Noninvasive analysis and minimally invasive in vivo experimental challenges of the skin barrier

Abstract

In this review, we aim to give a concise and selective overview of noninvasive biophysical analysis techniques for skin barrier analysis (transepidermal water loss, electrical methods, confocal Raman microspectroscopy, sebumeter, reflectance spectrophotometry, tristimulus colorimetry, diffuse reflectance spectroscopy and reflectance confocal microscopy), including advantages and limitations. Rather than giving an exhaustive description of the many techniques currently available, we show the usefulness of a representative selection of techniques in the functional and morphological evaluation of the skin barrier. Furthermore, we introduce human minimally invasive skin challenging models as a means to study the mechanisms regulating skin homoeostasis and disease and subsequently show how biophysical analysis techniques can be combined with these in vivo skin challenging models in the functional and morphological evaluation of the skin barrier in healthy human skin. We are convinced that the widespread application of biophysical analysis techniques in dermatological practice and in cosmetic sciences will prove invaluable in offering personalized and noninvasive skin treatment solutions. Furthermore, combining the human in vivo challenging models with these novel noninvasive techniques will provide valuable methodology and tools for detailed characterization of the skin barrier in health and disease.

Noninvasive objective skin measurement methods for rosacea assessment: a systematic review

“…Skin measurement tools were extracted by literature search and by exploring their PubMed MeSH-terms. 4,[22][23][24][25]28 We defined 'noninvasive' as every method that theoretically cannot lead to skin irritation, bleeding or scarring; this excluded biopsies, epilation of eyelashes/hairs, application of tape or glue onto the skin, and collection of skin scrapings or excretions from sebaceous follicles. Only studies involving adult patients with cutaneous facial rosacea were included (Table S1; see Supporting Information).…”

Noninvasive Skin Barrier Assessment: Multiparametric Approach and Pilot Study

“…Of all imaging tools, RCM is superior for noninvasive skin thickness measurements. Possible alternatives are high-frequency ultrasound, near-infrared spectroscopy, optical coherence tomography, or Raman spectroscopy; however, these devices have lower resolution and are also expensive [17,[37][38][39]. Moreover, they may not all be suitable for facial imaging due to their size (e.g., Raman spectroscopy).…”

“…In addition to water content and TEWL, other skin parameters may influence skin barrier function, such as natural moisturizing factor (NMF), SC thickness, dermal vasodilatation (erythema), intracellular lipids, and pH [2,4,15]. A wide array of noninvasive biophysical and imaging methods are available to assess most of these parameters [17]. In the current pilot study, we demonstrate the feasibility of combining a quartet of biophysical/imaging devices to measure the following four skin parameters noninvasively: erythema, TEWL, water content, and epidermal thickness.…”

Non-invasive depth profiling of the stratum corneum in vivo using confocal Raman microscopy considering the non-homogeneous distribution of keratin

“…50 µm in depths, at red/infrared excitation, i.e. it is well suited for non-invasive measurements of the entire SC in vivo [15]. A recent in vivo study using CRM confirmed the non-homogeneous distribution of lateral packing order of ICL, showing the prevalence of the orthorhombic phase in the depth of approx.…”