Gottfried Schmalz, Dorthe Arenholt-Bindslev, Silke Pfüller and Helmut Schweikl
The toxicity of dental alloys depends upon the quantity and chemical state of metal elements released from the alloy into the affected tissue. The purpose of the present study was to investigate the effects of various cell lines, various cell numbers, and various serum concentrations on the cytotoxicity of metal cations which are components of dental alloys. Aqueous salt solutions were tested on two continuous cell lines (L-929 mouse fibroblast-like cells and HaK hamster epithelial-like kidney cells) and on primary human gingival fibroblasts. The cell culture medium was routinely supplemented with 5% fetal calf serum. The influence of the serum concentration on the cytotoxic potencies of metal cations was investigated by increasing the concentration to 20% in one series of experiments with L-929 cells. Cell reactions were recorded with the MTT test after exposure for 24 hours. The rank order of the cytotoxicity of cations in L-929 cells (10,000 cells/well, 5% serum) from the most to the least toxic was: Ag+, Zn2+, Cd2+, Hg2+, Au3+, Pt4+, Co2+, Cu2+, Ni2+, Pd2+, Mn2+, Nb5+, Mo5+, Ga3+, Cr3+, In3+, Sn2+. A variation in cell number between 5000 and 10,000 cells/well did not influence the results. Furthermore, no differences were observed in the cytotoxic responses of the two continuous cell lines. Variation in the serum content of L-929 cell culture medium had no significant influence on the cytotoxicity of most metal cations, except for Nb5+, Ni2+ and Sn2+. Primary human gingival fibroblasts showed the same rank order of toxicity as the continuous cell lines, but at higher concentrations of the test materials.
Päivi Kopponen, Mirkka Asikainen, Riitta Törrönen, Kaisa Klemola, Jyrki Liesivuori and Sirpa Kärenlampi
The aim of this study was to investigate whether an in vitro test can give an indication of the overall toxicity of fabric extracts, and whether this toxicity correlates with the toxicity of the dyes and finishes used. Thirteen textile dyes and dyed/finished cotton fabrics were tested by using the Hepa-1 cytotoxicity test. Black sulphur and two blue reactive dyes were the most toxic, with IC50 (the concentration at which the total protein content was 50% of the protein content of non-exposed cells) values of 40–65μg/ml. The least toxic dyes, the black and yellow mix reactive dyes, had IC50 values of 825μg/ml and 703μg/ml, respectively. There was no correlation between the toxicities of the dyes and the fabric extracts; the extract from naphtholdyed fabric was the most cytotoxic. These results strongly support the hypothesis that the toxicity of a fabric extract cannot be predicted directly from the toxicity of the dye itself. The results also showed that flame-retardant and water/soil-repellent finishes can alter the cytotoxicity. In vitro tests, as exemplified by the Hepa-1 cytotoxicity test, could provide useful information for developing new ecotextiles.
Seval Korkmaz, Hülya Zeytinoglu, Melih Zeytinoglu, Süleyman
Aydin, Yusuf Öztürk, and Hüsnü Can Baser
The purpose was to evaluate the use of mouse T15 fibroblast cell cultures for the investigation of wound-healing activity. In order to investigate their mechanisms of action, the effects of drugs with wound-healing activities were compared by using morphometric analyses by microscopy after cell staining. A number of parameters were used to evaluate the effects of titrated extracts from Centella asiatica and dexpanthenol (drugs that have been used in medical practice for their wound-healing activities) on cultured mouse T15 fibroblasts. These parameters were: the total number of cells; the number of T15 cells in mitosis; the percentages of fusiform, polygonal, round and vacuole-containing cells; and the number of intracellular collagen granules. The results indicate that these two drugs exhibit wound-healing activities by activating fibroblast cells, and have cytoprotective effects, although their mechanisms of action on mouse T15 fibroblasts were different. On the basis of our findings, mouse T15 fibroblast cell cultures seem to be useful for the pharmacological screening of compounds with wound-healing activity.
The Registry of Cytotoxicity: Toxicity Testing in Cell Cultures to Predict Acute Toxicity (LD50) and to Reduce Testing in Animals1
This is a translation of a report on the Registry of Cytotoxicity (RC), originally published in German in 1998. The report presented an advanced in vitro method, which can significantly reduce the number of animals needed for the toxicity testing of a broad range of compounds/xenobiotics. With the RC method, it was possible to predict the oral or intravenous acute toxicity (LD50) which is a regulatory requirement for newly developed pharmaceuticals and industrial and household chemicals from the cytotoxicity data (mean IC50 = IC50X) obtained with mammalian cells. The RC method can be used before the in vivo test, and it does not pose any additional harm or suffering to laboratory animals. The RC method is of broad practical use: it can be applied, for example, in the pharmaceutical industry or the chemical industry in regulatory testing or in research. It is ready for validation, and could then be incorporated into OECD guidelines, thus reducing the total number of animals needed for regulatory toxicity testing. The RC method is based on the comparison of the IC50X values and the LD50 values by using linear regression analysis. With the RC method, it was possible to predict, within a predefined dose range, the acute oral LD50 for 252 of 347 xenobiotics, and the intravenous LD50 for rats and/or mice for 117 of 150 xenobiotics. Comparative studies showed that these results are highly reproducible.
Anne Huhtala, Sami K. Nurmi, Hanna Tähti, Lotta Salminen, Päivi Alajuuma, Immo Rantala, Heikki Helin and Hannu Uusitalo,
Alternatives to the Draize rabbit eye irritation test are currently being investigated. Because of morphological and biochemical differences between the rabbit and the human eye, continuous human cell lines have been proposed for use in ocular toxicology studies. Single cell-type monolayer cultures in culture medium have been used extensively in ocular toxicology. In the present study, an SV40-immortalised human corneal epithelial (HCE) cell line was characterised immunohistochemically, by using 13 different monoclonal antibodies to cytokeratins (CKs), ranging from CK3 to CK20. The results from the monolayer HCE cell cultures were compared with those from the corneal epithelium of human corneal cryostat sections. Previous studies have shown that the morphology of the HCE cell is similar to that of primary cultured human corneal epithelial cells, and that the cells express the cornea-specific CK3. In the study reported here, we show that the cell line also expresses CKs 7, 8, 18 and 19. These CKs are typically expressed by simple epithelial cells, and are not found in the human cornea in vivo. Therefore, the monolayer HCE cell line grown in culture medium does not express the CK pattern that is typical of human corneal epithelium. This should be taken into consideration when using HCE cell cultures in similar single cell-type experiments for ocular toxicology.