The skin microbiota refers to the microorganisms living on the skin, on its surface, but also more in depth. On 1 cm2 of human skin, up to a billion microorganisms are residing, including bacteria, fungi, mites, and viruses. Skin microbiota contributes to maintain a healthy cutaneous barrier. Skin and microorganisms live in symbiosis and bacteria help to the maintenance of the skin barrier, the immune system and limit pathogenic microorganism growth.
In cosmetics, molecules associated with skincare products last on the skin after their use in spite of several washings and these products can alter molecular and bacterial diversity. Cosmetic ingredients used that are either functional ingredients, such as preservatives, oils and emulsifiers, or active ingredients, have an impact on the skin microbiota and require particular attention. Preservatives, such as phenoxyethanol, parabens, and methylisothiazolinone, are known to inhibit the survival of skin commensal bacteria such as S. epidermidis. This change is dependent of the residual activity of the preservative in the cutaneous environment. Dermocosmetology industry must undergo studies on skin microbiota while developing new ingredients or products in order to ensure consumers that their products maintain, improve a healthy microbiome, or restore a healthy skin-microbiome balance in case of a disturbed microbiome. By the way, in 2019, the first certification of being “Microbiome-friendly”, set up by “MyMicrobiome”, appeared for a final cosmetic product. This certification is to validate that the product is contamination-free, that specific bacteria of the targeted area will be unharmed, that the microbiome diversity is preserved and that the skin balance is not disturbed (not by the suppression of commensals nor by the stimulation of pathogenic bacteria).
HCS Pharma is currently working on this issue developing an in vitro skin model targeting microbiota balance. At present, we offer you a standardized 2D in vitro skin microbiota model in 96-well plate made up of primary differentiated human keratinocytes and cutaneous bacteria (such as S. epidermidis, S. aureus) to reproduce as much as possible the physiological cutaneous microenvironment.