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Biomedical subjects

L C Clauss

Publications and source records attributed to L C Clauss.

4 recordsLinked to original sources
PubMed1991

Proliferation of normal human keratinocytes on silicone substrates.

Several polydimethylsiloxane elastomers and gels were tested as culture substrates for proliferating normal human epidermal keratinocytes. Growth kinetics of normal human keratinocytes (NHK) and dermal fibroblasts were compared on 'very soft', 'soft' and 'hard' silicone gels, as well as on standard cell culture polystyrene dishes. Water contact angles and chemical compositions (IRFT-HATR) of the different silicone surfaces were found to be equivalent, although very different from standard cell culture polystyrene. The topography of the surfaces as well as the shape of the keratinocytes and fibroblasts grown on the different substrates were visualized by scanning electron microscopy, and compared. Although the surface softness and topography of the substrates differed markedly, dermal fibroblasts proliferated in serum-containing medium in equivalent manner on all substrates. Again no correlation could be found between the characteristics and the attachment of the substrates and rapid proliferation of the epidermal keratinocytes in defined medium. The epidermal keratinocytes spread, secreted a structured extracellular matrix network and grew up to confluence on all silicone substrates (elastomers and gels), except the relatively 'hard' silicone gel; this could be due to a direct interference by the waves observed on the silicone gel surfaces.

Biocompatible Materials↗
PubMed1990

Cytotoxicity testing of wound dressings using normal human keratinocytes in culture.

Comparative cytotoxicity testing of 16 wound dressings of different composition show that normal human keratinocytes (NHK) growing on a fibroblastic feeder layer are as sensitive to toxic materials by direct contact as the confluent MRC5 fibroblasts used for standard cell culture cytotoxicity testing, and slightly more sensitive when extracts of the dressings were tested. After direct contact with each of the cell types, we found effects due to 12 dressing samples (75%), but the extracts of only 6 of them induced changes in cell shape or cell death on NHK, and 4 of them on MRC5 cells. In order to assess the compatibility of these dressings with a pure population of epidermal cells, the cell type responsible for reepidermization of healing wounds, we then tested the sensitivity, both to dressing samples and extracts, of normal human keratinocytes (NHK) grown in chemically defined medium and without a feeder layer: The results show epidermal cytocompatibility of 10 dressing extracts, while 6 others induced cytopathic effects. Three of these extracts specifically damaged epidermal cells and inhibited their proliferation. When comparing the sensitivities of NHK (in defined medium) and MRC5 cells, we observed complete correlation for 75% of the dressings by extract testing and in 94% of the cases after direct contact.

Bandages↗
PubMed1990

Terminal epidermal differentiation of human keratinocytes grown in chemically defined medium on inert filter substrates at the air-liquid interface.

A fully differentiated epithelium having the features of epidermis was obtained in vitro by culturing second-passage normal human keratinocytes (NHK) in the chemically defined medium MCDB 153 on inert filter substrates at the air-liquid interface for 14 d. Vertical sections stained for histology and indirect immunofluorescence studies show a correct stratification and expression of differentiation markers. The presence of desmosomes, keratohyalin granules, and lamellar granules, and the formation of a more than ten-layers stratum corneum was evidenced by electron microscopy. Moreover, lipids typical for differentiated epidermis were present in these cultures, including ceramides, which are thought to be responsible for the relative impermeability of the stratum corneum. Under our culture conditions, i.e., in defined medium and at the air-liquid interface, the use of de-epidermized dermis as a substrate did not stimulate keratinocyte differentiation more than acetate cellulose or polycarbonate filter membrane substrates. The obtaining of a well-differentiated epidermis grown in vitro on inert filters in a chemically defined medium should be useful as a standard system for studying epidermal differentiation, re-epidermization, cytotoxicity, epidermal permeation, and transepidermal drug delivery.

Adult↗