Human In Vitro Skin Models for Wound Healing and Wound Healing Disorders

Eumelanin pigment release from photo-crosslinkable methacrylated gelatin-based cryogels: Exploring the physicochemical properties and antioxidant efficacy in wound healing

Managing wounds in certain phases of the healing process still represents a big challenge. The oxidative stress, caused by reactive oxygen species (ROS), is one of the hallmarks controlling the wound healing-related process. Multifunctional biomaterials with excellent biocompatibility, tuneable properties, and easy functionalization, may allow realizing suitable three-dimensional (3D) and extracellular matrix (ECM)-mimicking structures, to efficiently control ROS levels. This might be a promising strategy for healing severe wounds. Herein, photo-crosslinkable methacrylated gelatin (GelMA)-based spongy-like cryogels (from 5 to 20 % w/v) incorporating Eumelanin from Black Soldier Flies (BSF-Eumel, 0.5 and 1.0 mg/mL), a pigment endowed with marked antioxidant properties, were developed. GelMA-based cryogels were fabricated by an easily handled and scalable cryogelation process followed by ultraviolet (UV) photo-crosslinking. BSF-Eumel sub-micrometer particles were embedded into GelMA-based cryogels by passive permeation of the solution within the polymeric network. BSF-Eumel addition resulted in more hydrophilic and porous structures, exhibiting a good stability and a prolonged release within 14 days. Furthermore, GelMA/BSF-Eumel cryogels exhibited good antioxidant activity, confirmed by a powerful quenching effect on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical (59 % at 1.0 mg/mL of BSF-Eumel). Moreover, GelMA/BSF-Eumel cryogels at the highest GelMA concentrations (10 and 20 % w/v) accelerated human dermal fibroblasts-adult (HDF-a) migration, promoting wound closure within 24 h. They also proved to mitigate oxidative stress, modulating the production of ROS levels and preventing superoxide dismutase (SOD) activity inhibition in HDFs stimulated by lipopolysaccharide (LPS), owing to the release of BSF-Eumel. Such remarkable outcomes make GelMA/BSF-Eumel cryogels a promising antioxidant platform for wound healing.

Topical Administration of Vitamin D2 Combined with Colloidal Silver Nanoparticles Promotes Wound Repair and Protection Against Skin Irritation and UVB Irradiation in 3D Reconstructed Human Skin Models

Background/Objectives: There is a great demand for novel, multipurpose, natural skin-care products in the global skin repair and sun protection markets. Within this framework, the potential benefits of topical Vitamin D2 (VD2) administration in combination with silver nanoparticles (AgNPs) were examined. Methods: Evaluating the efficacy of the VD2+AgNP cream in wound healing, skin irritation and UVB irradiation protection necessitated preclinical testing using reconstructed human skin equivalent models (prepared from human foreskins) containing both a fully stratified epidermal layer and underlying dermis. Results: Application of the cream significantly improved wound healing by stimulating keratinocyte re-epithelialization and dermal fibroblast migration in models subjected to full-thickness (scratch and biopsy punch) wounds, compared to untreated models. The VD2+AgNP cream, administered prior to the induction of skin irritation by 5% sodium dodecyl sulfate (SDS) afforded protection by ameliorating cell viability epidermal thickness and interleukin-1alpha levels. UVB exposure (50 mJ/cm2) significantly reduced cell viability and epidermal thickness (associated with increased epidermal breakage), as well as basal layer Ki67 and supra-basal layer involucrin expression, compared to the CTRL sham-irradiated models. The cream administered prior to UVB irradiation (protective capacity) showed greater efficacy in minimizing epidermal damage. This was reflected by significantly higher Ki67 and involucrin expression, as well as lower epidermal breakage, compared to models where the cream was applied following UVB irradiation (curative capacity). Conclusions: The VD2+AgNP cream shows multipurpose potential in skin protection. The underlying molecular mechanisms remain to be investigated.

Laminaria japonica polysaccharide nano‑silver film with synergistic antibiosis for wound healing

Facing the clinical challenge of uncontrolled bleeding and infection after trauma, it is urgent to obtain a new type of dressing with antibacterial and wound healing promoting activities and good biological safety. Polysaccharide was extracted from Laminaria japonica Aresch by water extraction and alcohol precipitation, and LA-1 was obtained after separation and purification by DEAE-52 cellulose column. LA-1 had →2,6)-β-Manp-(1→) as the main chain and →4)-OAC-β-Galp-(1→, →3)-α-Fucp(1→, →4)-β-ManpA-(1→ and →4). Then, A kind of (PSx%AN) membrane with hemostatic and antibacterial functions was prepared by solution casting with LA-1 as green reducing agent and stabilizer. The (PSx%AN) film was formed by the cross-linking reaction of LA-1, AgNO3, polyvinyl alcohol and starch (3:1), in which the starch interacted with the polyhydroxy structure of polyvinyl alcohol to form hydrogen bonds, which endowed the film with good mechanical strength and biocompatibility. In order to comprehensively evaluate the performance of (PSx%AN) membrane, the oxidation resistance, antibacterial activity and cytotoxicity were tested, and animal experiments were also carried out. The results of the anti-oxidation and anti-bacterial experiments showed that the (PSx%AN) film not only exhibited good anti-oxidation performance, but also demonstrated a strong inhibitory effect on S. aureus and E. coli, with the maximum inhibition zone diameters of 16.8 ± 0.3 mm and 11.0 ± 0.2 mm respectively. The full-thickness skin defect experiment demonstrated that the (PS1%AN) membrane exhibited superior results compared to other groups on the 11th day. Specifically, it effectively increased the hydroxyproline concentration to 4.69 ± 0.19 μg/mL and the total protein content to 551.09 ± 7.19 μg/mL. Additionally, it reduced inflammatory responses, shortened wound healing time in mice, and promoted tissue repair. These findings provide a novel perspective for the (PSx%AN) membrane as a potential hemostatic and anti-infective wound dressing.

Advancement of Nanomaterials- and Biomaterials-Based Technologies for Wound Healing and Tissue Regenerative Applications

Patients and healthcare systems face significant social and financial challenges due to the increasing number of individuals with chronic external and internal wounds that fail to heal. The complexity of the healing process remains a serious health concern, despite the effectiveness of conventional wound dressings in promoting healing. Recent advancements in materials science and fabrication techniques have led to the development of innovative dressings that enhance wound healing. To further expedite the healing process, novel approaches such as nanoparticles, 3D-printed wound dressings, and biomolecule-infused dressings have emerged, along with cell-based methods. Additionally, gene therapy technologies are being harnessed to generate stem cell derivatives that are more functional, selective, and responsive than their natural counterparts. This review highlights the significant potential of biomaterials, nanoparticles, 3D bioprinting, and gene- and cell-based therapies in wound healing. However, it also underscores the necessity for further research to address the existing challenges and integrate these strategies into standard clinical practice.

A standardized in vitro bioengineered skin for penetrating wound modeling

Over the years, significant progress has been made in developing cost-effective and ethical in vitro bioengineered skin substitutes to study cutaneous wound healing processes. Rodents and small animal models are not optimal due to physiological differences in their skin compared to human skin. The generation of reproducible and precise wounds is key to obtaining comparable results. We created a three-dimensional skin wounding model by growing a fully differentiated, stratified squamous epithelium from human keratinocytes at an air-liquid interface on a type I collagen scaffold concealed with human dermal BJ fibroblasts. To generate the wounds, a stamp with incorporated needles with a length of 250 µm was used to puncture the epidermis to produce standardized wounds. The stamping needle technique is a practical and inexpensive method for creating length-tailored wounds on three-dimensional skin models. The effectiveness of this technique in treating 3D skin models was demonstrated, accompanied by an evaluation of the model's functionality in terms of cell proliferation, differentiation, and immunological characteristics.

Ex Vivo Human Skin Model to Study Immediate and Early Local Responses to External Stimuli

Local responses of skin tissue to external stimuli are complex, thus exceeding the capability of in vitro methods but do not need the complexity of a whole organism to be simulated. Therefore, we established a human ex vivo skin model in our lab to study the local effects of various stimuli, such as burns and local topic treatments. In this chapter, we describe the experimental setup of the ex vivo model and additional technology of collecting dermal interstitial fluid. Further, we describe how exosome-like vesicles can be enriched from the dermal interstitial fluid, including their proof via nanoparticle tracking.

Lipid analysis of human primary dermal fibroblasts and epidermal keratinocytes after near-infrared exposure using mass spectrometry imaging

Photobiomodulation (PBM) therapy is the application of near-infrared (NIR) exposure to injuries or lesions to (among others) improve wound healing, reduce inflammation, and decreases acute and chronic pain. However, the understanding of the molecular mechanism of PBM, more specifically the effects of NIR on skin cells is still lacking behind. Lipids are essential components of cellular membranes that are integral to skin structure and function. This study aims to elucidate the impact of NIR exposure on the skin's lipidome by investigating the molecular effect of NIR exposure on single skin cells. Primary human dermal fibroblasts (NHDFa) and human epidermal keratinocytes (HEKa) were exposed to NIR (850 nm) with a dose of 6.5 J/cm2 for 5 consecutive days between 09.00 and 12.00 am. A workflow utilizing matrix-assisted laser desorption/ionization mass spectrometry imaging combined with liquid chromatography tandem mass spectrometry for lipidomics analysis was performed. This study provides evidence that adequate exposure of NIR influences lipid metabolism in NHDFa, whereas no alterations were found in HEKa. This work lays the groundwork in explaining the beneficial properties on both skin-related effects and systemic health benefits as seen in clinical studies.

Innervated Coculture Device to Model Peripheral Nerve-Mediated Fibroblast Activation

Cutaneous wound healing is a complex process involving various cellular and molecular interactions, resulting in the formation of a collagen-rich scar with imperfect function and morphology. Dermal fibroblasts are crucial to successful wound healing, migrating to the wound site where they are activated to provide extracellular matrix remodeling and wound closure. Peripheral nerves have been shown to play an important role in wound healing, with loss or damage to these nerves often leading to impaired healing and the formation of chronic nonhealing wounds. Previous research has suggested that sensory nerves secrete trophic factors that can regulate wound healing, including fibroblast activation; however, the direct cell-cell interaction between nerves and fibroblasts has not been extensively studied. To address this knowledge gap, we developed an in vitro co-culture model using a device called the IFlowPlate. This model supports the long-term viability of multiple cell types while allowing for direct contact between sensory nerve cells and dermal fibroblasts. Using the IFlowPlate, we demonstrate that co-culture of dorsal root ganglia with dermal fibroblasts increases fibroblast proliferation, collagen and α-smooth muscle actin expression, and secretion of pro-wound healing factors, suggesting that nerves can promote wound healing by modulating fibroblast activation. The IFlowPlate offers a user-friendly and high-throughput platform to study the in vitro interactions between nerves and a variety of cell types that can be applied to wound healing and other important biological processes.

Diversity of human skin three-dimensional organotypic cultures

Recently, significant strides have been made in the development of high-fidelity skin organoids, encompassing techniques such as 3D bioprinting, skin-on-a-chip systems, and models derived from pluripotent stem cells (PSCs), replicating appendage structures and diverse skin cell types. Despite the emergence of these state-of-the-art skin engineering models, human organotypic cultures (OTCs), initially proposed in the 1970s, continue to reign as the predominant in vitro cultured three-dimensional skin model in the field of tissue engineering. This enduring prevalence is owed to their cost-effectiveness, straight forward setup, time efficiency, and faithful representation of native human skin. In this review, we systematically delineate recent advances in skin OTC models, aiming to inform future efforts to enhance in vitro skin model fidelity and reproducibility.

Targeting the Complexity of In Vitro Skin Models: A Review of Cutting-Edge Developments

Skin in vitro models offer much promise for research, testing drugs, cosmetics, and medical devices, reducing animal testing and extensive clinical trials. There are several in vitro approaches to mimicking human skin behavior, ranging from simple cell monolayer to complex organotypic and bioengineered 3-dimensional models. Some have been approved for preclinical studies in cosmetics, pharmaceuticals, and chemicals. However, development of physiologically reliable in vitro human skin models remains in its infancy. This review reports on advances in in vitro complex skin models to study skin homeostasis, aging, and skin disease.

Targeted Antibacterial Endolysin to Treat Infected Wounds on 3D Full-Thickness Skin Model: XZ.700 Efficacy

Backgrounds/Objectives: Skin wound healing is a physiological process orchestrated by epithelial and mesenchymal cells able to restore tissue continuity by re-organizing themselves and the ECM. This research study aimed to develop an optimized in vitro experimental model of full-thickness skin, to address molecular and morphological modifications occurring in the re-epithelization and wound healing process. Methods: Wound healing starting events were investigated within an experimental window of 8 days at the molecular level by gene expression and immunofluorescence of key epidermal and dermal biomarkers. To mirror the behavior of infected wounds, the established wound healing model was then colonized with S. aureus, and the efficacy of a novel antibacterial agent, XZ.700, was investigated. Viable counts (CFU/tissue), IF, and ultrastructural analysis (SEM) were performed to evaluate S. aureus colonization inside and around the wound bed in an experimental window of 3 h of colonization and 24 h of treatment. Results: Endolysin showed an efficacy in counteracting bacterial growth and invasion within the wound bed, reducing the S. aureus load compared to its placebo, thanks to its selective antimicrobial activity interfering with biofilm formation. Conclusions: The preclinical in vitro infected wound model on FT-kin showed interesting applications to assess the repair efficacy of dermo-pharmaceutical and cosmetic formulations.

A programmable platform for probing cell migration and proliferation

The advent of advanced robotic platforms and workflow automation tools has revolutionized the landscape of biological research, offering unprecedented levels of precision, reproducibility, and versatility in experimental design. In this work, we present an automated and modular workflow for exploring cell behavior in two-dimensional culture systems. By integrating the BioAssemblyBot® (BAB) robotic platform and the BioApps™ workflow automater with live-cell fluorescence microscopy, our workflow facilitates execution and analysis of in vitro migration and proliferation assays. Robotic assistance and automation allow for the precise and reproducible creation of highly customizable cell-free zones (CFZs), or wounds, in cell monolayers and "hands-free," schedulable integration with real-time monitoring systems for cellular dynamics. CFZs are designed as computer-aided design models and recreated in confluent cell layers by the BAB 3D-Bioprinting tool. The dynamics of migration and proliferation are evaluated in individual cells using live-cell fluorescence microscopy and an in-house pipeline for image processing and single-cell tracking. Our robotics-assisted approach outperforms manual scratch assays with enhanced reproducibility, adaptability, and precision. The incorporation of automation further facilitates increased flexibility in wound geometry and allows for many experimental conditions to be analyzed in parallel. Unlike traditional cell migration assays, our workflow offers an adjustable platform that can be tailored to a wide range of applications with high-throughput capability. The key features of this system, including its scalability, versatility, and the ability to maintain a high degree of experimental control, position it as a valuable tool for researchers across various disciplines.

Human Skin Fibroblasts as an In Vitro Model Illustrating Changes in Collagen Levels and Skin Cell Migration Under the Influence of Selected Plant Hormones

Human skin fibroblasts are an excellent in vitro model for tracking the processes occurring in human skin and studying the potential impact of various biologically active substances on these processes. Two plant hormones, which are included in the cytokinins group-kinetin (K) and N-6-benzyladenine (BA)-have a positive effect on human skin. Therefore, an attempt was made to examine the effect they have on key skin functions, cell proliferation, and migration, as well as collagen synthesis in them. The effect of phytohormones was studied at selected concentrations for kinetin-10 μM and 1 μM-and for N-6-benzyladenine-1 μM and 0.1 μM. A wound-healing assay was used in order to analyze cell migration and proliferation. The content of total protein and collagen in cells and culture medium was determined. The obtained results confirm that the studied compounds induce cell migration and proliferation, as well as collagen biosynthesis. The positive effect of kinetin and N-6-benzyladenine on fibroblast metabolism that we have demonstrated allows us to indicate them as compounds with potentially therapeutic properties. Therefore, we conclude that they should be subjected to further molecular and in vivo studies focusing on pathologies connected with skin diseases and aging.

An In Vitro Artificial Wound Slough-Biofilm Model Developed for Evaluating a Novel Antibiofilm Technology

Eschar and slough in wounds serve as a reservoir for microorganisms and biofilms, damaged/devitalised cells, and inflammatory chemokines/cytokines, which work to initiate and prolong persistent inflammation and increase the risk of infection. Biofilm-related inflammation and infections are considered to be highly prevalent in acute wounds and chronic wounds. As slough is known to harbour biofilms, measuring the efficacy of antimicrobials in killing microbes both within and under slough is warranted. This highlights the need for more clinically relevant wound biofilm models to address this significant clinical need. Consequently, in this study, we developed an in vitro artificial wound slough (AWS) biofilm model produced by forming a biofilm below a layer of AWS, the latter of which was composed of the main protein components reported in wound eschar and slough, namely collagen, elastin, and fibrin. The model was employed to investigate the antibiofilm and antibacterial efficacy of a new patented smart next-generation antibiofilm technology composed of silver-zinc EDTA complexes and designed as a family of multifunctional metal complexes referred to as MMCs, in a liquid format, and to determine both the performance and penetration through AWS to control and manage biofilms. The results demonstrated the ability of the AWS-biofilm model to be employed for the evaluation of the efficacy of a new antibiofilm and antimicrobial next-generation smart technology. The results also demonstrated the potential for the proprietary EDTA multifunctional metal complexes to be used for the disruption of biofilms, such as those that form in chronic wounds.

Wound Closure Promotion by Leucine-Based Pseudo-Proteins: An In Vitro Study

Our research explores leucine-based pseudo-proteins (LPPs) for advanced wound dressings, focusing on their effects on wound healing in an in vitro model. We assessed three types of LPP films for their ability to enhance wound closure rates and modulate cytokine production. They all significantly improved wound closure compared to traditional methods, with the 8L6 and copolymer films showing the most pronounced effects. Notably, the latter exhibited an optimal cytokine profile: an initial burst of pro-inflammatory TNF-α, followed by a controlled release of IL-6 during the proliferative phase and a significant increase in anti-inflammatory IL-10 during remodeling. This balanced cytokine response suggests that the copolymer film not only accelerates wound closure but also supports a well-regulated healing process, potentially reducing fibrosis and abnormal scarring, underscoring the potential of copolymer LPPs as advanced wound dressing materials. Future research will aim to elucidate the specific signaling pathways activated by the copolymer LPP to better understand its mechanism of action. Overall, LPP films offer a promising approach to improving wound care and could lead to more effective treatments for complex wounds.

Establishing Primary and Stable Cell Lines from Frozen Wing Biopsies for Cellular, Physiological, and Genetic Studies in Bats

Bats stand out among mammalian species for their exceptional traits, including the capacity to navigate through flight and echolocation, conserve energy through torpor/hibernation, harbor a multitude of viruses, exhibit resistance to disease, survive harsh environmental conditions, and demonstrate exceptional longevity compared to other mammals of similar size. In vivo studies of bats are challenging for several reasons, such as difficulty in locating and capturing them in their natural environments, limited accessibility, low sample size, environmental variation, long lifespans, slow reproductive rates, zoonotic disease risks, species protection, and ethical concerns. Thus, establishing alternative laboratory models is crucial for investigating the diverse physiological adaptations observed in bats. Obtaining quality cells from tissues is a critical first step for successful primary cell derivation. However, it is often impractical to collect fresh tissue and process the samples immediately for cell culture due to the resources required for isolating and expanding cells. As a result, frozen tissue is typically the starting resource for bat primary cell derivation, but cells in frozen tissue are usually damaged and have low integrity and viability. Isolating primary cells from frozen tissues thus poses a significant challenge. Herein, we present a successfully developed protocol for isolating primary dermal fibroblasts from frozen bat wing biopsies. This protocol marks a significant milestone, as this is the first protocol specifically focused on fibroblast isolation from bat frozen tissue. We also describe methods for primary cell characterization, genetic manipulation of primary cells through lentivirus transduction, and the development of stable cell lines. © 2024 Wiley Periodicals LLC. Basic Protocol 1: Bat wing biopsy collection and preservation Support Protocol 1: Blood collection from bat venipuncture Basic Protocol 2: Isolation of primary fibroblasts from adult bat frozen wing biopsy Support Protocol 2: Primary fibroblast culture and subculture Support Protocol 3: Determination of growth curve and doubling time Support Protocol 4: Cell banking and thawing of primary fibroblasts Basic Protocol 3: Lentiviral transduction of bat primary fibroblasts Basic Protocol 4: Bat stable fibroblast cell line development Support Protocol 5: Bat fibroblast validation by immunofluorescence staining Basic Protocol 5: Chromosome counting.

Enhancing Wound Healing: A Comprehensive Review of Sericin and Chelidonium majus L. as Potential Dressings

Wound healing, a complex physiological process orchestrating intricate cellular and molecular events, seeks to restore tissue integrity. The burgeoning interest in leveraging the therapeutic potential of natural substances for advanced wound dressings is a recent phenomenon. Notably, Sericin, a silk-derived protein, and Chelidonium majus L. (C. majus), a botanical agent, have emerged as compelling candidates, providing a unique combination of natural elements that may revolutionize conventional wound care approaches. Sericin, renowned for its diverse properties, displays unique properties that accelerate the wound healing process. Simultaneously, C. majus, with its diverse pharmacological compounds, shows promise in reducing inflammation and promoting tissue regeneration. As the demand for innovative wound care solutions increases, understanding the therapeutic potential of natural products becomes imperative. This review synthesizes current knowledge on Sericin and C. majus, envisioning their future roles in advancing wound management strategies. The exploration of these natural substances as constituents of wound dressings provides a promising avenue for developing sustainable, effective, and biocompatible materials that could significantly impact the field of wound healing.

Wound Healing Potential of a Novel Sedum Species: S. album Murales

Natural wound healing products are in increased demand. The potential for unexplored Sedum species in wound healing was discovered based on benefits of the genus reported in traditional medicine. The objectives were to screen ten Sedum species for wound healing, to ascertain the optimal harvest period using the five best, and finally to investigate effects of extraction protocols on wound healing using the most promising species. Different protocols were used to extract leaf polyphenol and mucilage content. Wound healing was assessed from L929 fibroblast migration. April was the optimal harvest month for wound healing efficacy, whereas the highest polyphenol content and antioxidant activity were evident in September and November. S. album Murales (ALBU), the best candidate, was then compared with S. telephium (TELE), which is well recognized in skin care. The mucilage-containing aqueous extract of ALBU was shown for the first time to induce the highest fibroblast migration after 24 h, not evident in TELE. Moreover, functional constituents contained within the absolute acetone- and isopropanol-containing polyphenol pools from ALBU induced significantly higher migration compared to TELE. A prototype cream, containing the water- and solvent-extracted bioactive compounds was effective at inducing fibroblast migration at 24 h in ALBU. The potential of ALBU in wound healing was evidenced and warrants further investigation.

Exploring Synergistic Effects of Bioprinted Extracellular Vesicles for Skin Regeneration

Regenerative medicine represents a paradigm shift in healthcare, aiming to restore tissue and organ function through innovative therapeutic strategies. Among these, bioprinting and extracellular vesicles (EVs) have emerged as promising techniques for tissue rejuvenation. EVs are small lipid membrane particles secreted by cells, known for their role as potent mediators of intercellular communication through the exchange of proteins, genetic material, and other biological components. The integration of 3D bioprinting technology with EVs offers a novel approach to tissue engineering, enabling the precise deposition of EV-loaded bioinks to construct complex three-dimensional (3D) tissue architectures. Unlike traditional cell-based approaches, bioprinted EVs eliminate the need for live cells, thereby mitigating regulatory and financial obstacles associated with cell therapy. By leveraging the synergistic effects of EVs and bioprinting, researchers aim to enhance the therapeutic outcomes of skin regeneration while addressing current limitations in conventional treatments. This review explores the evolving landscape of bioprinted EVs as a transformative approach for skin regeneration. Furthermore, it discusses the challenges and future directions in harnessing this innovative therapy for clinical applications, emphasizing the need for interdisciplinary collaboration and continued scientific inquiry to unlock its full therapeutic potential.

Design Strategy of Microneedle Systems for Skin Wound Healing: Based on the Structure of Tips and Therapeutic Methodologies

The skin, being the largest organ of the human body, is susceptible to damage resulting in wounds that are vulnerable to pathogenic attacks and fail to provide effective protection for internal tissues. Therefore, it is crucial to expedite wound healing. In recent years, microneedles have garnered significant attention as an innovative drug delivery system owing to their noninvasive and painless administration, simplified application process, precise control over drug release, and versatile loading capabilities. Consequently, they hold immense potential for the treatment of skin wound. This review presents a comprehensive design strategy for the microneedle system in promoting skin wound healing. First, the process of skin wound healing and the characteristics of specific wounds are elucidated. The design strategies for microneedles are subsequently presented and classified based on their structural and therapeutic methodologies. Finally, a succinct recapitulation of the previously discussed points and a prospective analysis are provided.

Innovative Cosmeceutical Ingredients: Harnessing Selenosugar-Linked Hydroxycinnamic Acids for Antioxidant and Wound-Healing Properties

Selenosugars are gaining growing interest due to their antioxidant efficacy, and their ability to inhibit glycosidases, repair skin tissue or reduce endothelial dysfunction. Among selenosugars, those in which selenium replaces heterocyclic oxygen in a 5-membered sugar were our focus, and their coupling with phenolic compounds appears to be a strategy aimed at producing new compounds with enhanced antioxidant efficacy. In this context, the Mitsunobu reaction has been advantageously explored to obtain trans-p-coumaroyl-1,4-deoxy-2,3-O-isopropylidene-4-seleno-d-ribose, trans-caffeoyl-1,4-deoxy-2,3-O-isopropylidene-4-seleno-d-ribose, and trans-feruloyl-1,4-deoxy-2,3-O-isopropylidene-4-seleno-d-ribose. These compounds underwent removal of the iso-propylidene group, to provide the corresponding hydroxycinnamoyl-1,4-deoxy-4-seleno-d-ribose. All compounds were characterized by Nuclear Magnetic Resonance (NMR) spectroscopy and High-Resolution Mass Spectrometry (HRMS). This latter technique was pivotal for ensuing cellular metabolomics analyses. In fact, after evaluating the anti-radical efficacy through 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) methods, which underline the massive role of the phenolic moiety in establishing efficacy, the compounds, whose cytotoxicity was first screened in two highly oxidative-stress-sensitive cells, were tested for their wound healing properties towards human HaCaT keratinocytes cells. Caffeoyl- and feruloyl selenosugars exerted a dose-dependent repair activity, while, as highlighted by the metabolomic approach, they were poorly taken up within the cells.

Impact of donor pool size on the variability of platelet lysate-derived extracellular vesicles for regenerative medicine

Aim: The objective of the present study was to determine the variability of platelet lysate-derived extracellular vesicles (pEV), in terms of characteristics and functionality through wound healing assays, when isolated either from platelet concentrates (PC, obtained from 5 donors) or from multiple PC (MPC, that is 50 donors). Methods: pEV were isolated under GMP-like conditions in a clean room using Size Exclusion Chromatography (SEC). The differential characteristics between pEV obtained from PC (PC-EV) or MPC (MPC-EV) were evaluated by means of protein concentration, Nanoparticle Tracking Analysis (NTA), Transmission Electron Microscopy (TEM), and flow cytometry using the MACSPlex™ arrays for surface analysis profiling of EV. The functionality of the isolated pEV was determined in cell culture by metabolic activity and LDH activity determination and through a wound healing assay after 24 h treatment. Results: No significant differences were observed in the pEV characteristics evaluated, whether isolated from PC or MPC. As regards functionality, a higher wound closure percentage was obtained in those pEV pools isolated from PC (5 donors). No differences in the coefficient of variation (CV) were found when comparing all the evaluated variables of pEV derived either from PC (5 donors) or from MPC (50 donors). Conclusion: Our findings challenge the necessity of a larger donor pool for pEV isolation, revealing no significant variations in the analyzed variables of MPC-EV and PC-EV. Notably, our results suggest that, unlike platelet concentrates, a high number of donors is not required to reduce the variability of pEV, showing that the pool of only 5 donors can provide a consistent and reliable therapeutic product.

Safety and effectiveness of an antiseptic wound cleansing and irrigation solution containing polyhexamethylene biguanide

OBJECTIVE

There is currently a wide range of cleansing and irrigation solutions available for wounds, many of which contain antimicrobial agents. The aim of this study was to assess the safety of HydroClean Solution (HARTMANN, Germany), a polyhexamethylene biguanide (PHMB)-containing irrigation solution, in a standard cytotoxicity assay, and to assess its effect in a three-dimensional (3D) full-thickness model of human skin.

METHOD

A number of commercially available wound cleansing and irrigation solutions, including the PHMB-containing irrigation solution, were tested in a cytotoxicity assay using L929 mouse fibroblasts (ISO 10993-5:2009). The PHMB-containing irrigation solution was then assessed in an in vitro human keratinocyte-fibroblast 3D full-thickness wounded skin model to determine its effect on wound healing over six days. The effect of the PHMB-containing irrigation solution on tissue viability was measured using a lactate dehydrogenase (LDH) assay, and proinflammatory effects were measured using an interleukin-6 (IL-6) production assay.

RESULTS

The PHMB-containing irrigation solution was shown to be equivalent to other commercially available cleansing and irrigation solutions when tested in the L929 fibroblast cytotoxicity assay. When assessed in the in vitro 3D human full-thickness wound healing model, the PHMB-containing irrigation solution treatment resulted in no difference in levels of LDH or IL-6 when compared with levels produced in control Dulbecco's phosphate-buffered saline cultures. There was, however, a pronounced tissue thickening of the skin model in the periwound region.

CONCLUSION

The experimental data presented in this study support the conclusion that the PHMB-containing irrigation solution has a safety profile similar to other commercially available cleansing and irrigation solutions. Evidence also suggests that the PHMB-containing irrigation solution does not affect tissue viability or proinflammatory cytokine production, as evidenced by LDH levels or the production of IL-6 in a 3D human full-thickness wound healing model. The PHMB-containing irrigation solution stimulated new tissue growth in the periwound region of the skin model.

Bringing innovative wound care polymer materials to the market: Challenges, developments, and new trends

The development of innovative products for treating acute and chronic wounds has become a significant topic in healthcare, resulting in numerous products and innovations over time. The growing number of patients with comorbidities and chronic diseases, which may significantly alter, delay, or inhibit normal wound healing, has introduced considerable new challenges into the wound management scenario. Researchers in academia have quickly identified promising solutions, and many advanced wound healing materials have recently been designed; however, their successful translation to the market remains highly complex and unlikely without the contribution of industry experts. This review article condenses the main aspects of wound healing applications that will serve as a practical guide for researchers working in academia and industry devoted to designing, evaluating, validating, and translating polymer wound care materials to the market. The article highlights the current challenges in wound management, describes the state-of-the-art products already on the market and trending polymer materials, describes the regulation pathways for approval, discusses current wound healing models, and offers a perspective on new technologies that could soon reach consumers. We envision that this comprehensive review will significantly contribute to highlighting the importance of networking and exchanges between academia and healthcare companies. Only through the joint of these two actors, where innovation, manufacturing, regulatory insights, and financial resources act in harmony, can wound care products be developed efficiently to reach patients quickly and affordably.

Assessing Animal Models to Study Impaired and Chronic Wounds

Impaired healing wounds do not proceed through the normal healing processes in a timely and orderly manner, and while they do eventually heal, their healing is not optimal. Chronic wounds, on the other hand, remain unhealed for weeks or months. In the US alone, chronic wounds impact ~8.5 million people and cost ~USD 28-90 billion per year, not accounting for the psychological and physical pain and emotional suffering that patients endure. These numbers are only expected to rise in the future as the elderly populations and the incidence of comorbidities such as diabetes, hypertension, and obesity increase. Over the last few decades, scientists have used a variety of approaches to treat chronic wounds, but unfortunately, to date, there is no effective treatment. Indeed, while there are thousands of drugs to combat cancer, there is only one single drug approved for the treatment of chronic wounds. This is in part because wound healing is a very complex process involving many phases that must occur sequentially and in a timely manner. Furthermore, models that fully mimic human chronic wounds have not been developed. In this review, we assess various models currently being used to study the biology of impaired healing and chronic non-healing wounds. Among them, this paper also highlights one model which shows significant promise; this model uses aged and obese db/db-/- mice and the chronic wounds that develop show characteristics of human chronic wounds that include increased oxidative stress, chronic inflammation, damaged microvasculature, abnormal collagen matrix deposition, a lack of re-epithelialization, and the spontaneous development of multi-bacterial biofilm. We also discuss how important it is that we continue to develop chronic wound models that more closely mimic those of humans and that can be used to test potential treatments to heal chronic wounds.

Establishing Primary and Stable Cell Lines from Frozen Wing Biopsies for Cellular, Physiological, and Genetic Studies in Bats

Bats stand out among mammalian species for their exceptional traits, including the capacity to navigate through flight and echolocation, conserve energy through torpor/hibernation, harbor a multitude of viruses, exhibit resistance to disease, survive harsh environmental conditions, and demonstrate exceptional longevity compared to other mammals of similar size. In vivo studies of bats can be challenging for several reasons such as ability to locate and capture them in their natural environments, limited accessibility, low sample size, environmental variation, long lifespans, slow reproductive rates, zoonotic disease risks, species protection, and ethical concerns. Thus, establishing alternative laboratory models is crucial for investigating the diverse physiological adaptations observed in bats. Obtaining quality cells from tissues is a critical first step for successful primary cell derivation. However, it is often impractical to collect fresh tissue and process the samples immediately for cell culture due to the resources required for isolating and expanding cells. As a result, frozen tissue is typically the starting resource for bat primary cell derivation. Yet, cells in frozen tissue are usually damaged and represent low integrity and viability. As a result, isolating primary cells from frozen tissues poses a significant challenge. Herein, we present a successfully developed protocol for isolating primary dermal fibroblasts from frozen bat wing biopsies. This protocol marks a significant milestone, as this the first protocol specially focused on fibroblasts isolation from bat frozen tissue. We also describe methods for primary cell characterization, genetic manipulation of primary cells through lentivirus transduction, and the development of stable cell lines. Basic Protocol 1: Bat wing biopsy collection and preservation Support Protocol 1: Blood collection from bat- venipuncture Basic Protocol 2: Isolation of primary fibroblasts from adult bat frozen wing biopsy Support Protocol 2: Maintenance of primary fibroblasts Support Protocol 3: Cell banking and thawing of primary fibroblasts Support Protocol 4: Growth curve and doubling time Support Protocol 5: Lentiviral transduction of bat primary fibroblasts Basic Protocol 3: Bat stable fibroblasts cell lines development Support Protocol 6: Bat fibroblasts validation by immunofluorescence staining Support Protocol 7: Chromosome counting.

Understanding the ideal wound healing mechanistic behavior using in silico modelling perspectives: A review

Complexity of the entire body precludes an accurate assessment of the specific contributions of tissues or cells during the healing process, which might be expensive and time consuming. Because of this, controlling the wound's size, depth, and dimensions may be challenging, and there is not yet an efficient and reliable chronic wound model representation. Furthermore, given the inherent challenges associated with conducting non-invasive in vivo investigations, it becomes peremptory to explore alternative methodologies for studying wound healing. In this context, biologically-realistic mathematical and computational models emerge as a valuable framework that can effectively address this need. Therefore, it might improve our approach to understanding the process at its core. This article will examines all facets of wound healing, including the kinds, pathways, and most current developments in wound treatment worldwide, particularly in silico modelling utilizing both mathematical and structure-based modelling techniques. It may be helpful to identify the crucial traits through the feedback loop of computer models and experimental investigations in order to build innovative therapies to cure wounds. Hence the effectiveness of personalised medicine and more targeted therapy in the healing of wounds may be enhanced by this interdisciplinary expertise.

Recent Achievements in the Development of Biomaterials Improved with Platelet Concentrates for Soft and Hard Tissue Engineering Applications

Platelet concentrates such as platelet-rich plasma, platelet-rich fibrin or concentrated growth factors are cost-effective autologous preparations containing various growth factors, including platelet-derived growth factor, transforming growth factor β, insulin-like growth factor 1 and vascular endothelial growth factor. For this reason, they are often used in regenerative medicine to treat wounds, nerve damage as well as cartilage and bone defects. Unfortunately, after administration, these preparations release growth factors very quickly, which lose their activity rapidly. As a consequence, this results in the need to repeat the therapy, which is associated with additional pain and discomfort for the patient. Recent research shows that combining platelet concentrates with biomaterials overcomes this problem because growth factors are released in a more sustainable manner. Moreover, this concept fits into the latest trends in tissue engineering, which include biomaterials, bioactive factors and cells. Therefore, this review presents the latest literature reports on the properties of biomaterials enriched with platelet concentrates for applications in skin, nerve, cartilage and bone tissue engineering.

Features of apoptotic and proliferative processes in experimental infected radiation-induced skin ulcer under conditions of photodynamic therapy and the use of platelet-rich plasma

OBJECTIVE

. Aim: The purpose of the study was to identify the features of apoptotic and proliferative processes in experimental Staphylococcus aureus-infected radiation skin ulcer under conditions of photodynamic therapy and the use of platelet-rich plasma.

PATIENTS AND METHODS

Materials and Methods: An experimental study was conducted on 95 six-month-old male rats of the WAG population, which were divided into three groups. Group 1 included 25 animals that were simulated a radiation ulcer of the skin in the thigh area with subsequent application to its surface on the 7th day after irradiation with 0.2 ml of a suspension of the Staphylococcus aureus (ATCC 25923) reference strain (0.5 million microbial cells/cm2). Group 2 included 25 animals with Staphylococcus aureus-infected radiation skin ulcer, which were subjected to photodynamic therapy a day after infection. Group 3 included 45 animals with Staphylococcus aureus-infected radiation skin ulcers, which, 1 day after infection, received photodynamic therapy in the first half of the day, and in the second half of the day the periphery of the wound defect was injected with platelet-rich plasma. The material for the study was skin with underlying soft tissues from the area of radiation exposure. Histological, immunohistochemical, morphometric and statistical methods were used.

RESULTS

Results: In cases of simultaneous use of photodynamic therapy and platelet-rich plasma, compared with photodynamic therapy alone, the processes ofapoptosis and proliferation were more balanced, active, with a shift in the proliferative-apoptotic ratio towards proliferation processes and met the needs of the regenerative process. From the 10th to the 22nd day of the experiment these processes increased, which indicated active healing processes, that, during survey microscopy on the 22nd day, were manifested by the complete filling of the wound cavity with granulation and connective tissues with the presence of an epithelial layer on the surface of the regenerate. From the 22nd to the 45th day of the experiment, a decrease in the rate of regeneration was recorded, as evidenced by a decrease in the intensity of apoptotic and proliferative processes. The intensity of the latter was sufficient, which led to the healing of Staphylococcus aureus-infected radiation skin ulcer on the 45th day with complete restoration of the original structure of the skin.

CONCLUSION

Conclusions: Photodynamic therapy in combination with the use of platelet-rich plasma balancedly activates apoptotic and proliferative processes with a predominance of the latter in granulation and connective tissues filling the lumen of Staphylococcus aureus-infected radiation skin ulcer, which on the 45th day of the experiment leads to wound healing with complete restoration of the original structure of the skin.

A multi-functional double cross-linked chitosan hydrogel with tunable mechanical and antibacterial properties for skin wound dressing

Chitosan hydrogels with essential antibacterial properties and biocompatibility have great potential in tissue engineering and regeneration medicine. However, pure chitosan hydrogel could be limited by insufficient mechanical properties. In this work, we designed a multi-functional chitosan hydrogel based on the combination of chitosan methacrylate (CTSMA) and sulfhydrated chitosan (CTSSH), which is cross-linked simultaneously by free-radical polymerization reaction and Thiol-ene reaction. The CTSMA/CTSSH (CMS) hydrogels displayed superior tissue adhesive and mechanical properties when compared to pure CTSMA hydrogel. Additionally, the resulting hydrogels exhibited potent antimicrobial effects against both E. coli and S. aureus. Besides, the CMS hydrogels exhibited good biocompatibility as demonstrated by cytotoxicity and cell proliferation experiments using fibroblasts cells (L929) and adipose-derived stem cells (ADSCs). In vivo experiment, the repairing effect of hydrogels on full-thickness skin defect model in rats was studied. Histological and immunohistochemical staining results showed that CMS hydrogels promoted angiogenesis, dermal repair and epidermal regeneration. Overall, the study highlights the potential of the CMS hydrogels as a promising biomaterial in wound healing applications.

An effective device to enable consistent scratches for in vitro scratch assays

BACKGROUND

The in-vitro scratch assay is a useful method in wound healing research to assess cell migration. In this assay, a scratch is created in a confluent cell layer by mechanically removing cells through manual scraping with a sharp-edged tool. This step is traditionally done with pipette tips and is unsuitable for high-throughput assays, as the created scratches are highly variable in width and position. Commercially available solutions are often expensive, and require specific cultureware which might not be suitable for all studies.

RESULTS

In this study, we have developed a flexible cell scratch device comprising a single wounding tool, a guide and an imaging template for consistent and reproducible scratch assays in 96-well plates. Our results showed that the device produced a more consistent scratch profile compared to the conventional method of using pipette tips. The imaging template also allowed operators to easily locate and image the same region of interest at different time points, which potentially could be used for other assays.

CONCLUSIONS

Our flexible yet effective scratch device thus enables robust scratch assays that can be applied to different experimental needs, providing researchers with an easy and reliable tool for their studies.

Effect of Betulin Colloidal Particles on Proliferation and Cytokine Secretion of Human Skin Fibroblasts

The aim of the study was to obtain untreated and treated betulin colloidal particles and assess their effect on the viability, morphology, proliferation and cytokine secretion of human dermal fibroblasts. To improve bioavailability, betulin treatment was performed by an antisolvent precipitation technique. The average particle size after treatment in the aqueous dispersion decreased from 552.9 ± 11.3 to 278.2 ± 1.6 nm. Treated betulin colloidal particles showed no cytotoxicity up to a concentration of 400 µg·mL-1 in the colorimetric tetrazolium salt viability test (CCK-8). Moreover, the cell morphology was not changed in the presence of betulin colloidal particles at a concentration range from 0.78 to 400 µg·mL-1. The obtained results also show that betulin particles induce the secretion of the proinflammatory and angiogenesis-stimulating cytokine IL-8. However, further studies would be required to clarify the mechanism of IL-8 secretion induction.