Skin Pharmacology and Physiology最新文献

Sequential application of topical medications - applying two or more agents to the same anatomical site - is common in dermatologic practice, particularly for chronic inflammatory conditions requiring combination therapy. Despite its routine use, guidance on application order, timing, and vehicle compatibility remains limited, and the pharmacologic consequences of sequential topical application are not well defined. This review synthesizes current clinical, in vivo volunteer, and mechanistic in vitro/ex vivo evidence evaluating how sequential application influences percutaneous absorption, cutaneous bioavailability, and clinical outcomes. A qualitative literature search identified twelve eligible studies, including randomized controlled trials, in vivo human studies, and mechanistic diffusion and visualization models. Across heterogeneous designs, sequencing was not pharmacologically neutral. Observed effects were driven primarily by barrier state and vehicle/excipient interactions rather than formulation labels alone. Sequencing was most consequential when the first-applied product altered the stratum corneum through keratolysis, hydration or occlusion, or lipid film formation, or when vehicle interactions resulted in redissolution or redistribution of previously applied agents. In barrier-deficient conditions, such as atopic dermatitis, the order of application had less impact on clinical outcomes. Fixed-combination products generally demonstrated more consistent and predictable delivery than free sequential regimens. Collectively, the available evidence supports a mechanism-informed approach to topical sequencing and highlights the need for standardized, clinically relevant studies to guide application order and timing as combination topical therapy continues to expand.

Introduction: Recent progress in supramolecule research has led to a surge in its application in cosmetic products. However, comprehensive investigation of the potential benefits, especially differentiating biological activities and associating that with physical-chemical properties, remains to be established. In the current study, a supramolecular salicylic acid-betaine (Supra SA-B) was benchmarked to its physical mixture counterpart for its impact on epidermal homeostasis as well as insult potential when applied topically.

Methods: The structure of supra-SA-B and physical mixture of SA+B (1:1 molar ratio) were characterized by a powder X-ray diffractometer before and after dissolution in aqueous alcohol solution. For skin tolerance evaluation, SA, Supra-SA-B, and SA+B were applied systematically to primary human keratinocytes or topically on the surface of SkinEthic™ RHE reconstructed human epidermal models. Cell and model viabilities were assessed using MTT assay, respectively. Inflammatory cytokines produced by models were assessed using Luminex multi-plex assay. Histological morphology was evaluated by hematoxylin-eosin (HE) staining, with aquaporin-3 (AQP-3) and Ki67 measured by immunofluorescence (IF). Finally, RNA-sequencing was conducted to characterize overall biological response based on non-targeted transcriptomic profiles.

Results: Characteristic peaks remained the same for Supra-SA-B after freeze drying verified that their crystalline structures, including supramolecular, were retained in the current solution. With the addition of betaine and introduction of supramolecular format, Supra-SA-B treated groups demonstrated significantly higher cell viabilities comparing to SA or SA+B. With 18-hrs of treatment, Supra-SA-B treated group released less inflammatory cytokines. In addition, Supra-SA-B demonstrated better hydration effect with increased AQP-3 expression and more organized epidermal structure, in comparison to either SA alone or SA+B. Consistent result was observed in the RNA transcriptomic profiles of RHE models after treatment. Supra-SA-B did not induce major transcriptome drift as compared to SA or SA+B, with less evident negative impact on loricrin, and late cornified envelope (LCE) gene expression. At the same time, the boosting effect on hyaluronic acid synthase (HAS) was maintained across all the treatments vs. control.

Conclusion: Our findings indicated that Supra-SA-B ameliorated skin tolerance risk for SA, enhanced hydration with less insult on barrier functions, suggesting promising potential for cosmetic application.

Introduction: This study investigates the transdermal permeation efficiency and traceability of fluorescent nanodiamond-conjugated small extracellular vesicles (FND-sEVs) derived from umbilical cord mesenchymal stem cells (UCMSCs).

Methods: Firstly, the sEVs were isolated and characterized using transmission electron microscopy (TEM) and nanoparticle tracking analysis (NTA), confirming their typical cup-shaped morphology and size distribution (62.5-141.1 nm) consistent with canonical sEV properties. Subsequently, FNDs were conjugated to sEVs, forming FND-sEVs, whose composite structure-featuring a high-electron-density FND core surrounded by a vesicular sEV membrane-was verified by TEM. Conjugation efficiency was then validated via confocal microscopy, showing complete colocalization between FND fluorescence and Alexa Fluor 488-labeled wheat germ agglutinin (WGA)-tagged sEVs. Transdermal assessment was conducted using a skin tissue model, with magnetically modulated fluorescence (MMF) spectroscopy applied for background-free quantification.

Results: Leveraging the unique nitrogen-vacancy (NV⁻) centers in FNDs (fluorescence lifetime ~20 ns), MMF eliminated interference from skin autofluorescence (~3 ns) and enabled direct quantification in tissue digests without pre-separation. FND-sEVs were discovered to remain predominantly in the supernatant, with a measurable fraction permeating skin tissue layers, while their presence in the filtrate was negligible, thereby indicating limited transdermal passage.

Conclusion: Collectively, these findings establish FND-sEVs as a traceable platform for transdermal studies and highlight MMF as a robust tool for quantifying nanoscale vesicle distributions in complex biological matrices.

Introduction: Optical clearing (OC) of biological objects is a promising technique with broad potential in clinical and diagnostic applications, as it enhances imaging depth, spatial resolution, and contrast of acquired images or spectra. The aim of this study was to study the effects of the common optical clearing agents (OCAs) glycerol, fructose, dimethyl sulfoxide (DMSO) and iohexol (Omnipaque®) solutions at various concentrations and treatment durations on the stratum corneum (SC) of intact skin using confocal Raman microspectroscopy (CRM).

Methods: The pig ear was selected for study. Various OCAs were applied topically on the skin, including water solutions of DMSO (100%), fructose (50%), Omnipaque® (90% and 100%), glycerol (40%, 60%, 80%, 90% and 100%). Ex vivo measurements were carried out on porcine ear skin using a Model 3510 SCA confocal Raman microscope (RiverD International B.V., Rotterdam, the Netherlands).

Results: It was found that a 25%-25%-50% water-ethanol-fructose solution permeated the SC at all tested exposure times (5, 15, 30, and 45 min). Similarly, a mixture of 80% glycerol and 20% DMSO, applied for 45 min, also demonstrated effective penetration through the SC. Enhanced OC was achieved by combining OCAs with DMSO, ethanol, or distilled water. The highest OC efficiency was observed with a 25%-25%-50% water-ethanol-fructose solution and a mixture of 90% Omnipaque® with 10% DMSO, both applied for 5 minutes, resulting in a 4.1- and 4.2-fold increase, respectively, in signal intensity at a skin depth of 80 µm. It was shown that the optical properties of the skin can be controlled at a depth of approx. 80 μm. Almost all used OCAs, which are not occlusive from the conventional viewpoint, have an occlusion effect on the SC.

Conclusion: The findings of this study contribute to the identification of optimal OCA combinations - namely, a 25%-25%-50% water-ethanol-fructose solution and a mixture of 90% Omnipaque® with 10% DMSO, each applied for 5 minutes - for potential in vivo applications. Moreover, the results provide a strong foundation for future multimodal investigations aimed at developing advanced methods for visualizing biological tissues and organs and analyzing their biophysical parameters, in conjunction with controlled OC.

Introduction: Heart failure (HF) is an age-related condition that complicates heart disease. Currently the number of patients with HF continues to increase, representing a significant burden on the healthcare system. Prognostication of patients with HF may be performed with modern spectroscopic approaches.

Methods: This study proposes to utilize conventional spontaneous Raman spectroscopy and autofluorescence for the in vivo analysis of skin tissues to create a prognosis for patients with HF. We collected skin spectral data from 160 HF patients. 29 patients died during the one-year observation period. After the preprocessing of spectral data, we proposed a classification model for the prediction of mortality. This model utilizes projection on latent structures combined with discriminant analysis (PLS-DA). Stability of the model was demonstrated during division of the data into training and test.

Results: Analysis of full spectral data provided only 55% accuracy in a one-year mortality prediction, while analysis of autofluorescence and Raman spectral data provides 66% and 70% accuracy, respectively. The combination of autofluorescence and Raman spectroscopy provides an accuracy of 74% (68% sensitivity and 80% specificity) and an ROC AUC (Receiver Operating Characteristic - Area Under Curve) of 0.80 for the prediction of 1-year mortality in patients with HF. The most important Raman bands for the prediction of one-year mortality appeared at 1086-1180, 1320, 1465, and 1770 cm-1.

Conclusion: Raman spectroscopy could be a powerful tool for the prognosis of patients with HF; however, further studies on a larger cohort are required to demonstrate the applicability of the proposed spectral in vivo analysis.

This review summarizes published literature on in-vitro and ex-vivo test methods for pre-clinical evaluation of wound care products. There is currently no guidance from e.g. authorities on how wound care products, especially antimicrobial wound care products, should be assessed regarding their cell toxic effects and their antimicrobial performance. Even though ISO 10993-1 gives clear guidance for biocompatibility evaluation of medical devices, the corresponding methods do not reflect wound conditions. Regarding antimicrobial efficacy the first standard EN 17854 for wound dressings was published recently. For all other endpoints no standards are available. In addition, there are increased ethical considerations that animal testing should be avoided. This was first practiced in cosmetic industry and is now implemented presenting a central part of ISO 10993-1 for toxicity assessment of medical devices. At the same time, there is increasing evidence that in-vitro and ex-vivo methods can replace animal testing for certain endpoints with the advantage that a partially difficult transfer of data from animals to humans may not be needed anymore. This review presents a comprehensive overview of methods that can be used for pre-clinical evaluation of wound care products.

In recent years, multicolored tattoos have gained popularity among young individuals. However, the behavior of tattoo inks in the skin, including their distribution, accumulation, and long-term effects, remains poorly understood, partly due to limited in vivo imaging techniques. This study employs picosecond-pulsed two-photon excited fluorescence lifetime imaging microscopy (TPE-FLIM) to non-invasively visualize the deposition of colored tattoo ink pigments (blue, red, green, yellow, orange, purple and black) in human skin in vivo at depths of up to ≈150 µm. The study reveals that tattoo ink agglomerates are present across various skin layers, ranging from the stratum corneum to the reticular dermis. Tattoo ink pigments were predominantly observed within dermal cells, including mast cells, macrophages, and fibroblasts, suggesting that these cells act as long-term reservoirs for the pigments. Additionally, ink residues were detected in epidermal cells, including keratinocytes, dendritic cells, and basal cells, indicating a continuous low-level release of the ink even in old tattoos. Furthermore, the analysis showed that melanin can be distinguished from certain tattoo ink pigments using phasor approach combined with TPE autofluorescence imaging. The TPE-FLIM technique enables in vivo visualization of epidermal dendritic cells and dermal fibroblasts, which are otherwise undetectable using conventional optical methods without staining. This method holds significant potential for clinical dermatology by offering insights into cellular uptake, accumulation, and long-term effects of tattoo inks, thereby supporting the management of tattoo-related complications.

Introduction: Knowing thicknesses of skin-tissue layers within the depths of several hundred micrometers from the surface is highly important for numerous biomedical applications - cosmetology, treatment of wounds and burns, characterization of various lesions, etc. In this regard, optical coherence tomography (OCT) with its ability to non-invasively enable visualization depth of the order of one millimeter with a resolution of the order of several micrometers offers exceptional diagnostic possibilities largely unavailable to other techniques. This explains high interest to OCT utilization in dermatology.

Methods: This study demonstrates that appropriate physics-based processing of OCT data allows one to objectively reveal and automatically estimate thicknesses of morphological skin layers, even if they are not visible as optical layers with differing intensity in initial structural OCT scans. To this end, we apply recently developed efficient methods of spatially-resolved estimation of the scattering coefficient µs to locally characterize the scattering strength of scatterers in the tissue. Another useful parameter termed speckle contrast (SCI) characterizes fluctuations of scattering strengths of scatterers and their clustering. Mapping parameters µs and SCI enables differentiation of morphological skin layers, although in structural OCT scans they cannot be clearly delineated even by experts.

Results: Analysis of parameters µs and SCI for OCT data in vivo acquired in various localizations for women and man of various ages confirmed the possibility to clearly segment three medically significant skin layers: (i) stratum corneum, (ii) living-cell layer of epidermis, and (iii) upper dermis layer even if in the initial OCT scans these layers are hardly discernible. The present study is intentionally limited to healthy facial skin, for which significant variations in the layer thicknesses were demonstrated for various age groups, as well as in quite close localizations for the same person.

Conclusion: These findings underscore high potential of in vivo OCT-imaging supplemented with the analysis of speckle features and optical attenuation parameter for objective real-time differentiation of morphological skin layers, which is critically important for numerous applications (surgical reconstruction of skin wounds and/or burn injuries, controlled drug delivery in targeted skin layers, choice of therapy). Similar approach may be extended for diagnosing various skin diseases/pathologies.

Introduction The sacrum and posterior heel are two common areas where skin is exposed to pressure and shear forces which could lead to damage in the form of pressure ulcers. Despite their vulnerability, relatively few studies have explored their structural and physiological properties which predispose them to damage. The aim of this study was to characterise age- and anatomical site differences in the skin epidermal properties and microvasculature using optical coherence tomography (OCT), in younger and older adults. Methods Twenty-two younger (18-35 years) and 19 older healthy adults (55-70 years) completed three experimental visits, comprising of non-invasive OCT imaging to characterize skin epidermal properties and microvascular density. Extracted parameters from the captured images were optical attenuation coefficient (OAC), dermal brightness, epidermal thickness, surface roughness (Rq), microvascular plexus depth (µm) and vascular density (%). Results There were significant differences in the epidermal structural properties between the sacrum and heel across all parameters (P<0.001), except for roughness (P>0.05). The vascular density profiles plotted against skin depth were also significantly different between anatomical sites (P<0.001), with peak vascular density being more superficial in the heel: ~0.2mm vs. sacrum: ~0.4mm; (P<0.001). The sacrum had a greater maximum vascular density (~9%) compared to the heel (~7%; P<0.001). No significant differences were observed between the age groups (P>0.05). Conclusion Distinct differences were observed for epidermal and vascular density measurements between heel and sacral skin sites. However, there were no age-related differences, which may be associated with the older adult range (55-70 years) and healthy status. The structural and microvasculature insights could aid in the design of therapeutic interventions to promote tissue viability and health such as site-specific dressing and textiles.

Introduction: Eczematous cheilitis is a common manifestation in patients with atopic dermatitis, and restoration of lip barrier function is essential for effective management. Wet wrap dressing is a widely used adjuvant therapy for atopic dermatitis lesions; a similar approach may be beneficial for treating atopic cheilitis. This study aimed to evaluate the short-term effects of saline gauze wet dressing on lip barrier function and to compare the clinical efficacy of this method, as an adjunct to standard therapy, in patients with eczematous cheilitis.

Methods: Patients with eczematous cheilitis and age-matched healthy volunteers were enrolled. Lip barrier function was assessed via transepidermal water loss, stratum corneum hydration (SCH), pH, and erythema values. Short-term changes were measured at 15, 30, and 60 min after application of saline gauze wet dressing. In addition, a case-control design was used to compare the 7-day efficacy of gauze wet dressing as adjuvant therapy combined with topical glucocorticoid and petroleum jelly versus standard therapy alone.

Results: Compared with healthy controls, patients with eczematous cheilitis demonstrated impaired lip barrier function. Application of saline gauze wet dressing significantly improved SCH and normalized pH within 30 min, with sustained barrier restoration over the 7-day treatment period. The adjuvant therapy group showed significantly greater clinical improvement than controls, including marked resolution of fissures and erythema and enhanced barrier function.

Conclusion: Saline gauze wet dressing, as an adjunct to standard topical therapy, provides a simple, convenient, and cost-effective option for improving lip barrier function and accelerating clinical recovery in eczematous cheilitis, thereby enhancing therapeutic outcomes and patient satisfaction.