Kao research team discovers link between capillary blood flow and skin condition

In order to examine the capillaries in the skin, the team developed an image-processing technology that claims to “automatically discriminate capillaries in microscopic images of facial skin”​.

Capillaries are fine blood vessels branching away from the veins and arteries throughout the body. They supply oxygen and nutrients to the tissue while removing waste matter from the tissue.

According to Kao, the mechanism by which capillaries regulate blood flow differs from the veins and arteries.

Specifically, the capillary blood flow is regulated by the oxygen concentration of the tissue and metabolic activity.

“So far it has been impossible to precisely visualize and measure the extremely fine capillaries by discriminating them from the surrounding tissue. Much has yet to be learned about the relationship between the workings of the capillaries and the functions and metabolism of the skin and skin beauty,”​ said Kao.

Capillaries in relation to skin

This research is part of Kao’s ongoing research into the relationships between skin condition and physical functions such as blood circulation from a dermatological perspective.

In 2015, its research team discovered that people with a higher capacity to regulate blood flow in response to environmental changes tended to be people with less skin dryness.

Two years later, the firm conducted another study to examine how the skin condition correlates with the blood flow regulatory function of the capillaries in a resting state.

Researchers examined the skin capillaries of 98 Japanese women in their 20s to 60s under a microscope.

The study revealed that the blood flow regulatory functions correlate with more parameters of skin conditions than the regular capillary condition.

An analysis based on differences in age further revealed that women in their 20s and 30s with higher blood flow regulatory function tend to have better skin texture pattern.

On the other hand, women in their fifties and sixties with higher blood flow regulatory function have smaller cell sizes in the stratum corneum. This, Kao suggested, meant epidermal cells were activated.

Developing new imaging method

To examine the relationship between capillary blood vessels and skin condition in greater detail, Kao researchers developed an imaging technology to visually extract capillaries.

However, the presence of melanin and hair in and on facial skin makes it difficult to measure capillaries by conventional imaging techniques.

In order to get accurate imaging, Kao researchers constructed an algorithm for precisely discriminating the capillaries in microscopic images.

To confirm the precision of this process, the algorithm was compared with conventional manual methods conducted by trained experts.

In comparison, 96.6% of all the extracted images were in alignment with the annotated area.

Along with its earlier research, new findings suggest that blood flow regulatory function is linked to skin beauty.

“The development of a new evaluation method combining this visual discrimination algorithm and quantitative measurement of the capillaries from microscopic images of the skin will make it possible to assess the state and functions of capillaries and more fully investigate the links with facial skin,” ​said Kao.

It added that it planned to continue studying changes in the condition of the blood vessels to analyse the effects such as skin metabolism, dark spots, and fine lines.