Mechanism by Which Enhanced Blood Circulation Activates Epidermal Cells Newly Confirmed in Human Skin
The Dilation of Capillaries and the Supply of Oxygen Stimulate
Mitochondrial Metabolic Function

It has been said that promoting blood circulation improves skin condition, and Kao had already discovered, through research into the condition and function of capillaries, that there is indeed a relationship between blood circulation and epidermal skin condition. However, the mechanism by which enhanced blood circulation causes changes in the skin cells, or exactly what those changes are, had not been fully elucidated.

To test this hypothesis, Kao needed measurement technology capable of assessing the metabolic state of the mitochondria in epidermal cells of living human skin. Kao therefore focused on autofluorescence spectral analysis, which utilizes the natural fluorescence present within cells. When cells use oxygen to produce energy (adenosine triphosphate, ATP), the activity of the mitochondria changes. These changes appear as oxidation-reduction reactions of substances involved in energy metabolism, and it is known that autofluorescence characteristics also change accordingly. Kao has utilized this property to develop a technology for evaluating the energy state of cells in human skin using autofluorescence as an indicator.

Specifically, by optimizing conditions when taking measurements with confocal fluorescence microscopy and building a deep learning model to automatically extract cells from the stratum spinosum, Kao was able to reliably acquire autofluorescence spectral data and establish a method for highly accurate evaluation of the mitochondrial metabolic state of epidermal cells in human skin.

In October 2025, Kao conducted a test on seven Japanese men and women in their 30s and 40s, in which a carbon dioxide-containing composition capable of maintaining a high concentration of carbon dioxide gas was applied to the inside of their forearms for two minutes. Before application, and for up to ten minutes after the composition was removed, the autofluorescence spectra of the epidermal cells were acquired over time and analyzed. The results confirmed that application of the carbon dioxide-containing composition enhanced mitochondrial metabolic function^*1 compared with a carbon dioxide-free composition (Figure 1).

By using Kao’s technology for automatic visual extraction of the capillary region^*2 to analyze the state of the capillaries during these changes, Kao has confirmed that capillary dilation and mitochondrial metabolic function activity are linked, which suggests that enhanced blood circulation has a positive effect on cellular metabolism.

In order to verify this mechanism, Kao cultured human epidermal keratinocytes in environments having different oxygen concentrations, and analyzed their autofluorescence spectra. The results confirmed that mitochondrial metabolic function improves with increasing oxygen concentration (Figure 2). This suggests that the enhancement of mitochondrial metabolic function in epidermal cells observed when a carbon dioxide-containing composition is applied to human skin is due to increased oxygen supply resulting from capillary dilation.

Utilizing the knowledge it has amassed through its dermatological research, Kao has now established a new evaluation technology for visualizing the state of mitochondrial metabolism in epidermal cells in human skin, and has demonstrated that promoting blood circulation by applying a carbon dioxide-containing composition enhances mitochondrial metabolic function in epidermal cells. The results of this research support the idea that “good blood circulation improves skin condition” at the cellular level. Kao will continue to investigate the multifaceted effects of carbon dioxide on skin, and deepen its research into the relationship between capillary blood flow and beautiful, healthy skin.

Kao, a Japan-based manufacturer of personal care and household products, cosmetics, and specialty chemicals creates high-value-added products and services that provide care and enrichment for the life of all people and the planet. Through its brands such as Attack laundry detergent, Bioré and Jergens skin care products, Laurier sanitary products, Curél, SENSAI, and MOLTON BROWN cosmetics, and Oribe hair care products, Kao is part of the everyday lives of people across Asia, the Americas, Europe, the Middle East, and Africa. Combined with its chemical business, which contributes to a wide range of industries, Kao generates about 1,630 billion yen in annual sales. Kao employs about 32,600 people worldwide and has more than 130 years of history in innovation. As an enterprise that provides products people use on a daily basis, the Kao Group takes responsibility to actively reduce the environmental footprint of its products throughout the product lifecycle. This is laid out in Kao’s ESG strategy, the Kirei Lifestyle Plan, which launched in 2019.
Please visit the Kao Group website for additional information.