Ocular irritancy assessment of cosmetics formulations and ingredients: fluorescein leakage test.

During a COLIPA multicentre study carried out on 'Alternatives to Eye Irritation' two laboratories undertook the evaluation of the samples with the fluorescein leakage test (FLT). The lead laboratory (L'Oréal) proposed a prediction model (PM), which converts the in vitro data from this assay to a prediction of eye irritation. All the surfactant-containing substances were tested using the FLT if they were soluble in Hanks' balanced salt solution (HBSS). Briefly, confluent MDCK cells were exposed for 15 minutes to five fixed concentrations of the test substance. The amount of damage caused to the cellular monolayer was determined by the amount of fluorescein that leaked through the cell layer after a 4-hour period. The amount of test substance that produced 20% leakage compared with a cell-free control was determined (FL(20) H4). The FLT results transformed using the PM, generally predicted the in vivo classification (linear Kappa: 0.87+/-0.17 and 0.75+/-0.25). Where there were misclassifications, the category assigned was only one different from the observed in vivo score. There was generally good agreement between the two laboratories in this study. The model seems to be more appropriate for evaluation of non-irritants or moderate irritants than for severe irritants. This is relevant for the selection of cosmetic ingredients. Overall, the results of the FLT assay appeared to be encouraging.

A summary report of the COLIPA international validation study on alternatives to the draize rabbit eye irritation test.

The principal goal of this study was to determine whether the results from a set of selected currently available alternative methods as used by cosmetics companies are valid for predicting the eye irritation potential of cosmetics formulations and ingredients and, as a consequence, could be valid replacements for the Draize eye irritation test. For the first time in a validation study, prediction models (PMs) that convert the in vitro data from an assay to a prediction of eye irritation were developed for each alternative method before the study began. The PM is an unequivocal description of the relationship between the in vitro and the in vivo data and allows an objective assessment of the reliability and relevance of the alternative methods. In this study, 10 alternative methods were evaluated using 55 test substances selected as representative of substances commonly used in the cosmetics industry (23 ingredients and 32 formulations). Twenty of the single ingredients were common to the European Commission/British Home Office (EC/HO) eye irritation validation study (Balls et al., 1995b). The test substances were coded and supplied to the participating laboratories. The results were collected centrally and analysed independently, using statistical methods that had been agreed before the testing phase began. Each alternative method was then evaluated for reliability and relevance in assessing eye irritation potential. Using the criteria of both reliability and relevance as defined in the study, the preliminary results indicate that none of the alternative methods evaluated could be confirmed as a valid replacement for the Draize eye irritation test across the full irritation scale. However, three alternative methods-the fluorescein leakage test, the red blood cell assay (classification model) and the tissue equivalent assay-each satisfied one criterion of reliability or relevance. Further investigation of the decoded data from this study to explore more fully the relationship between the in vitro data and the in vivo data is recommended. Such a review may allow the development of new prediction models to be tested in a subsequent validation study.

Effects of exogenous FGFs on growth, differentiation, and survival of chick neural retina cells.

Fibroblast growth factors (FGFs) are known to play important roles in various processes including development and differentiation. Chick embryo neural retina cells, capable of transdifferentiation into lentoid bodies and pigmented cells, were used in vitro to examine the effects of exogenous acidic (aFGF) and basic FGF (bFGF) on proliferation and protein accumulation. We demonstrate that both factors increase the proliferation of glial cells and modulate the survival of neurons without affecting protein accumulation within these cells. Moreover, FGFs stimulate the differentiation of the photoreceptors. The rate of proliferation varies over the period of culture, with a maximum occurring after 2 weeks, followed by a decrease concommitant with the appearance of lentoid bodies. The concentration of aFGF was measured using an enzyme immuno assay and showed an accumulation of this protein only in bFGF-treated cultures, suggesting that bFGF positively modulates aFGF synthesis in neural retina cell cultures.

Spatial and temporal expression patterns of FGF receptor genes type 1 and type 2 in the developing chick retina.

Fibroblast growth factors are known to influence the growth and differentiation of cultured cells derived from the chick retina. The fibroblast growth factors can interact with a family of at least four closely related receptor kinases. To find a correlation between the presence of fibroblast growth factor receptors and eye development, the patterns of expression of transcripts encoding the type 1 (FGF-R1) and type 2 (FGF-R2) receptors in the developing chick retina have been studied. Northern blot analysis of RNA of the whole retina was used to observe that FGF-R1 transcripts are abundant at embryonic day 4 and then decrease until day 11. After this stage, the level of expression of FGF-R1 increases and its peak of expression at embryonic day 18 is concomitant with the detection of the opsin transcript. FGF-R2 transcript is also detected by Northern blots of RNA of the whole retina until embryonic day 6. However, the re-expression after embryonic day 11 of FGF-R2 could only be demonstrated by PCR studies. The same pattern of expression is observed with in situ hybridization of sagittal sections. The two genes are coexpressed in the pigmented epithelium and in the neural retina during embryonic development. The expression follows the retinal layering according to a gradient from the vitreous humor to the choroid. Quantification of the in situ hybridization signals demonstrates that the pattern of expression of both receptors diverges after embryonic day 6 between the pigmented epithelium and the neuronal cells.(ABSTRACT TRUNCATED AT 250 WORDS)