Effects of mechanical force on primary human fibroblasts derived from the gingiva and the periodontal ligament.

Previous experiments have shown that mechanical stress may alter the interactions between cells and extracellular matrix (ECM). The purpose of our study was to investigate the effects of mechanical load on metabolism and ECM expression of primary human periodontal cells. The influence of gravitational force on proliferation, lactate dehydrogenase (LDH) release, and tenascin expression of gingival (HGF) and periodontal ligament fibroblasts (HPDL), as well as their adhesion to various extracellular matrix (ECM) components, was determined. Cells were centrifuged in microplates or flat tubes for 16 hrs at 217 g. Neither an enhanced release of LDH nor an alteration of cell proliferation could be detected after centrifugation. However, the attachment of loaded gingival and periodontal ligament fibroblasts to all tested ECM components significantly decreased in comparison with controls (Wilcoxon-Mann-Whitney test; HGF, p < 0.05; HPDL, p < 0.01). Tenascin expression of mechanically stressed fibroblasts significantly increased in comparison with controls (p < 0.01).

Effects of BisGMA and TEGDMA on proliferation, migration, and tenascin expression of human fibroblasts and keratinocytes.

Previous studies have documented a marked cytotoxic potency of BisGMA and TEGDMA. The purpose of this investigation was to determine if these substances also affect proliferation, migration, and tenascin expression of primary human gingival fibroblasts (HGF) and immortalized human keratinocytes (HaCaT). These parameters play an important role in healing wounds. HGF and HaCaT cultures were incubated with TEGDMA and BisGMA. Cell proliferation (BrdU-assay) and migration (Boyden method) were determined 24 h after incubation. Tenascin expression was investigated four and seven days after treatment. Results were statistically evaluated by ANOVA using the Wilcoxon-Mann-Whitney test (p < 0.05). Proliferation of both cell types was significantly inhibited at concentrations > or = 0.25 mM (TEGDMA) or > or = 0.01 mM (BisGMA). Migration of HaCaT was significantly increased after incubation with BisGMA for 24 h. TEGDMA did not alter migration of HGF and HaCaT. In addition, TEGDMA had no effect on tenascin expression of both cell cultures. After 4 days of incubation, BisGMA (at a concentration of 0.01 mM) significantly reduced tenascin production of HaCaT cultures related to cell number. However, 7 days after treatment, BisGMA significantly increased tenascin expression of HGF and HaCaT cultures. Altogether, our results indicate that BisGMA can affect migration of keratinocytes and alters the expression of the extracellular matrix component tenascin. Thus, BisGMA may significantly influence the healing of injured oral tissues.

Effect of minoxidil on the mobility and differentiation of cultivated human keratinocytes.

The mode of topical action of minoxidil (U-10,858, CAS 38304-91-5) ist not entirely clear. The influence of minoxidil on the ultimate differentiation of keratinocytes was investigated. Human keratinocytes (HaCaT-cells) were incubated with minoxidil containing culture medium (10-250 micrograms/ml). Minoxidil inhibited in a concentration dependent manner cell mobility whereas the adhesion area and the cell circumference were increased. The minoxidil treated cultures had a higher desmosome density compared to parallel control cultures and they expressed the suprabasal keratins 1 and 10 (indicating progress in differentiation) earlier and to a larger extent than the controls. Keratins were revealed immunohistochemically and by two-dimensional polyacrylamide gel electrophoresis. The results suggest that minoxidil supports the differentiation of human keratinocytes.

Reactions of human keratinocytes in vitro after application of nicotine.

Nicotine is rapidly taken up by human keratinocytes (HaCaT cells) and after 3 h the uptake is approximately 50% of maximum. Cotinine, a metabolite of nicotine, was detected, thus demonstrating the metabolism of nicotine in HaCaT cells. Low nicotine concentrations (0.1-200 micrograms/ml) did not influence the incorporation rate of thymidine into DNA or amino acids into proteins. Inhibition of DNA and protein synthesis was only observed at concentrations > 200 micrograms/ml. After application of 400 micrograms/ml nicotine, the cells were vacuolated. This process was reversed after nicotine withdrawal. At low nicotine concentrations, no changes in microtubules and actin filaments could be detected. However, in the presence of nicotine (1-10 micrograms/ml), keratin filaments showed a more orderly pattern that controls, and the expression of the suprabasal keratins 1 and 10/11 was induced and increased according to the concentration of nicotine. The number of cornified envelopes also increased markedly. Nicotine concentrations > 100 micrograms/ml led to a disarrangement of keratin filaments and to a decrease in keratin expression and cornified envelope formation. Our results suggest that nicotine at concentrations up to 100 micrograms/ml is not an irritant but may induce cornification of the skin.

[Antiproliferative activity of a highly purified coal tar preparation in comparison with clobetasol-17-propionate]. / Antiproliferative Aktivität einer hochgereinigten Steinkohlenteer-Präparation im Vergleich mit Clobetasol-17-Propionat.

Coal tar and glucocorticosteroids are among the preparations used for the treatment of hyperproliferative inflammatory dermatosis. Coal tar generally seems to have a better effect on psoriasis capillitii than betamethasone-17-valerate. This finding is confirmed by investigations with human skin fibroblasts. The coal tar preparation Berniter has a strongly inhibitory effect on cell proliferation. The action of the preparation with tar can be clearly distinguished from the effect of the vehicle. At the ED50 concentration of the substance with tar, the vehicle without tar causes no inhibition. Based on weight equivalents Berniter has a greater inhibitory effect on proliferation of human skin fibroblasts than clobetasol-17-propionate. In the case of both substances protein biosynthesis is only affected at concentrations higher than those needed for the inhibition of proliferation. Berniter and the vehicle without tar have an equally strong effect on protein synthesis. Berniter affects the nucleoside triphosphatase bound to the nuclear membrane, and thus influences the nucleocytoplasmic transport of mRNA. The effect of the vehicle and the preparation containing tar on this parameter are very similar. Berniter has a positive effect on cell mobility. In preconfluent cultures the mobility of the cell is slightly increased and in confluent cultures significantly. Our results show that Berniter inhibits proliferation in cell cultures of human skin fibroblasts to a higher degree than clobetasol-17-propionate. It is to be assumed that neither the inhibition of protein synthesis nor the inhibition of mRNA transport play a causal role in the antiproliferative effect of coal tar. Inhibition of proliferation as a result of general damage to the cell can also be practically ruled out.