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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Inhibitory autocrine factors produced by the mesenchyme-derived hair follicle dermal papilla may be a key to male pattern baldness.

Hamada, K., Randall, Valerie A. January 2006 (has links)
No / BACKGROUND: Androgenetic alopecia, or male pattern baldness, is a common, progressive disorder where large, terminal scalp hairs are gradually replaced by smaller hairs in precise patterns until only tiny vellus hairs remain. This balding can cause a marked reduction in the quality of life. Although these changes are driven by androgens, most molecular mechanisms are unknown, limiting available treatments. The mesenchyme-derived dermal papilla at the base of the mainly epithelial hair follicle controls the type of hair produced and is probably the site through which androgens act on follicle cells by altering the regulatory paracrine factors produced by dermal papilla cells. During changes in hair size the relationship between the hair and dermal papilla size remains constant, with alterations in both dermal papilla volume and cell number. This suggests that alterations within the dermal papilla itself play a key role in altering hair size in response to androgens. Cultured dermal papilla cells offer a useful model system to investigate this as they promote new hair growth in vivo, retain characteristics in vitro which reflect their parent follicle's response to androgens in vivo and secrete mitogenic factors for dermal papilla cells and keratinocytes. OBJECTIVES: To investigate whether cultured dermal papilla cells from balding follicles secrete altered amounts/types of mitogenic factors for dermal papilla cells than those from larger, normal follicles. We also aimed to determine whether rodent cells would recognize mitogenic signals from human cells in vitro and whether factors produced by balding dermal papilla cells could alter the start of a new mouse hair cycle in vivo. METHODS: Dermal papilla cells were cultured from normal, balding and almost clinically normal areas of balding scalps and their ability to produce mitogenic factors compared using both human and rat whisker dermal papilla cells as in vitro targets and mouse hair growth in vivo. RESULTS: Normal scalp cells produced soluble factors which stimulated the growth of both human scalp and rat whisker dermal papilla cells in vitro, demonstrating dose-responsive mitogenic capability across species. Although balding cells stimulated some growth, this was much reduced and they also secreted inhibitory factor(s). Balding cell media also delayed new hair growth when injected into mice. CONCLUSIONS: Human balding dermal papilla cells secrete inhibitory factors which affect the growth of both human and rodent dermal papilla cells and factors which delay the onset of anagen in mice in vivo. These inhibitory factor(s) probably cause the formation of smaller dermal papillae and smaller hairs in male pattern baldness. Identification of such factor(s) could lead to novel therapeutic approaches.
2

The prostamide-related glaucoma therapy, bimatoprost, offers a novel approach for treating scalp alopecias

Khidhir, Karzan Ghafur, Woodward, D.F., Farjo, N.P., Farjo, B.K., Tang, E.S., Wang, J.W., Randall, Valerie A., Picksley, Stephen M. January 2013 (has links)
No / Balding causes widespread psychological distress but is poorly controlled. The commonest treatment, minoxidil, was originally an antihypertensive drug that promoted unwanted hair. We hypothesized that another serendipitous discovery, increased eyelash growth side-effects of prostamide F2α-related eyedrops for glaucoma, may be relevant for scalp alopecias. Eyelash hairs and follicles are highly specialized and remain unaffected by androgens that inhibit scalp follicles and stimulate many others. Therefore, we investigated whether non-eyelash follicles could respond to bimatoprost, a prostamide F2α analog recently licensed for eyelash hypotrichosis. Bimatoprost, at pharmacologically selective concentrations, increased hair synthesis in scalp follicle organ culture and advanced mouse pelage hair regrowth in vivo compared to vehicle alone. A prostamide receptor antagonist blocked isolated follicle growth, confirming a direct, receptor-mediated mechanism within follicles; RT-PCR analysis identified 3 relevant receptor genes in scalp follicles in vivo. Receptors were located in the key follicle regulator, the dermal papilla, by analyzing individual follicular structures and immunohistochemistry. Thus, bimatoprost stimulates human scalp follicles in culture and rodent pelage follicles in vivo, mirroring eyelash behavior, and scalp follicles contain bimatoprost-sensitive prostamide receptors in vivo. This highlights a new follicular signaling system and confirms that bimatoprost offers a novel, low-risk therapeutic approach for scalp alopecias.
3

Androgens trigger different growth responses in genetically identical human hair follicles in organ culture that reflect their epigenetic diversity in life

Miranda, Benjamin H., Charlesworth, Matthew R., Tobin, Desmond J., Sharpe, David T., Randall, Valerie A. 2017 October 1918 (has links)
Yes / Male sex hormones-androgens-regulate male physique development. Without androgen signaling, genetic males appear female. During puberty, increasing androgens harness the hair follicle's unique regenerative ability to replace many tiny vellus hairs with larger, darker terminal hairs (e.g., beard). Follicle response is epigenetically varied: some remain unaffected (e.g., eyelashes) or are inhibited, causing balding. How sex steroid hormones alter such developmental processes is unclear, despite high incidences of hormone-driven cancer, hirsutism, and alopecia. Unfortunately, existing development models are not androgen sensitive. Here, we use hair follicles to establish an androgen-responsive human organ culture model. We show that women's intermediate facial follicles respond to men's higher androgen levels by synthesizing more hair over several days, unlike donor-matched, androgen-insensitive, terminal follicles. We demonstrate that androgen receptors-androgen-activated gene transcription regulators-are required and are present in vivo within these follicles. This is the first human organ that involves multiple cell types that responds appropriately to hormones in prolonged culture, in a way which mirrors its natural behavior. Thus, intermediate hair follicles offer a hormone-switchable human model with exceptional, unique availability of genetically identical, but epigenetically hormone-insensitive, terminal follicles. This should enable advances in understanding sex steroid hormone signaling, gene regulation, and developmental and regenerative systems and facilitate better therapies for hormone-dependent disorders.
4

The roles of hepatocyte growth factor family members in androgen-regulation of human hair growth : a comparison of the expression of hepatocyte growth factor family members, HGF and MSP, and their receptors, c-Met and RON, in isolated hair follicles from normal and androgenetic alopecia (balding) scalp

Al-Waleedi, Saeed A. January 2010 (has links)
Androgens are the main regulators of human hair growth stimulating larger, terminal hair development e.g. beard and causing scalp balding, androgenetic alopecia. Hair disorders cause psychological distress but are poorly controlled. Androgens probably act by altering regulatory paracrine factors produced by the mesenchyme-derived dermal papilla. This study aimed to investigate paracrine factors involved in androgen-regulated alopecia, particularly hepatocyte growth factor (HGF) family members, by investigating their in vivo status. Balding and non-balding scalp hair follicles and their component tissues were isolated and analysed by molecular biological methods (reverse transcriptase-polymerase chain reaction (RT-PCR), quantitative PCR and DNA microarray analysis), cell culture and immunohistochemistry. Scalp follicles expressed a range of paracrine messenger genes. The dermal papilla, cultured dermal papilla cells and dermal sheath expressed several HGF family genes, while matrix cells only produced the receptor RON suggesting autocrine roles for HGF and MSP, but a paracrine route only for MSP. Comparing balding and non-balding follicles from the same individuals revealed the expected reduction in several keratin and keratin-related protein genes supporting this approach's validity. There were also significant differences in paracrine factors previously implicated in androgen action by in vitro studies. Several factors believed to increase during androgen stimulation of larger, darker follicles, e.g. IGF-I and SCF, were lowered in balding follicles, while putative inhibitory factors, e.g. TGFß-1, were increased. HGF and MSP and their receptors, c-Met and RON, were significantly reduced. These results increase our understanding of androgen action in human hair follicles; this could lead to better treatments for hair disorders.
5

Regulation of hair growth : prostaglandins and prostamides : studies confirming the growth stimulating effects of prostanoids and prostamides on human hair follicles in organ culture and locating their receptors using lipidomics, molecular biological and immunohistological approaches

Khidhir, Karzan Ghafur January 2010 (has links)
Hair growth disorders cause significant psychological distress, but are poorly controlled. Since prostaglandin F₂α (PGF₂α) and prostamide F₂α analogue glaucoma treatments cause eyelash growth as side-effects, they may be useful for alopecia. How they function is unknown; possibilities include direct action on hair follicles or stimulating follicular blood flow. It is important to clarify whether scalp follicles can also respond as human follicle response to androgens differ with body site. Therefore, human scalp follicles were grown in vitro in organ culture with PGF₂α, latanoprost, a PGF₂α analogue, and bimatoprost, a prostamide F₂α analogue, with, or without, appropriate antagonists, and the presence of PGF₂α (FP) and prostamide F₂α receptors were investigated using molecular biological and immunohiostochemical methods. Each treatment significantly stimulated follicle growth rate, the percentage of growing follicles, and the amount of hair produced in a dose-responsive manner (10nM-1μM); the receptor antagonists blocked these effects. Immunohistochemistry of frozen scalp sections demonstrated FP protein only in dermal papillae and connective tissue sheaths. RT-PCR identified FP and various prostamide F₂α receptors in anagen follicles and isolated dermal papillae and bulbar connective tissue sheath, but not in bulb matrix or other epithelial tissues. Therefore, isolated human scalp hair follicles can respond biologically to PGF₂α and related pharmaceuticals in organ culture via follicular receptors and express the genes and protein for FP and prostamide F₂α receptors. PGF₂α-related drugs appear to act directly on follicles via receptors in the regulatory dermal papilla. They offer an exciting, novel approach for treating alopecia and merit clinical investigation.
6

The roles of hepatocyte growth factor family members in androgen-regulation of human hair growth. A comparison of the expression of hepatocyte growth factor family members, HGF and MSP, and their receptors, c-Met and RON, in isolated hair follicles from normal and androgenetic alopecia (balding) scalp.

Al-Waleedi, Saeed A. January 2010 (has links)
Androgens are the main regulators of human hair growth stimulating larger, terminal hair development e.g. beard and causing scalp balding, androgenetic alopecia. Hair disorders cause psychological distress but are poorly controlled. Androgens probably act by altering regulatory paracrine factors produced by the mesenchyme-derived dermal papilla. This study aimed to investigate paracrine factors involved in androgen-regulated alopecia, particularly hepatocyte growth factor (HGF) family members, by investigating their in vivo status. Balding and non-balding scalp hair follicles and their component tissues were isolated and analysed by molecular biological methods (reverse transcriptase-polymerase chain reaction (RT-PCR), quantitative PCR and DNA microarray analysis), cell culture and immunohistochemistry. Scalp follicles expressed a range of paracrine messenger genes. The dermal papilla, cultured dermal papilla cells and dermal sheath expressed several HGF family genes, while matrix cells only produced the receptor RON suggesting autocrine roles for HGF and MSP, but a paracrine route only for MSP. Comparing balding and non-balding follicles from the same individuals revealed the expected reduction in several keratin and keratin-related protein genes supporting this approach's validity. There were also significant differences in paracrine factors previously implicated in androgen action by in vitro studies. Several factors believed to increase during androgen stimulation of larger, darker follicles, e.g. IGF-I and SCF, were lowered in balding follicles, while putative inhibitory factors, e.g. TGFß-1, were increased. HGF and MSP and their receptors, c-Met and RON, were significantly reduced. These results increase our understanding of androgen action in human hair follicles; this could lead to better treatments for hair disorders. / Saudi government
7

Regulation of hair growth: Prostaglandins and prostamides. Studies confirming the growth stimulating effects of prostanoids and prostamides on human hair follicles in organ culture and locating their receptors using lipidomics, molecular biological and immunohistological approaches.

Khidhir, Karzan Ghafur January 2010 (has links)
Kurdistan Regional Government/Ministry of Higher Education and Scientific Research

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