspects of androgenetic alopecia – Indian Journal of Dermatology, Venereology and Leprology

  https://ijdvl.com/genetic-and-molecular-aspects-of-androgenetic-alopecia/

  Heilmann et al. suggested a polygenic component to androgenetic alopecia that may be part of the complex biological pathways associated with androgenetic alopecia. […] The Notch signaling pathway is also involved in androgenetic alopecia. […] It has been demonstrated that epigenetic mechanisms involved in histone or DNA methylation modulate the accessibility of genes to the transcriptional machinery and are involved in gene regulation activities in which genomic DNA sequences remain unchanged. […] Androgens are crucial in androgenetic alopecia as they inhibit the expression of Wnt/B-catenin and produce a negative feedback in Notch signaling, both leading to miniaturization of the hair follicle. […] More studies of androgenetic alopecia at the molecular level are necessary as studies performed to analyze epigenetics are gene-specific.

• #25 An Updated Etiology of Hair Loss and the New Cosmeceutical Paradigm in Therapy: Clearing ‘the Big Eight Strikes’

  https://www.mdpi.com/2079-9284/10/4/106

  The only hair loss disorder that can manifest all eight strikes, described in this current commentary, is AGA. This is because the first one of the eight strikes is an androgen imbalance that is caused by excess dihydrotestosterone (DHT) in the scalp tissue. […] Most of the negative effects of excess DHT on the hair follicle start in the region of the hair follicle dermal papilla cells, the bulb. Androgen-mediated paracrine signaling leads to a regression of blood vessels in the hair follicle bulb region where dermal papilla cells are located, making them vulnerable to hypoxia and reactive oxygen species accumulation. […] Another biochemical factor that was identified as problematic in AGA is transforming growth factor beta (TGF-β). The isotype TGF-β1 is highly expressed in dermal papilla cells in balding scalps.

• #26 Male Androgenetic Alopecia – Endotext – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK278957/

  The observation that eunuchoidal patients with androgen-insensitivity syndrome and 5 alpha-reductase deficiency do not go bald suggests that MAA is induced by activation of follicular androgen receptors by DHT. […] Intrafollicular androgen over-activity may also be the result of local factors including an increased number of androgen receptors, functional polymorphisms of the androgen receptor, increased local production of DHT, and reduced local degradation of DHT. […] The 5 alpha reductase enzyme plays a central role through the intrafollicular conversion of testosterone to the more active metabolite DHT. DHT binds the androgen receptor with 5 times the avidity of testosterone and is more potent in its ability to cause downstream activation. […] Hair loss on the scalp progresses in an orderly and reproducible pattern, and is a function of factors intrinsic to each hair follicle. […] This intrinsic regulation is best demonstrated in hair transplantation experiments: occipital hairs maintain their resistance to MAA when transplanted to the vertex, and scalp hairs from the vertex transplanted to the forearm miniaturize at the same pace as hairs neighboring the donor site.

• #27

  https://journals.lww.com/cddr/fulltext/2022/06020/pathogenesis_of_androgenetic_alopecia.3.aspx

  The pathogenesis of androgenetic alopecia (AGA) is a complex interplay of genetic, hormonal, and environmental factors. […] In scalp follicles of susceptible individuals, androgens promote miniaturization of hair and shorten hair growth in the anagen stage, ultimately leading to AGA. […] The major circulating androgen, testosterone, is converted to the more potent androgen dihydrotestosterone by the enzyme 5-reductase (5R). […] Androgen receptors (ARs) and 5R are significantly more in balding scalp hair follicles than those from nonbalding follicles. […] The basic pathology of AGA is progressive miniaturization of the terminal hair follicles and eventual conversion of terminal hair to vellus hair. […] Although many mechanisms have been proposed, the actual mechanism of hair miniaturization has not yet been fully elucidated.

• #28 Androgenetic alopecia: MedlinePlus GeneticsLock

  https://medlineplus.gov/genetics/condition/androgenetic-alopecia/

  Studies suggest that variations in the AR gene result in androgen receptors that are more easily stimulated by androgens than normal, leading to increased activity of the receptors in hair follicles. It remains unclear, however, how these genetic changes increase the risk of hair loss in men and women with androgenetic alopecia. […] Researchers continue to investigate the connection between androgenetic alopecia and other medical conditions, such as coronary heart disease and prostate cancer in men and polycystic ovary syndrome in women.

• #29 Male and female pattern hair loss: Treatable and worth treating | Cleveland Clinic Journal of Medicine

  https://www.ccjm.org/content/88/3/173

  Pattern hair loss is a progressive, nonscarring form of hair loss characterized by gradual loss of terminal hair and follicular miniaturization to vellus hair fibers on the scalp in a characteristic distribution. It is the most common form of hair loss in both men and women and has psychosocial effects, including stress and diminished quality of life. […] Male and female pattern hair loss are polygenic conditions, which explains their high prevalence and variable phenotypic expression. […] Interestingly, genetic variations associated with the androgen receptor gene (AR) have been linked to development of male pattern hair loss, but genes for aromatase (CYP19A1), estrogen receptor-a (ESR1), type I 5-alpha reductase (SRD5A1), and insulin-like growth factor 2 (IGF-2) do not have any established association with it.

• #30 Androgenetic Alopecia: Practice Essentials, Background, Pathophysiology

  https://emedicine.medscape.com/article/1070167-overview

  A lymphocytic microfolliculitis targeting the bulge epithelium, along with deposits of epithelial basement membrane zone immunoreactants, are frequently seen in androgenetic alopecia in both sexes. Those cases with a positive immunoreactant profile respond better to combined-modality therapy than do those with a negative result. […] Numerous studies have identified 2 major genetic risk loci for androgenetic alopecia. These are the X-chromosomal AR/EDA2R locus and the PAX1/FOXA2 locus on chromosome 20. A recent genome-wide association study compared move than 1100 severely affected cases of androgenetic alopecia and controls to note differences in the 2 groups. The study indicated that HDAC9 is the third androgenetic alopecia susceptibility gene. […] The result of the study was that the sebaceous gland area of the androgenetic alopecia group was noticeably increased, while the size of each sebaceous gland remained unchanged. This suggests that overgrowth of the sebaceous gland and relative preservation of the follicular stem cells could be an important factor in the pathology of androgenetic alopecia.

• #31 Androgenetic Alopecia: Practice Essentials, Background, Pathophysiology

  https://emedicine.medscape.com/article/1070167-overview

  A lymphocytic microfolliculitis targeting the bulge epithelium, along with deposits of epithelial basement membrane zone immunoreactants, are frequently seen in androgenetic alopecia in both sexes. Those cases with a positive immunoreactant profile respond better to combined-modality therapy than do those with a negative result. […] Numerous studies have identified 2 major genetic risk loci for androgenetic alopecia. These are the X-chromosomal AR/EDA2R locus and the PAX1/FOXA2 locus on chromosome 20. A recent genome-wide association study compared move than 1100 severely affected cases of androgenetic alopecia and controls to note differences in the 2 groups. The study indicated that HDAC9 is the third androgenetic alopecia susceptibility gene. […] The result of the study was that the sebaceous gland area of the androgenetic alopecia group was noticeably increased, while the size of each sebaceous gland remained unchanged. This suggests that overgrowth of the sebaceous gland and relative preservation of the follicular stem cells could be an important factor in the pathology of androgenetic alopecia.

• #32 Causes – American Hair Loss Association

  https://www.americanhairloss.org/mens-hair-loss/causes/

  Androgenic alopecia, commonly known as male pattern baldness (MPB), is the primary cause of hair loss in men, and it can be triggered anytime after puberty due to the genetic susceptibility to the effects of Dihydrotestosterone (DHT) which varies widely. […] The gene associated with baldness, called the AR gene, is found on the “X” chromosome. A study of 12,806 men of European ancestry revealed that those with the AR gene had more than twice the risk of developing MPB compared to those without it. […] However, the AR gene is not the sole determinant of baldness. Further research in a 2017 review identified 63 genes that may play a role in male pattern baldness, with only six of them found on the “X” chromosome. Additionally, studies have shown that more than 80 percent of individuals experiencing noticeable balding had a father who also experienced hair loss.

• #33 New Insight Into the Pathophysiology of Hair Loss Trigger a Paradigm Shift in the Treatment Approach – JDDonline – Journal of Drugs in Dermatology

  https://jddonline.com/articles/new-insight-into-the-pathophysiology-of-hair-loss-trigger-a-paradigm-shift-in-the-treatment-approach-S1545961617S0135X/

  Hair loss affects millions of men and women of all ages and ethnicities, impacting appearance, social interactions, and psycho-emotional well-being. […] Across the spectrum of hair loss disorders, there has long been a segmentation into distinct mechanisms, driving the main trend in current therapeutics to focus on targeting single molecules or pathways. […] However, research points to similar dysregulation of intrinsic signaling pathways within follicle physiology that span the hair loss disorder spectrum with a common inflammatory component identified in most hair loss pathogenesis, including that of androgenetic alopecia (AGA). […] Disruption of immune pathways affecting the follicle occurs through increased expression of pro-apoptotic and pro-inflammatory cytokines, perifollicular micro-inflammation, and release of reactive oxygen species (ROS).

• #34 Androgenetic Alopecia: Practice Essentials, Background, Pathophysiology

  https://emedicine.medscape.com/article/1070167-overview

  A lymphocytic microfolliculitis targeting the bulge epithelium, along with deposits of epithelial basement membrane zone immunoreactants, are frequently seen in androgenetic alopecia in both sexes. Those cases with a positive immunoreactant profile respond better to combined-modality therapy than do those with a negative result. […] Numerous studies have identified 2 major genetic risk loci for androgenetic alopecia. These are the X-chromosomal AR/EDA2R locus and the PAX1/FOXA2 locus on chromosome 20. A recent genome-wide association study compared move than 1100 severely affected cases of androgenetic alopecia and controls to note differences in the 2 groups. The study indicated that HDAC9 is the third androgenetic alopecia susceptibility gene. […] The result of the study was that the sebaceous gland area of the androgenetic alopecia group was noticeably increased, while the size of each sebaceous gland remained unchanged. This suggests that overgrowth of the sebaceous gland and relative preservation of the follicular stem cells could be an important factor in the pathology of androgenetic alopecia.

• #35 Genetic and molecular aspects of androgenetic alopecia – Indian Journal of Dermatology, Venereology and Leprology

  https://ijdvl.com/genetic-and-molecular-aspects-of-androgenetic-alopecia/

  The replacement of terminal hair by vellus hair and a reduction in the total hair density are the major clinical features of androgenetic alopecia. […] Whether follicle miniaturization occurs mainly due to the activity of androgens is still a matter of debate. […] The role of microinflammation in the pathogenesis of androgenetic alopecia has been investigated by Jaworsky et al. who showed that the inflammatory cell infiltrate in the follicular bulge produces a progressive fibrosis of the perifollicular zone resulting in injury to follicular stem cells, impairment of normal hair cycling and finally, hair loss. […] The genetics of androgenetic alopecia is complex. […] Recent genome-wide association studies in AGA have identified strong association signals in the X chromosome. […] Genome-wide association studies and meta-analysis have been used to evaluate the complex inheritance of androgenetic alopecia.

• #36 Genetic and molecular aspects of androgenetic alopecia – Indian Journal of Dermatology, Venereology and Leprology

  https://ijdvl.com/genetic-and-molecular-aspects-of-androgenetic-alopecia/

  The replacement of terminal hair by vellus hair and a reduction in the total hair density are the major clinical features of androgenetic alopecia. […] Whether follicle miniaturization occurs mainly due to the activity of androgens is still a matter of debate. […] The role of microinflammation in the pathogenesis of androgenetic alopecia has been investigated by Jaworsky et al. who showed that the inflammatory cell infiltrate in the follicular bulge produces a progressive fibrosis of the perifollicular zone resulting in injury to follicular stem cells, impairment of normal hair cycling and finally, hair loss. […] The genetics of androgenetic alopecia is complex. […] Recent genome-wide association studies in AGA have identified strong association signals in the X chromosome. […] Genome-wide association studies and meta-analysis have been used to evaluate the complex inheritance of androgenetic alopecia.

• #37 Genetic and molecular aspects of androgenetic alopecia – Indian Journal of Dermatology, Venereology and Leprology

  https://ijdvl.com/genetic-and-molecular-aspects-of-androgenetic-alopecia/

  The replacement of terminal hair by vellus hair and a reduction in the total hair density are the major clinical features of androgenetic alopecia. […] Whether follicle miniaturization occurs mainly due to the activity of androgens is still a matter of debate. […] The role of microinflammation in the pathogenesis of androgenetic alopecia has been investigated by Jaworsky et al. who showed that the inflammatory cell infiltrate in the follicular bulge produces a progressive fibrosis of the perifollicular zone resulting in injury to follicular stem cells, impairment of normal hair cycling and finally, hair loss. […] The genetics of androgenetic alopecia is complex. […] Recent genome-wide association studies in AGA have identified strong association signals in the X chromosome. […] Genome-wide association studies and meta-analysis have been used to evaluate the complex inheritance of androgenetic alopecia.

• #38 An Updated Etiology of Hair Loss and the New Cosmeceutical Paradigm in Therapy: Clearing ‘the Big Eight Strikes’

  https://www.mdpi.com/2079-9284/10/4/106

  The big eight strikes define the alienable etiological components or comorbidities of hair loss. They are (1) an imbalance of androgens (DHT, testosterone, and SHBG) in cases of AGA; (2) an imbalance of prostaglandins (PGF2-α and PGD2); (3) overactive sebum production and sugar metabolism; (4) bacterial and fungal overgrowth; (5) micro-inflammation; (6) micro-scarring and collagen; (7) inefficient circulation and metabolism (i.e., cholesterol and scalp tension); and (8) nutrient deficiency (or nutrient metabolism, i.e., vitamin D). […] The eight strikes are interdependent. For example, controlling any one of the strikes can improve the other strikes. Thus, by improving each of the strikes, it becomes easier to improve the others, i.e., controlling inflammation can improve prostaglandin balance, controlling DHT can improve inflammation or fibrosis development, controlling bacterial overgrowth can improve inflammation and prostaglandin balance, and so on.

• #39 An Updated Etiology of Hair Loss and the New Cosmeceutical Paradigm in Therapy: Clearing ‘the Big Eight Strikes’

  https://www.mdpi.com/2079-9284/10/4/106

  The big eight strikes define the alienable etiological components or comorbidities of hair loss. They are (1) an imbalance of androgens (DHT, testosterone, and SHBG) in cases of AGA; (2) an imbalance of prostaglandins (PGF2-α and PGD2); (3) overactive sebum production and sugar metabolism; (4) bacterial and fungal overgrowth; (5) micro-inflammation; (6) micro-scarring and collagen; (7) inefficient circulation and metabolism (i.e., cholesterol and scalp tension); and (8) nutrient deficiency (or nutrient metabolism, i.e., vitamin D). […] The eight strikes are interdependent. For example, controlling any one of the strikes can improve the other strikes. Thus, by improving each of the strikes, it becomes easier to improve the others, i.e., controlling inflammation can improve prostaglandin balance, controlling DHT can improve inflammation or fibrosis development, controlling bacterial overgrowth can improve inflammation and prostaglandin balance, and so on.

• #40 Androgenetic alopecia: An update – Indian Journal of Dermatology, Venereology and Leprology

  https://ijdvl.com/androgenetic-alopecia-an-update/

  The signaling which follows at the dermal papillae and hair follicle interface in balding person results in premature termination of anagen associated with premature entry into catagen. […] Another recent advance is identification of the critical role of Wnt/ catenin signaling pathway in the maintenance of the DPC inductive properties required for hair follicle regeneration and growth of the hair shaft. […] The exact roles and processes related to hair follicle stems cells in AGA are not clear. It is considered that while KRT15(hi) stem cells are maintained in bald scalp, there is a defect in conversion of hair follicle stem cells to CD200-rich and CD34-positive progenitor cells, both of which are needed to maintain proper follicular activity. […] Androgenetic alopecia (AGA) is a multifactorial disorder caused by interactions between several genes and environmental factors.

• #41 Androgenetic alopecia: An update – Indian Journal of Dermatology, Venereology and Leprology

  https://ijdvl.com/androgenetic-alopecia-an-update/

  The signaling which follows at the dermal papillae and hair follicle interface in balding person results in premature termination of anagen associated with premature entry into catagen. […] Another recent advance is identification of the critical role of Wnt/ catenin signaling pathway in the maintenance of the DPC inductive properties required for hair follicle regeneration and growth of the hair shaft. […] The exact roles and processes related to hair follicle stems cells in AGA are not clear. It is considered that while KRT15(hi) stem cells are maintained in bald scalp, there is a defect in conversion of hair follicle stem cells to CD200-rich and CD34-positive progenitor cells, both of which are needed to maintain proper follicular activity. […] Androgenetic alopecia (AGA) is a multifactorial disorder caused by interactions between several genes and environmental factors.

• #42 Androgenetic alopecia: new insights into the… | F1000Research

  https://f1000research.com/articles/4-585

  The hair follicle is a complete mini-organ that lends itself as a model for investigation of a variety of complex biological phenomena, including stem cell biology, organ regeneration and cloning. […] Loss of attachment between the bulge stem cell population and the arrector pili muscle also explains why miniaturization is irreversible in AGA but not alopecia areata. […] A new model for the progression of AGA is presented. […] Follicular miniaturization is the histological hallmark of AGA. […] This is because the process of follicular miniaturization which occurs in AGA does not simultaneously affect all follicles within a follicular unit (FU). […] Miniaturization occurs initially in the secondary follicles, leading to the reduction in hair density that precedes visible baldness.

• #43 An Overview of Alopecias

  https://pmc.ncbi.nlm.nih.gov/articles/PMC3935391/

  After these early signals, the DP cells found in areas of AGA are known to enter senescence prematurely, and this phenomenon has been linked to the expression of cell cycle regulators p16INK4a/pRb. […] This novel research represents potential areas for advancement in therapy. […] The study has shed fresh insight into the genetics behind AA pathogenesis, which likely involves both innate and adaptive immunity. […] The importance of neuropeptides and the local hormonal axis is an ongoing area of inquiry regarding hair follicle biology and AA. […] Stress has traditionally been linked to the development of telogen effluvium. […] The process itself is physiological; the abnormality lies in the large number of hairs that are simultaneously affected, as regularly only 5%10% of hairs are in telogen phase.

• #44 ET-02 shows promising 6-fold increase in hair growth in androgenic alopecia – touchDERMATOLOGY

  https://touchderma.com/insight/et-02-androgenic-alopecia/

  A first-in-human trial suggests ET-02 could be a promising novel topical treatment for androgenic alopecia. Participants using the 5% ET-02 solution saw a six-fold increase in non-vellus hair count within five weeks. […] ET-02 (Eirion Therapeutics Inc.) is a topical small molecule designed to target and restore hair follicle stem cells, which are believed to play a key role in regulating hair growth but may become defective or inactive in androgenic alopecia (age-related hair loss). By addressing this stem cell dysfunction, it is hoped ET-02 will stimulate hair regrowth and potentially do so more effectively than current treatments, which do not directly target the underlying cause of this type of hair loss. […] These early data suggest that ET-02 could represent a promising new approach to hair loss treatment—one that focuses on restoring follicular stem cell function rather than merely stimulating hair growth. By addressing this underlying mechanism, ET-02 may not only promote hair regrowth but also help prevent androgenic alopecia.

• #45 Genetic and molecular aspects of androgenetic alopecia – Indian Journal of Dermatology, Venereology and Leprology

  https://ijdvl.com/genetic-and-molecular-aspects-of-androgenetic-alopecia/

  Heilmann et al. suggested a polygenic component to androgenetic alopecia that may be part of the complex biological pathways associated with androgenetic alopecia. […] The Notch signaling pathway is also involved in androgenetic alopecia. […] It has been demonstrated that epigenetic mechanisms involved in histone or DNA methylation modulate the accessibility of genes to the transcriptional machinery and are involved in gene regulation activities in which genomic DNA sequences remain unchanged. […] Androgens are crucial in androgenetic alopecia as they inhibit the expression of Wnt/B-catenin and produce a negative feedback in Notch signaling, both leading to miniaturization of the hair follicle. […] More studies of androgenetic alopecia at the molecular level are necessary as studies performed to analyze epigenetics are gene-specific.

• #46 Androgenetic alopecia: An update – Indian Journal of Dermatology, Venereology and Leprology

  https://ijdvl.com/androgenetic-alopecia-an-update/

  The signaling which follows at the dermal papillae and hair follicle interface in balding person results in premature termination of anagen associated with premature entry into catagen. […] Another recent advance is identification of the critical role of Wnt/ catenin signaling pathway in the maintenance of the DPC inductive properties required for hair follicle regeneration and growth of the hair shaft. […] The exact roles and processes related to hair follicle stems cells in AGA are not clear. It is considered that while KRT15(hi) stem cells are maintained in bald scalp, there is a defect in conversion of hair follicle stem cells to CD200-rich and CD34-positive progenitor cells, both of which are needed to maintain proper follicular activity. […] Androgenetic alopecia (AGA) is a multifactorial disorder caused by interactions between several genes and environmental factors.

• #47 Genetic and molecular aspects of androgenetic alopecia – Indian Journal of Dermatology, Venereology and Leprology

  https://ijdvl.com/genetic-and-molecular-aspects-of-androgenetic-alopecia/

  Heilmann et al. suggested a polygenic component to androgenetic alopecia that may be part of the complex biological pathways associated with androgenetic alopecia. […] The Notch signaling pathway is also involved in androgenetic alopecia. […] It has been demonstrated that epigenetic mechanisms involved in histone or DNA methylation modulate the accessibility of genes to the transcriptional machinery and are involved in gene regulation activities in which genomic DNA sequences remain unchanged. […] Androgens are crucial in androgenetic alopecia as they inhibit the expression of Wnt/B-catenin and produce a negative feedback in Notch signaling, both leading to miniaturization of the hair follicle. […] More studies of androgenetic alopecia at the molecular level are necessary as studies performed to analyze epigenetics are gene-specific.

• #48 Pattern hair loss – Wikipedia

  https://en.wikipedia.org/wiki/Pattern_hair_loss

  Although it is generally accepted that male pattern baldness follows a pattern of autosomal dominant inheritance, more recent research has shown that approximately 80% of bald men have bald fathers. This is greater than would be expected if pattern balding were a purely autosomal trait, and may suggest that there is an important paternal route of inheritance, either through a Y-chromosome gene or a paternal imprinting effect. […] Androgens can interact with the Wnt signalling pathway to cause hair loss. The initial programming of pilosebaceous units of hair follicles begins in utero. The physiology is primarily androgenic, with dihydrotestosterone (DHT) being the major contributor at the dermal papillae. […] Men with premature androgenic alopecia tend to have lower than normal values of sex hormone-binding globulin (SHBG), follicle stimulating hormone (FSH), testosterone, and epitestosterone when compared to men without pattern hair loss.

• #49 Stem cell secretome as a mechanism for restoring hair loss due to stress, particularly alopecia areata: narrative review | Journal of Biomedical Science | Full Text

  https://jbiomedsci.biomedcentral.com/articles/10.1186/s12929-022-00863-6

  The term „stem cell secretome” refers to the soluble factors synthesized by stem cells and utilized for cell-cell communication. […] Secretome accounts for a broad variety of serum proteins, growth factors, angiogenic factors, hormones, cytokines, extracellular matrix proteins, extracellular matrix proteases, and even, in low quantity, lipid mediators and genetic material that are considered to be encoded by around 10% of the human genome. […] Growth factors (GFs) of stem cell secretome activate DPCs to secrete proteins such as SDF1, MMP3 and biglycan which participate in the induction of Wnt signaling. […] SDF1 and bi-glycan activate Wnt 3a and thus canonical Wnt signaling pathway is induced ending up with high expression level of -catenin. […] The latter is a key regulator of hair follicle growth and a primary initiator of anagen phase.

• #50 An Updated Etiology of Hair Loss and the New Cosmeceutical Paradigm in Therapy: Clearing ‘the Big Eight Strikes’

  https://www.mdpi.com/2079-9284/10/4/106

  The only hair loss disorder that can manifest all eight strikes, described in this current commentary, is AGA. This is because the first one of the eight strikes is an androgen imbalance that is caused by excess dihydrotestosterone (DHT) in the scalp tissue. […] Most of the negative effects of excess DHT on the hair follicle start in the region of the hair follicle dermal papilla cells, the bulb. Androgen-mediated paracrine signaling leads to a regression of blood vessels in the hair follicle bulb region where dermal papilla cells are located, making them vulnerable to hypoxia and reactive oxygen species accumulation. […] Another biochemical factor that was identified as problematic in AGA is transforming growth factor beta (TGF-β). The isotype TGF-β1 is highly expressed in dermal papilla cells in balding scalps.

• #51 Pattern hair loss – Wikipedia

  https://en.wikipedia.org/wiki/Pattern_hair_loss

  Although hair follicles were previously thought to be permanently gone in areas of complete hair loss, they are more likely dormant, as recent studies have shown the scalp contains the stem cell progenitor cells from which the follicles arose. […] Transgenic studies have shown that growth and dormancy of hair follicles are related to the activity of insulin-like growth factor (IGF) at the dermal papillae, which is affected by DHT. […] Androgens have different effects at different follicles: they stimulate IGF-1 at facial hair, leading to growth, but can also stimulate TGF 1, TGF 2, dickkopf1, and IL-6 at the scalp, leading to catagenic miniaturization. […] The fact that hair loss is cumulative with age while androgen levels fall as well as the fact that finasteride does not reverse advanced stages of androgenetic alopecia remains a mystery, but possible explanations are higher conversion of testosterone to DHT locally with age as higher levels of 5-alpha reductase are noted in balding scalp, and higher levels of DNA damage in the dermal papilla as well as senescence of the dermal papilla due to androgen receptor activation and environmental stress.

• #52 Stem cell secretome as a mechanism for restoring hair loss due to stress, particularly alopecia areata: narrative review | Journal of Biomedical Science | Full Text

  https://jbiomedsci.biomedcentral.com/articles/10.1186/s12929-022-00863-6

  Secretome consists of VEGF, insulin-like growth factor (IGF), HGF, bone morphogenic proteins (BMPs), interleukin-6 (IL-6), macrophage colony-stimulating factor (M-CSF) and other cytokines. […] These are highly associated with hair regeneration through various mechanisms. […] Exosomes may transport valuable cargo between cells in a natural way, facilitating the transfer of genetic material within organisms. […] ADSC-Exosomes increased DPCs proliferation and migration while suppressing apoptosis. […] Following ADSC-Exosome therapy, RNA-sequencing indicated that the miR-22 and TNF-signaling pathways were significantly downregulated in DPCs. […] This potential treatment is devoid of serious side effects and is considered a natural non-synthetic product.

• #53 Pattern hair loss – Wikipedia

  https://en.wikipedia.org/wiki/Pattern_hair_loss

  Although hair follicles were previously thought to be permanently gone in areas of complete hair loss, they are more likely dormant, as recent studies have shown the scalp contains the stem cell progenitor cells from which the follicles arose. […] Transgenic studies have shown that growth and dormancy of hair follicles are related to the activity of insulin-like growth factor (IGF) at the dermal papillae, which is affected by DHT. […] Androgens have different effects at different follicles: they stimulate IGF-1 at facial hair, leading to growth, but can also stimulate TGF 1, TGF 2, dickkopf1, and IL-6 at the scalp, leading to catagenic miniaturization. […] The fact that hair loss is cumulative with age while androgen levels fall as well as the fact that finasteride does not reverse advanced stages of androgenetic alopecia remains a mystery, but possible explanations are higher conversion of testosterone to DHT locally with age as higher levels of 5-alpha reductase are noted in balding scalp, and higher levels of DNA damage in the dermal papilla as well as senescence of the dermal papilla due to androgen receptor activation and environmental stress.

• #54 UC Irvine-led researchers reveal new molecular mechanism for stimulating hair growth – UC Irvine News

  https://news.uci.edu/2023/06/21/uc-irvine-led-researchers-reveal-new-molecular-mechanism-for-stimulating-hair-growth/

  Our findings offer new insights into the impact of senescent cells on hair stem cell follicles and shed light on their role in tissue regeneration, says lead corresponding author Maksim Plikus, UCI professor of developmental and cell biology. […] The discovery may offer a road map for an entirely new generation of molecular therapies for androgenetic alopecia, a common form of hair loss in both women and men. […] We found that senescent pigment cells produce large quantities of a specific signaling molecule called osteopontin, which causes normally dormant and diminutive hair follicles to activate their stem cells for robust growth of long and thick hairs, said lead corresponding author Maksim Plikus, UCI professor of developmental and cell biology. […] The study involved mouse models with pigmented skin spots that had hyperactivated hair stem cells and displayed accelerated hair growth, strongly resembling the clinical observations documented in human hairy skin nevi.

• #55 Recent Advances in Understanding of the Etiopathogenesis, Diagnosis, and Management of Hair Loss Diseases

  https://www.mdpi.com/2077-0383/12/9/3259

  The contribution of “microinflammation,” which refers to histopathological peri-infundibular lymphocytic cell infiltrates, has been suggested in AGA and FPHL pathophysiology. […] AA is a non-scarring hair loss disorder characterized by autoimmunity targeting anagen HFs. Major advances have been made in our understanding of the etiopathogenesis of AA in which NKG2D+CD8+ cytotoxic T lymphocytes play major roles. […] A surge of interferon (IFN)-γ, secondary to the aforementioned insults, has been proposed to elicit the collapse of HF-IP and subsequent autoimmune-response-targeting HF autoantigens best represented by the activation of autoreactive cytotoxic NKG2D+CD8+ T cells plays central roles in AA pathogenesis. […] The JAK-STAT signaling pathway is located at downstream of these cytokines and is shown to be responsible for the prolongation of AA; based on this, JAK inhibitors were invented as the novel therapeutic agents for severe AA.

• #56 New Hair Growth Mechanism Discovered | UC San Francisco

  https://www.ucsf.edu/news/2017/05/407121/new-hair-growth-mechanism-discovered

  In experiments in mice, UC San Francisco researchers have discovered that regulatory T cells (Tregs; pronounced tee-regs), a type of immune cell generally associated with controlling inflammation, directly trigger stem cells in the skin to promote healthy hair growth. Without these immune cells as partners, the researchers found, the stem cells cannot regenerate hair follicles, leading to baldness. […] The new study published online May 26 in Cell suggests that defects in Tregs could be responsible for alopecia areata, a common autoimmune disorder that causes hair loss, and could potentially play a role in other forms of baldness, including male pattern baldness, Rosenblum said. […] In the new research, led by UCSF postdoctoral fellow and first author Niwa Ali, PhD, several lines of evidence suggested that Tregs play a role in triggering hair follicle regeneration.

• #57 New Hair Growth Mechanism Discovered | UC San Francisco

  https://www.ucsf.edu/news/2017/05/407121/new-hair-growth-mechanism-discovered

  Tregs role in triggering hair growth did not appear related to their normal ability to tamp down tissue inflammation, the researchers found. Instead, they discovered that Tregs trigger stem cell activation directly through a common cell-cell communication system known as the Notch pathway. […] Rosenblum said the findings may have implications for alopecia areata, an autoimmune disease that interferes with hair follicle regeneration and causes patients to lose hair in patches from their scalp, eyebrows, and faces. […] After his team first observed hair loss in Treg-deficient mice, Rosenblum learned that the genes associated with alopecia in previous studies are almost all related to Tregs, and treatments that boost Treg function have been shown to be an effective treatment for the disease. […] Rosenblum speculates that better understanding Tregs critical role in hair growth could lead to improved treatments for hair loss more generally.

• #58 Recent Advances in Understanding of the Etiopathogenesis, Diagnosis, and Management of Hair Loss Diseases

  https://www.mdpi.com/2077-0383/12/9/3259

  The contribution of “microinflammation,” which refers to histopathological peri-infundibular lymphocytic cell infiltrates, has been suggested in AGA and FPHL pathophysiology. […] AA is a non-scarring hair loss disorder characterized by autoimmunity targeting anagen HFs. Major advances have been made in our understanding of the etiopathogenesis of AA in which NKG2D+CD8+ cytotoxic T lymphocytes play major roles. […] A surge of interferon (IFN)-γ, secondary to the aforementioned insults, has been proposed to elicit the collapse of HF-IP and subsequent autoimmune-response-targeting HF autoantigens best represented by the activation of autoreactive cytotoxic NKG2D+CD8+ T cells plays central roles in AA pathogenesis. […] The JAK-STAT signaling pathway is located at downstream of these cytokines and is shown to be responsible for the prolongation of AA; based on this, JAK inhibitors were invented as the novel therapeutic agents for severe AA.

• #59 Alopecia areata: a review of diagnosis, pathogenesis and the therapeutic landscape :: Cambridge Media Journals

  https://journals.cambridgemedia.com.au/wpr/volume-30-number-1/alopecia-areata-review-diagnosis-pathogenesis-and-therapeutic-landscape

  Alopecia areata (AA) is a cytotoxic T cell-mediated autoimmune disease of largely unknown pathogenesis. The prevailing theory centres upon loss of hair follicle IP in genetically predisposed individuals following unknown environmental triggers. […] Collapse of hair follicle immune privilege (IP) has been implicated in AA pathogenesis. […] Recent mouse studies have shed light on the role of interferon (IFN) producing cytotoxic CD8+NKG2D+ effector T cells in AA pathogenesis. […] Collapse of hair follicle IP is associated with hair bulb outer root sheath keratinocyte MHC1 expression resulting in CD8+NKG2D+ effector T cells binding to damaged hair bulb. […] While AA is typically regarded as a type 1 inflammatory disease (IFN is the key cytokine), 15.6% of adults and 39.5% of children with AA have comorbid atopic dermatitis, a type 2 inflammatory disease. […] The differences between extrinsic and intrinsic atopic dermatitis may account for the different trajectories observed following treatment of comorbid AA with dupilumab.

• #60 New Hair Growth Mechanism Discovered | UC San Francisco

  https://www.ucsf.edu/news/2017/05/407121/new-hair-growth-mechanism-discovered

  In experiments in mice, UC San Francisco researchers have discovered that regulatory T cells (Tregs; pronounced tee-regs), a type of immune cell generally associated with controlling inflammation, directly trigger stem cells in the skin to promote healthy hair growth. Without these immune cells as partners, the researchers found, the stem cells cannot regenerate hair follicles, leading to baldness. […] The new study published online May 26 in Cell suggests that defects in Tregs could be responsible for alopecia areata, a common autoimmune disorder that causes hair loss, and could potentially play a role in other forms of baldness, including male pattern baldness, Rosenblum said. […] In the new research, led by UCSF postdoctoral fellow and first author Niwa Ali, PhD, several lines of evidence suggested that Tregs play a role in triggering hair follicle regeneration.

• #61 An Updated Etiology of Hair Loss and the New Cosmeceutical Paradigm in Therapy: Clearing ‘the Big Eight Strikes’

  https://www.mdpi.com/2079-9284/10/4/106

  The big eight strikes define the alienable etiological components or comorbidities of hair loss. They are (1) an imbalance of androgens (DHT, testosterone, and SHBG) in cases of AGA; (2) an imbalance of prostaglandins (PGF2-α and PGD2); (3) overactive sebum production and sugar metabolism; (4) bacterial and fungal overgrowth; (5) micro-inflammation; (6) micro-scarring and collagen; (7) inefficient circulation and metabolism (i.e., cholesterol and scalp tension); and (8) nutrient deficiency (or nutrient metabolism, i.e., vitamin D). […] The eight strikes are interdependent. For example, controlling any one of the strikes can improve the other strikes. Thus, by improving each of the strikes, it becomes easier to improve the others, i.e., controlling inflammation can improve prostaglandin balance, controlling DHT can improve inflammation or fibrosis development, controlling bacterial overgrowth can improve inflammation and prostaglandin balance, and so on.

• #62 Pattern hair loss – Wikipedia

  https://en.wikipedia.org/wiki/Pattern_hair_loss

  Multiple cross-sectional studies have found associations between early androgenic alopecia, insulin resistance, and metabolic syndrome, with low HDL being the component of metabolic syndrome with highest association. […] Premature androgenic alopecia and insulin resistance may be a clinical constellation that represents the male homologue, or phenotype, of polycystic ovary syndrome. […] With early-onset AGA having an increased risk of metabolic syndrome, poorer metabolic profiles are noticed in those with AGA, including metrics for body mass index, waist circumference, fasting glucose, blood lipids, and blood pressure.

• #63 Pattern hair loss – Wikipedia

  https://en.wikipedia.org/wiki/Pattern_hair_loss

  Multiple cross-sectional studies have found associations between early androgenic alopecia, insulin resistance, and metabolic syndrome, with low HDL being the component of metabolic syndrome with highest association. […] Premature androgenic alopecia and insulin resistance may be a clinical constellation that represents the male homologue, or phenotype, of polycystic ovary syndrome. […] With early-onset AGA having an increased risk of metabolic syndrome, poorer metabolic profiles are noticed in those with AGA, including metrics for body mass index, waist circumference, fasting glucose, blood lipids, and blood pressure.

• #64 Pattern hair loss – Wikipedia

  https://en.wikipedia.org/wiki/Pattern_hair_loss

  Multiple cross-sectional studies have found associations between early androgenic alopecia, insulin resistance, and metabolic syndrome, with low HDL being the component of metabolic syndrome with highest association. […] Premature androgenic alopecia and insulin resistance may be a clinical constellation that represents the male homologue, or phenotype, of polycystic ovary syndrome. […] With early-onset AGA having an increased risk of metabolic syndrome, poorer metabolic profiles are noticed in those with AGA, including metrics for body mass index, waist circumference, fasting glucose, blood lipids, and blood pressure.

• #65 A bald endeavour: recent discoveries in the balding mechanism and a possible holy grail | Signals Blog

  https://www.signalsblog.ca/a-bald-endeavour-recent-discoveries-in-the-balding-mechanism-and-a-possible-holy-grail/

  As a result, they escape from their original niche and migrate to the outer layers of the dermis, making them unable to contribute to growing hair. […] This process is not only associated with the lack of glue, but a loss of the stem cells collagen production. For androgenic alopecia specifically, this is thought to be largely due to testosterone, which after being converted into dihyrdrotestosterone (DHT), binds to the hair follicles dermal papilla receptors leading to cell death. […] Besides androgenic alopecia, a recent study by Morinaga et al. highlighted that obesity, due to its underlying cause of insulin resistance, triggers inflammation, reactive oxygen species and several signalling pathways that lead to accelerated hair follicle shrinking and stem cell differentiation. […] Obesity, along with repetitive hair cycles over time, diminishes hair follicle stem cell pools, and self-renewal capabilities, which leads to hair thinning.

• #66 An Overview of Alopecias

  https://pmc.ncbi.nlm.nih.gov/articles/PMC3935391/

  After these early signals, the DP cells found in areas of AGA are known to enter senescence prematurely, and this phenomenon has been linked to the expression of cell cycle regulators p16INK4a/pRb. […] This novel research represents potential areas for advancement in therapy. […] The study has shed fresh insight into the genetics behind AA pathogenesis, which likely involves both innate and adaptive immunity. […] The importance of neuropeptides and the local hormonal axis is an ongoing area of inquiry regarding hair follicle biology and AA. […] Stress has traditionally been linked to the development of telogen effluvium. […] The process itself is physiological; the abnormality lies in the large number of hairs that are simultaneously affected, as regularly only 5%10% of hairs are in telogen phase.

• #67 Researchers discover how chronic stress leads to hair loss — Harvard Gazette

  https://news.harvard.edu/gazette/story/2021/03/researchers-discover-how-chronic-stress-leads-to-hair-loss/

  Harvard University researchers have identified the biological mechanism by which chronic stress impairs hair follicle stem cells, confirming long-standing observations that stress might lead to hair loss. […] The researchers studied a mouse model of chronic stress and found that hair follicle stem cells stayed in a resting phase for a very long time without regenerating tissues. A major stress hormone produced by the adrenal glands, corticosterone, was upregulated by chronic stress; giving mice corticosterone reproduced the stress effect on the stem cells. […] This result suggests that elevated stress hormones indeed have a negative effect on hair follicle stem cells, Hsu said. […] Stress essentially just elevates this preexisting adrenal gland-hair follicle axis, making it even more difficult for hair follicle stem cells to enter the growth phase to regenerate new hair follicles, Hsu said.

• #68 Researchers discover how chronic stress leads to hair loss — Harvard Gazette

  https://news.harvard.edu/gazette/story/2021/03/researchers-discover-how-chronic-stress-leads-to-hair-loss/

  Under both normal and stress conditions, adding Gas6 was sufficient to activate hair follicle stem cells that were in the resting phase and to promote hair growth. […] Rather, the stress hormone prevented dermal papilla cells from secreting Gas6, a molecule that the researchers showed can activate the hair follicle stem cells. […] Stress depletes melanocyte stem cells directly via nerve-derived signals, while stress prevents hair follicle stem cells from making new hairs indirectly via an adrenal-gland-derived stress hormones impact on the niche. […] Because hair follicle stem cells are not depleted, it might be possible to reactivate stem cells under stress with mechanisms such as the Gas6 pathway. […] While there are important local factors, our findings suggest that the major switch for hair follicle stem cell activity is actually far away in the adrenal gland and it works by changing the threshold required for stem cell activation, Hsu said.

• #69 Stem cell secretome as a mechanism for restoring hair loss due to stress, particularly alopecia areata: narrative review | Journal of Biomedical Science | Full Text

  https://jbiomedsci.biomedcentral.com/articles/10.1186/s12929-022-00863-6

  An exposure to psychological stress can act as triggering or exacerbating factor for AA. […] MSCs, in particular, adipose-derived stem cells (ADSCs), are most commonly used in the field of treatment of diseases including skin disorders. […] This latter is characterized by immunological disturbances affecting the hair follicle (HF) and contributing to hair loss. […] Experimental studies on animal models primarily mice have tested and proven the tight association between stress/psycho-emotional state and hair loss. […] Perceived stress (internal or external) can stimulate neuroendocrine immune changes. […] It was shown that prolonged stress can increase inflammatory cytokines (e.g.INF-) leading to inflammation and ending up in apoptosis, cell senescence and premature catagen transition.

• #70 Stem cell secretome as a mechanism for restoring hair loss due to stress, particularly alopecia areata: narrative review | Journal of Biomedical Science | Full Text

  https://jbiomedsci.biomedcentral.com/articles/10.1186/s12929-022-00863-6

  CRF inhibits hair shaft elongation and proliferation of DPCs through arrest of division at G2/M phase. […] Stress resulting from hair loss contributes to a negative feedback elevating hair loss incidence. […] Hair follicle is an immune privilege site, it can tolerate the introduction of foreign antigens without inducing the immune response. […] However, its collapse contributes to the pathogenesis of autoimmune hair loss disorders including AA. […] Neurogenic stress is known to affect the immune system. […] Upon stressful events, CRH factor is released leading to mast cell degranulation, neuropeptide release, high number of CD8+T cell and Natural killer (NK) cells. […] Mast cell degranulation and neuropeptides release are responsible for the significant elevation in substance P.

• #71 Stem cell secretome as a mechanism for restoring hair loss due to stress, particularly alopecia areata: narrative review | Journal of Biomedical Science | Full Text

  https://jbiomedsci.biomedcentral.com/articles/10.1186/s12929-022-00863-6

  CRF inhibits hair shaft elongation and proliferation of DPCs through arrest of division at G2/M phase. […] Stress resulting from hair loss contributes to a negative feedback elevating hair loss incidence. […] Hair follicle is an immune privilege site, it can tolerate the introduction of foreign antigens without inducing the immune response. […] However, its collapse contributes to the pathogenesis of autoimmune hair loss disorders including AA. […] Neurogenic stress is known to affect the immune system. […] Upon stressful events, CRH factor is released leading to mast cell degranulation, neuropeptide release, high number of CD8+T cell and Natural killer (NK) cells. […] Mast cell degranulation and neuropeptides release are responsible for the significant elevation in substance P.

• #72 Recent Advances in Understanding of the Etiopathogenesis, Diagnosis, and Management of Hair Loss Diseases

  https://www.mdpi.com/2077-0383/12/9/3259

  Hair-loss diseases comprise heterogenous conditions with respective pathophysiology and clinicopathological characteristics. Major breakthroughs in hair follicle biology and immunology have led to the elucidation of etiopathogenesis of non-scarring alopecia (e.g., alopecia areata, AA) and cicatricial alopecia (e.g., lichen planopilaris, LPP). High-throughput genetic analyses revealed molecular mechanism underlying the disease susceptibility of hair loss conditions, such as androgenetic alopecia (AGA) and female pattern hair loss (FPHL). […] In the last two decades, major breakthroughs have been made in hair follicle (HF) biology and immunology, represented by the identification of bulge stem cells and discovery of HF immune privilege (HF-IP), enabling in-depth dissection of the pathomechanism underlying major forms of hair loss diseases such as IP-collapse in alopecia areata (AA) and the loss of stem cells in primary cicatricial alopecias, including lichen planopilaris (LPP). Recent genetic and epidemiological analysis elucidated disease susceptibility for androgenetic alopecia (AGA) and female pattern hair loss (FPHL) and revealed a possible link with environmental factors and frontal fibrosing alopecia (FFA).

• #73 Hair loss prevented by blocking ancient biological mechanism

  https://newatlas.com/health-wellbeing/hair-loss-prevention-isr/

  A surprise result in a lab experiment has led to the discovery of an ancient biological stress pathway that can trigger cells to stop making what’s needed to grow hair. […] The block was the result of the activation of an ancient biological pathway known as the Integrated Stress Response (ISR). This response gets switched on in cells that are under stress which can be caused by a host of issues, such as a viral infection or misshapen proteins. […] The scientists found that when the ISR pathway was activated in hair follicles, this 'stasis’ of cells stopped producing the all-important proteins needed for hair growth. […] While still early days, this accidental discovery of how ISR plays such a key role in cell functioning across diverse lifeforms from yeast to humans has researchers now focused on how the mechanism works in people suffering hair loss.

• #74 A bald endeavour: recent discoveries in the balding mechanism and a possible holy grail | Signals Blog

  https://www.signalsblog.ca/a-bald-endeavour-recent-discoveries-in-the-balding-mechanism-and-a-possible-holy-grail/

  Of course, hair loss doesnt just affect men after twenty, it also affects women as they get older (female-pattern baldness), and both sexes at younger ages due to contributing factors such as obesity, and polycystic ovarian syndrome (for women), disorders such as alopecia areata (autoimmune disease), as well as chronic stress and thyroid disorders. […] In the case of male- and female-patterned baldness, these conditions may often be referred to as androgen-induced or androgenetic alopecia, as androgen hormones (such as testosterone) play a key role by binding to the surface of hair follicle cells and attacking them. […] Balding men tend to have hair remaining at the back of the head because the hair follicle cells in this area lack sensitivity to the androgen hormone. […] According to Zhang et al., the young hair follicle in stem cells surrounding the hair bulge are tightly packed. However, during aging, the pool of stem cells located at the bulge eventually lose the glue (the cell adhesion molecules and extracellular matrix) that anchors them in this location.

• #75 Keratin-mediated hair growth and its underlying biological mechanism | Communications Biology

  https://www.nature.com/articles/s42003-022-04232-9

  Therefore, we hypothesized that exposure to keratins derived from apoptotic ORS cells during hair cycling might drive DP cell condensation and secondary HG formation through interaction with DP and ORS cells. […] These findings imply that hair keratin-mediated alterations in the protein and gene expression profiles indicate germ formation and further differentiation of ORS cells. […] Our study shows that intradermal injection of human hair-derived keratin promotes hair growth with enhanced formation of anagen hair follicles and an increase in the size of hair follicles. […] The interaction of P-cadherin with -catenin plays an important role in maintaining the anagen phase of the hair cycle, and -catenin-expressing cells migrated from the bulge region of the ORS undergo further differentiation in the follicle region.

• #76 An Updated Etiology of Hair Loss and the New Cosmeceutical Paradigm in Therapy: Clearing ‘the Big Eight Strikes’

  https://www.mdpi.com/2079-9284/10/4/106

  In this current review, research spanning the last decade (such as transcriptomic studies, phenotypic observations, and confirmed comorbidities) has been synthesized into an updated etiology of hair loss and applied to the new cosmeceutical paradigm of hair rejuvenation. The major etiological components in scalps with hair loss are denoted as the ‘big eight strikes’, which include the following: androgens, prostaglandins, overactive aerobic metabolism of glucose, bacterial or fungal over-colonization, inflammation, fibrosis, metabolism or circulation problems, and malnutrition. […] In cases of androgenetic alopecia or female pattern hair loss, both elevated DHT and increased frequency of androgen receptors lead to problems with the metabolism of glucose (sugar), redox imbalance, disruption to the electron transport chain, and PPAR-γ overactivity (the latter is unique to androgenetic alopecia, where the reverse occurs in other types of hair loss).

• #77 Clinical and preclinical approach in AGA treatment: a review of current and new therapies in the regenerative field | Stem Cell Research & Therapy | Full Text

  https://stemcellres.biomedcentral.com/articles/10.1186/s13287-024-03801-5

  It is seemed that this phenomena will be mostly irreversible although DHT levels were low as clinical evidence shows. Other injury factors such as inflammation or fibrosis are needed to be treated as well. These are the reasons why new regenerative therapies are necessary in order to restore damaged follicular mechanisms caused by a prolonged DHT action. The angiogenic and anti-inflammatory growth factors release, PRP functions and the supply of different cell populations have shown to be promising therapies in a near future. […] These regenerative therapies encompass various alternatives such as PRP and its newly generation of products called PRF, SVF, and stem cell-based therapies, including MSCs condicionated medium (MSCs-CM) and extracellular vesicles application. […] The effectiveness of MSCs derivatives treatment is attributed to their main function: organs and tissues homeostasis. Additionally, they exhibit the ability to secrete growth factors and anti-inflammatory cytokines thereby participating in immunomodulation within the niche and in lymphocyte infiltration reduction generally observed in these patients.

• #78 Recent Advances in Understanding of the Etiopathogenesis, Diagnosis, and Management of Hair Loss Diseases

  https://www.mdpi.com/2077-0383/12/9/3259

  The contribution of “microinflammation,” which refers to histopathological peri-infundibular lymphocytic cell infiltrates, has been suggested in AGA and FPHL pathophysiology. […] AA is a non-scarring hair loss disorder characterized by autoimmunity targeting anagen HFs. Major advances have been made in our understanding of the etiopathogenesis of AA in which NKG2D+CD8+ cytotoxic T lymphocytes play major roles. […] A surge of interferon (IFN)-γ, secondary to the aforementioned insults, has been proposed to elicit the collapse of HF-IP and subsequent autoimmune-response-targeting HF autoantigens best represented by the activation of autoreactive cytotoxic NKG2D+CD8+ T cells plays central roles in AA pathogenesis. […] The JAK-STAT signaling pathway is located at downstream of these cytokines and is shown to be responsible for the prolongation of AA; based on this, JAK inhibitors were invented as the novel therapeutic agents for severe AA.

• #79 Researchers discover how chronic stress leads to hair loss — Harvard Gazette

  https://news.harvard.edu/gazette/story/2021/03/researchers-discover-how-chronic-stress-leads-to-hair-loss/

  Under both normal and stress conditions, adding Gas6 was sufficient to activate hair follicle stem cells that were in the resting phase and to promote hair growth. […] Rather, the stress hormone prevented dermal papilla cells from secreting Gas6, a molecule that the researchers showed can activate the hair follicle stem cells. […] Stress depletes melanocyte stem cells directly via nerve-derived signals, while stress prevents hair follicle stem cells from making new hairs indirectly via an adrenal-gland-derived stress hormones impact on the niche. […] Because hair follicle stem cells are not depleted, it might be possible to reactivate stem cells under stress with mechanisms such as the Gas6 pathway. […] While there are important local factors, our findings suggest that the major switch for hair follicle stem cell activity is actually far away in the adrenal gland and it works by changing the threshold required for stem cell activation, Hsu said.

• #80 Q&A: Pelage’s Novel PP405 Advances to Phase 2a for Androgenetic Alopecia

  https://www.dermatologytimes.com/view/q-a-pelage-s-novel-pp405-advances-to-phase-2a-for-androgenetic-alopecia

  There were 3 main takeaways from our phase 1 study. First and of course, most importantly in a novel mechanism is safety and tolerability. We showed that across all patients, the drug was safe and well-tolerated. Importantly, we were able to, from the pharmacokinetics perspective, reach the target concentration in the hair follicles, but also have no systemic absorption, no detectable drug levels in the blood. The drug was actually specifically engineered for that, for maximum penetration into the skin with minimal blood absorption. […] Secondly, we demonstrated a proof of mechanism. The drug is an inhibitor of MPC, which is mitochondrial pyruvate carrier. It is a membrane transporter on mitochondria that is able to shift the aerobic, anaerobic metabolism of the cell. Essentially what this is able to do is modulate the levels of LDH within the cell, and essentially be able to shift the metabolism so that it is able to activate stem cells that are otherwise dormant within the hair follicle. Through biopsies taken in the phase 1 study of the hair follicle and subsequent biomarker analysis, we were able to show that this is indeed the mechanism by which this is working in human patients who received PP405 topically.

• #81 Weekly treatment with SAMiRNA targeting the androgen receptor ameliorates androgenetic alopecia | Scientific Reports

  https://www.nature.com/articles/s41598-022-05544-w

  Androgenetic alopecia (AGA) is the most common type of hair loss in men and women. Dihydrotestosterone (DHT) and androgen receptor (AR) levels are increased in patients with AGA, and DHT-AR signaling correlates strongly with AGA pathogenesis. […] Androgen and AR signaling plays an essential role in regulating the hair cycle and skin pathogenesis, including in AGA. […] DHT and AR levels are elevated in patients with AGA, and it has been reported that DHT-AR signaling is closely related to AGA pathogenesis. […] DHT-AR signaling is also involved in hair follicular miniaturization, leading to apoptosis of DPCs and keratinocytes and the progression of AGA. Based on the essential role of AR in AGA pathogenesis, suppression of AR expression may be an ideal approach for AGA treatment. […] This study demonstrates that inhibiting AR expression using SAMiRNA nanoparticles targeting human AR mRNA is an effective method for AGA treatment. AR68 treatment significantly reduced the AR mRNA and protein levels in HFDPCs and human hair follicles.

• #82

  https://link.springer.com/article/10.1007/s13659-020-00267-9

  Although there are only two FDA drugs (Topical Minoxidil and Oral Finasteride) are allowed for treating this AGA (Androgenic alopecia) but there are various side effects related to Minoxidil include facial hypertrichosis in 35% of women and contact dermatitis in 6.5% of patients and systemic finasteride also showed a large side effects including sexual dysfunction, mood disturbance and post-finasteride syndrome with related depression. […] At present accessible regular treatments of going bald utilizing synthetic drugs are as yet defective and have various restrictions. […] It has prompted an expanded enthusiasm w for alternative medicines with less reactions, for example, herbal plants having therapeutic potential constituents. […] Natural products envelop an assortment of subgroups including nutrients and minerals, botanicals, and probiotics, which are all internationally showcased as dietary enhancements and dont need Food and Drug Administration (FDA) endorsement.

• #83

  https://journals.lww.com/cddr/fulltext/2022/06020/pathogenesis_of_androgenetic_alopecia.3.aspx

  The pathogenesis of AGA involves two main components: (a) Hair follicle miniaturization, and (b) changes to the hair cycle. […] The changes in hair cycle dynamics (shortening of anagen and an increase in telogen duration) are the most important component of the pathogenesis of AGA. […] Hair follicle miniaturization is the histological hallmark of AGA. […] The dermal papilla is principal in the maintenance and control of hair growth and is likely to be the target of androgen-mediated events leading to follicle miniaturization and alterations in hair cycle. […] The process of follicular miniaturization which occurs in AGA does not simultaneously affect all follicles within a FU and this leads to diffuse thinning of hair in the initial days of AGA. […] It is thought that the disruption of movement of cells between the dermal papilla and dermal sheath in AGA causes a loss of cells from the dermal sheath, and then, the dermal papilla that leads to hair follicle miniaturization. […] To summarize, the pathogenesis of AGA is a combination of genetic and hormonal factors leading to miniaturization of hair and shortening of anagen and an increase in telogen duration.

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