Revitalizing the skin: Exploring the role of barrier repair moisturizers.

BACKGROUND: Moisturizers are designed to maintain skin health and treat dermatological conditions associated with impaired skin barrier function. However, differences in their composition account for the differences in their effect. AIMS: This narrative review aims to discuss the role of barrier repair moisturizers, highlight the role of different components in a moisturizer and their role in impaired skin conditions (e.g., dry, itchy, inflamed, sensitive skin, atopic eczema), and thereby empower dermatologists and pediatricians in selecting the right moisturizer. METHODS: PubMed, Embase, and Scopus electronic databases were searched from January 2000 to June 2023 for publications on skin barrier repair and use of barrier repair moisturizers for the treatment of dry, itchy, inflamed, sensitive skin, or atopic eczema. Studies conducted in humans, published in English for which full texts were freely available were included. RESULTS: The structure and composition of lipid lamellae within the stratum corneum play an important role in maintaining an effective skin barrier and protecting the body from various external assaults. Endocannabinoid mediators play an active role in maintaining skin barrier function. Moisturizers containing physiological lipids and functional ingredients (e.g., endocannabinoids such as palmitoylethanolamide [PEA]) and based on the principles of biomimic technology are demonstrated to be beneficial for the management of conditions associated with a disrupted skin barrier. CONCLUSIONS: Moisturizer based on the innovative biomimic formulation has good cosmetic efficacy and is generally well tolerated, and the addition of PEA might represent a new generation of compounds that may be beneficial for long-term management of impaired skin conditions.

Combining topical dermal infused exosomes with injected calcium hydroxylapatite for enhanced tissue biostimulation.

BACKGROUND: Exosome research continues to flourish. Subsequent knowledge surrounding indications, dose-response, safety, efficacy, and the ability to combine exosome treatment as a "skin primer"-for biostimulation modalities such as calcium hydroxylapatite (CaHA), platelet-rich plasma (PRP), and platelet-rich fibrin matrix (PRFM) is growing rapidly. The objective of this study was to develop safe, reproducible methods of improving topical exosome absorption to enhance the quality of skin either by themselves, or in combination with injectable CaHA. METHODS: Under IRB Approval (International Cell Surgical Society: ICSS-2022-007), 40 patients were enrolled in this study. Twenty patients underwent facial biostimulatory dermal infusion alone, to determine if this method allowed adequate exosome absorption. Five patients underwent facial biostimulatory infusion followed immediately by Dilute CaHA injection (1:1 dilution) to the face. Five patients underwent exosome biostimulatory dermal infusion followed immediately by hyperdilute CaHA (dilution 1:4) injection to the neck. Five patients underwent Facial Dilute CaHA injection (1:1 dilution) alone, without dermal infusion. Five patients underwent neck hyperdilute CaHA injection (1:4 dilution) alone, without dermal infusion. All patients had pretreatment Quantificare 3-D photo-documentation and skin analysis (Quantificare, France). In all patients, the skin was first cleansed with a gentle glycolic acid facial wash (Gregory MD). To induce a "homing inflammatory environment" for the exosomes, sea salt exfoliation was performed (SaltFacial®, SaltMed, Cardiff, CA). A nitric oxide-generating serum (N101 Pneuma Nitric Oxide, Austin, TX) was then applied to act as an enhanced vehicle for absorption. A 3 MHz ultrasound (SaltFacial®, SaltMed, Cardiff, CA) was then utilized to further deepen the absorption of the nitric oxide serum. A topical emulsion containing equal volumes (1.0 cc containing 1 million) of exosomes (Kimera Labs, Miramar, FL), 25 units of botulinum toxin (Xeomin, Merz Aesthetics, Raleigh, NC) and hyaluronic acid (Belatero, Merz Aesthetics, Raleigh, NC) was mixed via back-and-forth propulsion in a 3-cc syringe. When adequately mixed, the emulsion was then applied to the treatment areas. The cavitating ultrasound was then used to aid in the absorption of the emulsion. The patients were then treated with high-intensity LED therapy (SaltFacial®, SaltMed, Cardiff, CA), utilizing the collagen restoration preset program of combination red (660 nm) near-infrared (930 nm) wavelength for 20 min. Post-treatment Quantificare analysis was performed at 15 and 30 days after treatment. RESULTS: Without exception, all dermal infusion alone and CaHA injection alone patients showed an improvement in the tone, quality, and texture of their skin. Quantificare results showed consistent improvement in wrinkles, pores, skin evenness, improved vascularity, and a reduction in oiliness and unwanted pigment. When employed as a skin primer prior to injections (CaHA), enhanced and more rapid results were seen. CONCLUSIONS: Biostimulatory dermal infusion can be achieved utilizing topical placental mesenchymal stem cell-derived exosomes. These exosomes can be used alone, or mixed with ancillary ingredients such as botulinum toxin, hyaluronic acid dermal filler, and CaHA to customize and personalize treatments based upon individual patient needs. Topical absorption is enhanced with sea salt exfoliation, a topical nitric oxide-generating serum, and 3 MHz cavitating ultrasound. Post-absorption activity is enhanced with high-intensity LED treatment. The addition of CaHA injections after the topical exosome "priming of the skin" yielded enhanced skin quality faster than exosomes or CaHA alone.

Development of an improved inhibitor of Lats kinases to promote regeneration of mammalian organs.

The Hippo signaling pathway acts as a brake on regeneration in many tissues. This cascade of kinases culminates in the phosphorylation of the transcriptional cofactors Yap and Taz, whose concentration in the nucleus consequently remains low. Various types of cellular signals can reduce phosphorylation, however, resulting in the accumulation of Yap and Taz in the nucleus and subsequently in mitosis. We earlier identified a small molecule, TRULI, that blocks the final kinases in the pathway, Lats1 and Lats2, and thus elicits proliferation of several cell types that are ordinarily postmitotic and aids regeneration in mammals. In the present study, we present the results of chemical modification of the original compound and demonstrate that a derivative, TDI-011536, is an effective blocker of Lats kinases in vitro at nanomolar concentrations. The compound fosters extensive proliferation in retinal organoids derived from human induced pluripotent stem cells. Intraperitoneal administration of the substance to mice suppresses Yap phosphorylation for several hours and induces transcriptional activation of Yap target genes in the heart, liver, and skin. Moreover, the compound initiates the proliferation of cardiomyocytes in adult mice following cardiac cryolesions. After further chemical refinement, related compounds might prove useful in protective and regenerative therapies.

A Mixture of Topical Forms of Polydeoxyribonucleotide, Vitamin C, and Niacinamide Attenuated Skin Pigmentation and Increased Skin Elasticity by Modulating Nuclear Factor Erythroid 2-like 2.

It is well-known that increased oxidative stress caused by ultraviolet B (UV-B) radiation induces melanogenesis and activates metalloproteinases (MMPs), which degrade collagen and elastin fibers, leading to decreased skin elasticity. Various antioxidant agents, such as vitamin C and niacinamide, have been evaluated for use as treatments for photoaging or skin pigmentation. In this study, we evaluated the ability of a topical liquid formula of polydeoxyribonucleotide (PDRN), vitamin C, and niacinamide (PVN) delivered via a microneedling therapy system (MTS) to attenuate photoaging and pigmentation by increasing nuclear factor erythroid 2-like 2 (NRF2)/heme oxygenase-1 (HO-1) and decreasing MMP expression in a UV-B-radiated animal model. The effects of the PVN were compared with those of individual PDRN and hydroquinone (HQ) compounds. The expression of NRF2/HO-1 significantly increased in response to HQ, PDRN, and PVN in UV-B-radiated animal skin. The activity of nicotinamide adenine dinucleotide phosphate hydrogen oxidase decreased in response to HQ, PDRN, and PVN, and the superoxide dismutase activity increased. The expression of tumor protein p53 and microphthalmia-associated transcription factor and tyrosinase activity decreased in response to HQ, PDRN, and PVN, and this decrease was accompanied by decreased melanin content in the skin. The expression of nuclear factor kappa-light-chain enhancer of activated B cells and MMP2/3/9 decreased in response to HQ, PDRN, and PVN in UV-B-radiated skin. However, the expression of collagen type I α1 chain and the amount of collagen fibers that were evaluated by Masson's trichrome staining increased in response to HQ, PDRN, and PVN. The contents of elastin fibers, fibrillin 1/2 and fibulin 5 increased in response to HQ, PDRN, and PVN. In conclusion, PVN delivered via MTS led to decreased melanogenesis and destruction of collagen and elastin fibers by MMPs, and, thus, PVN decreased skin pigmentation and increased skin elasticity.

Chitosan/Alginate Hydrogel Dressing Loaded FGF/VE-Cadherin to Accelerate Full-Thickness Skin Regeneration and More Normal Skin Repairs.

The process of full-thickness skin regeneration is complex and has many parameters involved, which makes it difficult to use a single dressing to meet the various requirements of the complete regeneration at the same time. Therefore, developing hydrogel dressings with multifunction, including tunable rheological properties and aperture, hemostatic, antibacterial and super cytocompatibility, is a desirable candidate in wound healing. In this study, a series of complex hydrogels were developed via the hydrogen bond and covalent bond between chitosan (CS) and alginate (SA). These hydrogels exhibited suitable pore size and tunable rheological properties for cell adhesion. Chitosan endowed hemostatic, antibacterial properties and great cytocompatibility and thus solved two primary problems in the early stage of the wound healing process. Moreover, the sustained cytocompatibility of the hydrogels was further investigated after adding FGF and VE-cadherin via the co-culture of L929 and EC for 12 days. The confocal 3D fluorescent images showed that the cells were spherical and tended to form multicellular spheroids, which distributed in about 40-60 µm thick hydrogels. Furthermore, the hydrogel dressings significantly accelerate defected skin turn to normal skin with proper epithelial thickness and new blood vessels and hair follicles through the histological analysis of in vivo wound healing. The findings mentioned above demonstrated that the CS/SA hydrogels with growth factors have great potential as multifunctional hydrogel dressings for full-thickness skin regeneration incorporated with hemostatic, antibacterial, sustained cytocompatibility for 3D cell culture and normal skin repairing.

Plant-Based Foods for Skin Health: A Narrative Review.

The potential role of plant-based foods in the promotion of skin health is an emerging area of nutrition research. Plant-based foods are rich in bioactive compounds, including vitamin C, vitamin E, beta carotene, polyphenols, and phenolic acids, which can contribute to oxidant defense, lower inflammation, and promote structural support of the skin. Epidemiological studies have associated higher intakes of select fruits and vegetables with positive skin health. Beneficial effects of certain fruits, vegetables, nuts, legumes, and polyphenolic-rich beverages on the skin have been reported, with each of these providing a unique phytochemical composition. Although most studies use extracts, this review will focus on data from whole foods and minimally processed products. Collectively, the evidence to date suggests a promising future for plant-based dietary interventions that promote skin barrier health and function. However, additional research is required to address issues such as the optimal quality and duration of intake as well as potential mechanisms. Studies in the above areas will help formulate specific targeted dietary recommendations.

Dendrimer-Functionalized Metal Oxide Nanoparticle-Mediated Self-Assembled Collagen Scaffold for Skin Regenerative Application: Function of Metal in Metal Oxides.

Functionalized metal oxide nanoparticles cross-linked collagen scaffolds are widely used in skin regenerative applications because of their enhanced physicochemical and biocompatibility properties. From the safety clinical trials point of view, there are no reports that have compared the effects of functionalized metal oxide nanoparticles mediated collagen scaffolds for in vivo skin regenerative applications. In this work, triethoxysilane-poly (amido amine) dendrimer generation 3 (TES-PAMAM-G3 or G3)-functionalized spherical shape metal oxide nanoparticles (MO NPs: ZnO, TiO2, Fe3O4, CeO2, and SiO2, size: 12-25 nm) cross-linked collagen scaffolds were prepared by using a self-assembly method. Triple helical conformation, pore size, mechanical strength, and in vitro cell viability of MO-TES-PAMAM-G3-collagen scaffolds were studied through different methods. The in vivo skin regenerative proficiency of MO-TES-PAMAM-G3-collagen scaffolds was analyzed by implanting the scaffold on wounds in Wistar albino rats. The results demonstrated that MO-TES-PAMAM-G3-collagen scaffold showed superior skin regeneration properties than other scaffolds. The skin regenerative efficiency of MO NPs followed the order ZnO > TiO2 > CeO2 > SiO2 > Fe3O4 NPs. This result can be attributed to higher mechanical strength, cell viability, and better antibacterial activity of ZnO-TES-PAMAM-G3-collagen scaffold that leads to accelerate the skin regenerative properties in comparison to other metal oxide based collagen scaffolds.

PLGA-collagen-BPNS Bifunctional composite mesh for photothermal therapy of melanoma and skin tissue engineering.

The treatment of melanoma requires not only the elimination of skin cancer cells but also skin regeneration to heal defects. To achieve this goal, a bifunctional composite scaffold of poly(DL-lactic-co-glycolic acid) (PLGA), collagen and black phosphorus nanosheets (BPNSs) was prepared by hybridizing a BPNS-embedded collagen sponge with a PLGA knitted mesh. The composite mesh increased the temperature under near-infrared laser irradiation. The incorporation of BPNSs provided the PLGA-collagen-BPNS composite mesh with excellent photothermal properties for the photothermal ablation of melanoma cells both in vitro and in vivo. The PLGA-collagen-BPNS composite mesh had high mechanical strength for easy handling. The PLGA-collagen-BPNS composite mesh facilitated the proliferation of fibroblasts, promoted the expression of angiogenesis-related genes and the genes of components of the extracellular matrix for skin tissue regeneration. The high mechanical strength, photothermal ablation capability and skin tissue regeneration effects demonstrate that the bifunctional PLGA-collagen-BPNS composite mesh is a versatile and effective platform for the treatment of melanoma and the regeneration of skin defects.

Oral intake of a new full-spectrum hyaluronan improves skin profilometry and ageing: a randomized, double-blind, placebo-controlled clinical trial.

BACKGROUND: Skin aging is a physiological condition which leads to structural and functional changes in skin. Common signs of aging are the gradual decrease of hyaluronic acid (HA) in the skin and the appearance of wrinkles. Therefore, effective HA supplementation could counteract HA deficiency and improve skin parameters, providing a safe profile for use which is easily incorporated into daily routine. OBJECTIVES: To evaluate a food supplement containing a wide range of hyaluronans of different molecular weights (full-spectrum hyaluronan [FS-HA]) in order to ameliorate skin conditions in adult females. MATERIALS & METHODS: Sixty subjects showing mild-to-moderate skin aging signs were enrolled in a double-blind, randomized, placebo-controlled clinical trial to receive 200 mg/day of FS-HA (ExceptionHYAL® Star), or placebo, for 28 days. Dermatological parameters were evaluated at T0d and T28d. Product efficacy and tolerance were further evaluated using a self-assessment questionnaire. In addition, HA serum levels were weekly evaluated in a proportion of enrolled subjects. RESULTS: After only 28 days, subjects in the active arm showed a statistically significant improvement in all evaluated dermatological parameters related to skin aging. Skin became more hydrated (+10.6%) and protected from dehydration, with a decrease in both wrinkle depth (-18.8%) and volume (-17.6%) and increase in elasticity and firmness (+5.1%). Instrumental results were further confirmed by self-assessment questionnaire outcomes. CONCLUSION: Administration of a food supplement based on innovative hyaluronans from bio-fermentation, characterized by a wide range of molecular weights, resulted in a quick and significant amelioration of typical signs of skin aging.

Commensal-Related Changes in the Epidermal Barrier Function Lead to Alterations in the Benzo[a]Pyrene Metabolite Profile and Its Distribution in 3D Skin.

Polycyclic aromatic hydrocarbons (PAH) such as benzo[a]pyrene (B[a]P) are among the most abundant environmental pollutants, resulting in continuous exposure of human skin and its microbiota. However, effects of the latter on B[a]P toxicity, absorption, metabolism, and distribution in humans remain unclear. Here, we demonstrate that the skin microbiota does metabolize B[a]P on and in human skin in situ, using a recently developed commensal skin model. In this model, microbial metabolism leads to high concentrations of known microbial B[a]P metabolites on the surface as well as in the epidermal layers. In contrast to what was observed for uncolonized skin, B[a]P and its metabolites were subject to altered rates of skin penetration and diffusion, resulting in up to 58% reduction of metabolites recovered from basal culture medium. The results indicate the reason for this altered behavior to be a microbially induced strengthening of the epidermal barrier. Concomitantly, colonized models showed decreased formation and penetration of the ultimate carcinogen B[a]P-7,8-dihydrodiol-9,10-epoxide (BPDE), leading, in consequence, to fewer BPDE-DNA adducts being formed. Befittingly, transcript and expression levels of key proteins for repairing environmentally induced DNA damage such as xeroderma pigmentosum complementation group C (XPC) were also found to be reduced in the commensal models, as was expression of B[a]P-associated cytochrome P450-dependent monooxygenases (CYPs). The results show that the microbiome can have significant effects on the toxicology of external chemical impacts. The respective effects rely on a complex interplay between microbial and host metabolism and microbe-host interactions, all of which cannot be adequately assessed using single-system studies. IMPORTANCE Exposure to xenobiotics has repeatedly been associated with adverse health effects. While the majority of reported cases relate to direct substance effects, there is increasing evidence that microbiome-dependent metabolism of xenobiotic substances likewise has direct adverse effects on the host. This can be due to microbial biotransformation of compounds, interaction between the microbiota and the host's endogenous detoxification enzymes, or altered xenobiotic bioavailability. However, there are hardly any studies addressing the complex interplay of such interactions in situ and less so in human test systems. Using a recently developed microbially competent three-dimensional (3D) skin model, we show here for the first time how commensal influence on skin physiology and gene transcription paradoxically modulates PAH toxicity.

Dietary Ceramide Prepared from Soy Sauce Lees Improves Skin Barrier Function in Hairless Mice.

Dietary sphingolipids such as glucosylceramide and sphingomyelin are known to improve the skin barrier function of damaged skin. In this study, we focused on free-ceramide prepared from soy sauce lees, which is a byproduct of soy sauce production. The effects of dietary soy sauce lees ceramide on the skin of normal mice were evaluated and compared with those of dietary maize glucosylceramide. We found that transepidermal water loss value was significantly suppressed by dietary supplementation with soy sauce lees ceramide as effectively as or more effectively than maize glucosylceramide. Although the content of total and each subclass of ceramide in the epidermis was not significantly altered by dietary sphingolipids, that of 12 types of ceramide molecules, which were not present in dietary sources, was significantly increased upon ingestion of maize glucosylceramide and showed a tendency to increase with soy sauce lees ceramide intake. In addition, the mRNA expression of ceramide synthase 4 and involucrin in the skin was downregulated by sphingolipids. This study, for the first time, demonstrated that dietary soy sauce lees ceramide enhances skin barrier function in normal hairless mice, although further studies are needed to clarify the molecular mechanism.

Exosomes Derived from Fisetin-Treated Keratinocytes Mediate Hair Growth Promotion.

Enhanced telomerase reverse transcriptase (TERT) levels in dermal keratinocytes can serve as a novel target for hair growth promotion. Previously, we identified fisetin using a system for screening food components that can activate the TERT promoter in HaCaT cells (keratinocytes). In the present study, we aimed to clarify the molecular basis of fisetin-induced hair growth promotion in mice. To this end, the dorsal skin of mice was treated with fisetin, and hair growth was evaluated 12 days after treatment. Histochemical analyses of fisetin-treated skin samples and HaCaT cells were performed to observe the effects of fisetin. The results showed that fisetin activated HaCaT cells by regulating the expression of various genes related to epidermogenesis, cell proliferation, hair follicle regulation, and hair cycle regulation. In addition, fisetin induced the secretion of exosomes from HaCaT cells, which activated ß-catenin and mitochondria in hair follicle stem cells (HFSCs) and induced their proliferation. Moreover, these results revealed the existence of exosomes as the molecular basis of keratinocyte-HFSC interaction and showed that fisetin, along with its effects on keratinocytes, caused exosome secretion, thereby activating HFSCs. This is the first study to show that keratinocyte-derived exosomes can activate HFSCs and consequently induce hair growth.

Nanomaterials in Skin Regeneration and Rejuvenation.

Skin is the external part of the human body; thus, it is exposed to outer stimuli leading to injuries and damage, due to being the tissue mostly affected by wounds and aging that compromise its protective function. The recent extension of the average lifespan raises the interest in products capable of counteracting skin related health conditions. However, the skin barrier is not easy to permeate and could be influenced by different factors. In the last decades an innovative pharmacotherapeutic approach has been possible thanks to the advent of nanomedicine. Nanodevices can represent an appropriate formulation to enhance the passive penetration, modulate drug solubility and increase the thermodynamic activity of drugs. Here, we summarize the recent nanotechnological approaches to maintain and replace skin homeostasis, with particular attention to nanomaterials applications on wound healing, regeneration and rejuvenation of skin tissue. The different nanomaterials as nanofibers, hydrogels, nanosuspensions, and nanoparticles are described and in particular we highlight their main chemical features that are useful in drug delivery and tissue regeneration.

TGF-ß loaded exosome enhances ischemic wound healing in vitro and in vivo.

Rationale: With over seven million infections and $25 billion treatment cost, chronic ischemic wounds are one of the most serious complications in the United States. The controlled release of bioactive factor enriched exosome from finbrin gel was a promising strategy to promote wound healing. Methods: To address this unsolved problem, we developed clinical-grade platelets exosome product (PEP), which was incorporate with injectable surgical fibrin sealant (TISSEEL), to promote chronic wound healing and complete skin regeneration. The PEP characterization stimulated cellular activities and in vivo rabbit ischemic wound healing capacity of TISSEEL-PEP were performed and analyzed. Results: PEP, enriched with transforming growth factor beta (TGF-ß), possessed exosomal characteristics including exosome size, morphology, and typical markers including CD63, CD9, and ALG-2-interacting protein X (Alix). In vitro, PEP significantly promoted cell proliferation, migration, tube formation, as well as skin organoid formation. Topical treatment of ischemic wounds with TISSEEL-PEP promoted full-thickness healing with the reacquisition of hair follicles and sebaceous glands. Superior to untreated and TISSEEL-only treated controls, TISSEEL-PEP drove cutaneous healing associated with collagen synthesis and restoration of dermal architecture. Furthermore, PEP promoted epithelial and vascular cell activity enhancing angiogenesis to restore blood flow and mature skin function. Transcriptome deconvolution of TISSEEL-PEP versus TISSEEL-only treated wounds prioritized regenerative pathways encompassing neovascularization, matrix remodeling and tissue growth. Conclusion: This room-temperature stable, lyophilized exosome product is thus capable of delivering a bioactive transforming growth factor beta to drive regenerative events.

Comparative Morphological Study of the Formation of Reparative Regenerate during Skin Wound Healing in Rats under the Effect of Drugs and Bone Marrow.

We studied the formation of the reparative regenerate of the skin wound in rats under the effect of drug products based on keratan and secretome of bone marrow mesenchymal stem cells (MSC), as well as bone marrow cells (native and exposed to laser radiation with a wavelength of 1.56 µm). Due to the biological affinity for the dermal tissue, keratan preparations being applied to the skin stimulate regeneration of the wound defect. This substance in the form of a gel is characterized by high diffusion capacity, penetrates into the deeper layers of the dermis, and promotes the growth of the granulation tissue. Application of an ointment prepared on the basis of MSC secretome promotes quick transition of the healing process from the inflammatory to the regenerative stage. Thus, bone marrow cells were successfully used for skin wound healing. The results of the use of bone marrow cells for the healing of skin wounds were successful; bone marrow exposed to laser radiation demonstrated high efficiency in promoting reparative processes.

A Predictive Self-Organizing Multicellular Computational Model of Infant Skin Permeability to Topically Applied Substances.

Computational models of skin permeability are typically based on assumptions of fixed geometry and homogeneity of the whole epidermis or of epidermal strata and are often limited to adult skin. Infant skin differs quantitatively from that of the adult in its structure and its functional properties, including its barrier function to permeation. To address this problem, we developed a self-organizing multicellular epidermis model of barrier formation with realistic cell morphology. By modulating the parameters relating to cell turnover reflecting those in adult or infant epidermis, we were able to generate accordingly two distinct models. Emerging properties of these models reflect the corresponding experimentally measured values of epidermal and stratum corneum thickness. Diffusion of an externally applied substance (e.g., caffeine) was simulated by a molecular exchange between the model agents, defined by the individual cells and their surrounding extracellular space. By adjusting the surface concentration and the intercellular exchange rate, the model can recapitulate experimental permeability data after topical exposure. By applying these parameters to an infant model, we were able to predict the caffeine concentration profile in infant skin, closely matching experimental results. This work paves the way for a better understanding of skin physiology and function during the first years of life.

Functional Dissection of CD26 and Its Pharmacological Inhibition by Sitagliptin During Skin Wound Healing.

BACKGROUND Skin fibroblasts are primary mediators underlying wound healing and therapeutic targets in scar prevention and treatment. CD26 is a molecular marker to distinguish fibroblast subpopulations and plays an important role in modulating the biological behaviors of dermal fibroblasts and influencing skin wound repair. Therapeutic targeting of specific fibroblast subsets is expected to reduce skin scar formation more efficiently. MATERIAL AND METHODS Skin burn and excisional wound healing models were surgically established in mice. The expression patterns of CD26 during wound healing were determined by immunohistochemical staining, real-time RT-PCR, and western blot assays. Normal fibroblasts from intact skin (NFs) and fibroblasts in wounds (WFs) were isolated and sorted by fluorescence-activated cell sorting (FACS) into 4 subgroups - CD26⁺ NFs, CD26⁻ NFs, CD26⁺ WFs, and CD26⁻ WFs - for comparisons of their capacities of proliferation, migration, and collagen synthesis. Pharmacological inhibition of CD26 by sitagliptin in skin fibroblasts and during wound healing were further assessed both in vitro and in vivo. RESULTS Increased CD26 expression was observed during skin wound healing in both models. The CD26⁺ fibroblasts isolated from wounds had significantly stronger abilities to proliferate, migrate, and synthesize collagen than other fibroblast subsets. Sitagliptin treatment potently diminished CD26 expression, impaired the proliferation, migration, and collagen synthesis of fibroblasts in vitro, and diminished scar formation in vivo. CONCLUSIONS Our data reveal that CD26 is functionally involved in skin wound healing by regulating cell proliferation, migration, and collagen synthesis in fibroblasts. Pharmacological inhibition of CD26 by sitagliptin might be a viable strategy to reduce skin scar formation.

Ex Vivo Live Full-Thickness Porcine Skin Model as a Versatile In Vitro Testing Method for Skin Barrier Research.

Since the European Union (EU) announced their animal testing ban in 2013, all animal experiments related to cosmetics have been prohibited, creating a demand for alternatives to animal experiments for skin studies. Here, we investigated whether an ex vivo live porcine skin model can be employed to study the safety and skin barrier-improving effects of hydroxyacids widely used in cosmetics for keratolytic peels. Glycolic acid (1-10%), salicylic acid (0.2-2%), and lactobionic acid (1.2-12%) were used as representative substances for α-hydroxyacid (AHA), ß-hydroxyacid (BHA), and polyhydroxyacid (PHA), respectively. When hydroxyacids were applied at high concentrations on the porcine skin every other day for 6 days, tissue viability was reduced to 50-80%, suggesting that the toxicity of cosmetic ingredients can be evaluated with this model. Based on tissue viability, the treatment scheme was changed to a single exposure for 20 min. The protective effects of a single exposure of hydroxyacids on skin barrier function were evaluated by examining rhodamine permeability and epidermal structural components of barrier function using immunohistochemistry (IHC) and immunofluorescence (IF) staining. Lactobionic acid (PHAs) improved skin barrier function most compared to other AHAs and BHAs. Most importantly, trans-epidermal water loss (TEWL), an important functional marker of skin barrier function, could be measured with this model, which confirmed the significant skin barrier-protective effects of PHAs. Collectively, we demonstrated that the ex vivo live full-thickness porcine skin model can be an excellent alternative to animal experiments for skin studies on the safety and efficacy of cosmetic ingredients.

Skin wound healing assisted by angiogenic targeted tissue engineering: A comprehensive review of bioengineered approaches.

Skin injuries and in particular, chronic wounds, are one of the major prevalent medical problems, worldwide. Due to the pivotal role of angiogenesis in tissue regeneration, impaired angiogenesis can cause several complications during the wound healing process and skin regeneration. Therefore, induction or promotion of angiogenesis can be considered as a promising approach to accelerate wound healing. This article presents a comprehensive overview of current and emerging angiogenesis induction methods applied in several studies for skin regeneration, which are classified into the cell, growth factor, scaffold, and biological/chemical compound-based strategies. In addition, the advantages and disadvantages of these angiogenic strategies along with related research examples are discussed in order to demonstrate their potential in the treatment of wounds.

Topical application with conjugated linoleic acid ameliorates 2, 4-dinitrofluorobenzene-induced atopic dermatitis-like lesions in BALB/c mice.

Atopic dermatitis (AD) is a multifactorial chronic inflammatory skin disease characterized by skin barrier dysfunction, eczematous lesions, pruritus, and abnormal immune responses. In this study, we assessed the therapeutic effect of topical applied conjugated linoleic acid (CLA) on a murine AD model that was developed by repetitive applications of 2, 4-dinitrofluorobenzene (DNFB). 2% or 5% CLA could markedly ameliorate AD-like skin lesions, scratching behaviour and skin inflammation as evidenced by the reduced inflammatory blood cells, IgE and Th2-related cytokine levels, and the infiltration of mast cells and inflammatory cells to the dermal tissues. Moreover, topical application with CLA modulated skin barrier repair including maintaining a balanced skin pH and increasing skin hydration, partially mediated by upregulating skin barrier-related protein, filaggrin (FLG). In addition, topical CLA significantly dose-dependently inhibited pro-inflammatory cytokines including interleukin (IL)-6, IL-1ß, tumour necrosis factor (TNF)-α and pro-inflammatory enzyme expressions of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in inflamed mice skin. Its anti-inflammatory effect was associated with the inhibition of DNFB-stimulated IκBα and NF-κB p65 phosphorylation in mouse skin. Taken together, our results suggest that locally applied CLA exerts potentially protective effects against AD lesional skin at least in part, due to regulation of skin barrier function and inflammatory response.