Burned Mouse Model Research Articles

Dasatinib and erianin co-loaded ion-responsive in-situ hydrogel for effective treatment of corneal neovascularization

Corneal neovasularization (CNV) is one of the leading causes for visual impairment. Dasatinib is a multi-target tyrosine kinase inhibitor, which can inhibit both platelet derived growth factor receptor and Src family kinases. Erianin exhibits excellent anti-inflammatory and anti-angiogenic effects. In this study, dasatinib and erianin were found to synergically inhibit the proliferation, migration and tube formation of Ea.hy926 cells, the three most important cellular processes of CNV. Next, dasatinib and erianin were co-encapsulated in nanostructured lipid carriers (dasa-eri-NLC), which increased the solubility of dasatinib by about 1790 times, increased the solubility of erianin by about 3 times. To improve its retention time on the ocular surface, dasa-eri-NLC was mixed with gellan gum (dasa-eri-NLC-gel), which achieved a sol-gel transformation when got in contact with tears. The dasa-eri-NLC-gel exhibited good rheological properties with shear thinning properties, extended the ocular residence time by more than 6 times, sustained the drug release, improved the corneal permeability of drug and exhibited good biocompatibility. Finally, the in vivo anti-CNV effect was evaluated in an alkaline burned mouse model of CNV, in which, the dasa-eri-NLC-gel significantly impeded the development and pathological changes of CNV, inhibited the expression of TNF-α, VEGF-A, HIF-1α, Src, pSrc in the cornea. In summary, dasa-eri-NLC-gel safely and efficiently delivered dasatinib and erianin to the cornea and exhibited significantly anti-CNV effect via inhibiting various angiogenesis related cytokines or factors. Dasa-eri-NLC-gel showed a great promise for the treatment of CNV and our study laid a solid foundation for future clinical transformation.

Identification of bioactive compounds in Amphipterygium adstringens branch bark

Background: Cuachalalate (Amphipterygium adstringens) is one of Mexico’s most commercialised medicinal plants, and its natural populations are mainly found in this country. The high demand for stem bark (SB) has risked its survival, making it necessary to develop sustainable strategies.Aim: This study aimed to identify bioactive compounds in branch bark (BB) and evaluate their antipathogenic and antivirulence capacities.Setting: The study was conducted in the low deciduous forest (LDF) of the State of Puebla, Mexico.Methods: Bioactive metabolites in BB were profiled by high-performance thin-layer chromatography (HPTLC). The chemical composition of aqueous bark extracts was scrutinised by high-performance liquid chromatography-mass spectrometry (HPLC-EM-SQ-TOF system) and molecular network analysis. The folk method’s antipathogenic capacity was determined in a burn model in mice infected with Pseudomonas aeruginosa. Finally, the antivirulence properties of bark organic extracts were determined.Results: The BB contained masticadienoic, 3α-hydroxymasticadienoic and anacardic acids, also present in SB. The aqueous extracts showed the presence of flavonoids, catechins and saponins in both barks. The folk method using BB extracts significantly reduced mouse mortality and prevented sepsis development. This might be related to the capability of extracts to block the production of bacteria virulence factors.Conclusion: The similarity in bioactive metabolites and biological activity between SB and BB of cuachalalate suggests that using BB as a medicinal agent could be a practical and sustainable strategy. This approach could potentially prevent the overexploitation of cuachalalate’s SB, contributing to its conservation.Contribution: This study proposes a sustainable strategy for using cuachalalate as a medicinal agent using BB, a renewable source.

Encapsulation of Mentha aquatica methanol extract in alginate hydrogel promotes wound healing in a murine model of Pseudomonas aeruginosa burn infection

Burn injuries are the fourth most prevalent devastating form of trauma worldwide. Among the most extensively explored materials, composite dressings with alginate loaded with herbal extract can be mentioned. This research aimed to develop a sodium alginate (SA)-based hydrogel encapsulated with Mentha aquatica (MA) methanol extract and investigate its therapeutic efficacy in the infected burn mouse model. SEM, FTIR, in vitro extract release, HPLC, mechanical test, contact angle, swelling, degradability, and temperature response properties were used to analyze the hydrogel scaffold's physicochemical structure. Additionally, the antibacterial activity and MIC level of the extract, cell cytotoxicity, and macroscopic and microscopic analysis of the wound healing process were done using Masson's trichrome and hematoxylin-eosin staining. The physicochemical properties of the SA hydrogel encapsulated with MA extract were verified. The lowest inhibitory dose of the extract was determined to be 12.5 mg/ml. Application of SA/MA hydrogel to localized wounds of deep third-degree burns demonstrated faster tissue regeneration, collagen recovery, and eradication of bacterial infection. This research focused on the design and the preparation of a novel and effective biomaterials-based medical product, which has the potential to rehabilitate infected and injured skin tissue; therefore, it can be a promising candidate for wound dressing applications.

Preparation of sulfated arabinogalactan-loaded hydrogel for wound healing in mouse burn model

Sulfation of polysaccharides can affect their biological activity by introducing sulfate groups. Skin burns occur regularly and have a great impact on normal survival. In this study, sulfated arabinogalactan (SAG) was prepared by sulfation, and polyvinyl alcohol (PVA) was used to prepare hydrogels for the treatment of scalded skin in mouse. The results show that the main chain of SAG consists of →3-β-D-Galactose (Gal)-(1, →3, 6)-β-D-Gal-(1 and →4)-β-d-Glucose (Glc)-(1. The chain is a neutral polysaccharide composed of T-β-L-Arabinose (Araf)-(1→, with a molecular weight of 17.9 kDa. At the same time, PVA + SAG hydrogel can promote the scald repair of mouse skin by promoting collagen deposition and angiogenesis, and regulating the TLR4/MyD88/NF-κB signaling pathway. Interestingly, the effect of SAG on promoting the repair of scald wounds is enhanced after AG is derivatized by sulfation. Therefore, the preparation of SAG by sulfation can promote scald repair, and has great application potential in the field of food and medicine.

Formulation and optimization of surfactant-modified chitosan nanoparticles loaded with cefdinir for novel topical drug delivery: Elevating wound healing efficacy with enhanced antibacterial properties

Burn wounds remain a significant global health concern, frequently exacerbated by bacterial infections that hinder healing and raise morbidity rates. Cefdinir, a third-generation cephalosporin antibiotic, is used to treat various conditions, but it has limitations such as low water solubility, limited bioavailability, and a short biological half-life. This study aimed to fabricate and optimize novel surfactant-based Cefdinir-loaded chitosan nanoparticles (CFD-CSNPs) for enhancing topical CFD delivery and efficacy in burn healing. Box-Behnken Design (BBD) was employed to develop optimized CFD-CSNPs using Design Expert® software, where the independent factors were chitosan concentration, chitosan: sodium tripolyphosphate ratio, pH, and surfactant type. Particle size PS, zeta potential ZP, Polydispersity index PDI, and entrapment efficiency EE% were evaluated as dependent factors. CFD-CSNPs were produced using the ionic gelation method. The optimized formula was determined and then examined for further in vitro and in vivo assessments. The optimized CFD-CSNPs exhibited acceptable PS, PDI, and ZP values. The EE% of CFD from CSNPs reached 57.89 % ± 1.66. TEM analysis revealed spherical morphology. In vitro release studies demonstrated a biphasic release profile up to (75.5 % ± 3.8) over 48 hrs. The optimized CFD-CSNPs showed improved antimicrobial efficacy against the tested microorganisms, exhibiting superior performance for both biofilm prevention and eradication. Enhanced wound healing activity was achieved by the optimized CFD-CSNPs in both in vitro and in vivo studies as confirmed by scratch wound assay and skin burn mice model. The current study advocates the efficacy of the innovative topical application of CFD-CSNPs for wound healing purposes and treatment of wound infections.

Propellant-free foam formulation with tamanu oil microemulsion and nanocurcumin for enhanced burn healing

Several commercial topical formulations are currently available to treat burns, including ointments, gels, and creams. However, these options come with a major drawback as they require a strong dispersing force to apply the drug to large areas of the skin, which can cause pain and discomfort to already sensitive burns. Conversely, foam is a soft, porous, easy-to-spread dosage form that does not require direct contact with the wound, making it an excellent option for treating sensitive, painful, and extensive burns. In this study, we aimed to develop a novel non-propellent foamed microemulsion-based system of tamanu oil and nanocurcumin for effective, safe, and fast-acting treatment of burns. We successfully formulated a stable and homogeneous microemulsion containing tamanu oil, nanocurcumin, and Labrasol/Plurol Oleique CC 497 (6:1) as surfactant/cosurfactant. The final formulation resulted in a stable, transparent, pale-yellow, and homogeneous microemulsion with a pH value of 5.05 and a density of 1.01 g/cm3. The foam generated by the non-propellent foam dispenser had a density of 0.08 g/cm3 and the foam completely broke after 30 min. In the third-degree burn mice model, the percentage of wound area reduction after 21 days of treatment was 86.67 ± 2.89% for the novel non-propellent foamed system, which was comparable to Silvirin cream (positive control) and significantly higher than saline (negative control). We believe that our propellant-free foam containing tamanu oil and nanocurcumin exhibits a promising candidate for wound healing, especially burn injuries.

Gold nanoclusters on a silk fibroin scaffold accelerate fibroblast proliferation and improve burn recovery in a mouse burn model

Delayed wound healing in skin burn injuries is common owing to inhibition of proliferation caused by excessive inflammation, necrosis, autophagy, and oxidative stress. Gold nanoclusters modified with lipoic acid (AuNCs) exhibited antioxidant and anti-inflammatory effects in a murine burn healing model. However, the impact of the AuNCs on dermal cell proliferation and granulation tissue formation remains unclear. We therefore examined their effects on dermal cell proliferation, the cell cycle, and the signaling pathways involved. AuNCs were combined with a silk fibroin scaffold and tested in a mouse burn model and human dermal fibroblasts in vitro. Combined with the silk fibroin scaffold, 50 nmol/L of AuNCs activated fibroblast differentiation, collagen deposition, and angiogenesis, increasing granulation-tissue formation, reducing tissue necrosis and systemic inflammatory response, and improving wound healing in the model. The AuNCs increased PI3K/Akt signaling pathway phosphorylation in human dermal fibroblasts, upregulating protein expression of cyclin A, B, and CDK1, which participate in the G2/M cell cycle phase, ultimately promoting fibroblast proliferation. These findings support the beneficial effects of AuNCs on burn wound healing. We suggested that AuNCs on a silk fibroin scaffold or other vector is a potential clinical strategy for burn wound treatment.

Recombinant human growth hormone promotes wound angiogenesis in burned mice through the ERK signaling pathway.

Burns are the most severe type of trauma, and the resulting ischemia and hypoxia damage can promote the dysfunction and even failure of tissues and organs throughout the body, endangering patients' life safety. Recombinant human growth hormone (rhGH) has the functions of promoting protein synthesis to reverse negative nitrogen balance, accelerating wound healing, and improving immune function, which is widely used in the treatment of burns. However, the exact mechanism and pathway of rhGH's action is not yet fully understood. In this study, we observed the wound repair effect of recombinant human growth hormone (rhGH) on burned mice and further analyzed the mechanism of action, which can provide more comprehensive reference opinions for clinical practice. First, by establishing a burn mouse model and and intervening with different doses of rhGH, we found that the wound healing capacity of mice was significantly enhanced and the inflammatory and oxidative stress responses were obviously alleviated, confirming the excellent promotion of wound repair and anti-inflammatory and antioxidant effects of rhGH. Subsequently, we found that the expression of p-ERK1/2/ERK1/2, EGF, TGF-β, and VEGF proteins was elevated in the traumatic tissues of mice after rhGH intervention, suggesting that the pathway of action of rhGH might be related to the activation of ERK pathway to promote the regeneration of traumatic capillaries.

Multifunctional On-Demand Removability Hydrogel Dressing Based on in Situ Formed AgNPs, Silk Microfibers and Hydrazide Hyaluronic Acid for Burn Wound Healing.

Elevated temperatures can deactivate tissues in the burn wound area, allowing pathogenic bacteria to multiply on the wound surface, ultimately leading to local or systemic infection. An ideal burn dressing should provide antibacterial properties and facilitate painless dressing changes. Silk microfibers coated with poly (2, 3, 4-trihydroxybenzaldehyde)(referred to as mSF@PTHB) to in situ reduce AgNO3 to silver nanoparticles (AgNPs) in a hydrazide hyaluronic acid-based hydrogel are utilized. The findings indicate a more homogeneous distribution of the silver elements compared to directly doped AgNPs, which also conferred antioxidant and antibacterial properties to the hydrogel. Moreover, hydrogels containing pH-responsive dynamic acylhydrazone bonds can undergo a gel-sol transition in a weak acid environment, leading to the painless removal of adhesive hydrogel dressings. Notably, the on-demand replaceable self-healing antioxidant hydrogel dressing exhibits antibacterial effects and cytocompatibility in vitro, and the wound-healing performance of the hydrogel is validated by treating a burn mouse model with full-thickness skin defects. It is demonstrated that hydrogel dressings offer a viable therapeutic approach to prevent infection and facilitate the healing of burn wounds.

Luminol-conjugated cyclodextrin biological nanoparticles for the treatment of severe burn-induced intestinal barrier disruption.

The breakdown of intestinal barrier integrity occurs after severe burn injury and is responsible for the subsequent reactions of inflammation and oxidative stress. A new protective strategy for the intestinal barrier is urgently needed due to the limitations of the traditional methods. Recently, the application of nanoparticles has become one of the promising therapies for many inflammation-related diseases or oxidative damage. Herein, we developed a new anti-inflammatory and antioxidant nanoparticle named luminol-conjugated cyclodextrin (LCD) and aimed to evaluate its protective effects in severe burn-induced intestinal injury. First, LCD nanoparticles, engineered with covalent conjugation between luminol and β-cyclodextrin (β-CD), were synthesized and examined. Then a mouse burn model was successfully established before the mouse body weight, intestinal histopathological manifestation, permeability, tight junction (TJ) expression and pro-inflammatory cytokines were determined in different groups. The proliferation, apoptosis, migration and reactive oxygen species (ROS) of intestinal epithelial cells (IECs) were assessed. Intraepithelial lymphocytes (IELs) were isolated and cultured for analysis by flow cytometry. LCD nanoparticle treatment significantly relieved the symptoms of burn-induced intestinal injury in the mouse model, including body weight loss and intestinal permeability abnormalities. Moreover, LCD nanoparticles remarkably recovered the mechanical barrier of the intestine after severe burn, renewed TJ structures, promoted IEC proliferation and migration, and inhibited IEC apoptosis. Mechanistically, LCD nanoparticles dramatically alleviated pro-inflammation factors (tumor necrosis factor-α, IL-17A) and ROS accumulation, which could be highly involved in intestinal barrier disruption. Furthermore, an increase in IL-17A and the proportion of IL-17A+Vγ4+ γδ T subtype cells was also observed in vitro in LPS-treated Vγ4+ γδ T cells, but the use of LCD nanoparticles suppressed this increase. Taken together, these findings demonstrate that LCD nanoparticles have the protective ability to ameliorate intestinal barrier disruption and provide a therapeutic intervention for burn-induced intestinal injury.

Glutamine promotes the proliferation of intestinal stem cells via inhibition of TP53-induced glycolysis and apoptosis regulator promoter methylation in burned mice.

Intestinal stem cells (ISCs) play a pivotal role in maintaining intestinal homeostasis and facilitating the restoration of intestinal mucosal barrier integrity. Glutamine (Gln) is a crucial energy substrate in the intestine, promoting the proliferation of ISCs and mitigating damage to the intestinal mucosal barrier after burn injury. However, the underlying mechanism has not yet been fully elucidated. The objective of this study was to explore the mechanism by which Gln facilitates the proliferation of ISCs. A mouse burn model was established to investigate the impact of Gln on intestinal function. Subsequently, crypts were isolated, and changes in TP53-induced glycolysis and apoptosis regulator (TIGAR) expression were assessed using real-time quantitative polymerase chain reaction (RT-qPCR), western blotting, immunohistochemistry, and immunofluorescence. The effects of TIGAR on cell proliferation were validated through CCK-8, EdU, and clonogenicity assays. Furthermore, the effect of TIGAR on Yes-associated protein (YAP) nuclear translocation and ferroptosis was examined by western blotting and immunofluorescence staining. Finally, dot blot analysis and methylation-specific PCR were performed to evaluate the effect of Gln on TIGAR promoter methylation. The mRNA and protein levels of TIGAR decreased after burn injury, and supplementation with Gln increased the expression of TIGAR. TIGAR accelerates the nuclear translocation of YAP, thereby increasing the proliferation of ISCs. Concurrently, TIGAR promotes the synthesis of nicotinamide adenine dinucleotide phosphate (NADPH) and glutathione to suppress ferroptosis in ISCs. Subsequent investigations demonstrated that Gln inhibits TIGAR promoter methylation by increasing the expression of the demethylase ten-eleven translocation. This change increased TIGAR transcription, increased NADPH synthesis, and reduced oxidative stress, thereby facilitating the restoration of intestinal mucosal barrier integrity post-burn injury. Our data confirmed the inhibitory effect of Gln on TIGAR promoter methylation, which facilitates YAP translocation into the nucleus and suppresses ferroptosis, ultimately promoting the proliferation of ISCs.

Suppression of overactivated immunity in the early stage is the key to improve the prognosis in severe burns.

Severe burns can lead to systemic inflammatory response syndrome (SIRS) and multiple organ dysfunction syndrome (MODS) due to inflammation-immunity dysregulation. This study aimed to identify key immune-related molecules and potential drugs for immune regulation in severe burn treatment. Microarray datasets GSE77791 and GSE37069 were analyzed to identify immune-related differentially expressed genes (DEGs), enriched pathways and prognosis-related genes. The DGIdb database was used to identify potentially clinically relevant small molecular drugs for hub DEGs. Hub DEGs were validated by total RNA from clinical blood samples through qPCR. The efficacy of drug candidates was tested in a severe burn mouse model. Pathologic staining was used to observe organ damage. Enzyme Linked Immunosorbent Assay (ELISA) was used to detect the serum IL-1b, IL-6, TNF-a and MCP-1 contents. Activation of the NF-κB inflammatory pathway was detected by western blotting. Transcriptome sequencing was used to observe inflammatory-immune responses in the lung. A total of 113 immune-related DEGs were identified, and the presence of immune overactivation was confirmed in severe burns. S100A8 was not only significantly upregulated and identified to be prognosis-related among the hub DEGs but also exhibited an increasing trend in clinical blood samples. Methotrexate, which targets S100A8, as predicted by the DGIdb, significantly reduces transcription level of S100A8 and inflammatory cytokine content in blood, organ damage (lungs, liver, spleen, and kidneys) and mortality in severely burned mice when combined with fluid resuscitation. The inflammatory-immune response was suppressed in the lungs. S100A8 with high transcription level in blood is a potential biomarker for poor severe burn prognosis. It suggested that methotrexate has a potential application in severe burn immunotherapy. Besides, it should be emphasized that fluid resuscitation is necessary for the function of methotrexate.

Antimicrobial, Antioxidant, and Anti-Inflammatory Nanoplatform for Effective Management of Infected Wounds.

Burn wound healing continues to pose significant challenges due to excessive inflammation, the risk of infection, and impaired tissue regeneration. In this regard, an antibacterial, antioxidant, and anti-inflammatory nanocomposite (called HPA) that combines a nanosystem using hexachlorocyclotriphosphazene and the natural polyphenol of Phloretin with silver nanoparticles (AgNPs) is developed. HPA effectively disperses AgNPs to mitigate any toxicity caused by aggregation while also showingthe pharmacological activities of Phloretin. During the initial stage of wound healing, HPA rapidly releases silver ions from its surface to suppress bacterial activity. Moreover, these nanoparticles are pH-sensitive and degrade efficiently in the acidic infection microenvironment, gradually releasing Phloretin. This sustained release of Phloretin helps scavenge overexpressed reactive oxygen species in the infected microenvironment area, thus reducing the upregulation of pro-inflammatory cytokines. The antibacterial activity, free radical clearance, and regulation of inflammatory factors of HPA through in vitro experiments are validated. Additionally, its effects using an infectious burn mouse model in vivo are evaluated. HPA is found to promote collagen deposition and epithelialization in the wound area. With its synergistic antibacterial, antioxidant, and anti-inflammatory activities, as well as favorable biocompatibilities, HPA shows great promise as a safe and effective multifunctional nanoplatform for burn injury wound dressings.

Efficacy of a Mexican folk remedy containing cuachalalate (Amphipterygium adstringens (Schltdl.) Schiede ex Standl) for the treatment of burn wounds infected with Pseudomonas aeruginosa

Ethnopharmacological relevanceCuachalalate (Amphipterygium adstringens) stem bark has been used to heal wounds and counteract microbial infections since pre-Hispanic times. However, its effect in treating infected burns remains unclear. Study objectivesTo determine the antipathogenic capacity of a folk remedy (FR) containing cuachalalate stem bark to treat lesions caused by thermal damage and bacterial infection. Materials and methodsThe antipathogenic capacity of the hexanic extract (HE) and FR was evaluated in a burned mouse model infected with Pseudomonas aeruginosa. Second to third-degree burns were induced with 95 °C water in CD1 mice in similar ratios of males to females. The mice were randomly grouped into non-inoculated (Group 1) and P. aeruginosa inoculated. The latter were divided into untreated infection (Group 2) and infection topically treated with HE (Group 3), silver sulfadiazine (Group 4), and tween 80 (Group 5). In the case of FR, the lesions were washed with an aqueous extract (AE) and applied powdered stem bark (Group 6). Animal survival, establishment of the bacteria in the lesions, and systemic dispersion were determined. In addition, histopathological analysis was performed. The chemical composition of the AE was analyzed through molecular networking analysis, and the antivirulence capacity was determined through the inhibition of pyocyanin production and caseinolytic activity. ResultsOnly the FR showed antipathogenic activity and increased animal survival by 50% by reducing the systemic dispersion of P. aeruginosa. In addition, it stimulated the formation of granulation tissue and the generation of new blood vessels. The AE did not show bactericidal activity but reduced bacterial virulence, and glycosylated flavonoids and catechins were identified as its main constituents. ConclusionsThe results of this study contribute to validating the effectiveness of a popular remedy containing cuachalalate stem bark for treating burns infected with P. aeruginosa.

Radiosterilized Pig Skin, Silver Nanoparticles and Skin Cells as an Integral Dressing Treatment for Burns: Development, Pre-Clinical and Clinical Pilot Study.

Radiosterilized pig skin (RPS) has been used as a dressing for burns since the 1980s. Its similarity to human skin in terms of the extracellular matrix (ECM) allows the attachment of mesenchymal stem cells, making it ideal as a scaffold to create cellularized constructs. The use of silver nanoparticles (AgNPs) has been proven to be an appropriate alternative to the use of antibiotics and a potential solution against multidrug-resistant bacteria. RPS can be impregnated with AgNPs to develop nanomaterials capable of preventing wound infections. The main goal of this study was to assess the use of RPS as a scaffold for autologous fibroblasts (Fb), keratinocytes (Kc), and mesenchymal stem cells (MSC) in the treatment of second-degree burns (SDB). Additionally, independent RPS samples were impregnated with AgNPs to enhance their properties and further develop an antibacterial dressing that was initially tested using a burn mouse model. This protocol was approved by the Research and Ethics Committee of the INRLGII (INR 20/19 AC). Transmission electron microscopy (TEM) and dynamic light scattering (DLS) analysis of the synthesized AgNPs showed an average size of 10 nm and rounded morphology. Minimum inhibitory concentrations (MIC) and Kirby-Bauer assays indicated that AgNPs (in solution at a concentration of 125 ppm) exhibit antimicrobial activity against the planktonic form of S. aureus isolated from burned patients; moreover, a log reduction of 1.74 ± 0.24 was achieved against biofilm formation. The nanomaterial developed with RPS impregnated with AgNPs solution at 125 ppm (RPS-AgNPs125) facilitated wound healing in a burn mouse model and enhanced extracellular matrix (ECM) deposition, as analyzed by Masson's staining in histological samples. No silver was detected by energy-dispersive X-ray spectroscopy (EDS) in the skin, and neither by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) in different organs of the mouse burn model. Calcein/ethidium homodimer (EthD-1), 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT), and scanning electron microscopy (SEM) analysis demonstrated that Fb, Kc, and MSC could attach to RPS with over 95% cell viability. Kc were capable of releasing FGF at 0.5 pg above control levels, as analyzed by ELISA assays. An autologous RPS-Fb-Kc construct was implanted in a patient with SDB and compared to an autologous skin graft. The patient recovery was assessed seven days post-implantation, and the patient was followed up at one, two, and three months after the implantation, exhibiting favorable recovery compared to the gold standard, as measured by the cutometer. In conclusion, RPS effectively can be used as a scaffold for the culture of Fb, Kc, and MSC, facilitating the development of a cellularized construct that enhances wound healing in burn patients.

Rapamycin inhibits corneal inflammatory response and neovascularization in a mouse model of corneal alkali burn

Alkali burn-induced corneal injury often causes inflammation and neovascularization and leads to compromised vision. We previously reported that rapamycin ameliorated corneal injury after alkali burns by methylation modification. In this study, we aimed to investigate the rapamycin-medicated mechanism against corneal inflammation and neovascularization. Our data showed that alkali burn could induce a range of different inflammatory response, including a stark upregulation of pro-inflammatory factor expression and an increase in the infiltration of myeloperoxidase- and F4/80-positive cells from the corneal limbus to the central stroma. Rapamycin effectively downregulated the mRNA expression levels of tumor necrosis factor-alpha (TNF-α), interleukin-1beta (IL-1β), toll-like receptor 4 (TLR4), nucleotide binding oligomerization domain-like receptors (NLR) family pyrin domain-containing 3 (NLRP3), and Caspase-1, and suppressed the infiltration of neutrophils and macrophages. Inflammation-related angiogenesis mediated by matrix metalloproteinase-2 (MMP-2) and rapamycin restrained this process by inhibiting the TNF-α upregulation in burned corneas of mice. Rapamycin also restrained corneal alkali burn-induced inflammation by regulating HIF-1α/VEGF-mediated angiogenesis and the serum cytokines TNF-α, IL-6, Interferon-gamma (IFN-γ) and granulocyte-macrophage colony-stimulating factor (GM-CSF). The findings of this study indicated rapamycin may reduce inflammation-associated infiltration of inflammatory cells, shape the expression of cytokines, and balance the regulation of MMP-2 and HIF-1α-mediated inflammation and angiogenesis by suppressing mTOR activation in corneal wound healing induced by an alkali injury. It offered novel insights relevant for a potent drug for treating corneal alkali burn.

Activation of Sestrin2 accelerates deep second-degree burn wound healing through PI3K/AKT pathway

Deep second-degree burns heal slowly, and promoting the healing process is a focus of clinical research. Sestrin2 is a stress-inducible protein with antioxidant and metabolic regulatory effects. However, its role during acute dermal and epidermal re-epithelialization in deep second-degree burns is unknown. In this study, we aimed to explore the role and molecular mechanism of sestrin2 in deep second-degree burns as a potential treatment target for burn wounds. To explore the effects of sestrin2 on burn wound healing, we established a deep second-degree burn mouse model. Then we detected the expression of sestrin2 by western blot and immunohistochemistry after obtaining the wound margin of full-thickness burned skin. The effects of sestrin2 on burn wound healing were explored in vivo and in vitro through interfering sestrin2 expression using siRNAs or the small molecule agonist of sestrin2, eupatilin. We also investigated the molecular mechanism of sestrin2 in promoting burn wound healing by western blot and CCK-8 assay. Our in vivo and in vitro deep second-degree burn wound healing model demonstrated that sestrin2 was promptly induced at murine skin wound edges. The small molecule agonist of sestrin2 accelerated the proliferation and migration of keratinocytes, as well as burn wound healing. Conversely, the healing of burn wounds was delayed in sestrin2-deficient mice and was accompanied by the secretion of inflammatory cytokines as well as the suppression of keratinocyte proliferation and migration. Mechanistically, sestrin2 promoted the phosphorylation of the PI3K/AKT pathway, and inhibition of PI3K/AKT pathway abrogated the promoting role of sestrin2 in keratinocyte proliferation and migration. Therefore, sestrin2 plays a critical role in activation of the PI3K/AKT pathway to promote keratinocyte proliferation and migration, as well as re-epithelialization in the process of deep second-degree burn wound repair.

Engineered Superinfective Pf Phage Prevents Dissemination of Pseudomonas aeruginosa in a Mouse Burn Model.

Pf is a filamentous bacteriophage integrated in the chromosome of most clinical isolates of Pseudomonas aeruginosa. Under stress conditions, mutations occurring in the Pf genome result in the emergence of superinfective variants of Pf (SI-Pf) that are capable of circumventing phage immunity; therefore, SI-Pf can even infect Pf-lysogenized P. aeruginosa. Here, we identified specific mutations located between the repressor and the excisionase genes of Pf4 phage in the P. aeruginosa PAO1 strain that resulted in the emergence of SI-Pf. Based on these findings, we genetically engineered an SI-Pf (eSI-Pf) and tested it as a phage therapy tool for the treatment of life-threatening burn wound infections caused by PAO1. In validation experiments, eSI-Pf was able to infect PAO1 grown in a lawn as well as biofilms formed in vitro on polystyrene. eSI-Pf also infected PAO1 present in burned skin wounds on mice but was not capable of maintaining a sustained reduction in bacterial burden beyond 24 h. Despite not lowering bacterial burden in burned skin tissue, eSI-Pf treatment completely abolished the capability of P. aeruginosa to disseminate from the burn site to internal organs. Over the course of 10 days, this resulted in bacterial clearance and survival of all treated mice. We subsequently determined that eSI-Pf induced a small-colony variant of P. aeruginosa that was unable to disseminate systemically. This attenuated phenotype was due to profound changes in virulence determinant production and altered physiology. Our results suggest that eSI-Pf has potential as a phage therapy against highly recalcitrant antimicrobial-resistant P. aeruginosa infections of burn wounds. IMPORTANCE Pseudomonas aeruginosa is a major cause of burn-related infections. It is also the most likely bacterial infection to advance to sepsis and result in burn-linked death. Frequently, P. aeruginosa strains isolated from burn patients display a multidrug-resistant phenotype necessitating the development of new therapeutic strategies and prophylactic treatments. In this context, phage therapy using lytic phages has demonstrated exciting potential in the control P. aeruginosa infection. However, lytic phages can present a set of drawbacks during phage therapy, including the induction of bacterial resistance and limited bacteria-phage interactions in vivo. Here, we propose an alternative approach to interfere with P. aeruginosa pathogenesis in a burn infection model, i.e., by using an engineered superinfective filamentous phage. Our study demonstrates that treatment with the engineered Pf phage can prevent sepsis and death in a burn mouse model.

Oxygen-releasing hydrogels promote burn healing under hypoxic conditions

Hypoxic nonhealing wounds are a common complication in chronic patients, and chronic hypoxia is the main reason for delayed wound healing, so local wound oxygenation may be an effective way to address this problem. Here, we proposed a system consisting of oxygen-releasing microsphere (GC) and self-healing hydrogel (QGO). QGO/GC hydrogel could promote survival, migration and tube formation of human umbilical vein endothelial cells under hypoxic conditions. Moreover, QGO/GC hydrogels exhibited biocompatibility in vitro and in vivo. The hypoxic mouse burn model further confirmed that QGO/GC hydrogel could promote tissue repair by reducing inflammation (TNF-α and IL-1β), increasing angiogenesis (CD31, VEGF and α-SMA) and collagen deposition. This study provided an effective oxygen-releasing hydrogel that could offer a simple and effective method for the clinical treatment of chronic hypoxic wounds. Statement of significanceBurn injury is caused by various exogenous factors such as friction, cold, radiations, electricity, chemicals, hot surfaces or liquids. Severe burn can damage the entire skin layer, and the healing process is delayed due to an unbalanced inflammatory response, excessive reactive oxygen species, lack of angiogenesis (insufficient nutrient and oxygen availability), and susceptibility to infection. In the present study, we proposed an oxygen-releasing hydrogel (QGO/GC). QGO/GC hydrogel could promote survival, migration, and tube formation of human umbilical vein endothelial cells under hypoxic conditions. And QGO/GC hydrogels could promote tissue repair by reducing inflammation, increasing angiogenesis and collagen deposition. This work provided an effective oxygen-releasing hydrogel for the clinical management of chronic hypoxic wounds.

Examination of the effects of kefir on healing factors in a mice burn model infected with E.coli, S.aureus and P.aeruginosa using qRT-PCR

Burn areas are susceptible to bacterial growth and infections, particularly in cases with lengthy periods of hospital stay. Burn wound healing, which involves various molecular and cellular mechanisms, continues to be a significant problem. Growth factors and cytokines play an active and vital role in wound healing. In the present study, the effects of kefir on wound healing in a 2nd-degree mouse burn model infected with e.coli, s.aureus and p.aeruginosa were investigated in vitro. In order to clarify the effects of kefir in the wound healing process, the macroscopic changes in kefir-applied scar tissue as well as wound depth and width were examined and IL-1α, IL-1β, IL-6, IL-8, IL-10 and TNF-α, VEGF, TGF-β protein levels were determined using the qRT-PCR method. The findings of the present study show that kefir has a positive impact on the factors playing a role in wound healing and accelerates the healing process.