Hair fibre production by human hair follicles in whole-organ culture

In vivo induction of hair growth by dermal cells isolated from hair follicles after extended organ culture

Successful hair follicle organ culture has been established for some time, but hair growth in vitro is limited and generally terminates prematurely in comparison with in vivo. The reasons why growth stops in culture are as yet unknown. In this investigation, adult rat vibrissa follicles for which growth in culture is limited to about 10 d, were maintained in vitro for a minimum of 20 d after the hair shaft stopped growing. The pattern of fiber growth and long-term follicle pathology reflected the initial hair cycle stage at the time of isolation. Furthermore, there was evidence that a group of follicles put into culture when in late anagen were attempting to cycle in vitro. Microscopy showed that, in spite of widespread pathologic changes to the follicle epithelium, dermal cells in the follicle showed remarkable resilience. Their viability was confirmed when primary cell cultures were established from isolated dermal tissue. These cells labeled positively for alpha-smooth muscle actin, an established marker of hair follicle dermal cell phenotype in vitro. Moreover, isolated dermal tissue induced hair growth when implanted into inactivated hair follicles in vivo. These data confirm that the cessation in hair growth is not due to a loss of the inductive capacity in the dermal component. Long-term organ culture may provide opportunities to investigate factors that are expressed or lost during hair growth cessation. In addition it may be possible to develop this method further to obtain a reliable and predictable model of hair follicle cycling in vitro.

Wool follicle matrix cells: culture conditions and keratin expression in vitro

Wool follicle matrix cell cultures were initiated as explants from Tukidale (carpet wool) sheep primary follicle bulbs after removal of the outer root sheath. Successful explantation required coculture on collagen with intact dermal papillae. Cells had a typical epidermal morphology (pavements of flattened. polyhedral cells). Extracellular matrix from dermal papillae, conditioned media, separation of dermal papilla from bulb matrices by tissue culture inserts and feeder layers were unable to support matrix cell explantation. Cultures could be maintained for up to 14 passages during which time the cells became larger with an increased cytoplasmic/nuclear ratio and irregular outline. Proliferation of matrix cells was greater on laminin than with either collagen type I or type IV. Proliferation was considerably reduced under serum-free conditions. This was most apparent at low calcium (0.09 mmol/L). By Northern hybridization matrix cells were found to express keratin K18 at all stages of culture. Keratin K 1.15 expression was evident by the tenth passage. The wool-specific keratin K2.10 was not detected. The data demonstrate that successful wool matrix cell culture is achievable. Keratin gene expression occurs in these cells and varies with the stage of culture.

Serum-free culture of wool follicles: effects of nutrients, growth factors and hormones

A serum-free culture system allowed the continued growth of fibre from follicles for 8-10 days. Fibre growth was responsive to changes in the level of calcium, glucose and amino acids in the culture medium, and was stimulated by the inclusion of insulin (10 micrograms/mL) in the medium. Culture of follicles in the presence of conditioned media from dermal papilla cells or of mitomycin-treated dermal papilla cells had no effect on fibre growth. Neither thyroid hormones nor hydrocortisone altered fibre growth. The progressive decline in fibre growth during follicle culture was accompanied by morphological changes in the follicle bulb. Oxidative damage did not appear to be the cause of these changes as there was no increase in fibre growth rate or longevity when antioxidants were used. This model provides a useful system to study the direct effects of various hormonal, nutritional and growth factors of fibre growth and follicle metabolism.

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.

Interleukin-1beta-induced inhibition of hair growth in vitro is mediated by cyclic AMP

Interleukin (IL)-1 has been shown to be a potent inhibitor of hair growth in vitro. We hypothesized that this cytokine might be a decisive factor causing hair loss during the lymphocytic attack in alopecia areata. Neither the intracellular pathways involved in hair growth inhibition mediated by IL-1beta nor the signal transduction processes within hair follicles in general are known. We therefore investigated the intracellular signals involved in human hair growth in vitro. Hair follicles were isolated from scalp biopsies by microdissection, and hair growth was measured daily by image analysis. We assessed intracellular signal transducing elements using specific inhibitors or activators either alone or in combination with IL-1beta. The calcium ionophore A 23187 induced a rapid and complete arrest of hair growth, and phorbol-12-myristate-13-acetate (PMA), genistein, or IL-1beta decreased hair growth by approximately 60%-80%. IL-1beta-elicited hair growth arrest was not antagonized by calphostin C, a specific inhibitor of protein kinase C. In contrast, coincubation of IL-1beta with pertussis toxin or H 1004 neutralized the effect of IL-1beta, and dibutyryl-cAMP and cholera toxin, an activator of adenylate cyclase, inhibited hair growth. These data suggest that cAMP acts as a second messenger for IL-1beta-induced inhibition of hair growth. Moreover, our data indicate that in vitro hair growth is dependent on intracellular Ca2+ levels and activation of tyrosine kinase as well as protein kinase C. We were unable to detect a signal transducing element responsible for enhanced hair growth in vitro.

Whole hair follicle culture

In this article the authors have reviewed the historical background behind the organ culture of whole hair follicles. The methods developed by the authors and others for the isolation and whole organ maintenance of hair follicles from both human and other species are described. How whole organ models have been used to further understanding of the biology of the hair follicle and how they may be used in the future are discussed.

Effects of epidermal growth factor and transforming growth factor alpha on the function of wool follicles in culture

The development of a procedure to culture wool follicles from Merino sheep in serum-free conditions has enabled us to investigate the actions of epidermal growth factor (EGF) and transforming growth factor alpha (TGF alpha) on follicle function, including fibre growth. Follicles grown in the absence of growth factors maintained their anagen morphology for 6 days as determined by light microscopy. During this time they incorporated [3H]thymidine into the DNA of the bulb matrix and outer root sheath (ORS) cells and produced fibre keratins as detected by immunohistochemistry. In the presence of EGF and TGF alpha, fibre production ceased after 4 days, as it does following the administration of EGF in vivo. Cessation of fibre growth was not accompanied by regression of the follicle bulb which occurs in vivo. Follicle length growth did not differ significantly from controls and cells in the bulb continued to proliferate. Usually, the structure of the dermal papillae resembled that in control follicles, which was also in marked contrast to changes reported in vivo. In EGF- and TGF alpha-treated follicles, [3H]thymidine continued to be incorporated into DNA of the ORS and bulb after fibre growth ceased. Although wool keratin synthesis ceased, cytokeratins of the epidermis and ORS continued to be produced in the bulb as detected by immunochemistry. These bulb cells were also positive for the periodic acid-Schiff (PAS) reaction indicating the presence of glycogen, a normal component of ORS cells. The observations that cell proliferation continued in the bulb, that glycogen was present and that soft keratins were expressed in these cells suggest that the bulb cell population was induced to differentiate into an ORS phenotype by EGF and TGF alpha.

Cytokines and growth factors influence hair growth in vitro. Possible implications for the pathogenesis and treatment of alopecia areata

Factors that influence the growth of the anagen hair follicle or initiate the switch to a catagen growth pattern have so far not been definitely determined, but there is increasing evidence that cytokines and growth factors play an important role during these processes. Recently we detected an aberrant in situ expression pattern of cytokines of the Th1 type (IFN gamma, IL-2) plus IL-1 beta expression in untreated alopecia areata (AA), and a switch to high levels of IL-10 TGF-beta 1 expression after successful treatment with the contact allergen diphenylcyclopropenone (DCP). Hence the question arose as to whether cytokines are able to arrest hair growth and whether IL-10 or TGF beta 1 have the capacity to antagonize this process. Using whole-organ cultures of microdissected human hair follicles we studied the effect of a panel of cytokines and growth factors on hair growth and on the gross morphology of the hair follicles in vitro. IL-2, IL-10 and IFN-gamma had no effect in this regard, whereas TGF beta 1 partially inhibited hair growth and EGF, TNF alpha and IL-1 beta completely abrogated it. EGF and TNF alpha induced the formation of a club-like hair follicle, similar to catagen morphology of the hair bulb, whereas hair follicles grown in the presence of IL-1 beta or TGF beta 1 showed no particular morphological changes. We conclude that cytokines and growth factors are pivotal regulators of hair growth at least in vitro. IL-1 is suggested as playing an important role during the pathogenesis of AA. Possible mediators of therapeutic contact dermatitis (IL-10, TGF beta 1, TNF alpha, PGE2) are, at least in vitro, not able to antagonize the IL-1 beta-triggered hair growth inhibition. Therefore, we infer that these mediators rather "modulate' the immune response in AA.

Protein kinase C inhibits human hair follicle growth and hair fibre production in organ culture

In this study we have used a human hair follicle whole-organ culture system to examine the effects of 12-O-tetradecanoyl-phorbol-13-acetate (TPA), a potent activator of protein kinase C (PKC), on hair follicle growth and hair fibre production. Anagen hair follicles were isolated from human facial skin by microdissection and placed in suspension culture in supplemented Williams E medium. Hair follicle and hair fibre lengths were measured daily using an inverted microscope and cumulative growth values were calculated. Treatment with TPA resulted in a potent, dose-dependent inhibition of total cumulative hair follicle growth (IC50 = 1 nM). Hair follicles grew at a comparable rate for 4 days in the presence or absence of 10 nM TPA, after which growth of TPA-treated follicles ceased while control follicles grew by a further 0.8 mm over the subsequent 6 days. In contrast, 10 nM TPA treatment did not affect hair fibre elongation for a period of 8 days, after which TPA-treated fibre production ceased while control fibres grew by a further 0.79 mm over the subsequent 7 days. Incubation of hair follicles with TPA resulted in a 41% inhibition of hair fibre protein synthesis, as measured biochemically from the incorporation of 3H-leucine using a differential akali extraction method. The inhibitory effect of TPA on follicle growth was partially prevented by preincubation with the selective PKC inhibitor H-7, and almost completely prevented by preincubation with the more potent PKC inhibitor Ro 31-7549. Neither agent alone significantly affected follicle growth at concentrations that reversed the TPA response. These findings indicate that PKC is a negative regulator of hair follicle growth, and suggest that PKC may play a part in the transduction of follicular growth-inhibitory signals.

Biphasic effect of 1,25-dihydroxyvitamin D3 on human hair follicle growth and hair fiber production in whole-organ cultures

We have used a whole-organ culture system to investigate the effects of 1,25(OH)2D3 on human hair follicle growth and hair fiber production. Relatively low concentrations (1-10 nM) of 1,25(OH)2D3 stimulated the cumulative growth of hair follicles and hair fibers, by 52% and 36%, respectively (concentration producing 50% of the maximal response [EC50] values of 0.3 nM). The initial rates of follicle and fiber growth were increased, whereas the respective growth periods were unaffected. At higher concentrations of 1,25(OH)2D3, there was a dose-dependent inhibition of both follicle and fiber growth (IC50 values of 100 nM), in part due to reduction in the growth periods. There was a marked delay between the onset of 1,25(OH)2D-induced hair follicle and hair fiber growth inhibition. Incubation of hair follicles with 100 nM 1,25(OH)2D3 resulted in a rapid, transient inhibition of DNA synthesis (55% inhibition at 24 h), followed by a gradual return to control levels at day 4. Prolonged (> 5 h), incubation in the presence of 100 nM of 1,25 (OH)2D3 was required for follicle growth inhibition to be manifest. Ro 31-7549, a selective inhibitor of protein kinase C, did not prevent 1,25(OH)2D3-induced inhibition of hair follicle growth. These data suggest that 1,25(OH)2D3 may play a physiologic role in maintaining optimal hair follicle activity, and that elevation of 1,25(OH)2D3 may inhibit hair growth in vivo.