Wounds In Diabetic Mice Research Articles

Therapeutic Potential of Exosomes Derived from Diabetic Adipose Stem Cells in Cutaneous Wound Healing of db/db Mice.

(1) Background: Diabetes impairs angiogenesis and wound healing. Paracrine secretion from adipose stem cells (ASCs) contains membrane-bound nano-vesicles called exosomes (ASC-Exo) but the functional role and therapeutic potential of diabetic ASC-Exo in wound healing are unknown. This study aims to investigate the in vivo mechanistic basis by which diabetic ASC-Exo enhance cutaneous wound healing in a diabetic mouse model. (2) Methods: Topically applied exosomes could efficiently target and preferentially accumulate in wound tissue, and the cellular origin, ASC or dermal fibroblast (DFb), has no influence on the biodistribution pattern of exosomes. In vivo, full-thickness wounds in diabetic mice were treated either with ASC-Exo, DFb-Exo, or phosphate-buffered saline (PBS) topically. ASC-Exo stimulated wound healing by dermal cell proliferation, keratinocyte proliferation, and angiogenesis compared with DFb-Exo and PBS-treated wounds. (3) Results: Diabetic ASC-Exo stimulated resident monocytes/macrophages to secrete more TGF-β1 and activate the TGF-β/Smad3 signaling pathway. Fibroblasts activated by TGF-β1containing exosomes from ASCs initiate the production of TGF-β1 protein in an autocrine fashion, which leads to more proliferation and activation of fibroblasts. TGF-β1 is centrally involved in diabetic ASC-Exo mediated cellular crosstalk as an important early response to initiating wound regeneration. (4) Conclusions: The application of diabetic ASC-Exo informs the potential utility of a cell-free therapy in diabetic wound healing.

Estrogen Facilitates the Healing of Diabetic Wounds via Ameliorating the Function of Bone Marrow Mesenchymal Stem Cells

We inted to elucidate the impacts of estrogen on the bone marrow-originated endothelial progenitor cells (BM-EPC) and mesenchymal stem cells (BM-MSC) as well as on diabetic wound healing. The skin injury models were established using the diabetic mice (db+/db+) and non-diabetic vector mice and then treated with estrogen-based or placebo-based cream. On the 5th day following injury, BM cells were collected for quantification of EPCs and MSCs and colony-forming units along with analysis of wound healing rate and densities of blood vessels and scars following whole-body perfusion. EPCs were identified through staining of VEGFR1 and CD34 by immunohistochemistrical analyses. In contrast to placebo, treatment with estrogen significantly intensified the colony formation of EPC and MSC, and further promoted the viability and proliferation potential of cells. Meanwhile, estrogen-treated mice exhibited increased recruitment of EPC to the diabetic wounds along with increased vascular density. Additionally, on day 6 after injury, estrogen significantly accelerated wound healing, which was mediated by the enhanced collagen deposition through boosting MSC activation and differentiation, resulting in elevated scar density. In conclusion, estrogen prompts wound healing of diabetic mice via ameliorating the function of BM-derived EPC and MSC, so as to accelerate the neovascularization at the sites of wounds in diabetic mice.

Neutralizing Staphylococcus aureus Virulence with AZD6389, a Three mAb Combination, Accelerates Closure of a Diabetic Polymicrobial Wound.

ABSTRACTNonhealing diabetic foot ulcers (DFU), a major complication of diabetes, are associated with high morbidity and mortality despite current standard of care. Since Staphylococcus aureus is the most common pathogen isolated from nonhealing and infected DFU, we hypothesized that S. aureus virulence factors would damage tissue, promote immune evasion and alter the microbiome, leading to bacterial persistence and delayed wound healing. In a diabetic mouse polymicrobial wound model with S. aureus, Pseudomonas aeruginosa, and Streptococcus pyogenes, we report a rapid bacterial proliferation, prolonged pro-inflammatory response and large necrotic lesions unclosed for up to 40 days. Treatment with AZD6389, a three-monoclonal antibody combination targeting S. aureus alpha toxin, 4 secreted leukotoxins, and fibrinogen binding cell-surface adhesin clumping factor A resulted in full skin re-epithelization 21 days after inoculation. By neutralizing multiple virulence factors, AZD6389 effectively blocked bacterial agglutination and S. aureus-mediated cell killing, abrogated S. aureus-mediated immune evasion and targeted the bacteria for opsonophagocytic killing. Neutralizing S. aureus virulence not only facilitated S. aureus clearance in lesions, but also reduced S. pyogenes and P. aeruginosa numbers, damaging inflammatory mediators and markers for neutrophil extracellular trap formation 14 days post initiation. Collectively, our data suggest that AZD6389 holds promise as an immunotherapeutic approach against DFU complications.IMPORTANCE Diabetic foot ulcers (DFU) represent a major complication of diabetes and are associated with poor quality of life and increased morbidity and mortality despite standard of care. They have a complex pathogenesis starting with superficial skin lesions, which often progress to deeper tissue structures up to the bone and ultimately require limb amputation. The skin microbiome of diabetic patients has emerged as having an impact on DFU occurrence and chronicity. DFU are mostly polymicrobial, and the Gram-positive bacterium Staphylococcus aureus detected in more than 95% of cases. S. aureus possess a collection of virulence factors which participate in disease progression and may facilitate growth of other pathogens. Here we show in a diabetic mouse wound model that targeting some specific S. aureus virulence factors with a multimechanistic antibody combination accelerated wound closure and promoted full skin re-epithelization. This work opens promising new avenues for the treatment of DFU.

Local Administration of Ginkgolide B Using a Hyaluronan-Based Hydrogel Improves Wound Healing in Diabetic Mice.

The delayed and incomplete healing of diabetic wounds remains a major concern of global healthcare. The complex biological processes within the diabetic wound, such as chronic inflammation, impaired blood vessel growth and immature collagen remodeling, dramatically cause the failure of current treatments. Thus, emerging therapeutic strategies are highly desirable. Ginkgolide B (GB, a natural product extracted from the leaves of Ginkgo biloba L.) has been applied in the treatment of cerebrovascular and cardiovascular disorders, which is mainly due to the anti-oxidative, anti-inflammatory and proliferative effects. In this study, the role of GB in facilitating the anti-inflammatory and pro-healing effects on diabetic wounds was for the first time confirmed using in vitro, ex vivo and in vivo experimental methods. As a consequence, GB was able to significantly achieve the activities of anti-inflammation, re-epithelialization, and pro-angiogenesis. Previously, a hydrogel has been developed using the high molecular weight hyaluronan (hyaluronic acid, HA) in our laboratory. In this study, this hydrogel was utilized in vivo for local administration of GB to the full-thickness wounds of diabetic mice. The resultant hydrogel formulation (HA-GB) resulted in the reduction of inflammation, the enhancement of re-epithelialization and angiogenesis, and the modulation of collagens from type III to type I, significantly promoting the healing outcome as compared with a commercially available wound dressing product (INTRASITE Gel). This study confirms a great therapeutic promise of HA-GB for the chronic wounds of diabetic patients.

Combinatorial Use of Therapeutic ELP-Based Micelle Particles in Tissue Engineering.

Elastin-like peptides (ELPs) are a versatile platform for tissue engineering and drug delivery. Here, micelle forming ELP chains are genetically fused to three therapeutic molecules, keratinocyte growth factor (KGF), stromal cell-derived growth factor 1 (SDF1), and cathelicidin (LL37), to be used in wound healing. Chronic wounds represent a growing problem worldwide. A combinatorial therapy approach targeting different aspects of wound healing would be beneficial, providing a controlled and sustained release of active molecules, while simultaneously protecting these therapeutics from the surrounding harsh wound environment. The results of this study demonstrate that the conjugation of the growth factors KGF and SDF1 and the antimicrobial peptide LL37 to ELPs does not affect the micelle structure and that all three therapeutic moieties retain their bioactivity in vitro. Importantly, when the combination of these micelle ELP nanoparticles are applied to wounds in diabetic mice, over 90 % wound closure is observed, which is significantly higher than when the therapeutics are applied in their naked forms. The application of the nanoparticles designed here is the first report of targeting different aspect of wound healing synergistically.

Chi@HMPB@CBD nanocomplexes for laser-assisted therapy of MRSA-infected cutaneous wounds in normal and MKR diabetic mice

The emergence and spreading of methicillin-resistant Staphylococcus aureus (MRSA) have become one of the main reasons for the surgical failure even for the death. Thus, there is an urgent need to develop efficient antimicrobial alternatives for eradicating it so as to improve the therapy efficiency of related diseases. Although the synthesized metal nanoparticles showed the MRSA-killing function in vitro, their biosafety in vivo application is still in controversy due to the potential toxicity and induced multidrug resistance. Recently, plant natural compounds with high antibacterial activity and special mechanisms different from antibiotics have attracted wide interest for developing new anti-MRSA regents. In this work, new nanocomplexes of Chi@HMPB@CBD based on natural compounds of cannabidiol (CBD) and chitosan (Chi) were designed for eradicating MRSA. In vitro results demonstrate that Chi@HMPB@CBD NPs plus laser irradiation can efficiently kill MRSA by inducing bacterial surface perforation, content leakage, ROS production, and ATP reduction. In vivo results show that the combination of Chi@HMPB@CBD NPs plus laser can effectively remove bacteria and accelerate wound healing of MRSA-infected normal and diabetes mellitus mice by up-regulating VEGF and CD31. Moreover, Chi@HMPB@CBD NPs possessing excellent biocompatibility and ultra-low toxicity in vitro significantly delayed the time for multidrug-resistance induction, comparing with silver nanoparticles. In our point, the “green therapeutics” against MRSA show great potential in clinical application.

HUC-MSCs lyophilized powder loaded polysaccharide ulvan driven functional hydrogel for chronic diabetic wound healing

In this study, we used the polysaccharide ulvan from the green macroalgae Ulva fenestrata to prepare the hydrogel for chronic diabetic wound healing. A natural polysaccharide-based hydrogel matrix (UC-DPA-Ag hydrogel) was prepared using ulvan dialdehyde, chitosan, dopamine (DPA) and silver nanoparticles (Ag NPs). Human umbilical cord mesenchymal stem cell lyophilized powder (hUC-MSCs) was loaded into the hydrogel to develop a novel chronic diabetic wound healing material (UC-DPA-Ag@hUC-MSCs). The resulting hydrogel features adequate mechanical properties, swelling capability, adhesiveness, antioxidant, antibacterial ability, and promoting cell proliferation and migration. In vivo wound healing in type II diabetic mellitus mouse wound model showed that hUC-MSCs loaded UC-DPA-Ag hydrogel could accelerate wound healing effectively. This advanced hydrogel provides a facile and effective way for diabetic chronic wound management. Furthermore, it offers a new route for the utilizing Ulva as a valuable biomaterial for the global and large-scale production of valued added biomaterials.

A chlorogenic acid-loaded hyaluronic acid-based hydrogel facilitates anti-inflammatory and pro-healing effects for diabetic wounds

The impaired wound healing of diabetic patients is a major healthcare issue worldwide. Current therapeutic strategies usually fail due to the complex biological processes within diabetic wounds such as chronic inflammation, damaged blood vasculature, and immature collagen remodeling. Therefore, emerging treatments are urgently required. Chlorogenic acid (CGA, a phenolic compound found in human dietary products) has demonstrated a number of health-improving properties, including anti-oxidant, anti-inflammatory, anti-microbial, anti-diabetic, and lipid-lowing functions. In this study, the capacity of CGA for promoting diabetic wound healing was assessed using in vitro and ex vivo experimental approaches. Consequently, CGA significantly achieved the anti-inflammatory activity, re-epithelializing effect, and pro-angiogenic function. A hyaluronic acid-based hydrogel (HA, it has been previously developed in our laboratories) was subsequently used in vivo for local administration of CGA to the full-thickness wounds of diabetic mice. The resulting formulation (CGA-HA) significantly improved the healing effects relative to a commercial wound dressing (INTRASITE Gel), which was accompanied with the reduction of inflammation, enhancement of re-epithelialization and angiogenesis, and maturation of collagen remodeling. Our study confirms the potential of CGA-HA in the clinical application for diabetic wound healing.

Poly-quercetin-based nanoVelcro as a multifunctional wound dressing for effective treatment of chronic wound infections

Comprehensive wound dressings for bacterial wound treatment requires a combination of antibacterial, antioxidative, and anti-inflammatory effects and endotoxin neutralization. Here, we report a novel nanoVelcro dressing made from quercetin (QNV) through alkaline-mediated catalytic polymerization and crosslinking. These dressings can effectively inhibit the growth of Gram-negative, Gram-positive and multidrug-resistant bacteria in complicated medium (e.g., human plasma) through ultrastrong bacterial wrapping. QNV shows a minimum inhibitory concentration (MIC) of 10 μg mL−1 against the tested bacteria, which is 5-fold lower than that of monomeric quercetin. In addition to its superior antibacterial activity, QNV exhibits the inherent antioxidative and inflammatory activities of quercetin. More importantly, QNV wrapping further prevents bacteria from releasing toxins during infection, inhibiting the subsequent inflammatory response. QNV, in contrast to silver nanoparticles and 3 M wound care dressings, effectively inhibits bacterial growth and wound inflammation in methicillin-resistant Staphylococcus aureus (MRSA) − infected wounds in diabetic mice by accelerating the wound closure rate. Our results reveal that the use of QNV in the design of an ultrastrong bacterial binder is promising for the development of multifunctional wound dressings for the treatment of chronic infectious wounds.

Photopolymerized Zwitterionic Hydrogels with a Sustained Delivery of Cerium Oxide Nanoparticle-miR146a Conjugate Accelerate Diabetic Wound Healing.

In the United States, $87 billion per year is spent on the care of diabetic ulcers alone. Although the pathophysiology of diabetic wound healing is multifaceted, high systemic levels of inflammation and increased reactive oxygen species are often implicated in the wound healing impairment. Zwitterionic materials have been demonstrated to reduce inflammation and increase extracellular matrix deposition in wound beds, and here, we demonstrate a fabrication method for photopolymerized zwitterionic hydrogels that also enables sustained drug delivery over time. A therapeutic molecule of interest that is examined in this work is cerium oxide nanoparticle tagged with microRNA-146a (CNP-miR146a) to combat both oxidative stress and inflammation. The hydrogels are composed of zwitterionic and nonzwitterionic monomers, and the hydrogel formation occurs in the absence of a crosslinker. The hydrogels exhibit a wide range of stiffness and mechanical properties depending on their monomer content. Additionally, these hydrogels exhibit sustained release of nanoparticles and proteins. Finally, when employed in an in vivo diabetic mouse wound healing model, the zwitterionic hydrogels alone and laden with the CNP-miR146a conjugate significantly improved the rate of diabetic wound healing. Overall, these materials have excellent potential to be used as a topical treatment for chronic diabetic wounds.

Antimicrobial peptide derived from insulin-like growth factor-binding protein 5 improves diabetic wound healing.

Impaired keratinocyte functions are major factors that are responsible for delayed diabetic wound healing. In addition to its antimicrobial activity, the antimicrobial peptide derived from insulin-like growth factor-binding protein 5 (AMP-IBP5) activates mast cells and promotes keratinocyte and fibroblast proliferation and migration. However, its effects on diabetic wound healing remain unclear. Human keratinocytes were cultured in normal or high glucose milieus. The production of angiogenic growth factor and cell proliferation and migration were evaluated. Wounds in normal and streptozotocin-induced diabetic mice were monitored and histologically examined. We found that AMP-IBP5 rescued the high glucose-induced attenuation of proliferation and migration as well as the production of angiogenin and vascular endothelial growth factors in keratinocytes. The AMP-IBP5-induced activity was mediated by the epidermal growth factor receptor, signal transducer and activator of transcription 1 and 3, and mitogen-activated protein kinase pathways, as indicated by the inhibitory effects of pathway-specific inhibitors. In vivo, AMP-IBP5 markedly accelerated wound healing, increased the expression of angiogenic factors and promoted vessel formation in both normal and diabetic mice. Overall, the finding that AMP-IBP5 accelerated diabetic wound healing by protecting against glucotoxicity and promoting angiogenesis suggests that AMP-IBP5 might be a potential therapeutic target for treating chronic diabetic wounds.

An Electrospun Scaffold Loaded with an Enteromorpha Polysaccharide for Accelerated Wound Healing in Diabetic Mice.

The design and development of innovative multifunctional wound dressing materials in engineered biomaterials is essential for promoting tissue repair. In this study, nanofibrous wound dressing materials loaded with anti-inflammatory ingredients were manufactured by a promising electrospinning strategy, and their capability for treating diabetic wounds was also investigated. A scaffold blend consisting of an Enteromorpha polysaccharide and polyvinyl alcohol (PVA) was fabricated. The in vitro and in vivo studies confirmed the efficacy of PVA/EPP1 fiber. We found that PVA/EPP1 fiber accelerated the repair of a full-thickness skin wound in diabetic mice. The results suggest that this scaffold could effectively shorten the wound healing time by inhibiting inflammatory activity, which makes it a promising candidate for the treatment of hard-to-heal wounds caused by diabetes.

A Guanosine-Quadruplex Hydrogel as Cascade Reaction Container Consuming Endogenous Glucose for Infected Wound Treatment-A Study in Diabetic Mice.

Diabetic foot ulcers infected with antibiotic‐resistant bacteria form a severe complication of diabetes. Antimicrobial‐loaded hydrogels are used as a dressing for infected wounds, but the ongoing rise in the number of antimicrobial‐resistant infections necessitates new, nonantibiotic based designs. Here, a guanosine‐quadruplex (G4)‐hydrogel composed of guanosine, 2‐formylphenylboronic acid, and putrescine is designed and used as a cascade‐reaction container. The G4‐hydrogel is loaded with glucose‐oxidase and hemin. The first cascade‐reaction, initiated by glucose‐oxidase, transforms glucose and O2 into gluconic acid and H2O2. In vitro, this reaction is most influential on killing Staphylococcus aureus or Pseudomonas aeruginosa in suspension, but showed limited killing of bacteria in biofilm‐modes of growth. The second cascade‐reaction, however, transforming H2O2 into reactive‐oxygen‐species (ROS), also enhances killing of biofilm bacteria due to hemin penetration into biofilms and interaction with eDNA G‐quadruplexes in the biofilm matrix. Therewith, the second cascade‐reaction generates ROS close to the target bacteria, facilitating killing despite the short life‐time of ROS. Healing of infected wounds in diabetic mice proceeds faster upon coverage by these G4‐hydrogels than by clinically common ciprofloxacin irrigation. Moreover, local glucose concentrations around infected wounds decrease. Concluding, a G4‐hydrogel loaded with glucose‐oxidase and hemin is a good candidate for infected wound dressings, particularly in diabetic patients.

Biomineralized synthesis of palladium nanoflowers for photothermal treatment of cancer and wound healing

Photothermal therapy uses photothermal agents (PTAs) to convert light energy to heat energy under near-infrared light to kill local tumors in cancer patients or speed up wound healing in diabetic patients. However, it is difficult to achieve high photothermal conversion efficiency for most of PTAs. Herein, daptomycin (Dap) micelles-stabilized palladium nanoflowers (Dap-PdNFs) were prepared for the first time. The palladium nanoflowers (PdNFs) inside of the Dap-PdNFs were 106 nm. The temperature of the Dap-PdNFs solution quickly rose from 26.8 °C to 52.0 °C within 10 min under irradiation with high photothermal conversion efficiency up to 38%. In addition, the cell viability of HeLa cells and HT-29 cells of Dap-PdNFs exceeded 95% in the absence of near-infrared light, indicating that Dap-PdNFs had good biocompatibility. Meanwhile, the inhibition rate of Dap-PdNFs on HeLa cells was as high as 71.2% under irradiation of 808 nm near-infrared light. More importantly, Dap-PdNFs had a good healing effect on wounds of diabetic mice under irradiation of 808 nm near-infrared light. In short, this research provides a facile method for the application of Dap-PdNFs in safe and efficient tumor treatment and wound healing.

Milk exosomes-mediated miR-31-5p delivery accelerates diabetic wound healing through promoting angiogenesis

The refractory diabetic wound has remained a worldwide challenge as one of the major health problems. The impaired angiogenesis phase during diabetic wound healing partly contributes to the pathological process. MicroRNA (miRNA) is an essential regulator of gene expression in crucial biological processes and is a promising nucleic acid drug in therapeutic fields of the diabetic wound. However, miRNA therapies have limitations due to lacking an effective delivery system. In the present study, we found a significant reduction of miR-31-5p expression in the full-thickness wounds of diabetic mice compared to normal mice. Further, miR-31-5p has been proven to promote the proliferation, migration, and angiogenesis of endothelial cells. Thus, we conceived the idea of exogenously supplementing miR-31-5p mimics to treat the diabetic wound. We used milk-derived exosomes as a novel system for miR-31-5p delivery and successfully encapsulated miR-31-5p mimics into milk exosomes through electroporation. Then, we proved that the miR-31-5p loaded in exosomes achieved higher cell uptake and was able to resist degradation. Moreover, our miRNA-exosomal formulation demonstrated dramatically improved endothelial cell functions in vitro, together with the promotion of angiogenesis and enhanced diabetic wound healing in vivo. Collectively, our data showed the feasibility of milk exosomes as a scalable, biocompatible, and cost-effective delivery system to enhance the bioavailability and efficacy of miRNAs.

PH-switchable nanozyme cascade catalysis: a strategy for spatial\u2013temporal modulation of pathological wound microenvironment to rescue stalled healing in diabetic ulcer

The management of diabetic ulcer (DU) to rescue stalled wound healing remains a paramount clinical challenge due to the spatially and temporally coupled pathological wound microenvironment that features hyperglycemia, biofilm infection, hypoxia and excessive oxidative stress. Here we present a pH-switchable nanozyme cascade catalysis (PNCC) strategy for spatial–temporal modulation of pathological wound microenvironment to rescue stalled healing in DU. The PNCC is demonstrated by employing the nanozyme of clinically approved iron oxide nanoparticles coated with a shell of glucose oxidase (Fe3O4-GOx). The Fe3O4-GOx possesses intrinsic glucose oxidase (GOx), catalase (CAT) and peroxidase (POD)-like activities, and can catalyze pH-switchable glucose-initiated GOx/POD and GOx/CAT cascade reaction in acidic and neutral environment, respectively. Specifically, the GOx/POD cascade reaction generating consecutive fluxes of toxic hydroxyl radical spatially targets the acidic biofilm (pH ~ 5.5), and eradicates biofilm to shorten the inflammatory phase and initiate normal wound healing processes. Furthermore, the GOx/CAT cascade reaction producing consecutive fluxes of oxygen spatially targets the neutral wound tissue, and accelerates the proliferation and remodeling phases of wound healing by addressing the issues of hyperglycemia, hypoxia, and excessive oxidative stress. The shortened inflammatory phase temporally coupled with accelerated proliferation and remodeling phases significantly speed up the normal orchestrated wound-healing cascades. Remarkably, this Fe3O4-GOx-instructed spatial–temporal remodeling of DU microenvironment enables complete re-epithelialization of biofilm-infected wound in diabetic mice within 15 days while minimizing toxicity to normal tissues, exerting great transformation potential in clinical DU management. The proposed PNCC concept offers a new perspective for complex pathological microenvironment remodeling, and may provide a powerful modality for the treatment of microenvironment-associated diseases.Graphical

Dedifferentiated Schwann cell-derived TGF-β3 is essential for the neural system to promote wound healing.

Rationale: Wound healing is among the most complicated physiological processes and requires the synchronization of various cell types with distinct roles to re-establish the condition of the original skin. Patients affected by peripheral neuropathies often experience failure to heal. Loss of Schwann cells (SCs), a crucial population of peripheral nervous system cells in skin, may contribute to chronic wounds. However, the role of SCs in wound healing are poorly understood.Methods: The activity of SCs was investigated by using a cell atlas of the wound healing process, which was generated by integrating single-cell RNA sequencing (scRNA-seq) libraries covering different states of mouse back skin. The results of in silico analysis were validated by in vitro cell culture and in vivo mouse model. Selective inhibitors and conditional RNAi by virus transfection were utilized to investigate the role of SCs in wound healing. Findings from mouse experiments were further verified in scRNA-seq analysis of diabetic patients.Results: Our in silico analysis revealed the heterogeneous cellular components of skin and the dynamic interactions of neural crest derived cells (NCs) with other cell types. We found that SCs dedifferentiated at an early stage of wound repair with upregulated Wnt signaling. We also identified dedifferentiated SC (dSC) defect in diabetic wounds in both mouse and human. Wnt inhibition at the wound site repressed SC dedifferentiation, leading to defective repair. Furthermore, dSCs derived TGF-β3, which is context-dependent, promoted the migration of fibroblasts and keratinocytes. Moreover, TGF-β3 supplementation enhanced the healing of chronic wounds in diabetic mice with impaired SCs.Conclusion: Our study thus advances the understanding of the roles of neural-derived cells in skin regeneration and suggests a potential therapeutic strategy for wound healing disorders.

Multifunctional Elastin-Like Polypeptide Fusion Protein Coacervates Inhibit Receptor-Mediated Proinflammatory Signals and Promote Angiogenesis in Mouse Diabetic Wounds.

Objective: Chronic skin wounds are one of the most devastating complications in diabetic patients due to the formation of advanced glycation end-products (AGEs) resulting from nonenzymatic glycation of proteins and lipids in hyperglycemia. AGEs, upon binding their receptors (RAGEs), trigger proinflammatory signals that impair wound healing in diabetes and contribute to the pathology of chronic skin wounds. Approach: We previously developed a recombinant fusion protein containing the binding domain of RAGE (vRAGE) linked to elastin-like polypeptides (ELPs) that acts as a competitive inhibitor of AGEs, and another ELP fusion protein containing stromal cell-derived factor 1 (SDF1) that promotes revascularization. In this study, we report the effects of protein coacervates incorporating both vRAGE-ELP and SDF1-ELP on wound healing in an in vitro diabetes-mimicking cell culture system, and in in vivo in full-thickness wounds on diabetic mice. Results: The combination of vRAGE-ELP and SDF1-ELP increased cell metabolic activity in AGE-stimulated endothelial cells, promoted in vitro tube formation and accelerated healing in an in vitro cell migration assay. When used in a single topical application on full-thickness excisional skin wounds in diabetic mice, wound closure in the combination groups reached almost 100% on postwounding day 35, compared to 62% and 85% on the same days in animals treated with fibrin gel control and vehicle control consisting of ELP alone. Innovation: To our knowledge, this is the first study that attempts to reverse the AGE-RAGE-mediated signaling as well as to promote cell proliferation and vascularization in one single treatment. Conclusion: The codelivery of vRAGE-ELP and SDF1-ELP has potential for the treatment of diabetic wounds.

Microalgae-based bioactive hydrogel loaded with quorum sensing inhibitor promotes infected wound healing

Interaction between bacterial species is through quorum sensing (QS), a process that regulates and coordinates genes in virulence activities and biofilm formation. QS contributes to the slowdown of tissue repair during the wound healing process by inducing chronic inflammation of the wound. Here, we developed a multifunctional QS inhibitor based on a bioactive hydrogel system to interrupt the QS of bacteria, relieve hypoxia, and destroy biofilms, and thus accelerate the healing of infected wounds in diabetic mice. We loaded berberine (BBR, a QS inhibitor, and antibacterial agent) into a natural living microalgae Spirulina platensis (SP) to form a bioactive hydrogel (BBR@SP gel) in combination with carboxymethyl chitosan/sodium alginate. Under laser irradiation, the BBR@SP gel could constantly release BBR and produce reactive oxygen species, resulting in a synergistic QS inhibition against methicillin-resistant Staphylococcus aureus (MRSA) combined chemo-photodynamic therapy. The BBR@SP gel also suppresses and destroys biofilm formation and down-regulates the expression of virulence factors. We found that the BBR@SP gel could accelerate MRSA-infected diabetic wound healing by promoting angiogenesis, skin regeneration, and suppressing the inflammatory response. Our work presents an innovative antimicrobial strategy that eliminates drug-resistant bacteria by synergistic chemo-photodynamic killing effect, relieving biofilm hypoxia, and blocking QS simultaneously, which may open up new prospects in solving antimicrobial drug resistance and combating biofilm-related infections.

Mmu-miR-145a-5p Accelerates Diabetic Wound Healing by Promoting Macrophage Polarization Toward the M2 Phenotype.

Diabetic wounds are recalcitrant to healing. One of the important characteristics of diabetic trauma is impaired macrophage polarization with an excessive inflammatory response. Many studies have described the important regulatory roles of microRNAs (miRNAs) in macrophage differentiation and polarization. However, the differentially expressed miRNAs involved in wound healing and their effects on diabetic wounds remain to be further explored. In this study, we first identified differentially expressed miRNAs in the inflammation, tissue formation and reconstruction phases in wound healing using Illumina sequencing and RT-qPCR techniques. Thereafter, the expression of musculus (mmu)-miR-145a-5p (“miR-145a-5p” for short) in excisional wounds of diabetic mice was identified. Finally, expression of miR-145a-5p was measured to determine its effects on macrophage polarization in murine RAW 264.7 macrophage cells and wound healing in diabetic mice. We identified differentially expressed miRNAs at different stages of wound healing, ten of which were further confirmed by RT-qPCR. Expression of miR-145a-5p in diabetic wounds was downregulated during the tissue formation stage. Furthermore, we observed that miR-145a-5p blocked M1 macrophage polarization while promoting M2 phenotype activation in vitro. Administration of miR-145a-5p mimics during initiation of the repair phase significantly accelerated wound healing in db/db diabetic mice. In conclusion, our findings suggest that rectifying macrophage function using miR-145a-5p overexpression accelerates diabetic chronic wound healing.