Density-dependent regulation of skin-fibroblast glycosaminoglycans in vitro: control by a secreted factor

Effects of retinoids on glycosaminoglycan synthesis by human skin fibroblasts grown as monolayers and within contracted collagen lattices

Fibroblasts grown within contracted collagen lattices synthesize substantially less glycosaminoglycans than fibroblasts grown as monolayers on a plastic substrate. [3H]glucosamine incorporation into hyaluronate was reduced by 70%, and incorporation into sulphated glycosaminoglycans was reduced by 40%. However, incorporation into heparan sulphate and chondroitin sulphates was reduced by 14 and 49%, respectively, resulting in a substantial change in the proportions of the individual glycosaminoglycans. On the basis of [3H]glucosamine incorporation, hyaluronate constituted 80% of the total glycosaminoglycans synthesized in monolayer cultures, but only 67% in collagen lattice cultures. Incorporation of 35SO4 into chondroitin sulphates was reduced by 22%, whereas no change was observed in heparan sulphates following culture within collagen lattices. Exposure of the fibroblast cultures to retinoic acid (10(-6) mol/l) and retinyl propionate (2 x 10(-6) mol/l) resulted in a decrease in the incorporation of [3H]glucosamine into hyaluronate by up to 41% in monolayer cultures, and 25% in collagen lattice cultures. The retinoids stimulated the incorporation of [3H]glucosamine into heparan sulphate by up to 72%, and chondroitin sulphates by up to 30%, whereas 35SO4 incorporation remained essentially unaltered. Only modest changes in the incorporation of both isotopes into fibroblast sulphated glycosaminoglycans were observed following exposure to the retinoids in lattice cultures. Q-Sepharose ion-exchange chromatography at pH 2.0 revealed that there was no change in the degree of polymer sulphation of either chondroitin sulphate or heparan sulphate isolated from collagen lattice cultures compared with monolayer cultures. Retinoic acid (10(-6) mol/l) treatment did, however, reduce the degree of polymer sulphation of heparan sulphates and chondroitin sulphates in both monolayer and lattice cultures.(ABSTRACT TRUNCATED AT 250 WORDS)

Stimulation of glycosaminoglycan synthesis in cultured fibroblasts by hyperbaric oxygen

In this study we examined the effect of hyperbaric oxygen treatment on the synthesis of glycosaminoglycans by fibroblasts isolated from wounds and normal skin. Fibroblast cultures were exposed to seven treatments of intermittent hyperbaric oxygen, and then metabolically labelled with D-[6-(3)H] glucosamine. Hyaluronic acid and proteoglycan synthesis were determined by measuring the radioactivity precipitated with cetylpyridinium chloride before and after digestion with hyaluronidase. Hyperbaric oxygen treatment resulted in an increased synthesis of hyaluronic acid and proteoglycans by fibroblasts from wounds and normal skin. Overall, the average increase in total glycosaminoglycan synthesis after hyperbaric oxygen treatment was 28%, whereas fibroblast proliferation was decreased by 7%. These results suggest that one of the effects of this treatment on a wound may be to increase the ratio of extracellular matrix to cells. Such a change could have important consequences for cellular activities essential for effective wound healing, such as migration of cells into the wound and control of cell function.

The metabolism of fibroblasts from normal and fibrotic skin is inhibited by minoxidil in vitro

The effects of minoxidil in vitro were studied using fibroblasts grown from the lesional skin of patients with lichen sclerosus et atrophicus, morphoea and from the skin of normal individuals. The proliferation of all fibroblast lines over 3 days was inhibited in proportion to the concentration of minoxidil, being 20% or less of controls at 1 mM, where cell viability was only marginally reduced (84 +/- 2% vs. 88 +/- 2% (SEM) in controls). At 5 mM there was usually a net loss of cells and only 72% of those remaining were viable. In contrast, minoxidil at 0.1-1 mM stimulated the proliferation of foreskin keratinocytes by up to 130%. Contraction of collagen lattices containing the three types of fibroblasts was inhibited by 22-26% with 1 mM minoxidil after 5 days and by 50-94% with 5 mM. Secretion of glycosaminoglycans by normal fibroblasts showed concentration-dependent reduction, being 25 +/- 6% of that of untreated cultures with 1 mM minoxidil. These findings show that minoxidil has a range of inhibitory effects on both normal and abnormal skin fibroblasts in vitro, which contrast with its stimulation of skin epithelial cells, and support suggestions that it may provide a useful topical treatment for keloids and other fibroses.

Glycosaminoglycans production by cultured skin fibroblasts from the Pasini and Cockayne-Touraine forms of dominant dystrophic epidermolysis bullosa

Qualitative and quantitative comparisons of glycosaminoglycans e (GAG) production were made on fibroblast lines cultured from the skin of six patients with the Pasini (albopapuloid) form of dominant dystrophic epidermolysis bullosa, six with the non-albopapuloid form (Cockayne-Touraine), eight lines from patients with simplex or recessive dystrophic epidermolysis bullosa and eight lines from normal individuals. A reasonable match of donor age and gender, site, and passage number was achieved. Contrary to an earlier report, the lines from the Pasini group were unexceptional in the amount of GAG they secreted and the proportions of sulfated and nonsulfated GAG showed no consistent difference from the Cockayne-Touraine or control lines. The Pasini lines secreted 77 +/- 18 (SEM) microgram GAG-uronic acid per 10(7) cells and the Cockayne-Touraine lines 81 +/- 12 micrograms at equivalent cells densities. Sulfated GAG represented averages of 19 +/- 4+ in Pasini lines, 17 +/- 5% in Cockayne-Touraine, and 14 +/- 3% in controls. These findings are consistent with current views of albopapuloid lesions as an unreliable clinical sign in epidermolysis bullosa and bring into question the validity of the Pasini entity.

Failure of a helium-neon laser to affect components of wound healing in vitro

The red light of a helium-neon (He-Ne) laser has been reported to stimulate wound healing and cell growth. To investigate the nature of its influence on wound healing we have studied seven components of the healing process in vitro: human skin fibroblast, epithelial and endothelial cell proliferation, cellular migration from skin explants, collagen lattice contraction, collagen synthesis and glycosaminoglycans (GAG) secretion. We used a 5 mW He-Ne laser emitting a I mm diameter beam of wavelength 633 nm. Cellular proliferation was not affected by irradiation three times a day for 3 days. There was no effect on cellular migration or on the rate of collagen lattice contraction. The rate of collagen synthesis, measured as the incorporation of 3H-proline into collagenase-sensitive protein, was no greater than that of controls and GAG secretion did not increase in the irradiated group. We have not found any significant effects of He-Ne irradiation.

Proliferation and glycosaminoglycans secretion in fibroblasts from psoriatic skin: differential responses to retinoids

The effects of four retinoids, all-trans-retinoic acid (tretinoin), 13-cis-retinoic acid (isotretinoin), R0 10-1670 (etretin) and the arotinoid, R0 15-0778, on fibroblast proliferation and glycosaminoglycans (GAG) secretion in vitro were studied. Fibroblasts lines cultured from normal skin (HSF) were compared with those from lesional (PSA) and non-lesional (PSB) psoriatic skin. In general, the retinoids inhibited proliferation; the action was cytostatic, in rank order tretinoin greater than isotretinoin greater than etretin greater than arotinoid. The psoriatic cells tended to be more sensitive than the HSF lines, overall mean proliferation values (+/- SEM), as a percentage of untreated controls being: HSF 72 ++- 3, PSA 61 +/- 3 and PSB 54 +/- 3. Stimulation of GAG secretion at low concentrations (10(-7) M) of all four retinoids, declined as concentrations increased, and secretion was inhibited at 10(-4)M in PSB fibroblasts. Calculation of effects on GAG secretion due to changes in cell density confirmed the rank order for direct stimulation of secretion as arotinoid greater than etretin greater than isotretinoin greater than tretinoin. Electrophoresis of [3H]-labelled glycosaminoglycans secreted in the presence of 10(-7) M arotinoid showed that it was predominantly hyaluronic acid, as in untreated cells. These data confirm that different retinoids have contrasting levels of effects on mesenchymal cells and suggest a greater sensitivity to drugs in fibroblasts from psoriatic skin.