Evonik has developed a skin microbiome model that it says allows, for the first time, a scientifically substantiated evaluation of the influence of cosmetic ingredients and products in laboratory tests.
The German firm is currently testing cosmetic ingredients from its own product portfolio to obtain evidence-based information on their microbiome-friendliness.
Cosmetic producers and consumers are increasingly interested in scientific evidence of the efficacy of cosmetics. In addition, the data will give Evonik a basis for developing even better cosmetic ingredients.
The skin microbiome—comprising all bacteria, fungi, and viruses found in the skin—varies from one person to another. It is exposed to many internal and external influences, from diet to sunlight.
The occurrence of specific strains of bacteria is characteristic of certain skin zones, which can be described as sebaceous, moist or dry.
“Many modern cosmetics advertise that they are microbiome-friendly,” says Stefan Pelzer, who is responsible for microbiome research at Evonik. “However, the tests used at present do not fully replicate the complexity of the skin microbiome.”
As a rule, the impact of the ingredients of a cosmetic product on individual strains of bacteria is screened. The complex interaction between microorganisms is not taken into account.
By contrast, Evonik’s new skin microbiome model looks carefully at precisely these interactions and mutual interdependencies in the laboratory. For this, between eight and ten typical skin microbes are co-cultivated.
In other words, the conditions are chosen so that all strains of bacteria can proliferate and interact. That is a specific strength of this new approach.
Parameters are the increase or decrease in the biomass and changes in the diversity of the cultures for a test substance compared with a control.
They are then entered in an evaluation matrix as “microbiome-boosting,” “microbiome-friendly,” “microbiome-modulating,” or “microbiome-impairing.”
Every significant change in the diversity of the bacteria is regarded as adverse because the protective function of the skin microbiome depends on the natural equilibrium of the microorganisms.
The microbiome consortium is grown on microplates. These standardized plates allow investigation of 48 individual samples simultaneously. Moreover, this is quantifiable and cheaper than previous methods.
Pelzer said: “Our new model closes the gap between simple but less meaningful conventional in vitro tests and more time-consuming in vivo studies on test persons.”
In addition to the co-culture model for balanced skin, Stefan Pelzer’s team has already developed a model for skin that is susceptible to acne.
Further models are to be developed in collaboration with customers in the cosmetics industry.
Moreover, work to enhance complexity has already started. One possibility would be combining the bacterial co-cultures with tissue and cell culture models.
