Human Skin Cells Research Articles

Cutaneous T cell lymphoma atlas reveals malignant TH2 cells supported by a B cell-rich tumor microenvironment

AbstractCutaneous T cell lymphoma (CTCL) is a potentially fatal clonal malignancy of T cells primarily affecting the skin. The most common form of CTCL, mycosis fungoides, can be difficult to diagnose, resulting in treatment delay. We performed single-cell and spatial transcriptomics analysis of skin from patients with mycosis fungoides-type CTCL and an integrated comparative analysis with human skin cell atlas datasets from healthy and inflamed skin. We revealed the co-optation of T helper 2 (TH2) cell-immune gene programs by malignant CTCL cells and modeling of the tumor microenvironment to support their survival. We identified MHC-II+ fibroblasts and dendritic cells that can maintain TH2 cell-like tumor cells. CTCL tumor cells are spatially associated with B cells, forming tertiary lymphoid structure-like aggregates. Finally, we validated the enrichment of B cells in CTCL and its association with disease progression across three independent patient cohorts. Our findings provide diagnostic aids, potential biomarkers for disease staging and therapeutic strategies for CTCL.

Antioxidant Effect of a Plant-Derived Extracellular Vesicles’ Mix on Human Skin Fibroblasts: Induction of a Reparative Process

Plant-Derived Extracellular Vesicles extracellular vesicles (PDEVs) from organic agriculture (without the use of pesticides and microbicides) contain high levels of antioxidants. Organic PDEVs have shown an increased antioxidant power compared to PDEVs from single plants, suggesting a synergistic effect of the bioactives constitutively expressed in the PDEVs from single fruits. With this study, we wanted to investigate the beneficial effects of a mix of PDEVs on human skin cells. We found detectable levels of citric acid, ascorbic acid, glutathione, catalase, and SOD in a mix of PDEVs deriving from five different fruits (grape, red orange, papaya, pomegranate, and tangerine). We then treated H2O2-conditioned fibroblasts with the mix of PDEVs. The results showed that the PDEVs’ mixture reverted the H2O2-induced redox imbalance, restoring mitochondrial homeostasis, with a strong reduction of mitochondrial anion superoxide and an increase in sirtuin levels. The antioxidant action was consistent with wound repair on a lesion produced in a fibroblast’s monolayer. This result was consistent with an increased level of vimentin and matrix metalloproteinase-9, whose expression is directly related to the efficiency of the reparative processes. These data support a beneficial role of PDEVs in both preventing and treating skin injuries through their potent antioxidant and reparative activities.

Microemulsion containing Kaffir lime oil using photo-crosslinkable bio-based copolymer

The research aimed to prepare a microemulsion of Kaffir lime oil (KLO) using photocrosslinkable bio-based copolymers as polymer shells. First, cinnamyl alcohol was used as a biomonomer, which was functionalized with methacrylic anhydride via an esterification reaction to contain a double bond named cinnamyl methacrylate. Then, it was copolymerized with methacrylic acid by solution iodine transfer polymerization, resulting in polymethacrylic acid-block-polycinnamyl methacrylate-block-poly methacrylic acid (PMAA-b-PCMA-b-PMAA) with a molecular weight of 2700 g/mol and a chain length of PMAA-b-PCMA-b-PMAA equals 7: 6: 7 units. After that, PMAA-b-PCMA-b-PMAA (BioSurf) was used as the polymer shell to encapsulate KLO in a microemulsion system cooperative with Tween 80 (surfactant; Surf) and ethanol (co-surfactant; CoSurf). The ratio of kaffir lime oil: Surf-CoSurf was varied from 1: 9 to 9: 1 (wt) where Surfmix was BioSurf: Surf: Co-Surf ratio of 1: 1: 1 (wt) dispersed in water at 400 rpm for 5 min. The optimal contents of oil, Surfmix, and water were 6 %, 24 %, and 70 %, respectively, with the nanocapsule size at about 68 nm. After UV curing at 254 nm for 120 min, the dimerization of cinnamyl groups in PCMA was confirmed by UV spectroscopy, where the absorbance peaks of cinnamyl groups at 283 and 294 nm significantly decreased. The encapsulated KLO was slowly permeating skin which was only 10 % after 1 h, with the anti-inflammatory percentage of inhibited nitric oxide production in macrophage cells at 19.24 ± 1.63. Moreover, nanocapsules did not show toxicity to human skin cells at concentrations less than or equal to 1 v/v%. Moreover, the microemulsion is thermodynamically stable at 4 °C, 30 °C, and 45 °C. The encapsulation of KLO in microemulsion might be an alternative candidate for cosmetic products and related applications.

Evaluation of the Cytotoxicity Effects of Bacteriophage VbɸPA-1 on the Virulent Pseudomonas aeruginosa, A375 Human Skin Melanoma Epithelial, and HFSF PI3 Human Skin Fibroblast Cells

Background: Gram-negative bacteria are the most common infectious bacteria and are life-threatening in burn patients. Phage therapy studies can help the hospital community eliminate these bacterial pathogens. Objectives: This study aimed to evaluate the effects of the isolated bacteriophages from hospital wastewater against Gram-negative pathogenic bacteria and investigate their cytotoxicity on two human skin cell lines. Methods: The bacterial strains were isolated from burn wound infections. Bacteriophages were isolated from the hospital wastewater treatment plant in Isfahan, Iran. Transmission electron microscopy, spot tests, and restriction enzyme digestion were considered for phage identification. Finally, the lactate dehydrogenase (LDH) and tetrazolium-based MTT assays were used to realize the cytotoxicity impacts of the isolated phages. The statistical analysis of cell viability was performed using a two-way analysis of variance (ANOVA). Results: The results showed that among the isolated strains, P. aeruginosa strain NEG_RA1300 (GenBank accession number: MW845642) was sensitive to the isolated phage VbɸPA-1. The TEM results showed a possible viral taxonomy of VbɸPA-1 based on its morphology, which belonged to the Myoviridae (T4-like phages). The MTT and LDH experiments showed no cytotoxicity of VbɸPA-1 on two tested cell lines. Conclusions: Based on the results, the inhibitory effect of isolated phage on P. aeruginosa isolated from burn wounds with no toxic effect on cell lines was very significant. This phage can also be an acceptable selection against burn wound infections.

P2RY6 deletion promotes UVB-induced skin carcinogenesis by activating the PI3K/AKT signal pathway.

Our previous research has demonstrated that P2RY6 functions as an oncogene in DMBA/TPA-induced two-stage chemical skin carcinogenesis in mice. However, considering that human skin cancer is predominantly attributed to UV radiation from sunlight, additional investigations are needed to elucidate the role of P2RY6 in UVB-induced skin carcinogenesis. Surprisingly, we found that P2ry6-deficient mice exhibited marked promotion to UVB-induced skin papilloma formation compared with wild-type mice, suggesting its tumor-suppressive role in UVB-induced skin cancer. Additionally, a P2ry6 gene knockout promoted skin hyperplasia induced by short-term UVB irradiation, while UDP, the ligand of P2RY6, could inhibit the short-term UVB-induced increase of epiderma thickness in mouse skin. Furthermore, UVB irradiation could significantly upregulate P2RY6 expression in human and mouse skin cells. These results indicated that P2RY6 may play a crucial protective role in resisting the UVB-induced formation of skin tumors. At the molecular level, the loss of the P2RY6 gene inhibits the ubiquitination modification and expression of XPC after UVB irradiation in skin keratinocytes, resulting in the accumulation of CPDs (cyclobutane pyrimidine dimers). We have also demonstrated that P2RY6 deletion activates the PI3K/AKT signaling pathway both invitro and invivo. The CPD accumulation and acute inflammatory response enhanced by the loss of the P2RY6 gene can be reversed by an AKT inhibitor. These findings suggest that P2RY6 may act as a tumor suppressor in UVB-induced skin cancer by regulating the PI3K/AKT signaling pathway.

On-demand imidazolidinyl urea-based tissue-like, self-healable, and antibacterial hydrogels for infectious wound care

Bacterial wound infections are a growing challenge in healthcare, posing severe risks like systemic infection, organ failure, and sepsis, with projections predicting over 10 million deaths annually by 2050. Antibacterial hydrogels, with adaptable extracellular matrix-like features, are emerging as promising solutions for treating infectious wounds. However, the antibacterial properties of most of these hydrogels are largely attributed to extrinsic agents, and their mechanisms of action remain poorly understood. Herein we introduce for the first time, modified imidazolidinyl urea (IU) as the polymeric backbone for developing tissue-like antibacterial hydrogels. As-designed hydrogels behave tissue-like mechanical features, outstanding antifreeze behavior, and rapid self-healing capabilities. Molecular dynamics (MD) simulation and density functional theory (DFT) calculation were employed to well-understand the extent of H-bonding and metal-ligand coordination to finetune hydrogels’ properties. In vitro studies suggest good biocompatibility of hydrogels against mouse fibroblasts & human skin, lung, and red blood cells, with potential wound healing capacity. Additionally, the hydrogels exhibit good 3D printability and remarkable antibacterial activity, attributed to concentration dependent ROS generation, oxidative stress induction, and subsequent disruption of bacterial membrane. On top of that, in vitro biofilm studies confirmed that developed hydrogels are effective in preventing biofilm formation. Therefore, these tissue-mimetic hydrogels present a promising and effective platform for accelerating wound healing while simultaneously controlling bacterial infections, offering hope for the future of wound care.

The Anti-proliferative Effect, Apoptotic Induction, and Cell Cycle Arrest of Tetra Halo Ruthenate Nanocomposites in Different Human Cancer Cell Lines.

Chemotherapy is the most common cancer treatment, and metallic anticancer compounds have generated increasing amounts of interest since the discovery of cisplatin. More recently, scientists have focused on ruthenium-based compounds as alternatives for platinum compounds, which seem like ideal therapeutic anticancer alternatives to platinum derivatives. The present study aims to assess whether one or more of three Ruthenium-based nanocomposites, namely Ru+Lysine+CTAB (RCTL), Ru+CTAB (RCT), and Ru+Lysine (RL) exhibit pronounced anti-proliferative properties against different cancer cells. Three Ruthenium nanocomposites have been synthesized by standard chemical methods and characterized by Dynamic light scattering (DLS) and Transmission electron microscopy (TEM). The cytotoxic effect of the three composites has been evaluated by MTT in-vitro assay for different human cancer cell lines, namely MCF7, HepG2, A549, and PC3 versus normal human skin cell line (BJ1). The molecular underlying mechanisms of cytotoxicity have been assessed via qRT-PCR for pro-apoptotic makers P53 and Casp-3, and anti-apoptotic marker Bcl-2 as well as flow cytometric analysis of the cell cycle. Among the 3 nanocomposites, RCTL gave the best sensitivity and cytotoxicity especially on HepG2 with IC50 0.55 µg/ml but was still toxic on normal cell line with dose <12.5 µg/ml. RCTL and RCT nanocomposites have demonstrated a significant increase in the expression of P53 and Casp-3 markers versus untreated controls, but a significant reduction in the expression of Bcl-2. There was a direct correlation between the cytotoxic effect and the degree of apoptosis in the different cancer cell lines. The present study has also proved cell cycle arrest at G2-M and pre-G1 phases under the effect of IC50 of RCTL and RCT nanocomposites in different cancer lines with the best effect being achieved in HepG2 cells. Ruthenium nanocomposites seem to open a new avenue in cancer therapy.

Capparis sepiaria-Loaded Sodium Alginate Single- and Double-Layer Membrane Composites for Wound Healing.

Background: Effective wound dressing is the key solution to combating the increased death rate and prolonged hospital stay common to patients with wounds. Methods: Sodium alginate-based single- and double-layer membranes incorporated with Capparis sepiaria root extract were designed using the solvent-casting method from a combination of polyvinyl alcohol (PVA), Pluronic F127 (PF127), and gum acacia. Results: The successful preparation of the membranes and loading of the extract were confirmed using Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The prepared membranes were biodegradable and non-toxic to human skin cells (HaCaT), with high biocompatibility of 92 to 112% cell viability and good hemocompatibility with absorbance ranging from 0.17 to 0.30. The membrane's highest water vapor transmission rate was 1654.7333 ± 0.736 g/m2/day and the highest % porosity was 76%. The membranes supported cellular adhesion and migration, with the highest closure being 68% after 4 days compared with the commercial wound dressings. This membrane exhibited enhanced antimicrobial activity against the pathogens responsible for wound infections. Conclusions: The distinct features of the membranes make them promising wound dressings for treating infected wounds.

Atomic scale investigation and cytocompatibility of copper and zinc-loaded phosphate-based glasses prepared by coacervation

Phosphate-based glasses (PBGs) are bioresorbable materials that find application in the field of controlled drug delivery and tissue engineering. The structural arrangements of the phosphate units in PBGs, along with the knowledge of how therapeutic metallic ions are embedded in the phosphate network are important in understanding the degradation and targeted release properties of these materials. Using a combination of Raman spectroscopy, high-energy X-ray diffraction and 31P and 23Na solid-state magic angle spinning nuclear magnetic resonance, the atomic structure of coacervate PBGs in the system P2O5-CaO-Na2O-MOx (M = Cu or Zn) with loadings of 2, 10 and 15 mol % of M2+ have been studied as functions of composition and calcination temperature. After drying at room temperature, the structures of the phosphate network in PBG-Cu and PBG-Zn are quite similar, with that of PBG-Zn exhibiting slightly higher connectivity. Heating at 300 °C causes degradation of the polyphosphate chains, even though Q2 species remain predominant. X-ray photoelectron spectroscopy demonstrates that Cu in calcined PBGs is present in both oxidation states +1 and +2, with a predominance of the +2 state. Cu and Zn ion release data after 24 h exposure of PBGs in deionized water and cell medium DMEM show that release is proportional to their loadings. Cytotoxicity MTT assays of dissolution products of PBG-Cu/ZnX calcined at 300 °C on human osteosarcoma cells (MG-63) and on human skin cells (HaCaTs) showed good cellular response for all compositions, indicating that PBGs have great potential for both hard and soft tissue regeneration.

Heavy Metals and Cosmetics Industry: A Review Article

Trace amounts of heavy metals are present during cosmetic products manufacturing. (1) Therefore, they should be kept to a minimum acceptable level as stated by the FDA and pharmacopeias. (2) It is so far known that human external contact with these substances rarely result in a significant systemic exposure. However, many research studies showed that frequent local exposure to cosmetic products containing heavy metals may pose a risk of heavy metal contamination. (1,2) Heavy metals such as mercury (Hg) are added to skin-whitening products, causing acute or chronic damage to human skin cells. (1) Moreover, contamination of hair dyes and deodorants with Aluminum (Al) and Lead (Pb) threaten consumers' health dangerously for carcinogenic effects. Other possible side effects included microcytic anemia and osteomalacia. (3) Additionally, it was found that Al provokes further side effects on human mental health as dialysis dementia and it has also been associated with the neurodegenerative disease, Alzheimer's disease (AD) in adults. (4) Furthermore, Pb is a core component of many lipsticks, which reflects a high systemic absorption due to wrong consumers' habits. Frequent use of lipsticks containing Pb specially by children and adolescents has been significantly linked to neurodevelopmental disorders such as autism and attention-deficit-hyperactivity-disorder (ADHD) symptoms in children. (5) Therefore, strict regulations should be set for cosmetics manufacturing and quality control measurements should be assigned for pre- and post-marketed cosmetic products.

Preparation of fragmented polyethylene nanoplastics using a focused ultrasonic system and assessment of their cytotoxic effects on human cells

With the growing prevalence of plastic use, the environmental release of plastic waste is escalating, and fragmented nanoscale plastic particles are emerging as significant environmental threats. This study aimed to evaluate the cytotoxic effects of fragmented polyethylene nanoplastics (PE NPs) manufactured using a focused ultrasonic system. The ultrasonic irradiation process generated fragmented PE NPs with a geometric mean diameter of 85.14 ± 5.37 nm and a size range of 25–350 nm. To assess cytotoxicity, we conducted a series of tests on various human cell lines, including stomach, blood, colon, lung, skin, liver, and brain-derived cells. The testing involved MTS-based cell viability assays to evaluate direct impacts on cell viability, lactate dehydrogenase (LDH) leakage assays to measure membrane damage, and ELISA to quantify TNF-α release as an indicator of inflammation. Although PE-NPs did not immediately induce apoptosis, significant LDH leakage and elevated TNF-α levels were observed across all cell lines, indicating membrane damage and inflammatory responses. Additionally, flow cytometry and TEM analyses revealed the intracellular accumulation of PE-NPs, further supporting their cytotoxic potential. These results demonstrate that fragmented PE-NPs can disrupt cellular membranes and induce inflammatory responses through accumulation within cells. The findings suggest that these NPs pose potential hazards to cell viability and underscore the need for further research into their environmental and health impacts.

Effects of Plant Meristem-Cell-Based Cosmetics on Menopausal Skin: Clinical Data and Mechanisms.

A randomised open clinical/laboratory study was performed to evaluate the safety and cosmetic efficacy of facial cosmetics for females during the menopausal period. The cosmetics contain active ingredients of meristem cells derived from the medicinal plants Leontopodium alpinum, Buddeleja davidii, Centella asiatica, and Echinacea angustifolia. Recently, the major bioactive molecules of these medicinal plants (leontopodic acid, verbascoside, asiaticoside, and echinacoside, respectively) have been thoroughly evaluated in vitro for molecular pathways and cellular mechanisms and their preventive/curative effects on human skin cells exposed to factors promoting premature skin ageing and cellular senescence. Nevertheless, clinical data on their safety/efficacy to ageing human skin are scarce. This clinical study enrolled 104 Caucasian females in pre-menopause, menopause, or post-menopause periods. They applied cosmetic serums daily for 1 month. Questionnaires and instrumental and biochemical methods were used to assess dermatological/ophthalmological safety and cosmetic efficacy through changes of the skin physiology markers characteristic of ageing/menopause (elasticity, barrier functions, moisture, sebum, ultrasonic properties, and collagen content and structure). Quantitative microbiological tests were carried out for skin microbiota fluctuations. Data showed that the cosmetics were safe, and they shifted the skin physiology parameters to a younger biological age, enhanced collagen synthesis, inhibited lipid peroxidation, and favoured normal microbiota.

High-yield, plant-based production of an antimicrobial peptide with potent activity in a mouse model.

Plants offer a promising chassis for the large-scale, cost-effective production of diverse therapeutics, including antimicrobial peptides (AMPs). However, key advances will reduce production costs, including simplifying the downstream processing and purification steps. Here, using Nicotiana benthamiana plants, we present an improved modular design that enables AMPs to be secreted via the endomembrane system and sequestered in an extracellular compartment, the apoplast. Additionally, we translationally fused an AMP to a mutated small ubiquitin-like modifier sequence, thereby enhancing peptide yield and solubilizing the peptide with minimal aggregation and reduced occurrence of necrotic lesions in the plant. This strategy resulted in substantial peptide accumulation, reaching around 2.9 mg AMP per 20 g fresh weight of leaf tissue. Furthermore, the purified AMP demonstrated low collateral toxicity in primary human skin cells, killed pathogenic bacteria by permeabilizing the membrane and exhibited anti-infective efficacy in a preclinical mouse (Mus musculus) model system, reducing bacterial loads by up to three orders of magnitude. A base-case techno-economic analysis demonstrated the economic advantages and scalability of our plant-based platform. We envision that our work can establish plants as efficient bioreactors for producing preclinical-grade AMPs at a commercial scale, with the potential for clinical applications.

Identification of a new human senescent skin cell marker ribonucleoside-diphosphate reductase subunit M2 B.

In skin aging, it has been hypothesized that aging fibroblasts accumulate within the epidermal basal layer, dermis, and subcutaneous fat, causing abnormal tissue remodeling and extracellular matrix dysfunction, thereby inducing an aging-related secretory phenotype (SASP). A new treatment for skin aging involves the specific elimination of senescent skin cells, especially fibroblasts within the dermis and keratinocytes in the basal layer. This requires the identification of specific protein markers of senescent cells, such as ribonucleoside-diphosphate reductase subunit M2 B (RRM2B), which is upregulated in various malignancies in response to DNA stress damage. However, the behavior and role of RRM2B in skin aging remain unclear. Therefore, we examined whether RRM2B functions as a senescence marker using a human dermal fibroblast model of aging. In a model of cellular senescence induced by replicative aging and exposure to ionizing radiation or UVB, RRM2B was upregulated at the gene and protein levels. This was correlated with decreased uptake of the senescence-associated β-galactosidase activity and proliferation marker bromodeoxyuridine. RRM2B upregulation was concurrent with the increased expression of SASP factor genes. Furthermore, using fluorescence flow cytometry, RRM2B-positive cells were recovered more frequently in the aging cell population. In aging human skin, RRM2B was also found to be more abundant in the dermis and epidermal basal layer than other proteins. Therefore, RRM2B may serve as a clinical marker to identify senescent skin cells.

The Impact of Temperature and the Duration of Freezing on a Hydrogel Used for a 3D-Bioprinted In Vitro Skin Model.

Skin bioprinting has the potential to revolutionize treatment approaches for injuries and surgical procedures, while also providing a valuable platform for assessing and screening cosmetic and pharmaceutical products. This technology offers key advantages, including flexibility and reproducibility, which enable the creation of complex, multilayered scaffolds that closely mimic the intricate microenvironment of native skin tissue. The development of an ideal hydrogel is critical for the successful bioprinting of these scaffolds with incorporated cells. In this study, we used a hydrogel formulation developed in our laboratory to fabricate a 3D-bioprinted skin model. The hydrogel composition was carefully selected based on its high compatibility with human skin cells, incorporating alginate, methyl cellulose, and nanofibrillated cellulose. One of the critical challenges in this process, particularly for its commercialization and large-scale production, is ensuring consistency with minimal batch-to-batch variations. To address this, we explored methods with which to preserve the physicochemical properties of the hydrogels, with a focus on freezing techniques. We validated the pre-frozen hydrogels' printability, rheology, and mechanical and surface properties. Our results revealed that extended freezing times significantly reduced the viscosity of the formulations due to ice crystal formation, leading to a redistribution of the polymer chains. This reduction in viscosity resulted in a more challenging extrusion and increased macro- and microporosity of the hydrogels, as confirmed by nanoCT imaging. The increased porosity led to greater water uptake, swelling, compromised scaffold integrity, and altered degradation kinetics. The insights gained from this study lay a solid foundation for advancing the development of an in vitro skin model with promising applications in preclinical and clinical research.

Development of a highly effective recombinant protein from human collagen type III Alpha 1 (COL3A1) to enhance human skin cell functionality

Development of a highly effective recombinant protein from human collagen type III Alpha 1 (COL3A1) to enhance human skin cell functionality

P26-01 Hexagonal boron nitride (hBN) and hBN-reinforced thermoplastic polyurethane composite: an in vitro hazard characterization using human skin and lung cells

P26-01 Hexagonal boron nitride (hBN) and hBN-reinforced thermoplastic polyurethane composite: an in vitro hazard characterization using human skin and lung cells

Investigation of genotoxicity induced by intermediate frequency magnetic field combined with ionizing radiation: In vitro study on human fibroblast cells

These days, exposure to electromagnetic fields has become omnipresent in modern society. Not only the extremely-low frequency and radiofrequency, but also intermediate frequency (IF) magnetic field (MF) might be absorbed in the human body resulting in an ever-growing concern about their possible health effects. Devices, such as induction cooktops, chargers, compact fluorescent lamps, touchscreens and electric vehicles emit a wide range of intermediate frequency fields. We investigated the effects of 22 kHz or 250 kHz intermediate frequency magnetic field exposure on the human skin cells. We also examined the adaptive response phenomenon; whether IF MF exposure could possibly reduce the harmful genotoxic effects of ionizing radiation. To get answers to these questions, in vitro studies were carried out on fibroblast cells to investigate the effects on oxidative stress, DNA damage and micronucleus formation. We found a decreased micronucleus formation due to the 22 kHz IF MF exposure and significantly increased oxidative stress in fibroblast cells, which were exposed only to 250 kHz IF MF. We were unable to detect the protective or co-genotoxic effects of intermediate frequency magnetic field exposure combined with ionizing radiation, thus we found no evidence for the adaptive response phenomena.

Temperature Is a Key Factor Governing the Toxic Impact of Ultra-Violet Radiation-Emitting Nail Dryers When Used on Human Skin Cells.

The skin is the largest organ in the body and the only one to come into contact with solar UV radiation (UVR). UVA (320-400nm) is a significant contributor to UV-related skin damage. The UVA spectrum makes up over 95% of solar-UV energy reaching the earth's surface causing the majority of the visible signs of skin photoaging. Many consumer products also emit UVA, including nail dryers. There have been sporadic reports suggesting that these units may be contributing to skin cancer incidence. This notion was recently bolstered by a finding that nail dryer-irradiated mammalian skin cells develop a mutational signature consistent with UVA exposure. This report was surprising considering the comparatively low level of UVA to which the skin is exposed during nail treatments. In this research, we investigated how UVA-emitting devices caused cytotoxic/genotoxic impact after only low levels of UVA exposure. Our data showed that levels of UVA in the unit are highly variable and location dependent. We confirm previous reports that using prolonged exposure protocols could induce significant levels of DNA damage. It was also determined that UV-induced DNA damage only partially correlated with the level of UVA fluency. On investigation, we found that the unit had a rapid increase in internal temperature when in use. Exposing human cells to these elevated temperatures acted synergistically with UVA to magnify the cytotoxic and genotoxic impact of UV irradiation.

Role of mesenchymal stem cell conditioned medium on wound healing using a developed 3D skin model.

Alternative 3-dimensional (3D) skin models that replicate in vivo human skin are required to investigate important events during wound healing, such as collective cell migration, epidermal layer formation, dermal substrate formation, re-epithelialisation and collagen production. In this study, a matched human 3D skin equivalent model (3D-SEM) was developed from human skin cells (fibroblast and keratinocytes), characterised using haematoxylin and eosin, immunofluorescence staining and microRNA profiling. The 3D-SEM was then functionally tested for its use in wound healing studies. Mesenchymal stem cells (MSCs) were isolated and characterised according to the criteria stipulated by the International Society for Cell Therapy. Cytokine and growth factor secretions were analysed by enzyme-linked immunosorbent assay. MSC-conditioned medium (MSC-CM) was then tested for wound healing capacity using the developed 3D-SEM at different timepoints i.e., at one, two and four weeks. The constructed 3D-SEM showed consistent development of skin-like structures composed of dermal layers and epidermal layers, with the ability to express epidermal differentiation markers and full stratification. They also showed prolonged longevity in culture media, retaining full differentiation and stratification within the four weeks. MicroRNA profiling revealed a strong correlation in microRNA expression between the developed 3D-SEM and the original native skin (p<0.001; R=0.64). Additionally, MSC-CM significantly enhanced migration, proliferation and differentiation of epidermal cells in the wounded models compared to control models at the different timepoints. In conclusion, in this study, the developed 3D-SEM mimicked native skin at the cellular and molecular levels, and clearly showed the important stages of skin regeneration during the healing process. MSC secretome contains growth factors that play a pivotal role in the healing process and could be used as a therapeutic option to accelerate skin healing.