Inflammatory Microenvironment of Skin Wounds

Double Enzyme Active Hydrogel Program Regulates the Microenvironment of Staphylococcus aureus-Infected Pressure Ulcers

The treatment of infected pressure ulcers (IUPs) requires addressing diverse microenvironments. A pressing challenge is to effectively enhance the regenerative microenvironment at different stages of the healing process, tailoring interventions as needed. Here, a dual enzyme mimetic and bacterial responsive self-activating antimicrobial hydrogel designed to enhance IPUs healing is introduced. This hydrogel incorporates pH-responsive dual enzyme-active nanoplatforms (HNTs-Fe-Ag) encapsulated within a methacrylate-modified silk fibroin (SFMA) and dopamine methacrylamide (DMA) matrix. This composite hydrogel exhibits adaptive microenvironment regulation capabilities. Under the low pH microenvironment of bacterial infection, it has excellent antimicrobial activity by self-activating the •OH generation in conjunction with photothermal effects. Under the neutral and alkaline microenvironment of chronic inflammation, it catalyzes the decomposition of hydrogen peroxide (H2O2) to produce oxygen (O2), thereby alleviating hypoxia and scavenging reactive oxygen species (ROS), which in turn remodulates the phenotype of macrophages. The composite hydrogel demonstrates on-demand therapeutic effects in the microenvironment of infected wounds, significantly enhancing the regenerative microenvironment of IUPs by promoting wound closure, inflammation regulation, and collagen deposition through self-activated antimicrobial action during infection and adaptive hypoxia relief during recovery. This approach offers a novel strategy for developing smart wound dressings.

Lactobacillus rhamnosus GG and Bifidobacterium animalis subsp. lactis BB-12 promote infected wound healing via regulation of the wound microenvironment

Infected wounds can result in complex clinical complications and delayed healing, presenting a significant global public health challenge. This study explored the effects of topical application of two probiotics, Lactobacillus rhamnosus GG (LGG) and Bifidobacterium animalis subsp. lactis BB-12, on the microenvironment of infected wounds and their impact on wound healing. LGG and BB-12 were applied separately and topically on the Staphylococcus aureus (S. aureus)-infected skin wounds of the rat model on a daily basis. Both probiotics significantly accelerated wound healing, demonstrated by enhanced granulation tissue formation and increased collagen deposition, with BB-12 showing superior efficacy. LGG and BB-12 both effectively inhibited neutrophil infiltration and decreased the expression of pro-inflammatory cytokines tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). Notably, BB-12 markedly reduced IL-6 levels, while LGG significantly lowered TNF-α, transforming growth factor-β (TGF-β) and vascular endothelial growth factor (VEGF). Additionally, both probiotics promoted macrophage polarization towards the anti-inflammatory M2 phenotype. Microbiota analysis revealed that LGG and BB-12 significantly decreased the abundance of pathogenic bacteria (e.g. Staphylococcus and Proteus) and increased the proportion of beneficial bacteria (e.g. Corynebacterium). Particularly, BB-12 was more effective in reducing Staphylococcus abundance, whereas LGG excelled in promoting Corynebacterium growth. These findings suggest the ability of LGG and BB-12 to modulate the wound microenvironment, enhance wound healing and provide valuable insights for the management of infected wounds.

Lymphangiogenesis: novel strategies to promote cutaneous wound healing

The cutaneous lymphatic system regulates tissue inflammation, fluid balance and immunological responses. Lymphangiogenesis or lymphatic dysfunction may lead to lymphedema, immune deficiency, chronic inflammation etc. Tissue regeneration and healing depend on angiogenesis and lymphangiogenesis during wound healing. Tissue oedema and chronic inflammation can slow wound healing due to impaired lymphangiogenesis or lymphatic dysfunction. For example, impaired lymphangiogenesis or lymphatic dysfunction has been detected in nonhealing wounds such as diabetic ulcers, venous ulcers and bedsores. This review summarizes the structure and function of the cutaneous lymphatic vessel system and lymphangiogenesis in wounds. Furthermore, we review wound lymphangiogenesis processes and remodelling, especially the influence of the inflammatory phase. Finally, we outline how to control lymphangiogenesis to promote wound healing, assess the possibility of targeting lymphangiogenesis as a novel treatment strategy for chronic wounds and provide an analysis of the possible problems that need to be addressed.

Bioinspired Collagen Scaffold Loaded with bFGF-Overexpressing Human Mesenchymal Stromal Cells Accelerating Diabetic Skin Wound Healing via HIF-1 Signal Pathway Regulated Neovascularization

The healing of severe chronic skin wounds in chronic diabetic patients is still a huge clinical challenge due to complex regeneration processes and control signals. Therefore, a single approach is difficult in obtaining satisfactory therapeutic efficacy for severe diabetic skin wounds. In this study, we adopted a composite strategy for diabetic skin wound healing. First, we fabricated a collagen-based biomimetic skin scaffold. The human basic fibroblast growth factor (bFGF) gene was electrically transduced into human umbilical cord mesenchymal stromal cells (UC-MSCs), and the stable bFGF-overexpressing UC-MSCs (bFGF-MSCs) clones were screened out. Then, an inspired collagen scaffold loaded with bFGF-MSCs was applied to treat full-thickness skin incision wounds in a streptozotocin-induced diabetic rat model. The mechanism of skin damage repair in diabetes mellitus was investigated using RNA-Seq and Western blot assays. The bioinspired collagen scaffold demonstrated good biocompatibility for skin-regeneration-associated cells such as human fibroblast (HFs) and endothelial cells (ECs). The bioinspired collagen scaffold loaded with bFGF-MSCs accelerated the diabetic full-thickness incision wound healing including cell proliferation enhancement, collagen deposition, and re-epithelialization, compared with other treatments. We also showed that the inspired skin scaffold could enhance the in vitro tube formation of ECs and the early angiogenesis process of the wound tissue in vivo. Further findings revealed enhanced angiogenic potential in ECs stimulated by bFGF-MSCs, evidenced by increased AKT phosphorylation and elevated HIF-1α and HIF-1β levels, indicating the activation of HIF-1 pathways in diabetic wound healing. Based on the superior biocompatibility and bioactivity, the novel bioinspired skin healing materials composed of the collagen scaffold and bFGF-MSCs will be promising for healing diabetic skin wounds and even other refractory tissue regenerations. The bioinspired collagen scaffold loaded with bFGF-MSCs could accelerate diabetic wound healing via neovascularization by activating HIF-1 pathways.

MOFs and MOF-Based Composites as Next-Generation Materials for Wound Healing and Dressings

In recent years, there has been growing interest in developing innovative materials and therapeutic strategies to enhance wound healing outcomes, especially for chronic wounds and antimicrobial resistance. Metal-organic frameworks (MOFs) represent a promising class of materials for next-generation wound healing and dressings. Their high surface area, pore structures, stimuli-responsiveness, antibacterial properties, biocompatibility, and potential for combination therapies make them suitable for complex wound care challenges. MOF-based composites promote cell proliferation, angiogenesis, and matrix synthesis, acting as carriers for bioactive molecules and promoting tissue regeneration. They also have stimuli-responsivity, enabling photothermal therapies for skin cancer and infections. Herein, a critical analysis of the current state of research on MOFs and MOF-based composites for wound healing and dressings is provided, offering valuable insights into the potential applications, challenges, and future directions in this field. This literature review has targeted the multifunctionality nature of MOFs in wound-disease therapy and healing from different aspects and discussed the most recent advancements made in the field. In this context, the potential reader will find how the MOFs contributed to this field to yield more effective, functional, and innovative dressings and how they lead to the next generation of biomaterials for skin therapy and regeneration.

Extracellular Vesicles Derived from Opuntia ficus-indica Fruit (OFI-EVs) Speed Up the Normal Wound Healing Processes by Modulating Cellular Responses

Plant-derived extracellular vesicles (EVs) have been recognized as important mediators of intercellular communication able to transfer active biomolecules across the plant and animal kingdoms. EVs have demonstrated an impressive array of biological activities, displaying preventive and therapeutic potential in mitigating various pathological processes. Indeed, the simplicity of delivering exogenous and endogenous bioactive molecules to mammalian cells with their low cytotoxicity makes EVs suitable agents for new therapeutic strategies for a variety of pathologies. In this study, EVs were isolated from Opuntia ficus-indica fruit (OFI-EVs) and characterized by particle size distribution, concentration, and bioactive molecule composition. OFI-EVs had no obvious toxicity and demonstrated a protective role in the inflammatory process and oxidative stress in vitro model of chronic skin wounds. The results demonstrated that pretreatment with OFI-EVs decreased the activity and gene expression of pro-inflammatory cytokines (IL-6, IL-8, and TNF-α) in the LPS-stimulated human leukemia monocytic cell line (THP-1). Furthermore, OFI-EVs promote the migration of human dermal fibroblasts (HDFs), speeding up the normal wound healing processes. This study sheds light, for the first time, on the role of OFI-EVs in modulating important biological processes such as inflammation and oxidation, thereby identifying EVs as potential candidates for healing chronic cutaneous wounds.

A Dynamic Protocol to Explore NLRP3 Inflammasome Activation in Cerebral Organoids

The NLRP3 inflammasome plays a crucial role in the inflammatory response, reacting to pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs). This response is essential for combating infections and restoring tissue homeostasis. However, chronic activation can lead to detrimental effects, particularly in neuropsychiatric and neurodegenerative diseases. Our study seeks to provide a method to effectively measure the NLRP3 inflammasome's activation within cerebral organoids (COs), providing insights into the underlying pathophysiology of these conditions and enabling future studies to investigate the development of targeted therapies.

Exploring the Wound Healing Potential of a Cuscuta chinensis Extract-Loaded Nanoemulsion-Based Gel

Cuscuta chinensis (C. chinensis) presents many pharmacological activities, including antidiabetic effects, and antioxidant, anti-inflammatory, and antitumor properties. However, the wound care properties of this plant have not yet been reported. Therefore, this research aimed to evaluate the antioxidant, anti-inflammatory, and antibacterial activities of ethanol and ethyl acetate C. chinensis extracts. The phytochemical markers in the extracts were analyzed using high-performance liquid chromatography (HPLC). Then, the selected C. chinensis extract was developed into a nanoemulsion-based gel for wound care testing in rats. The results showed that both of the C. chinensis extracts exhibited antioxidant activity when tested using 2,2-Diphenyl-1-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP), and lipid peroxidation inhibition assays. They reduced the expression of IL-1β, IL-6, and TNF-α in RAW264.7 cells induced with lipopolysaccharide (LPS). The ethyl acetate extract also had antibacterial properties. Kaempferol was found in both extracts, whereas hyperoside was found only in the ethanol extract. These compounds were found to be related to the biological activities of the extracts, confirmed via molecular docking. The C. chinensis extract-loaded nanoemulsions had a small particle size, a narrow polydispersity index (PDI), and good stability. Furthermore, the C. chinensis extract-loaded nanoemulsion-based gel had a positive effect on wound healing, presenting a better percentage wound contraction Fucidin cream. In conclusion, this formulation has the potential for use as an alternative wound treatment and warrants further study in clinical trials.

Engineering Copper-Containing Nanoparticles-Loaded Silicene Nanosheets with Triple Enzyme Mimicry Activities and Photothermal Effect for Promoting Bacteria-Infected Wound Healing

Skin wounds accompanied by bacterial infections threaten human health, and conventional antibiotic treatments are ineffective for drug-resistant bacterial infections and chronically infected wounds. The development of non-antibiotic-dependent therapeutics is highly desired but remains a challenging issue. Recently, 2D silicene nanosheets with considerable biocompatibility, biodegradability, and photothermal-conversion performance have received increasing attention in biomedical fields. Herein, copper-containing nanoparticles-loaded silicene (Cu2.8O@silicene-BSA) nanosheets with triple enzyme mimicry catalytic (peroxidase, catalase, and oxidase-like) activities and photothermal function are rationally designed and fabricated for efficient bacterial elimination, angiogenesis promotion, and accelerated wound healing. Cu2.8O@silicene-BSA nanosheets display excellent antibacterial activity through synergistic effects of reactive oxygen species generated from multiple catalytic reactions, intrinsic bactericidal activity of released Cu2+ ions, and photothermal effects, achieving high antibacterial efficiencies on methicillin-resistant Staphylococcus aureus (MRSA) of 99.1 ± 0.7% in vitro and 97.2 ± 1.6% in vivo. In addition, Cu2.8O@silicene-BSA nanosheets exhibit high biocompatibility for promoting human umbilical vein endothelial cell (HUVEC) proliferation and angiogenic differentiation. In vivo experiments reveal that Cu2.8O@silicene-BSA nanosheets with synergistic photothermal/chemodynamic therapeutics effectively accelerate MRSA-infected wound healing by eliminating bacteria, alleviating inflammation, boosting collagen deposition, and promoting angiogenesis. This research presents a promising strategy to engineer photothermal-assisted nanozyme catalysis for bacteria-invaded wound healing.

Wound Repair and Ca2+ Signalling Interplay: The Role of Ca2+ Channels in Skin

The process of wound healing is intricate and tightly controlled, involving a number of different cellular and molecular processes. Numerous cellular functions, especially those related to wound healing, depend critically on calcium ions (Ca2+). Ca2+ channels are proteins involved in signal transduction and communication inside cells that allow calcium ions to pass through cell membranes. Key Ca2+ channel types involved in wound repair are described in this review.

Gelatin but not type I collagen promotes bacteria phagocytosis in PMA-treated U937 human lymphoma cells

PURPOSE

Besides comprising scaffolding, extracellular matrix components modulate many biological processes including inflammation and cell differentiation. We previously found precoating cell plates with extracellular matrix collagen I, or its denatured product gelatin, causes aggregation of macrophage-like human lymphoma U937 cells, which are induced to differentiation by phorbol myristate treatment. In the present study, we investigated the influence of gelatin or collagen I precoating on the bacteria phagocytosis in PMA-stimulated U937 cells.

MATERIALS AND METHODS

Colony forming units of phagocytosed bacteria, Giemsa-staining of cells with phagocytosed bacteria, confocal microscopic and flow cytometric analysis of cells with phagocytosed FITC-labeled bacteria and non-bioactive latex beats were conducted.

RESULTS

Gelatin precoating enhances the phagocytosis of both Gram-negative and positive bacteria, as shown by the increased colony forming units of bacteria phagocytosed by cells, and increased intracellular bacteria observed after Giemsa-staining. But collagen I has no marked influence. Confocal microscopy reveals that both live and dead FITC-bacteria were phagocytosed more in the cells with gelatin-coating but not collagen-coating. Of note, both gelatin and collagen I coating had no influence on the phagocytosis of non-bioactive latex beads. Since gelatin-coating increases autophagy but collagen I has no such impact, we are curious about the role of autophagy. Inhibiting autophagy reduced the phagocytosis of bacteria, in cells with gelatin-coating, while stimulating autophagy enhanced phagocytosis.

CONCLUSION

This study finds the bacteria-phagocytosis stimulatory effect of gelatin in PMA-treated U937 cells and reveals the positive regulatory role of autophagy, predicting the potential use of gelatin products in anti-bacterial therapy.

Role of Hemigraphis alternata in wound healing: metabolomic profiling and molecular insights into mechanisms

Hemigraphis alternata (H. alternata), commonly known as Red Flame Ivy, is widely recognized for its wound healing capabilities. However, the pharmacologically active plant components and their mechanisms of action in wound healing are yet to be determined. This study presents the mass spectrometry-based global metabolite profiling of aqueous and ethanolic extract of H. alternata leaves. The analysis identified 2285 metabolites from 24,203 spectra obtained in both positive and negative polarities. The identified metabolites were classified under ketones, carboxylic acids, primary aliphatic amines, steroids and steroid derivatives. We performed network pharmacology analysis to explore metabolite-protein interactions and identified 124 human proteins as targets for H. alternata metabolites. Among these, several of them were implicated in wound healing including prothrombin (F2), alpha-2A adrenergic receptor (ADRA2A) and fibroblast growth factor receptor 1 (FGFR1). Gene ontology analysis of target proteins enriched cellular functions related to glucose metabolic process, platelet activation, membrane organization and response to wounding. Additionally, pathway enrichment analysis revealed potential molecular network involved in wound healing. Moreover, in-silico docking analysis showed strong binding energy between H. alternata metabolites with identified protein targets (F2 and PTPN11). Furthermore, the key metabolites involved in wound healing were further validated by multiple reaction monitoring-based targeted analysis.

Nanozyme-Engineered Hydrogels for Anti-Inflammation and Skin Regeneration

Inflammatory skin disorders can cause chronic scarring and functional impairments, posing a significant burden on patients and the healthcare system. Conventional therapies, such as corticosteroids and nonsteroidal anti-inflammatory drugs, are limited in efficacy and associated with adverse effects. Recently, nanozyme (NZ)-based hydrogels have shown great promise in addressing these challenges. NZ-based hydrogels possess unique therapeutic abilities by combining the therapeutic benefits of redox nanomaterials with enzymatic activity and the water-retaining capacity of hydrogels. The multifaceted therapeutic effects of these hydrogels include scavenging reactive oxygen species and other inflammatory mediators modulating immune responses toward a pro-regenerative environment and enhancing regenerative potential by triggering cell migration and differentiation. This review highlights the current state of the art in NZ-engineered hydrogels (NZ@hydrogels) for anti-inflammatory and skin regeneration applications. It also discusses the underlying chemo-mechano-biological mechanisms behind their effectiveness. Additionally, the challenges and future directions in this ground, particularly their clinical translation, are addressed. The insights provided in this review can aid in the design and engineering of novel NZ-based hydrogels, offering new possibilities for targeted and personalized skin-care therapies.

Hydrogel-Based Skin Regeneration

The skin is subject to damage from the surrounding environment. The repair of skin wounds can be very challenging due to several factors such as severe injuries, concomitant infections, or comorbidities such as diabetes. Different drugs and wound dressings have been used to treat skin wounds. Tissue engineering, a novel therapeutic approach, revolutionized the treatment and regeneration of challenging tissue damage. This field includes the use of synthetic and natural biomaterials that support the growth of tissues or organs outside the body. Accordingly, the demand for polymer-based therapeutic strategies for skin tissue defects is significantly increasing. Among the various 3D scaffolds used in tissue engineering, hydrogel scaffolds have gained special significance due to their unique properties such as natural mimicry of the extracellular matrix (ECM), moisture retention, porosity, biocompatibility, biodegradability, and biocompatibility properties. First, this article delineates the process of wound healing and conventional methods of treating wounds. It then presents an examination of the structure and manufacturing methods of hydrogels, followed by an analysis of their crucial characteristics in healing skin wounds and the most recent advancements in using hydrogel dressings for this purpose. Finally, it discusses the potential future advancements in hydrogel materials within the realm of wound healing.

Hyaluronic Acid-Based Reactive Oxygen Species-Responsive Multifunctional Injectable Hydrogel Platform Accelerating Diabetic Wound Healing

Diabetic wounds are more likely to develop into complex and severe chronic wounds. The objective of this study is to develop and assess a reactive oxygen species (ROS)-responsive multifunctional injectable hydrogel for the purpose of diabetic wound healing. A multifunctional hydrogel (HA@Cur@Ag) is successfully synthesized with dual antioxidant, antibacterial, and anti-inflammatory properties by crosslinking thiol hyaluronic acid (SH-HA) and disulfide-bonded hyperbranched polyethylene glycol (HB-PBHE) through Michael addition; while, incorporating curcumin liposomes and silver nanoparticles (AgNPs). The HA@Cur@Ag hydrogel exhibits favorable biocompatibility, degradability, and injectivity. The outcomes of in vitro and in vivo experiments demonstrate that the hydrogel can effectively be loaded with and release curcumin liposomes, as well as silver ions, thereby facilitating diabetic wound healing through multiple mechanisms, including ROS scavenging, bactericidal activity, anti-inflammatory effects, and the promotion of angiogenesis. Transcriptome sequencing reveals that the HA@Cur@Ag hydrogel effectively suppresses the activation of the tumour necrosis factor (TNF)/nuclear factor κB (NF-κB) pathway to ameliorate oxidative stress and inflammation in diabetic wounds. These findings suggest that this ROS-responsive multifunctional injectable hydrogel, which possesses the ability to precisely coordinate and integrate intricate biological and molecular processes involved in wound healing, exhibits notable potential for expediting diabetic wound healing.

Biobran-loaded core/shell nanofibrous scaffold: a promising wound dressing candidate

This research examined the effectiveness of Biobran as a bioactive substance that could potentially improve wound healing. It also looked at how Biobran affects the properties of a nanofibrous scaffold made through coaxial electrospinning. This is the first study exploring the use of Biobran in this context and its interaction with nanofibrous scaffolds. The scaffolds were composed of poly(ε-caprolactone) (PCL) in the shell and various concentrations of Biobran blended with polyvinyl alcohol (PVA) in the core. The properties of the scaffolds were characterized by SEM, TEM, FTIR, XRD, TGA, DSC, stress-strain test, WCA, release test, MTT cytotoxicity assay, wound scratching assay, and the dye exclusion method using trypan blue. The scaffolds loaded with Biobran exhibited a more compact and smooth morphology compared with the scaffold without Biobran. The physical interaction and crystallinity of the polymers in the scaffolds were also affected by Biobran in a concentration-dependent manner. This positively influenced their tensile strength, elongation at break, thermal stability, and hydrophilicity. The porosity, water uptake capacity, and WVTR of the nanofibrous scaffolds are within the optimal ranges for wound healing. The release rate of Biobran, which revealed a biphasic release pattern, decreased with increasing Biobran concentration, resulting in controlled and sustained delivery of Biobran from the nanofiber scaffolds. The cell viability assays showed a dose-dependent effect of Biobran on WISH cells, which might be attributed to the positive effect of Biobran on the physicochemical properties of the nanofibrous scaffolds. These findings suggest that Biobran-loaded core/shell nanofiber scaffolds have a potential application in wound healing as an ideal multifunctional wound dressing.

Mechanism and application of β-adrenoceptor blockers in soft tissue wound healing

Soft tissue damage stimulates sympathetic nerves to release large amounts of catecholamine hormones which bind to β-adrenergic receptors (β-ARs) on the cell membrane surface. It activates the downstream effector molecules and impairs soft tissue wound healing. β-blockers specifically inhibit β-ARs activation in acute/chronic skin lesions and ulcerative hemangiomas. They also accelerate soft tissue wound healing by shortening the duration of inflammation, speeding keratinocyte migration and reepithelialization, promoting wound contraction and angiogenesis, and inhibiting bacterial virulence effects. In addition, β-blockers shorten wound healing periods in patients with severe thermal damage by reducing the hypermetabolic response. While β-blockers promote/inhibit corneal epithelial cell regeneration and restores limbal stem/progenitor cells function, it could well accelerate/delay corneal wound healing. Given these meaningful effects, a growing number of studies are focused on examining the efficacy and safety of β-blockers in soft tissue wound repair, including acute and chronic wounds, severe thermal damage, ulcerated infantile hemangioma, corneal wounds, and other soft tissue disorders. However, an intensive investigation on their acting mechanisms is imperatively needed. The purpose of this article is to summerize the roles of β-blockers in soft tissue wound healing and explore their clinical applications.

Advances in Chronic Wound Management: From Conventional Treatment to Novel Therapies and Biological Dressings

Chronic wounds can be classified as diabetic foot ulcers, pressure ulcers, or venous leg ulcers. Chronic wound management has become a threat to clinicians and constitutes a major healthcare burden. The healing process of chronic wounds requires many factors to work in concert to achieve optimal healing. Various treatment options, ranging from hypoxia to infection, have evolved considerably to address the challenges associated with chronic wound healing. The conventional and accelerating treatments for chronic wounds still represent an unmet medical need due to the complex pathophysiology of the chronic wound microenvironment. In clinical settings, traditional chronic wound care practices rely on nonspecific topical treatment, which can reduce pain and alleviate disease progression with varying levels of success but fail to completely cure the wounds. Conventional wound dressings, such as hydrocolloids, gauze, foams, and films, have also shown limited success for the treatment of chronic wounds and only act as a physical barrier and absorb wound exudates. Emerging advances in treatment approaches, including novel therapies (stem cells, microRNAs, and nanocarrier-based delivery systems) and multifunctional biological dressings, have been reported for chronic wound repair. This review summarizes the challenges offered by chronic wounds and discusses recent advancements in chronic wound treatment.

Skin innate immune response against fungal infections and the potential role of trained immunity

Fungal skin infections are distributed worldwide and can be associated with economic and social traits. The immune response related to skin cells is complex and its understanding is essential to the comprehension of each cell's role and the discovery of treatment alternatives. The first studies of trained immunity (TI) described the ability of monocytes, macrophages and natural killer (NK) cells to develop a memory-like response. However, the duration of TI does not reflect the shorter lifespan of these cells. These conclusions supported later studies showing that TI can be observed in stem and haematopoietic cells and, more recently, also in non-immune skin cells such as fibroblasts, highlighting the importance of resident cells in response to skin disorders. Besides, the participation of less studied proinflammatory cytokines in the skin immune response, such as IL-36γ, shed light into a new possibility of inflammatory pathway blockade by drugs. In this review, we will discuss the skin immune response associated with fungal infections, the role of TI in skin and clinical evidence supporting opportunities and challenges of TI and other inflammatory responses in the pathogenesis of fungal skin infections.

Advancements in engineered exosomes for wound repair: current research and future perspectives

Wound healing is a complex and prolonged process that remains a significant challenge in clinical practice. Exosomes, a type of nanoscale extracellular vesicles naturally secreted by cells, are endowed with numerous advantageous attributes, including superior biocompatibility, minimal toxicity, and non-specific immunogenicity. These properties render them an exceptionally promising candidate for bioengineering applications. Recent advances have illustrated the potential of exosome therapy in promoting tissue repair. To further augment their therapeutic efficacy, the concept of engineered exosomes has been proposed. These are designed and functionally modifiable exosomes that have been tailored on the attributes of natural exosomes. This comprehensive review delineates various strategies for exosome engineering, placing specific emphasis on studies exploring the application of engineered exosomes for precision therapy in wound healing. Furthermore, this review sheds light on strategies for integrating exosomes with biomaterials to enhance delivery effectiveness. The insights presented herein provide novel perspectives and lay a robust foundation for forthcoming research in the realm of cutaneous wound repair therapies.

Gallium-based metal-organic frameworks loaded with antimicrobial peptides for synergistic killing of drug-resistant bacteria

Increased antibiotic resistance has made bacterial infections a global concern, which requires novel non-antibiotic-dependent antibacterial strategies to address the menace. Antimicrobial peptides (AMPs) are a promising antibiotic alternative, whose antibacterial mechanism is mainly to destroy the membrane of bacteria. Gallium ions exhibit an antibacterial effect by interfering with the iron metabolism of bacteria. With the rapid development of nanotechnology, it is worth studying the potential of gallium-AMP-based nanocomposites for treating bacterial infections. Herein, novel gallium-based metal-organic frameworks (MOFs) were synthesized at room temperature, followed by in situ loading of the model AMP melittin. The obtained nanocomposites exhibited stronger antibacterial activity than pure MEL and gallium ions, achieving the effects of "one plus one is greater than two". Moreover, the nanocomposites showed favorable biocompatibility and accelerated healing of a wound infected by methicillin-resistant Staphylococcus aureus by down-regulation of inflammatory cytokines IL-6 and TNF-α. This work presents an innovative antibacterial strategy to overcome the antibiotic resistance crisis and expand the application of AMPs.

The anti-inflammation and skin-moisturizing effects of Boehmeria tricuspis-mediated biosynthesized gold nanoparticles in human keratinocytes

Introduction: Recently, nanotechnology has emerged as a potential technique for skin generation, which has several treatment advantages, such as decreased drug cytotoxicity and enhanced skin penetration. Boehmeria tricuspis (BT) belongs to the Urticaceae family and is rich in phenolic and flavonoid compounds. In this study, we biosynthesized gold nanoparticles (BT-AuNPs) using BT extract to explore their anti-inflammatory and skin-moisturizing properties in keratinocytes. Methods: Field-emission transmission electron microscopy, energydispersive X-ray spectrometry, dynamic light scattering, and Fourier-transforminfrared spectroscopy were used to examine the synthesized BT-AuNPs. qRT-PCR, western blot, and ELISA were applied for investigating the effect of BT-AuNPs on anti-inflammation and moisturizing activity in HaCaT cells. Results: At concentrations below 200 μg/mL, BT-AuNPs had no cytotoxic effect on keratinocytes. BT-AuNPs dramatically alleviated the expression and secretion of inflammatory chemokines/cytokine, such as IL-6, IL-8, TARC, CTACK, and RANTES in keratinocytes stimulated by tumor necrosis factor-α/interferon-γ (T + I). These anti-inflammatory properties of BT-AuNPs were regulated by inhibiting the NF-κB and MAPKs signaling pathways. Furthermore, BT-AuNPs greatly promoted hyaluronic acid (HA) production by enhancing the expression of hyaluronic acid synthase genes (HAS1, HAS2, and HAS3) and suppressing the expression of hyaluronidase genes (HYAL1 and HYAL2) in HaCaT cells. Discussion: These results suggest that BT-AuNPs can be used as a promising therapeutic alternative for treating skin inflammation. Our findings provide a potential platform for the use of BT-AuNPs as candidates for treating inflammatory skin diseases and promoting skin health.

Utilization of Lyotropic Liquid Crystalline Gels for Chronic Wound Management

Management of chronic wounds is becoming a serious health problem worldwide. To treat chronic wounds, a suitable healing environment and sustained delivery of growth factors must be guaranteed. Different therapies have been applied for the treatment of chronic wounds such as debridement and photodynamic therapy. Among them, growth factors are widely used therapeutic drugs. However, at present, growth factor delivery systems cannot meet the demand of clinical practice; therefore new methods should be developed to meet the emerging need. For this reason, researchers have tried to modify hydrogels through some methods such as chemical synthesis and molecule modifications to enhance their properties. However, there are still a large number of limitations in practical use like byproduct problems, difficulty to industrialize, and instability of growth factor. Moreover, applications of new materials like lyotropic liquid crystalline (LLC) on chronic wounds have emerged as a new trend. The structure of LLC is endowed with many excellent properties including low cost, ordered structure, and excellent loading efficiency. LLC can provide a moist local environment for the wound, and its lattice structure can embed the growth factors in the water channel. Growth factor is released from the high-concentration carrier to the low-concentration release medium, which can be precisely regulated. Therefore, it can provide sustained and stable delivery of growth factors as well as a suitable healing environment for wounds, which is a promising candidate for chronic wound healing and has a broad prospective application. In conclusion, more reliable and applicable drug delivery systems should be designed and tested to improve the therapy and management of chronic wounds.

Fibroblasts - the cellular choreographers of wound healing

Injuries to our skin trigger a cascade of spatially- and temporally-synchronized healing processes. During such endogenous wound repair, the role of fibroblasts is multifaceted, ranging from the activation and recruitment of innate immune cells through the synthesis and deposition of scar tissue to the conveyor belt-like transport of fascial connective tissue into wounds. A comprehensive understanding of fibroblast diversity and versatility in the healing machinery may help to decipher wound pathologies whilst laying the foundation for novel treatment modalities. In this review, we portray the diversity of fibroblasts and delineate their unique wound healing functions. In addition, we discuss future directions through a clinical-translational lens.

A Multifunctional Polyethylene Glycol/Triethoxysilane-Modified Polyurethane Foam Dressing with High Absorbency and Antiadhesion Properties Promotes Diabetic Wound Healing

The delayed healing of chronic wounds, such as diabetic foot ulcers (DFUs), is a clinical problem. Few dressings can promote wound healing by satisfying the demands of chronic wound exudate management and tissue granulation. Therefore, the aim of this study was to prepare a high-absorption polyurethane (PU) foam dressing modified by polyethylene glycol (PEG) and triethoxysilane (APTES) to promote wound healing. PEG-modified (PUE) and PEG/APTES-modified (PUESi) dressings were prepared by self-foaming reactions. Gauze and PolyMem were used as controls. Next, Fourier transform-infrared spectroscopy, thermomechanical analyses, scanning electron microscopy and tensile strength, water absorption, anti-protein absorption, surface dryness and biocompatibility tests were performed for in vitro characterization. Wound healing effects were further investigated in nondiabetic (non-DM) and diabetes mellitus (DM) rat models. The PUE and PUESi groups exhibited better physicochemical properties than the gauze and PolyMem groups. Moreover, PUESi dressing showed better anti-adhesion properties and absorption capacity with deformation. Furthermore, the PUESi dressing shortened the inflammatory phase and enhanced collagen deposition in both the non-DM and DM animal models. To conclude, the PUESi dressing not only was fabricated with a simple and effective strategy but also enhanced wound healing via micronegative-pressure generation by its high absorption compacity with deformation.

Spatial transcriptomics reveals asymmetric cellular responses to injury in the regenerating spiny mouse (Acomys) ear

In contrast to other mammals, the spiny mouse (Acomys) regenerates skin and ear tissue, which includes hair follicles, glands, and cartilage, in a scar-free manner. Ear punch regeneration is asymmetric with only the proximal wound side participating in regeneration. Here, we show that cues originating from the proximal side are required for normal regeneration and use spatially resolved transcriptomics (tomo-seq) to understand the molecular and cellular events underlying this process. Analyzing gene expression across the ear and comparing expression modules between proximal and distal wound sides, we identify asymmetric gene expression patterns and pinpoint regenerative processes in space and time. Moreover, using a comparative approach with nonregenerative rodents (Mus, Meriones), we strengthen a hypothesis in which particularities in the injury-induced immune response may be one of the crucial determinants for why spiny mice regenerate whereas their relatives do not. Our data are available in SpinyMine, an easy-to-use and expandable web-based tool for exploring Acomys regeneration-associated gene expression.

Carbon Dots from Camelina Decorating hFGF2-Linked Camelina Lipid Droplets Cooperate to Accelerate Wound Healing

Constant oxidative stress at the wound site prolongs the inflammation period and slows down the proliferation stage. In order to shorten the inflammatory period meanwhile promote the proliferative activity of fibroblasts, herein, we synthesized novel camelina-derived carbon dots (CDs) decorating on hFGF2-linked camelina lipid droplets (CLD-hFGF2) to form nanobiomaterial CDs-CLD-hFGF2. The CDs-CLD-hFGF2 possesses peroxidase activity and has effective reactive oxygen species radical scavenging activity while achieving proliferation of NIH/3T3 cells under oxidative stress in vitro. In the acute wound model, wound healing after CDs-CLD-hFGF2 treatment reached nearly 92% on the 10th day, compared with 82% for CLD-hFGF2. Moreover, the wound site showed significant anti-inflammatory effects characterized by the downregulation of pro-inflammatory factors and the upregulation of anti-inflammatory factor levels. Overall, this study provided a strategy for the comprehensive utilization of camelina oil crops and revealed a promising future that could be considered an effective method for wound healing on the skin.

Borrelia burgdorferi-mediated induction of miR146a-5p fine tunes the inflammatory response in human dermal fibroblasts

Colonization of a localized area of human skin by Borrelia burgdorferi after a bite from an infected tick is the first step in the development of Lyme disease. The initial interaction between the pathogen and the human host cells is suggested to impact later outcomes of the infection. MicroRNAs (miRNAs) are well known to be important regulators of host inflammatory and immune responses. While miRNAs have been shown to play a role in the inflammatory response to B. burgdorferi at late stages of infection in the joints, the contributions of miRNAs to early B. burgdorferi infection have yet to be explored. To address this knowledge gap, we used the published host transcriptional responses to B. burgdorferi in erythema migrans skin lesions of early Lyme disease patients and a human dermal fibroblasts (HDFs)/B. burgdorferi co-culture model to predict putative upstream regulator miRNAs. This analysis predicted a role for miR146a-5p in both, B. burgdorferi-infected skin and -stimulated HDFs. miR146a-5p was confirmed to be significantly upregulated in HDF stimulated with B. burgdorferi for 24 hours compared to uninfected control cells. Furthermore, manipulation of miR146a-5p expression (overexpression or inhibition) altered the B. burgdorferi driven inflammatory profile of HDF cells. Our results suggest that miR146a-5p is an important upstream regulator of the transcriptional and immune early response to early B. burgdorferi infection.

M2 macrophage-derived exosome-encapsulated microneedles with mild photothermal therapy for accelerated diabetic wound healing

Due to local overactive inflammatory response and impaired angiogenesis, current treatments for diabetic wounds remain unsatisfactory. M2 macrophage-derived exosomes (MEs) have shown considerable potential in biomedical applications, especially since they have anti-inflammatory properties that modulate macrophage phenotypes. However, exosome-based strategies still have limitations, such as short half-lives and instability. Herein, we develop a double-layer microneedle-based wound dressing system (MEs@PMN) by encapsulating MEs in the needle tips and polydopamine (PDA) nanoparticles in backing layer to simultaneously suppress inflammation and improve angiogenesis at the wound site. In vitro, released MEs increased macrophage polarization towards the M2 phenotype. In addition, mild heat (40 ​°C) generated by the photosensitive PMN backing layer contributed to improved angiogenesis. More importantly, MEs@PMN also showed promising effects in diabetic rats. The uncontrolled inflammatory response at the wound site was inhibited by MEs@PMN during a 14-day period; in addition, MEs and the photothermal effects produced by PMN provided a combined proangiogenic effect by improving the expression of CD31 and vWF. Collectively, this study provides a simple and efficient cell-free strategy for suppressing inflammation and promoting vascular regeneration to treat diabetic wounds.

On-Off Phagocytosis and Switchable Macrophage Activation Stimulated with NIR for Infected Percutaneous Tissue Repair of Polypyrrole-Coated Sulfonated PEEK

Intelligent control of the immune response is essential for obtaining percutaneous implants with good sterilization and tissue repair abilities. In this study, polypyrrole (Ppy) nanoparticles enveloping a 3D frame of sulfonated polyether ether ketone (SP) surface are constructed, which enhance the surface modulus and hardness of the sulfonated layer by forming a cooperative structure of simulated reinforced concrete and exhibit a superior photothermal effect. Ppy-coated SP could quickly accumulate heat on the surface by responding to 808 nm near-infrared (NIR) light, thereby killing bacteria, and destroying biofilms. Under NIR stimulation, the phagocytosis and M1 activation of macrophages cultured on Ppy-coated SP are enhanced by activating complement 3 and its receptor, CD11b. Phagocytosis and M1 activation are impaired along with abolishment of NIR stimulation in the Ppy-coated SP group, which is favorable for tissue repair. Ppy-coated SP promotes Collagen-I, vascular endothelial growth factor, connective tissue growth factor, and α-actin (Acta2) expression by inducing M2 polarization owing to its higher surface modulus. Overall, Ppy-coated SP with enhanced mechanical properties could be a good candidate for clinical percutaneous implants through on-off phagocytosis and switchable macrophage activation stimulated with NIR.

Therapeutic potential of naringin in improving the survival rate of skin flap: A review

Naringin is the main component of Drynaria. Modern pharmacological studies have shown that naringin has a wide range of pharmacological activities, including antioxidant, anti-inflammatory, anti-apoptotic, anti-ulcer, and anti-osteoporosis effects. Its therapeutic effects have been observed in various clinical models, such as atherosclerosis, cardiovascular diseases, diabetes, neurodegenerative diseases, and rheumatic diseases. This review investigates the pharmacological effects of naringin and the associated mechanisms in improving flap survival. This review will also provide a reference for future rational application of naringin, especially in research to improve flap survival.

Gelatin and Bioactive Glass Composites for Tissue Engineering: A Review

Nano-/micron-sized bioactive glass (BG) particles are attractive candidates for both soft and hard tissue engineering. They can chemically bond to the host tissues, enhance new tissue formation, activate cell proliferation, stimulate the genetic expression of proteins, and trigger unique anti-bacterial, anti-inflammatory, and anti-cancer functionalities. Recently, composites based on biopolymers and BG particles have been developed with various state-of-the-art techniques for tissue engineering. Gelatin, a semi-synthetic biopolymer, has attracted the attention of researchers because it is derived from the most abundant protein in the body, viz., collagen. It is a polymer that can be dissolved in water and processed to acquire different configurations, such as hydrogels, fibers, films, and scaffolds. Searching "bioactive glass gelatin" in the tile on Scopus renders 80 highly relevant articles published in the last ~10 years, which signifies the importance of such composites. First, this review addresses the basic concepts of soft and hard tissue engineering, including the healing mechanisms and limitations ahead. Then, current knowledge on gelatin/BG composites including composition, processing and properties is summarized and discussed both for soft and hard tissue applications. This review explores physical, chemical and mechanical features and ion-release effects of such composites concerning osteogenic and angiogenic responses in vivo and in vitro. Additionally, recent developments of BG/gelatin composites using 3D/4D printing for tissue engineering are presented. Finally, the perspectives and current challenges in developing desirable composites for the regeneration of different tissues are outlined.

Advances in 3D skin bioprinting for wound healing and disease modeling

Even with many advances in design strategies over the past three decades, an enormous gap remains between existing tissue engineering skin and natural skin. Currently available in vitro skin models still cannot replicate the three-dimensionality and heterogeneity of the dermal microenvironment sufficiently to recapitulate many of the known characteristics of skin disorder or disease in vivo. Three-dimensional (3D) bioprinting enables precise control over multiple compositions, spatial distributions and architectural complexity, therefore offering hope for filling the gap of structure and function between natural and artificial skin. Our understanding of wound healing process and skin disease would thus be boosted by the development of in vitro models that could more completely capture the heterogeneous features of skin biology. Here, we provide an overview of recent advances in 3D skin bioprinting, as well as design concepts of cells and bioinks suitable for the bioprinting process. We focus on the applications of this technology for engineering physiological or pathological skin model, focusing more specifically on the function of skin appendages and vasculature. We conclude with current challenges and the technical perspective for further development of 3D skin bioprinting.

Highway to heal: Influence of altered extracellular matrix on infiltrating immune cells during acute and chronic lung diseases

Environmental insults including respiratory infections, in combination with genetic predisposition, may lead to lung diseases such as chronic obstructive pulmonary disease, lung fibrosis, asthma, and acute respiratory distress syndrome. Common characteristics of these diseases are infiltration and activation of inflammatory cells and abnormal extracellular matrix (ECM) turnover, leading to tissue damage and impairments in lung function. The ECM provides three-dimensional (3D) architectural support to the lung and crucial biochemical and biophysical cues to the cells, directing cellular processes. As immune cells travel to reach any site of injury, they encounter the composition and various mechanical features of the ECM. Emerging evidence demonstrates the crucial role played by the local environment in recruiting immune cells and their function in lung diseases. Moreover, recent developments in the field have elucidated considerable differences in responses of immune cells in two-dimensional versus 3D modeling systems. Examining the effect of individual parameters of the ECM to study their effect independently and collectively in a 3D microenvironment will help in better understanding disease pathobiology. In this article, we discuss the importance of investigating cellular migration and recent advances in this field. Moreover, we summarize changes in the ECM in lung diseases and the potential impacts on infiltrating immune cell migration in these diseases. There has been compelling progress in this field that encourages further developments, such as advanced in vitro 3D modeling using native ECM-based models, patient-derived materials, and bioprinting. We conclude with an overview of these state-of-the-art methodologies, followed by a discussion on developing novel and innovative models and the practical challenges envisaged in implementing and utilizing these systems.

Involvement of Inflammation and Its Resolution in Disease and Therapeutics

Inflammation plays a critical role in the response to and survival from injuries and/or infections. It occurs in two phases: initiation and resolution; however, when these events do not resolve and persist over time, the inflammatory response becomes chronic, prompting diseases that affect several systems and organs, such as the vasculature and the skin. Here, we reviewed inflammation that occurs in selected infectious and sterile pathologies. Thus, the immune processes induced by bacterial sepsis as well as T. cruzi and SARS-CoV-2 infections are shown. In addition, vaccine adjuvants as well as atherosclerosis are revised as examples of sterile-mediated inflammation. An example of the consequences of a lack of inflammation resolution is given through the revision of wound healing and chronic wounds. Then, we revised the resolution of the latter through advanced therapies represented by cell therapy and tissue engineering approaches, showing how they contribute to control chronic inflammation and therefore wound healing. Finally, new pharmacological insights into the management of chronic inflammation addressing the resolution of inflammation based on pro-resolving mediators, such as lipoxin, maresin, and resolvins, examining their biosynthesis, biological properties, and pharmacokinetic and pharmaceuticals limitations, are given. We conclude that resolution pharmacology and advanced therapies are promising tools to restore the inflammation homeostasis.

Logic-Based Diagnostic and Therapeutic Nanoplatform with Infection and Inflammation Monitoring and Microenvironmental Regulation Accelerating Wound Repair

Infectious cutaneous wounds are a thorny clinical problem. The microenvironment of the infectious wound is complicated and changes at different healing stages. Traditional treatments either have a single effect such as anti-inflammation, antibacteria, or angiogenesis or a simple mixture of several functions. They fail to deal with the change of the physiological healing process, leading to unsatisfactory outcomes. Herein, we have designed a logic-based smart nanoplatform (named as ZEM), aiming to self-monitor the wound microenvironment and accordingly react to the changes of the healing process, fitting multiple needs of physiological repair at different stages. ZEM was synthesized using zeolitic imidazolate framework-8 (ZIF-8) coated with an epigallocatechin gallate (EGCG)/Mg²⁺ complex. We characterized ZEM in the aspects of morphology, physical and chemical properties, and ion release pattern. At the initial stage, ZEM sensed the weakly acidic environment and responsively released a large number of zinc ions to eliminate bacterial infection. Then came the second inflammation stage, where ZEM responded to the oxidative stress of the local wound area with EGCG absorbing excessive reactive oxygen species (ROS), contributing to the downregulation of intracellular ROS. Meanwhile, local inflammation was alleviated by reducing the expression of proinflammatory M1 phenotype factors (IL-6, TNF-α, and IL-1β). Since the balance of local ROS had been achieved, the resulting disintegration of the EGCG/Mg²⁺ complex gave rise to the sustainable release of Mg²⁺ at the proliferation stage, promoting vascularized healing. In vivo animal experiments further proved the diagnostic and therapeutic functions of ZEM. All these results demonstrated that ZEM was a promising treatment strategy in soft tissue engineering.

The role of the tumor microenvironment in colorectal cancer and the potential therapeutic approaches

BACKGROUND

Colorectal cancer (CRC) with a high prevalence is recognized as the fourth most common cause of cancer-related death globally. Over the past decade, there has been growing interest in the network of tumor cells, stromal cells, immune cells, blood vessel cells, and fibroblasts that comprise the tumor microenvironment (TME) to identify new therapeutic interventions.

METHODS

Databases, such as Google Scholar, PubMed, and Scopus, were searched to provide an overview of the recent research progress related to targeting the TME as a novel therapeutic approach.

RESULTS

Tumor microenvironment as a result of the cross talk between these cells may result in either advantages or disadvantages in tumor development and metastasis, affecting the signals and responses from the surrounding cells. Whilst chemotherapy has led to an improvement in CRC patients' survival, the metastatic aspect of the disease remains difficult to avoid.

CONCLUSIONS

The present review emphasizes the structure and function of the TME, alterations in the TME, its role in the incidence and progression of CRC, the effects on tumor development and metastasis, and also the potential of its alterations as therapeutic targets. It should be noted that providing novel studies in this field of research might help us to achieve practical therapeutic strategies based on their interaction.