With the increase of human span life people demand to live and look better. In a world whereappearance is synonymous of health, the demand of new cosmetic has literally exploded. Amongcosmetic treatments, skin care represents a large part of the business of beauty. From 2017 to2023, world-wide non-surgical skin cosmetic treatments business will have a compound annualgrowth rate between 4.7% and 5.3% [1]. The increased demand of non-surgical beautytreatments pushed cosmetic research during the last years. In Europe since 2013 cosmetic testson animal model are definitively banned. This encouraged researchers to develop newapproaches to study skin “in-vitro” using either re-constructed tissue structure or attempting tomimic skin microenvironment parameters. Cell culture has been used since a long time to studyorgan functions in laboratory. In the last decades cell culture has greatly evolved in order tomimic the real tissue structure and microenvironment. Cells are cultivated in three dimensionsand media are adapted to better simulate the extracellular environment. Attempting to get closerto the physiological micro-environment of a cell, scientists underestimated often a keyparameter: the oxygen level [2]. While oxygen represents the 21% of the air gases, in humantissues, its percentage is significantly lower. In skin, it can vary from 7% to 1%. To be as closeas possible to skin microenvironment, in our lab we grow human skin cells either in classicnormoxic condition (18% O2) or in physioxic condition (3% O2). Oxygen has a key role in cellrespiration and in reactive oxygen species (ROS) production. We have already demonstrated thatskin cells raised in physioxia produce lower quantity of reactive oxygen and nitrogen species(RONS) even when exposed to plasma treatment [3]. In this study we evaluated the effect of aCold Atmospheric Plasma (CAP) treatment on human skin cell raised either in normoxia or inphysioxia. In particular, modulating plasma parameters from our helium Plasma Gun, weinvestigated the ability of CAP to improve cell viability and extracellular matrix production suchas collagen, hyaluronic acid and elastin, macromolecules involved in maintaining the health andbeauty of the skin.