Mouse Vibrissa Follicles Research Articles

Trans-species hair growth induction by human hair follicle dermal papillae.

A series of experimental bioassays has shown that the dermal papilla of the adult rodent vibrissa hair follicle retains unique inductive properties. In view of the many phenotypic and functional differences between specific hair follicle types, and the growing interest in hair follicle biology and disease, it remains important to establish that the human hair follicle dermal papilla has equivalent capabilities. In this study we tested the ability of human hair follicle papillae to induce hair growth when implanted into transected, athymic mouse vibrissa follicles. The implanted papillae that interacted with mouse follicle epithelium created new fibre-producing follicle end bulbs. The origin of the papillae in the recombinant structures was confirmed using laser capture microdissection and human specific gender determination by PCR. The demonstration that intact adult human dermal papillae can induce hair growth has implications for molecular analysis of basic hair growth mechanisms, particularly since the study involved common epithelial-mesenchymal signalling and recognition properties across species. It also improves the prospects for a cell-based clinical approach to hair follicle disorders.

Hair Cycle Stage of the Mouse Vibrissa Follicle Determines Subsequent Fiber Growth and Follicle Behavior In Vitro

The establishment of culture models representative of all aspects of in vivo hair follicle behavior is an important goal for theoretic and analytic studies. Rodent vibrissa follicles have regular, predictable, and relatively short growth cycles. In this investigation, we took advantage of these properties; we classified mouse vibrissa follicles according to different phases in the hair cycle and then compared fiber growth and morphologic changes in culture. Follicles isolated in the early phase of the growth cycle produced fine growing fibers with an average growth that exceeded 3 mm over 15 d. Even when hair growth had slowed or halted subsequently, histology showed that these follicles retained an anagen-like morphology. By contrast, follicles isolated toward the end of the growing cycle produced thicker fibers for much shorter periods, after which growth ceased and the fibers lifted up from the base of the follicle. Internally, these specimens resembled their telogen counterparts in situ. Follicles isolated in mid-growth demonstrated intermediate fiber growth characteristics. In organ culture, mouse vibrissa follicles therefore closely reflect their in vivo origin in growth characteristics and cycle timing. These data provide new opportunities for studying hair growth cycle mechanisms in vitro, but present a caveat for quantitative studies because there may be a greater growth cycle-related variation than has previously been assumed.

Stimulation of Hair Growth by Topical Application of FK506, a Potent Immunosuppressive Agent

FK506, a macrolide antibiotic produced by Streptomyces tsukubaensis, is known as a potent T cell-specific immunosuppressant, and is effective against graft rejection after organ transplantation. Topical application of FK506 (0.03-1 mumol) to dorsal skin of CD-1 mice stimulated hair growth in a dose-dependent manner. Unlike topical application, oral administration of 30 mg/kg of FK506, a dose that induces marked immunosuppression, did not stimulate significant hair growth. Topical application of FK506 also stimulated hair growth of rats and Syrian golden hamsters. FK506 stimulated hair growth even in SCID mice that lack both B- and T-cell immunity. Therefore, it is unlikely that the hair growth-stimulatory effect of FK506 results from its immunosuppressive effect. FK506 (0.01-1 microM) stimulated both [3H]thymidine and [3H]glycine uptakes to cultured mouse vibrissae follicles in a concentration-dependent manner. Moreover, when the follicles were treated with FK506 (1 microM) for 16 d, the size of the follicles (length of hair plus follicle) increased slightly but significantly. On the other hand, the size of the non-treated follicles did not increase significantly. These results indicate that FK506 directly stimulates hair follicles. Long-term treatment of mice with FK506, i.e., topical application of 1 mumol FK506 twice a week for 6 months, did not affect body weight gain of mice, and the FK506-treated mice looked healthy. FK506 may be useful as a stimulant of hair growth.

Ultrastructural localization and quantification of extracellular calcium binding sites in mouse vibrissa and human scalp follicles.

The purpose of these experiments was to determine if an extracellular calcium binding site gradient is evident in freshly dissected or cultured mouse vibrissa and human scalp follicles and to measure possible drug effects on this gradient. Mouse vibrissae were cultured with or without either minoxidil or pinacidil, and human scalp follicles were cultured with or without epidermal growth factor. Anagen vibrissa and scalp follicles were dissected and placed in culture for 4 h to 4 days, then fixed in a solution containing lanthanum chloride and prepared for either quantitative energy-dispersive X-ray microanalysis (X-ray) or qualitative transmission electron microscopy (TEM). Since lanthanum has a high charge density it displaces Ca2+ ions from anionic binding sites. TEM analysis revealed extensive accumulation of electron-dense lanthanum deposits in the intercellular compartment of differentiating cells in the hair shaft and inner root sheath in the apex of the follicular bulb. Sparse lanthanum precipitate was observed in the intercellular space of the proliferative cells at the base of the bulb. This gradient of lanthanum precipitate was evident in both freshly dissected and cultured vibrissa and scalp hair follicles, irrespective of treatment with drugs that grow hair or epidermal growth factor. X-ray microanalysis indicated that percent by weight of lanthanum was markedly higher in the apex compared to the base of the follicular bulb in vibrissa and scalp follicles. These qualitative and quantitative data demonstrate that an extracellular calcium binding site gradient exists in cultured vibrissa and scalp hair follicles, and that this gradient is not significantly affected by hair growth altering drugs including minoxidil or pinacidil, and epidermal growth factor.

Potassium Channel Conductance: A Mechanism Affecting Hair Growth both In Vitro and In Vivo

The opening of intracellular potassium channels has been suggested as a mechanism regulating hair growth. Enhancing the flux of potassium ions is a mechanism shared by several structurally diverse antihypertensive agents including minoxidil sulfate (the active metabolite of minoxidil), pinacidil, P-1075 (a potent pinacidil analog), RP-49,356, diazoxide, cromakalim, and nicorandil. Of these drugs, minoxidil, pinacidil, and diazoxide have been reported to elicit hypertrichosis in humans. This potassium channel hypothesis was examined by testing these drugs for effects on hair growth both in vitro and in vivo. For the in vitro studies, mouse vibrissae follicles were cultured for 3 d with drug and the effects on hair growth were measured by metabolic labeling. All drugs, except diazoxide, enhanced cysteine incorporation into the hair shafts of the cultured vibrissae. Diazoxide was poorly soluble and thus was tested only at low doses. Minoxidil, P-1075, cromakalim, and RP-49,356 were also evaluated in vivo by measuring hair growth effects in balding stumptail macaque monkeys. The drugs were administered topically to defined sites on balding scalps once per day for 4-5 months and the amount of hair grown was determined by monthly measurements of shaved hair weight. Three of the drugs produced significant increases in hair weight whereas, the RP-49,356 had no effect. These studies provide correlative evidence that the opening of potassium channels is an important regulatory mechanism for hair growth. This provides the impetus for further studies on this potentially important mechanism affecting hair biology.

Interaction of minoxidil with pigment in cells of the hair follicle: an example of binding without apparent biological effects.

To identify minoxidil target cells in hair follicles we followed the uptake of radiolabeled drug in mouse vibrissae follicles both in vitro and in vivo. Autoradiography showed that both 3H-minoxidil and 3H-minoxidil sulfate accumulated in the differentiating epithelial matrix cells superior to the dermal papilla, a distribution similar to that of pigment. Minoxidil localized in melanocytes, melanocyte processes, and areas of greater melanin concentrations within the epithelial cells. Although uptake of minoxidil was significantly less in unpigmented follicles, the drug stimulated proliferation and differentiation of both pigmented and unpigmented follicles. Labeled minoxidil bound to Sepia melanin and was displaced with unlabeled minoxidil and other electron donor drugs. This interaction with melanin acts as a targeting mechanism of minoxidil to pigmented hair follicles but has no apparent functional significance in hair growth. This work illustrates how measurement of drugs in hair may be biased by pigmentation.

Organ culture of mouse vibrissal follicles. 1. Effect of anticancer agent on DNA synthesis

Organ culture of mouse vibrissal follicles. 1. Effect of anticancer agent on DNA synthesis

Either chick embryo dermis or retinoid‐treated mouse dermis can initiate glandular morphogenesis from mammalian epidermal tissue

Excess retinoids can cause developing mouse vibrissa follicles to be transformed into mucous glands in organ culture. The objective was to test the hypothesis that retinoids act in this system by altering morphogenetic properties of the dermis. After inititation by retinoic acid (RA) in organ culture, glands were shown to develop further in embryonic skin grafted to the chick chorioallantoic membrane (CAM). Recombinants of 12.5 day mouse epidermis with untreated or RA-treated mouse or chick dermis were then grafted to CAM for 7 days. For homospecific recombinants, 13.5 day mouse dermis originated from 11.5 day skin cultured for 2 days, with or without 5.2 microgram/ml RA. For heterospecific recombinants, 12 day dermis came from chick embryos, previously injected with 250 microgram RA. Glands were absent from the homospecific recombinants including untreated mouse dermis, but appeared in 26% of those with RA-treated dermis. Among heterospecific recombinants, 75% of those with RA-treated chick dermis and 29% of those with untreated dermis had glands. Untreated 10-12 day chick skin contained two forms of endogenous vitamin A, retinol (4.5 microgram/g protein) and dehydroretinol (3.7 microgram/g protein), while 13-14 day mouse skin contained only retinol (1.8 microgram/g protein), as shown by high performance liquid chromatography. RA injection increased retinol and dehydroretinol in chick skin, while RA was undetectable. Thus RA can act through mouse dermis to form epithelial glands and through chick dermis to increase the incidence of glands. The glands in recombinants with untreated chick dermis may result from the higher levels of endogenous retinoids in chick skin, compared with mouse skin.

Early lesions of mouse vibrissal follicles:: their influence on dendrite orientation in the cortical barrelfield.

There is a statistically significant order in the tangential orientation of stellate cell dendrites, both spiny and smooth, in layer IV of the barrelfield of the mouse parietal cortex. Neurones situated in a barrel side have most of their dendrites oriented towards the barrel hollow; those situated in the hollow preferentially orient their dendrites parallel to the long axis of the barrel. A quantitative measure of the orientation of individual dendrites in barrelfields of 60-day old mice was obtained using a semi-automatic computer-microscope and a minicomputer. In the same manner, the dendrite orientation of layer IV stellate cells was determined in barrelfields, whose (cytoarchitectonic) pattern had been experimentally altered through lesions of the middle row of the mystacial vibrissal follicles at birth. The dendrites of these cells are oriented in harmony with the novel parcellation of the cortex. Consequently, for cells in the altered areas of the barrelfields, the dendrite orientation is different from that of cells with identical positions in a normal field (see Fig. 8). We tentatively interpret these findings as an adaptation of dendrite orientation to an altered pattern of thalamic input to layer IV that, in turn, is a consequence of the peripheral manipulation.

The Stability of Vitamin A-induced Metaplasia of Mouse Vibrissa Follicles In Vitro

Tests were made of the stability of the previously described glandular morphogenesis and mucous metaplasia of embryonic mouse vibrissa follicles produced in vitro by excess vitamin A. The changes in individual follicles were observed in living tissue explants and serial sections. Upper lip skin of 13.5-day embryos underwent budding from vibrissa follicles to form branching glands which secreted mucus after 10--14 days in medium containing 4.7 microgram/ml retinol. If this medium was replaced with standard medium after 7 days, glandular morphogenesis and metaplasia continued unaffected, although some hair follicle bases returned to their original morphogenetic program. Similar results were obtained with skin of 13-day embryos treated with vitamin A (6.0 MG/ML) for only 3 days. The moderate degree of glandular morphogenesis in 15-day skin with vitamin A (4.7 microgram/ml) was not altered by the simultaneous addition of a high dose of cortisol (18 microgram/ml). It is suggested that the initiation of glandular morphogenesis of follicles differs from the initiation of mucous metaplasia in embryonic chick epidermis by vitamin A, in that it resembles a new secondary embryonic induction rather than a modulation of the epithelium.

The long term effect of repeated pluckings on the function of the mouse vibrissal follicles.

Single mouse vibrissae were plucked repeatedly at the same time of the cycle (10--15 days after eruption) for ten successive cycles from eight individual follicles. After three pluckings the first grey whisker appeared, after six pluckings all were grey. Two follicles stopped producing whiskers after seven pluckings and another two after the 8th. Henceforth only 50% of the follicles continued producing whiskers until the end of the experiment. All the follicles which ceased to produce whiskers had a keratogenous cyst occupying most of the follicle in direct contact with the dermal papilla. In all cases the isolated dermal papilla was condensed and rounded in shape. Both loss of pigment and cyst formation could be due to the mechanical damage in the follicle caused by repeated plucking.

Phagocytosis by Outer Root Sheath Cells on the Mouse Vibrissae (Sinus Hairs)

Phagocytic cells are present at all levels of the outer root sheath of mouse vibrissa (sinus hair) follicles. Occasionally these cells are seen in the process of engulfing other cells; more often phagocytic cells are seen which contain one or more vacuoles whose contents are in various stages of digestion. Most of the phagocytosed cells contain many tonofilaments and a reduced amount of cytoplasm. A few of the vacuoles contain no filaments. As one vibrissa after another grows from the follicle without an intervening rest period, the outer root sheath changes in size and shape to accommodate both the club hair and actively growing vibrissa. Phagocytosis appears to play a role in the continuous reshaping of the outer root sheath.