60 ANTI-AGEING
Transferring pigmentation from forearm to face
Remo Campiche, Mathias Gempeler, Dominik Imfeld - DSM Nutritional Products Sarah Gougeon, Marie Cherel, Magalie Roche - Newtone Technologies, Lyon, France
Irradiating the skin is an established method for studying pigmentation, UV damage and photoageing, and for inducing erythema to assess the efficacy and determine the sun protection factor (SPF) of UV filters. In order to develop and test active ingredients that can help prevent photoageing and modulate visible pigmentation, the cosmetics industry is particularly interested in studying photoageing and cutaneous tanning reactions. Cosmetic scientists use skin irradiation
to help them understand how to prevent pigmentation reactions, which provide a model for ageing-dependent hyperpigmentation and uneven skin tone1-3
(UVR) with a wavelength below 400 nm was used to irradiate skin4-6
.
. Historically, UV radiation . More recently, high
energy visible (HEV) or ‘blue’ light, which has a wavelength of 400-500 nm, has also been used to induce cutaneous pigmentation7-9 From an ethical viewpoint there are
concerns regarding the irradiation of skin. Both UVA and UVB have been shown to induce DNA damage extensively, such as the formation of 8oxo-guanosin moieties for UVA and cyclobutyl pyrimidine dimer formation for UVB10,11 UVA and UVB contribute significantly to
. Irradiation of forearm site
photoageing by inducing oxidative stress events12
, inflammation13,14
of enzymes responsible for extracellular matrix (ECM) degradation, particularly matrix-metalloproteases15-17
and melanoma20 . ABSTRACT and the up-regulation . As such, UVR is
still considered to be the main contributor to both cutaneous ageing and skin cancers such as squamous cell carcinoma18 carcinoma19
While it usually only takes from a few
seconds to a couple of minutes to induce a skin reaction with UVR irradiation due to its high energy, it takes up to an hour to induce visible signs of skin damage comparable to real life outdoor situations with HEV irradiation9
. Facial
skin is constantly exposed to environmental threats, such as solar irradiation, pollution and weather conditions22
. It is therefore
especially prone to photoageing, dryness and inflammatory conditions. Many enzymes responsible for inflammation
and ECM degradation are up-regulated in facial skin compared to photo-protected skin23 Moreover, the skin barrier has been found to be
. Pigmentation colour data processed & acquired Face photograph acquired , basal cell . In addition, HEV
has been shown to contribute significantly to photoageing and cosmetically relevant changes in skin pigmentation21
There is interest, particularly within the cosmetics industry, in understanding what pigmentation reactions and their modulation look like on the face. We have therefore developed methods that enable us to transfer pigmentation digitally from volunteers’ inner forearms to their faces. Using these methods, we can predict facial pigmentation reactions, based on the reaction on surrogate body sites such as the forearm, without irradiating the face.
weaker in facial skin than in other body sites24 .
Therefore, facial skin needs special care and protection. Taking all this into account, it seems logical
that artificially irradiating skin on the face for the purposes of science or to develop commercial skin care products should be avoided and would be of ethical concern. Nevertheless, the cosmetics industry, in particular, is interested in the effects of solar irradiation on the face, and irradiation on other, surrogate body sites is considered second best.
Simulation of pigmentation is digitally applied to the photograph of the face
Skin pigmentation darkens (suntan simulation)
Pigmentation photographed & mapped
with Chromameter
Figure 1: Flow chart illustrating method Note: Pigmentation reaction is induced on the forearm, then digitally applied on face images to simulate facial tanning as if the face had been irradiated instead of the forearm
PERSONAL CARE March 2022
www.personalcaremagazine.com
Pigmentation colour data applied
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