The effects of nickel and chromium on human keratinocytes: differences in viability, cell associated metal and IL-1alpha release.

This study was carried out to assess the effects of chromium and nickel upon isolated keratinocytes as an in vitro model of human skin. Keratinocytes were isolated from healthy volunteer skin samples of unknown metal sensitivity (n=10) and were compared with cells from patient biopsies of known metal sensitivity (n=7). Cells were dosed with a concentration range of nickel and chromium (0-10,000 microM) and cellular mitochondrial activity, viability, metal uptake and cytokine release were measured.

Dopa oxidase activity in the hair, skin and ocular melanocytes is increased in the presence of stressed fibroblasts.

We previously reported that mesenchymal cells (dermal fibroblasts and dermal papilla cells) can stimulate dopa oxidase activity in the skin melanocytes. This study extends the investigation of the influence of the fibroblast in a comparative study of melanogenesis in melanocytes from the hair, the skin and the eye. Culture of melanocytes with normal proliferative dermal fibroblasts slightly increased dopa oxidase activity of the hair, skin and ocular melanocytes (by 17, 11 and 28%, respectively), but co-culture with fibroblasts recovering from storage in liquid nitrogen or growth-arrested by means of gamma radiation showed much greater effects.

Cellular and hormonal regulation of pigmentation in human ocular melanocytes.

The purpose of this study was to examine some of the factors that may be relevant to regulating pigmentation in the human eye, specifically whether choroidal and iridial melanocytes are sensitive to regulation by epithelial and stromal cells and alpha-melanocyte stimulating hormone (alpha-MSH). Human choroidal and iridial melanocytes were established in culture and co-cultured with epithelial cells and stromal cells derived both from skin and from eye in order to determine their influence on choroidal and iridial melanocyte dopa oxidase activity. In all cases, co-culture of melanocytes with either epithelial cells or fibroblasts led to an increase in dopa oxidase activity during 5 days of co-culture.

A comparative study of the effect of pigment on drug toxicity in human choroidal melanocytes and retinal pigment epithelial cells.

The aim of this study was to investigate whether the presence of pigment affects the sensitivity of pigmented cells of the eye, retinal pigment epithelium (RPE) and choroidal melanocytes (CMs) to the cytotoxic effects of xenobiotic drugs. Two approaches were used to compare pigmented versus unpigmented cells: RPE cells were repigmented by phagocytosis of synthetic melanin; UVB irradiation was used to induce an increase in pigment in both RPE and CMs. Three drugs known to induce toxicity in the eye, tamoxifen, chloroquine and thioridazine, were used to assess the sensitivity of cells to xenobiotic drugs.