Personal care products offering efficacy on the biomechanical properties of the skin are often linked to the category of anti-aging claims. These products are associated with various functionalities such as lifting, firming, remodeling, plumping, sculpting, restructuring or toning. Firmness and tone are skin attributes constantly impacted by the exposome (concept developed by Dr. Jean Krutman in 2016) and all the non-genetic factors that influence skin aging.
However, what methods exist today to assess the performance of active ingredients and cosmetics on the biomechanical properties of the skin?
In vivo objectification of the firmness and tone of the skin
Beyond consumer tests and scoring by experts, we have categorized the evaluation of the biomechanical properties of the skin into 2 parts: one dedicated to direct measurements and the second dedicated to indirect evaluation.
Direct biometrological assessments are intended to measure the elasticity and firmness of the dermis using various instrumentations which make it possible to quantify in several regions of the face and body:
Dynaskin by Eotech, Orion
SkinFlex by Orion
Cutometer and Cutiscan by Courage & Khazaka
DermaLab Elasticity by Cortex
Indentometer by Courage & Khazaka
Real-time deformation using several techniques – balistometry, aspiration, indentation, or air flow – is performed one or more times on the surface of the skin. Then, the induced biomechanical behavior is measured by the principle of optical projection or fringes.
Ratings by experts using specific visual and tactile scales are complementary analyzes that can also be supplemented by volunteer self-assessment or specific consumer studies.
Indirect measurements analyze the evaluation of parameters related to the biomechanical properties of the skin and provide information on: collagen, facial analysis and volume, molecular composition, proteomics and metagenomics, size and shape of the dermis , appearance and structure of the skin. You can retrieve the different analysis methods from the table below or connect to the clinical tests platform.
The preliminary discussion with the CROs to design the study (schedule, duration, conditions of use of the products, inclusion criteria, choice of instrumentation, etc.), seems essential to define the best protocol to support the justification of the allegation.
The evolution of technology in non-contact probe, data acquisition and processing with the use of AI algorithm can set the direction for non-contact and optical solutions. Today, the “must have” is the illustrative result but the simple use of a photo is not yet viable to assess changes in firmness, tone or elasticity of the skin. Maybe soon!
Analysis of the Extra-Cellular Matrix [ECM] using in vitro quantification
The goals of personal care are to keep the skin in good condition and to preserve its elasticity and resistance. The “firmness” performance improves the density of the dermal extracellular matrix [ECM]. This “renowned” matrix plays one of the essential roles of the physical and biomechanical properties of the dermis with this complex network of extracellular macromolecules providing cells with structural, bioactive molecules and a biochemical support.
The ECM made up of around 100 proteins is a dynamic network controlling the proliferation, adhesion, migration, polarity, differentiation and apoptosis of cells. In vitro or ex vivo tests can target the various biological mechanisms offering unlimited possibilities for the management of complaints.
What are the main components of ECM that can be studied?
1. Collagens, the backbone of tissue architecture, are classified into 3 main types:
fibrillar collagens (types I, II, III),
non-fibrillar network-forming collagens (type IV), which make up a non-fibrillar network.
collagens associated with fibrils (types IX, XII) and others (type VI).
Glycosaminoglycans (GAGs) are polysaccharides and help retain water. The diversity of proteoglycans and their strong interaction with growth factors and their receptors provide a structural basis for a multitude of biological functions. They are divided into four groups: hyaluronic acid, keratan sulfate, chondroitin / dermatan sulfate, and heparan sulfate.
2. Laminins form networks that remain in close association with cells through interactions with cell surface receptors.
3. The role of fibronectin fibrils is the attachment and migration of cells, like a “biological glue”.
4. Elastin fibers impart elasticity and, through LOX-mediated cross-links with tropoelastin, ultimately form desmosine or episodesmosine.
In conclusion, this incredible network, substrate for matrix metalloproteinases (MMP), stores bioactive fragments and adhesive proteins is also modulated by the exogenous environment. The specific biochemical properties of ECM can be investigated in a number of ways through the analysis of its various components and their interaction, and provides a “golden” carrier for substantiating ingredient and finished product claims.