SkinEthic™ RHE for in vitro evaluation of skin irritation of medical device extracts

The "Big Three" in biocompatibility testing of medical devices: implementation of alternatives to animal experimentation-are we there yet?

Biocompatibility testing ensures the safety of medical devices by assessing their compatibility with biological systems and their potential to cause harm or adverse reactions. Thus, it is a critical part of the overall safety evaluation process for medical devices. Three primary types of biocompatibility tests-cytotoxicity, irritation, and sensitisation assessment-are standard for nearly all medical devices. However, additional biocompatibility tests, such as genotoxicity, systemic toxicity, hemocompatibility, and implantation studies, may also be necessary, depending on the device's nature and intended use. The testing is partly conducted in vitro, but the industry still heavily relies on animal experiments. Compared to other industrial sectors, implementing alternatives in medical device biocompatibility testing has been notably slower. This delay can be attributed to the absence of specific validation processes tailored to medical devices and the resulting hesitation regarding the predictive capacity of these alternative methods despite their successful applications in other domains. This review focuses on the progress and obstacles to implementing new approach methodologies in the areas of cytotoxicity, irritation and sensitisation testing of medical devices. While challenges persist in adopting these innovative methods, the trend towards embracing alternatives remains robust. This trend is driven by technological advancements, ethical considerations, and growing industrial interest and support, all collectively contributing to advancing safer and more effective medical devices.

In vitro assessment of inflammatory skin potential of poly(methyl methacrylate) at non-cytotoxic concentrations

Poly(methyl methacrylate) (PMMA) is considered an attractive substrate material for fabricating wearable skin sensors such as fitness bands and microfluidic devices. Despite its widespread use, inflammatory and allergic responses have been attributed to the use of this material. Therefore, the main objective of this study was to obtain a comprehensive understanding of potential biological effects triggered by PMMA at non-cytotoxic concentrations using in vitro models of NIH3T3 fibroblasts and reconstructed human epidermis (RhE). It was hypothesized that concentrations that do not reduce cell viability are sufficient to activate pathways of inflammatory processes in the skin. The study included cytotoxicity, cell metabolism, cytokine quantification, histopathological, and gene expression analyses. The NIH3T3 cell line was used as a testbed for screening cell toxicity levels associated with the concentration of PMMA with different molecular weights (MWs) (i.e., MW ~5,000 and ~15,000 g/mol). The lower MW of PMMA had a half-maximal inhibitory concentration (IC50 ) value of 5.7 mg/cm2 , indicating greater detrimental effects than the higher MW (IC50  = 14.0 mg/cm2 ). Non-cytotoxic concentrations of 3.0 mg/cm2 for MW ~15,000 g/mol and 0.9 mg/cm2 for MW ~5,000 g/mol) induced negative metabolic changes in NIH3T3 cells. Cell viability was severely reduced to 7% after the exposure to degradation by-products generated after thermal and photodegradation degradation of PMMA. PMMA at non-cytotoxic concentrations still induced overexpression of pro-inflammatory cytokines, chemokines, and growth factors (IL1B, CXCL10, CCL5, IL1R1, IL7, IL17A, VEGFA, FGF2, IFNG, IL15) on the RhE model. The inflammatory response was also supported by histopathological and gene expression analyses of PMMA-treated RhE, indicating tissue damage and gene overexpression. Results suggested that non-cytotoxic concentrations of PMMA (3.0 to 5.6 mg/cm2 for MW ~15,000 g/mol and 0.9 to 2.1 mg/cm2 for MW ~5,000 g/mol) were sufficient to negatively alter NIH3T3 cells metabolism and activate inflammatory events in the RhE skin.

In vitro assessment of skin irritation and corrosion properties of graphene-related materials on a 3D epidermis

The increasing use of graphene-related materials (GRMs) in many technological applications, ranging from electronics to biomedicine, needs a careful evaluation of their impact on human health. Skin contact can be considered one of the most relevant exposure routes to GRMs. Hence, this study is focused on two main adverse outcomes at the skin level, irritation and corrosion, assessed following two specific Test Guidelines (TGs) defined by the Organization for Economic Co-operation and Development (OECD) (439 and 431, respectively) that use an in vitro 3D reconstructed human epidermis (RhE) model. After the evaluation of their suitability to test a large panel of powdered GRMs, it was found that the latter were not irritants or corrosive. Only GRMs prepared with irritant surfactants, not sufficiently removed, reduced RhE viability at levels lower than those predicting skin irritation (≤50%, after 42 min exposure followed by 42 h recovery), but not at levels lower than those predicting corrosion (<50%, after 3 min exposure or <15% after 1 h exposure). As an additional readout, a hierarchical clustering analysis on a panel of inflammatory mediators (interleukins: IL-1α, IL-1β, IL-6, and IL-18; tumor necrosis factor-α and prostaglandin E2) released by RhE exposed to these materials supported the lack of irritant and pro-inflammatory properties. Overall, these results demonstrate that both TGs are useful in assessing GRMs for their irritant or corrosion potential, and that the tested materials did not cause these adverse effects at the skin level. Only GRMs prepared using toxic surfactants, not adequately removed, turned out to be skin irritants.

Investigation on the Biological Safety and Activity of a Gluconolactone-Based Lotion for Dermocosmetic Application

(1) Background: Cosmeceuticals are formulas enriched with active ingredients that exert efficacy on different skin molecular targets. (2) Methods: Cell viability and the absence of potential irritant risk were evaluated on keratinocytes (HaCaT), fibroblasts (NHDF), adipocytes (3T3-L1), sebocytes (PCi-SEB_CAU) and reconstructed human epidermis (RHE), respectively. Several treatments were performed to evaluate the ability of the lotion to stimulate the production of collagen and elastin, stimulate the differentiation of keratinocytes and reduce the number of senescent cells following UVB stimulation. In addition, the modulation of genes involved in the production, storage and accumulation of sebum were investigated. (3) Results: The results obtained demonstrated the biosafety of the formula in all cell lines tested. The 24-h treatment with non-cytotoxic concentrations determined an increase in the expression of the collagen (COL1A1), elastin (ELN) and involucrin (IVL) genes, while a reduction of peroxisome proliferator-activated receptor-gamma (PPARγ) gene expression and a reduction of SA-βgal-positive cells were found. Moreover, the treatment did not interfere with normal steroid 5-alpha reductase (5RDA3) gene expression levels. (4) Conclusions: Data collected demonstrated the biosafety of the lotion, the non-comedogenic property and a multi targets anti-aging effect. In particular, data collected on the booster lotion make it a valid way to counteract the pore dilatation aging related.

Recent Options and Techniques to Assess Improved Bioavailability: In Vitro and Ex Vivo Methods

Bioavailability assessment in the development phase of a drug product is vital to reveal the disadvantageous properties of the substance and the possible technological interventions. However, in vivo pharmacokinetic studies provide strong evidence for drug approval applications. Human and animal studies must be designed on the basis of preliminary biorelevant experiments in vitro and ex vivo. In this article, the authors have reviewed the recent methods and techniques from the last decade that are in use for assessing the bioavailability of drug molecules and the effects of technological modifications and drug delivery systems. Four main administration routes were selected: oral, transdermal, ocular, and nasal or inhalation. Three levels of methodologies were screened for each category: in vitro techniques with artificial membranes; cell culture, including monocultures and co-cultures; and finally, experiments where tissue or organ samples were used. Reproducibility, predictability, and level of acceptance by the regulatory organizations are summarized for the readers.

Preliminary Study on an Alternative Test Method with MCTT HCETM for Ocular Irritation Test of Ophthalmic Medical Devices

The sustained growth of the market for ophthalmic medical devices has increased the demand for alternatives to animal testing for the evaluation of eye irritation. The International Organization for Standardization has acknowledged the need to develop novel in vitro tests to replace animal testing. Here, we evaluated the applicability of an alternative method based on a human corneal model to test the safety of ophthalmic medical devices. 2-Hydroxyethyl methacrylate (HEMA) and Polymethyl methacrylate (PMMA), which are used to fabricate contact lenses, were used as base materials. These materials were blended with eye irritant and non-irritant chemicals specified in the OECD Test Guideline (TG) 492 and Globally Harmonized System (GHS) classification. Then, three GLP-certified laboratories performed three replicates using the developed method using 3D reconstructed human cornea epithelium, MCTT HCE^TM. OECD TG 492 describes the procedure used to evaluate the eye hazard potential of the test chemical based on its ability to induce cytotoxicity in a reconstructed human cornea-like epithelium (RhCE) tissue. Results: The within-laboratory reproducibility (WLR) and between-laboratory reproducibility (BLR) were both 100%. When a polar extraction solvent was used, the sensitivity, specificity, and accuracy were all 100% in each laboratory. When a non-polar extraction solvent was used, the sensitivity was 80%, the specificity was 100%, and the accuracy was 90%. The proposed method exhibited excellent reproducibility and predictive capacity within and between laboratories. Therefore, the proposed method using the MCTT HCE^TM model could be used to evaluate eye irritation caused by ophthalmic medical devices.

Malassezia restricta-mediated Lipoperoxidation: A Novel Trigger in Dandruff

Dandruff is a common scalp disorder with multiple microbial and host-related factors contributing to its aetiology, including alterations in scalp sebum. Despite existing evidence that the yeast Malassezia restricta plays a key role in the onset of dandruff, the interplay of these factors is poorly understood. Recently, squalene monohydroperoxide and malondialdehyde were established as biomarkers of dandruff-afflicted scalp, highlighting the role of sebum lipoperoxidation in the triggering and maintenance of dandruff, although its mechanism of action is unknown. The current study provides evidence that M. restricta mediates sebum peroxidation, leading to production of squalene monohydroperoxide and malondialdehyde. Furthermore, in vitro data show that these lipoperoxidation products act on epidermal cells and alter the skin barrier. These results support the role of Malassezia restricta-induced lipoperoxides as triggers of dandruff, which suggests that blocking their production could be a novel anti-dandruff treatment approach.

Modeling an Optimal 3D Skin-on-Chip within Microfluidic Devices for Pharmacological Studies

Preclinical research remains hampered by an inadequate representation of human tissue environments which results in inaccurate predictions of a drug candidate’s effects and target’s suitability. While human 2D and 3D cell cultures and organoids have been extensively improved to mimic the precise structure and function of human tissues, major challenges persist since only few of these models adequately represent the complexity of human tissues. The development of skin-on-chip technology has allowed the transition from static 3D cultures to dynamic 3D cultures resembling human physiology. The integration of vasculature, immune system, or the resident microbiome in the next generation of SoC, with continuous detection of changes in metabolism, would potentially overcome the current limitations, providing reliable and robust results and mimicking the complex human skin. This review aims to provide an overview of the biological skin constituents and mechanical requirements that should be incorporated in a human skin-on-chip, permitting pharmacological, toxicological, and cosmetic tests closer to reality.

ISO 10993-23 In vitro irritation testing for medical devices: Substantiating applicability to mild irritants and non-extractables

Irritation testing is an integral part of the biocompatibility assessment of medical devices and has historically been conducted on animals, either by direct contact or with polar and non-polar solvent extracts. In 2018 an ISO-sponsored interlaboratory validation study demonstrated that two reconstituted human epidermis (RhE) based assays, which were adapted from validated methods used for industrial chemicals, produced results essentially equivalent to those obtained with in vivo tests. This led to the publication of the ISO 10993-23:2021 standard on irritation testing, which states that RhE-based assays are now the preferred method. The 2018 validation study evaluated strong irritants, so we tested nine mild irritants (GHS Category 3), neat and spiked at different concentrations into medical device extracts, per ISO 10993-23:2021. The results substantiated the applicability of RhE-based assays for evaluating mild irritants in medical device extracts. Moreover, the 2018 validation study tested solid extractable medical device materials but did not consider non-extractable medical device materials (e.g., creams, gels, or sprays). By testing nine marketed non-extractable materials, either neat or spiked with irritants, we also confirmed that RhE-based assays are readily applicable to such medical device materials.

Impact of microstructure on cell behavior and tissue mechanics in collagen and dermal decellularized extra-cellular matrices

Skin models are used for many applications such as research and development or grafting. Unfortunately, most lack a proper microenvironment producing poor mechanical properties and inaccurate extra-cellular matrix composition and organization. In this report we focused on mechanical properties, extra-cellular matrix organization and cell interactions in human skin samples reconstructed with pure collagen or dermal decellularized extra-cellular matrices (S-dECM) and compared them to native human skin. We found that Full-thickness S-dECM samples presented stiffness two times higher than collagen gel and similar to ex vivo human skin, and proved for the first time that keratinocytes also impact dermal mechanical properties. This was correlated with larger fibers in S-dECM matrices compared to collagen samples and with a differential expression of F-actin, vinculin and tenascin C between S-dECM and collagen samples. This is clear proof of the microenvironment's impact on cell behaviors and mechanical properties. STATEMENT OF SIGNIFICANCE: In vitro skin models have been used for a long time for clinical applications or in vitro knowledge and evaluation studies. However, most lack a proper microenvironment producing a poor combination of mechanical properties and appropriate biological outcomes, partly due to inaccurate extra-cellular matrix (ECM) composition and organization. This can lead to limited predictivity and weakness of skin substitutes after grafting. This study shows, for the first time, the importance of a complex and rich microenvironment on cell behaviors, matrix macro- and micro-organization and mechanical properties. The increased composition and organization complexity of dermal skin decellularized extra-cellular matrix populated with differentiated cells produces in vitro skin models closer to native human skin physiology.

Effect of Melatonin on Psoriatic Phenotype in Human Reconstructed Skin Model

Psoriasis is an inflammatory and auto-immune skin-disease characterized by uncontrolled keratinocyte proliferation. Its pathogenesis is not still fully understood; however, an aberrant and excessive inflammatory and immune response can contribute to its progression. Recently, more attention has been given to the anti-inflammatory and immunomodulators effects of melatonin in inflammatory diseases. The aim of this paper was to investigate the effect of melatonin on psoriatic phenotype and also in S. aureus infection-associated psoriasis, with an in vitro model using Skinethic Reconstructed Human Epidermis (RHE). An in vitro model was constructed using the RHE, a three-dimensional-model obtained from human primary-keratinocytes. RHE-cells were exposed to a mix of pro-inflammatory cytokines, to induce a psoriatic phenotype; cells were also infected with S. aureus to aggravate psoriasis disease, and then were treated with melatonin at the concentrations of 1 nM, 10 nM, and 50 nM. Our results demonstrated that melatonin at higher concentrations significantly reduced histological damage, compared to the cytokine and S. aureus groups. Additionally, the treatment with melatonin restored tight-junction expression and reduced pro-inflammatory cytokine levels, such as interleukin-1β and interleukin-12. Our results suggest that melatonin could be considered a promising strategy for psoriasis-like skin inflammation, as well as complications of psoriasis, such as S. aureus infection.

Development of Epidermal Equivalent from Electrospun Synthetic Polymers for In Vitro Irritation/Corrosion Testing

The development of products for topical applications requires analyses of their skin effects before they are destined for the market. At present, the ban on animal use in several tests makes the search for in vitro models (such as artificial skin) necessary to characterize the risks involved. In this work, tissue engineering concepts were used to manufacture collagen-free three-dimensional scaffolds for cell growth and proliferation. Two different human skin models-reconstructed human epidermis and full-thickness skin-were developed from electrospun scaffolds using synthetic polymers such as polyethylene terephthalate, polybutylene terephthalate, and nylon 6/6. After the construction of these models, their histology was analyzed by H&E staining and immunohistochemistry. The results revealed a reconstructed epidermal tissue, duly stratified, obtained from the nylon scaffold. In this model, the presence of proteins involved in the epidermis stratification process (cytokeratin 14, cytokeratin 10, involucrin, and loricrin) was confirmed by immunohistochemistry and Western blot analysis. The nylon reconstructed human epidermis model's applicability was evaluated as a platform to perform irritation and corrosion tests. Our results demonstrated that this model is a promising platform to assess the potential of dermal irritation/corrosion of chemical products.

Pre-validation of SENS-IS assay for in vitro skin sensitization of medical devices

According to ISO 10993-1:2018, the skin sensitization potential of all medical devices must be evaluated, and for this endpoint ISO 10993-10:2010 recommends the use of in vivo assays. The goal of the present study was to determine if the in vitro SENS-IS assay could be a suitable alternative to the current in vivo assays. The SENS-IS assay uses the Episkin Large and SkinEthic RHE reconstructed human epidermis models to evaluate marker genes. In our study, the SENS-IS assay correctly identified 13 sensitizers spiked in a non-polar solvent. In a subsequent analysis six medical device silicone samples previously impregnated with sensitizers were extracted with polar and non-polar solvents. The SENS-IS assay correctly identified five of these extracts, while a sixth extract, which contained the weak sensitizer phenyl benzoate, was classified as negative. However, when this extract was concentrated, or a longer exposure time was used, the assay was able to detect phenyl benzoate. The SENS-IS assay was transferred to a naïve laboratory which correctly identified sensitizers in six blinded silicone samples, including the one containing phenyl benzoate. In light of these results, we conclude that the SENS-IS assay is able to correctly identify the presence of sensitizers in medical devices extracts.

The suitability of reconstructed human epidermis models for medical device irritation assessment: A comparison of In Vitro and In Vivo testing results

The ISO 10993 standards on biocompatibility assessment of medical devices discourage the use of animal tests when reliable and validated in vitro methods are available. A round robin validation study of in vitro reconstructed human epidermis (RhE) assays was performed as potential replacements for rabbit skin irritation testing. The RhE assays were able to accurately identify strong irritants in dilute medical device extracts. However, there was some uncertainty about whether RhE tissues accurately predicted the results of the rabbit skin patch or intracutaneous irritation test. To address that question, this paper presents in vivo data from the round robin and subsequent follow-up studies. The follow-up studies included simultaneous in vitro RhE model and in vivo testing of round robin polymer samples and the results of dual in vitro/in vivo testing of currently marketed medical device components/materials. Our results show for the first time that for both pure chemicals and medical device extracts the intracutaneous rabbit test is more sensitive to detect irritant activity than the rabbit skin patch test. The studies showed that the RhE models produced results that were essentially equivalent to those from the intracutaneous rabbit skin irritation test. Therefore, it is concluded that RhE in vitro models are acceptable replacements for the in vivo rabbit intracutaneous irritation test for evaluating the irritant potential of medical devices.

Novel cytokine marker available for skin irritation testing of medical devices using reconstructed human epidermis models

In biological safety evaluation of medical devices, false-negative results have been observed during skin irritation testing using the reconstructed human epidermis (RhE) model when measuring cell viability as a single marker. Therefore, to improve testing accuracy, this study conducted a comprehensive survey and performance evaluation of cytokines to identify a second marker. In addition to IL-1α, macrophage migration inhibitory factor (MIF) was newly identified as a candidate marker, in the Bio-Plex assay of EpiDerm model exposed to polymer sample extracts. Irritation based on cell viability level was not accurately determined in LabCyte model using silicone spiked with 25% heptanoic acid (HA). By contrast, the irritation potency was accurately assessed in detail by measuring IL-1α or MIF. Further, IL-1α and MIF levels in EpiDerm, LabCyte, and EpiSkin models stimulated with sodium dodecyl sulfate (SDS) were inversely correlated with cell viability, and were detected even at low SDS concentrations without cell toxicity. Additionally, MIF demonstrated greater S/N ratio and dose-dependency at high SDS concentrations in some models compared to IL-1α. These results indicated that MIF might be a useful second marker for improving the sensitivity and accuracy of skin irritation testing with RhE models.

Skin irritation potential of graphene-based materials using a non-animal test

Besides inhalation, skin contact may be considered one of the most relevant exposure routes to graphene-based materials (GBMs). However, very few data on the cutaneous toxicity of these materials are available, so far. This study is focused on skin irritation potential of a panel of GBMs: few-layer graphene (FLG), exfoliated by ball milling of graphite, FLG exfoliated by ultrasonication using sodium dodecyl sulfate (FLG-SDS) or sodium dodecylbenzenesulfonate (FLG-SDBS), CVD-graphene, obtained by chemical vapor deposition, graphene oxide (GO) and reduced GO (rGO). Skin irritation was assessed using the SkinEthic™ Reconstructed human Epidermis (RhE), following the Organisation for Economic Co-operation and Development (OECD) Test Guideline (TG) 439. Even though not validated for nanomaterials, the OCED TG 439 turned out to be applicable also for GBM testing, since no interference with the methylthiazolyldiphenyl-tetrazolium bromide (MTT) reduction, used as a final readout, was found. Furthermore, direct epidermal exposure to powdered GBMs mimics the actual human exposure, avoiding interference by the cell culture medium (protein corona formation). Only GBMs prepared with irritant surfactants (FLG-SDS and FLG-SDBS), but not the others, reduced RhE viability at levels lower than those predicting skin irritation (≤50%), suggesting irritant properties. This result was further confirmed by measuring cytokine (IL-1α, IL-6 and IL-8) release by GBM-treated RhE and by histological analysis as additional readouts to implement the guideline. On the whole, these results demonstrate that GBMs prepared with non-irritant exfoliation agents do not induce skin irritation after a single acute exposure.

Dermo-epidermal organotypic cultures for in vitro evaluation of skin irritation and corrosion

In recent years, in-vitro skin models for chemical hazard identification have been developed. Most of them consist only of human keratinocytes, neglecting the contribution of other skin constituents. Cultures containing the dermal and epidermal component provide an attractive system to investigate, in a more realistic model, toxicological responses, which represents a distinct advantage over keratinocytes-based models that do not mimic faithfully the in vivo environment. This study aimed to validate dermo-epidermal organotypic cultures (ORGs) as a platform to perform irritation and corrosion tests. Skin models were constructed by seeding keratinocytes on fibroblast-containing fibrin gels. After 21 days, the ORGs were evaluated histologically, and the irritant and corrosion potential was determined by means of viability measurements (MTT assay) and cytokine release, according to 431 and 439 OECD tests guidelines. Skin models showed similar histological characteristics to native skin and were able to classify different substances with high accuracy, showing their applicability to skin irritation and corrosion tests. Although cytokines release seems to be chemical-dependent, a tendency was observed, leading to the improvement of the prediction capacity. Nevertheless, further studies should be done to reduce variability in order to increase prediction capacity.

Recovering Cucurbita pepo cv. 'Lungo Fiorentino' Wastes: UHPLC-HRMS/MS Metabolic Profile, the Basis for Establishing Their Nutra- and Cosmeceutical Valorisation

Food-waste is produced throughout all the food supply chain, with a large part already achieved at farm level. In fact, fruits and vegetables, which do not satisfy aesthetic demands, cannot be marketed, but their recovery could favour their valorisation for the obtainment of highly qualified goods. In this context, faulty zucchini fruits (cultivar 'Lungo Fiorentino'), intended for disposal, were rescued as effective, inexpensive and bio-sustainable source for cosmeceutical purposes. Zucchini fruits underwent extraction and fractionation to obtain ZLF-O and ZLF-A extracts, which were chemically characterized by UHPLC-HRMS. ZLF-A extract, rich in flavonols and flavones, scavenged massively DPPH• and ABTS•+, and was not cytotoxic at doses up to 200 μ g/mL. Thus, ZLF-A was incorporated into a base cream formula. Zucchini-based emulsion was deeply screened for its antiradical properties and cytotoxicity towards human keratinocytes and fibroblasts. ZLF-A-enriched cream, whose chemical stability was assessed over time and mimicking different storage conditions, was further tested on reconstructed epidermis disks (EpiskinTM). The recovery of valuable chemical substances from zucchini agro-food waste, complying with the principles of valorisation and sustainable development, can represent a new market force for local farmers. Data acquired were eager to convey a suitable reuse of nutraceuticals rich zucchini waste.

Transcriptional profiling of lactic acid treated reconstructed human epidermis reveals pathways underlying stinging and itch

The incidence of sensitive skin with stinging and itch following chemical exposure in products such as cosmetics is increasing, but molecular mechanisms underlying this pathophysiology remain understudied. Here we performed transcriptional analysis of reconstructed human epidermis (RHE) 1, 6, and 24 h following topical lactic acid (LA) application, a known inducer of the sensitive skin reaction. Since little is known about the specific role of keratinocyte transcriptional changes in mediating stinging and itch, we performed pathway analysis using several publically available databases and then focused on significantly changed transcripts involved in stress responses and itch signaling using the Comparative Toxicogenomics Database. LA treatment induced damage-associated genes HSPA1A, DDIT3, IL1A, and HMGB2. Neurotrophic factors including BDNF, ARTN, PGE2, and chemokines were also upregulated. Stimulation of the RHE with 5% LA did not reduce cell viability, but reduced the trans-epidermal electric resistance, suggesting barrier dysfunction. Accordingly, skin barrier formation genes such as filaggrins (FLG, FLG2) and corneodesmosin (CDSN) were downregulated. To our knowledge, this is the first study focusing on transcriptional changes underlying the stinging response of keratinocytes upon LA stimulation. While follow-up research is needed, this study provides new insight into the mechanisms underlying the sensitive skin reaction.

Evaluation of safety and skin tolerability of organic cotton pads in case of irritative vulvitis

BACKGROUND

The woman vaginal environment is a fragile and delicate ecosystem that is often impaired by physical and chemical agents. This condition tends to damage skin barrier causing allergic reactions that lead to chronic irritating conditions.

METHODS

Clinical and in-vitro studies were performed on organic cotton pads in order to assess if their use can prevent the onset of irritant conditions. During clinical studies, the panelists' skin and mucosae state were checked through a gynecological clinical examination in order to assess tissue dryness and alterations. Moreover, each panelist answered a sensorial questionnaire at the end of the test. Data were gathered and the product acceptability of use was registered in terms of itching, irritations and burning feelings. The panelist score was calculated based on VNS Scale (0-10, where 0 is the minimum value and 10 is the maximum).

RESULTS

From a careful analysis of the first part of the study, it is possible to state that the tested product (organic cotton pads) has proved to reduce the onset of irritative phenomena and slight undesired effects caused by the conventional use of synthetic pads. In-vitro tests were conducted to study possible biological processes involved during allergic and sensitizing events produced by vulvitis. In particular, a pro-sensitizing test, a skin irritation on RHE (adapted from OECD 439) and tests to assess the soothing activity were performed on cell substrates.

CONCLUSIONS

Results demonstrated that organic cotton pads, in each part, are safe and do not impair any physiological activities of the tissue substrates.