Cosmetics & Personal Care | Monthly bulletin | February 2026

Understanding skin structure: how to assess dermal collagen

Collagen is a fundamental determinant of dermal structure, mechanical strength and skin function. It accounts for an average of ~85 to 90% of all dermal fibres. With ageing or pathological or environmental stress, collagen quantity and organisation progressively change, causing visible changes and making it a key target for cosmetic and dermatological innovation.

Early stage evaluations often begin with 3D skin models and human skin explants, where dedicated staining techniques help visualise dermal thickness, collagen density, fibre organisation, and collagen subtypes. These platforms offer rapid, mechanism-oriented insights and support the biological relevance of active ingredients.

In vivo, non-invasive imaging technologies provide direct access to dermal collagen in real time.

• Spectrophotometry (with SIAscopy) maps collagen distribution beneath the skin surface.
• High-frequency ultrasound (20 MHz) quantifies dermal thickness, echogenicity, and the subepidermal low echogenic band (SENEB), closely linked to collagen density and photoaging.
• OCT offers cross-sectional visualisation of dermal structure.
• LC-OCT delivers high-resolution images of the dermal microarchitecture and collagen organisation.
• Confocal laser scanning microscopy reveals fine collagen bundles in the superficial dermis.
• Multiphoton tomography provides unique, label-free imaging of collagen fibres using SHG, enabling precise assessment of fibre density and orientation.

In vivo, non-invasive Raman spectroscopy can also be used to study the helical conformation of collagen in the dermis. In normal skin, most Raman scatters, especially in protein-specific regions, is gathered from the dermis. The protein that contributes most significantly to the spectra is collagen, since it accounts for >80% of the dermal fibres.

Skin firmness and elasticity are heavily influenced by dermal collagen. Measuring biomechanical properties – via suction, torsion, indentation, or pressure-based technologies – offers an indirect but highly relevant way to assess collagen-related improvements and support product performance claims.

Our CRO network provides a full suite of direct and indirect collagen assessment methods, enabling robust, customised clinical strategies to substantiate collagen related efficacy claims – from mechanisms of action to in vivo demonstration.

Early skin colonisation: why environmental conditions matter

The skin microbiome plays a fundamental role in barrier integrity, hydration and immune balance. Yet, while much research has focused on microbial diversity, far less attention has been given to early interspecies interactions and the environmental conditions that shape them.

In collaboration with Clarins, Eurofins BIO-EC has published new research investigating the early co-colonisation of Staphylococcus epidermidis and Staphylococcus aureus on reconstructed epidermis and human skin explants.

Rather than focusing on late-stage infection models, this work explored the very first hours of bacterial adhesion and their short-term impact on key barrier markers under different relative humidity conditions.

Although there were lots of detailed findings, three key messages were prevalent:

• Environmental humidity influences microbial behaviour
  Under highly humid laboratory conditions, co-inoculation of both bacterial species led to increased early adhesion. This effect was not observed under dry or physiologically relevant humidity levels.
  Takeaway: Experimental conditions can significantly influence microbiological outcomes. Physiological relevance is essential when designing microbiome-related studies.

• Early microbial interactions can affect hydration markers
  Co-colonisation was associated with measurable modulation of Natural Moisturising Factors (NMFs), central to stratum corneum hydration.
  Takeaway: Even short-term microbial interactions may influence biochemical pathways linked to moisturisation, a key consideration when substantiating hydration or barrier-support claims.

• Barrier responses are model-dependent
  Responses observed in reconstructed epidermis differed from those seen in native skin explants, particularly for filaggrin expression.
  Takeaway: Model selection is strategic. The architecture and environmental exposure of the test system directly affect biological interpretation and claim robustness.

These findings reinforce several strategic principles:

• Integrate physiologically relevant environmental parameters into testing protocols
• Combine complementary skin models to strengthen predictivity
• Consider early microbial events when evaluating barrier and hydration performance

Scientific credibility in microbiome research depends not only on what is measured, but how and under which conditions it is measured.

Read the full scientific publication: Frontiers | Early skin colonization by Staphylococcus epidermidis and Staphylococcus aureus reveals environment-dependent synergistic effects

Menopause as a distinct model of cutaneous ageing: Implications for advanced cosmetic testing

Menopause constitutes a specific biological model of skin ageing driven by the abrupt decline in oestrogen and its downstream effects on cutaneous homeostasis. This transition should not be interpreted as a simple acceleration of chronological ageing. Oestrogen depletion affects keratinocyte proliferation and differentiation, epidermal lipid synthesis, dermal extracellular matrix turnover and neurovascular regulation. Within the first five years post-menopause, up to 30% of dermal collagen may be lost, accompanied by measurable reductions in skin thickness and elasticity.

Clinically, these molecular changes translate into increased transepidermal water loss (TEWL), delayed barrier recovery, reduced dermal density, heightened neurosensory reactivity and frequently diffuse hair thinning. Such features justify dedicated evaluation strategies rather than extrapolation from conventional anti-ageing protocols.

Hydration claims in menopausal skin require more than single time-point corneometry. Dynamic TEWL measurements following a controlled barrier challenge, assessment of recovery kinetics and high-resolution imaging of epidermal thickness provide more discriminating endpoints. At molecular level, evaluation of markers such as filaggrin, aquaporin-3 and key enzymes involved in ceramide biosynthesis strengthens mechanistic substantiation and enhances claim robustness.

Loss of firmness represents another hallmark of the menopausal transition. Instrumental biomechanical assessments (e.g. cutometry or torsion analysis) gain significance when interpreted alongside structural imaging and biomarkers linked to collagen synthesis, elastin organisation and matrix metalloproteinase regulation. This integrated approach allows products to be positioned as modulators of dermal matrix homeostasis within a clearly defined hormonal context.

Altered vascular and neurocutaneous responses, clinically expressed as flushing, erythema and increased sensitivity, further differentiate menopausal skin. Quantitative colourimetry, microcirculation imaging and validated sensory assessment tools are essential to substantiate soothing and redness-reducing claims. In parallel, hormone-related hair thinning demands robust phototrichogram analysis, fibre diameter measurements and, where relevant, exploration of follicular biomarkers to support scalp-targeted efficacy.

Beyond structural parameters, menopause encompasses a significant psycho-physiological dimension. Hormonal fluctuations influence sleep quality, mood stability and stress perception, factors that may modify product experience and adherence. While remaining within the cosmetic regulatory framework, integration of validated quality-of-life questionnaires and selected physiological indicators enables substantiation of claims related to comfort, confidence and overall well-being.

This paradigm contributes to the rise of precision-driven hormonal cosmetics. Effective product development requires stratified study populations, well-characterised hormonal status, and multicentric, multi-ethnic investigations reflecting the diversity of phototypes and lived experiences across global markets. Importantly, endocrine transitions are not exclusive to women; andropause-associated changes may similarly impact skin physiology and hair density, calling for adapted evaluation models.

In this evolving landscape, Eurofins Cosmetics & Personal Care supports brands through tailored, integrated testing strategies combining clinical, instrumental, molecular and behavioural endpoints. By translating hormonal science into robust, regulatory-compliant evidence, we enable the development of innovative cosmetic solutions aligned with the complex and diverse realities of hormonal skin transitions.

What’s next?

Trade shows

PCHI - 18-20 March

Hangzhou, China – Stand 8B23

Conference: Ex vivo skin model as an inexhaustible source of innovation for cosmetic testing | March 18 at 4:00 PM | NTS A | Mr. Nikita Radionov, PhD

More information: https://www.eurofins.com/cosmetics/media-centre/pchi-2026/

Cosmetotest - 18-19 March

Lyon, France

Conference: Clinical Studies Conducted on Cosmetic Products Related to Menopause | March 18 at 9:10 AM | Anne Sirvent