Evaluation of ingredients for specific applications:an in vitro skin tolerance approach

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  • October 30, 2016
  • 3 mins of read time

Evaluation of ingredients for specific applications:an in vitro skin tolerance approach

Mathilde Bergal, Catherine Bulcourt, Mickael Puginier, Florence Rodenas, Alicia Roso
2016, 29th IFSCC congress

Introduction:

Initially driven by legislative and ethical concerns, there is nowadays no doubt that reconstructed human epithelia model is a useful tool as preclinical test for assessing the tolerance of cosmetic or personal care products and ingredients as well. Depending on the legislation and the need of each geographic zone, dermopharmaceutical or cosmetic producers develop suitable formulations for specific applications onto human external mucous membranes or for sensitive target populations, such as products for intimate use, oral care or baby products. There is consequently a need for the ingredient suppliers to build an in vitro testing strategy in order to provide more targeted tolerance data for manufacturers and help them to select well tolerated ingredients. The goal of this study is to investigate the behavior of key versatile cosmetic raw materials, at appropriate use levels, with different reconstructed human epithelia models. Even if these screening models are not including all markers and physiological specificities of humans, they estimate the tolerance of ingredients and products on the target epithelia tested.

Methods

  • Raw materials 

Essential ingredients were chosen in accordance to the perspective of designing simple, minimalist formulas. Each raw material is tested at a realistic efficient-cost dose in simple dilutions.

  • In vitro assessment of ingredients effects on three in vitro models
    • Reconstructed vaginal epithelia (SkinEthic HVE model); assessment of cytoxic effects (MTT) after four application times (until 24h).
    • Reconstructed human “immature” epidermis, characterized by a shorter cultured state (SkinEthic RHE model at 10 days); assessment of cytotoxic effects (MTT), inflammatory response (IL1α release) and histological parameters after 16 hours of application.
    • Reconstructed gingival epithelia (SkinEthic HGE model); assessment of cytoxic effects (MTT) after four application times (until 24h).

Results and discussion

The different results obtained from these models give a first idea of the tolerance of several ingredients on specific targets. 

The “immature” reconstructed human epidermis model was obviously demonstrated to be more sensitive than the standard model, based on cellular viability. The three parameters assessed within this model enriched the analysis and contribute to select the well tolerated potential candidates. 

Depending on company objective, these tolerance data can help to choose the best ingredient according to the final application or to select a unique versatile ingredient when the goal is to design a global “chassis” formula.

Conclusion 

These three in vitro reconstructed epithelia models seem to be interesting tools, for screening the tolerance of ingredients intended to be used on external mucous membranes or for specific target population like babies. These tolerance data constitute input data to be integrated in a global safety assessment before conducting clinical trials. Further investigation on ingredient combinations will need to be conducted to evaluate possible interactions.

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