The proliferation and cell cycle phase composition of human dermal fibroblasts cultured on or in type I collagen lattices (reconstituted dermis model) were examined. On collagen lattices, as compared with conventional cultures on plastic dishes, the proliferation of human dermal fibroblasts was suppressed, being arrested at about one-half the saturation density after 10 days of culture. In collagen lattices, proliferation was further suppressed, being nearly arrested within 4-7 days of culture. Cells were analyzed for cell cycle phases by two-color flow cytometry using DNA staining and S phase cell staining with FITC-conjugated antibromodeoxyuridine antibody. After 5 days of culture, the number of S phase cells on collagen lattices was 49.3% of that on plastic dishes, with an increase in G0G1 phase cells of 79.8%. In collagen lattices, the number of S phase cells was very small (4.3% of all cells), and most of the cells accumulated in G0G1 phase. These findings suggest that the cell cycle of fibroblasts is arrested at G0G1 phase by their interaction with collagen. On the basis of these results, the reconstituted dermis model using collagen lattice is considered to be analogous to the dermis in vivo with respect to cell growth and cell cycle phase composition.
Human dermal fibroblasts were cultured in a hydrated type I collagen lattice. When collagen fibers were arranged in one direction, fibroblasts were arranged in the same direction. Cell proliferation was markedly suppressed in the collagen lattice as compared with that on plastic, with growth being arrested after day 5. No differences in proliferation were observed between aligned cells and randomly oriented cells. Flow cytometry with DNA staining was performed to analyze each phase of the cell cycle of fibroblasts. Among the 10,000 cell population, S phase cells on day 2 of culture accounted for 43% on plastic but were markedly inhibited to 25% in the lattice. On day 4, S phase cells accounted for 33% on plastic but only for 10% in the lattice. These findings suggest that cell advancement to the S phase is markedly inhibited in the collagen lattice, resulting in accumulation of most of cells in the G0G1 phase. The present study clearly showed that culture in the collagen lattice allowed alignment of fibroblasts with a definite orientation as observed in vivo and produced a status resembling that in vivo in terms of proliferation and cell cycle phase composition.
The effects of human recombinant tumor necrosis factor-alpha (TNF-alpha) on human keratinocytes cultured in a serum-free medium were investigated. TNF-alpha markedly suppressed cell growth. The growth-inhibitory effect was reversible and cytostatic at a concentration of 1-5 U/ml, but appeared to be irreversible and cytocidal at 10 U/ml. The growth suppressive effect was more marked when TNF-alpha was added in the late growth phase or preconfluent phase than when it was added in early or mid-growth phases. No effects of TNF-alpha on cell adhesion to the substrate were observed. These results indicate that TNF-alpha is a very potent anti-proliferative agent for human keratinocytes.
A 2-year-old girl having a bald nodule on the scalp is reported. The tumor was circular, hemispherically elevated and had a dull reddish color. Roentgenologic studies revealed a defect of the underlying skull bone, and spina bifída occulta on the first and second sacral vertebra were found. Craniotomy was carried out. The tumor extended into the falx cerebri and reached to the tentorium cerebelli, and was not connected with the cerebrum. Histological examination showed insular brain tissue containing glial cells in the lower dermis. Around this tissue, there seemed to be vascular leptomeninges with numerous melanocytes and thickened fibrous elements, probably dura. From these findings, this case was diagnosed as a variant of encephalomeningocele, and as melanocytes physiologically exist on the leptomeninges, melanocytes in an encephalomeningocele may diagnostically identify the leptomeninges.
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