Full-thickness Cutaneous Wound Model Research Articles

Co-delivery of simvastatin and microRNA-21 through liposome could accelerates the wound healing process

The gene delivery approach, mainly microRNAs (miRNA) as key wound healing mediators, has recently received extensive attention. MicroRNA-21 (miR-21) has strongly impacted wound healing by affecting the inflammation and proliferation phases. Previous studies have also demonstrated the beneficial effect of simvastatin on wound healing. Therefore, we designed a dual-drug/gene delivery system using PEGylated liposomes that could simultaneously attain the co-encapsulation and co-delivery of miRNA and simvastatin (SIM) to explore the combined effect of this dual-drug delivery system on wound healing.The PEG-liposomes for simvastatin and miR-21 plasmid (miR-21-P/SIM/Liposomes) were prepared using the thin-film hydration method. The liposomes showed 85 % entrapment efficiency for SIM in the lipid bilayer and high physical entrapment of miR-21-P in the inner cavity. In vitro studies demonstrated no cytotoxicity for the carrier on normal human dermal fibroblast cells (NHDF) and 97 % cellular uptake over 2 h incubation. The scratch test revealed excellent cell proliferation and migration after treatment with miR-21-P/SIM/Liposomes. For the in vivo experiments, a full-thickness cutaneous wound model was used. The wound closure on day 8 was higher for Liposomal formulation containing miR-21-P promoting faster re-epithelialization. On day 12, all treated groups showed complete wound closure. However, following histological analysis, the miR-21-P/SIM/Liposomes revealed the best tissue regeneration, similar to normal functional skin, by reduced inflammation and increased re-epithelialization, collagen deposition and angiogenesis.In conclusion, the designed miR-21-P/SIM/Liposomes could significantly accelerate the process of wound healing, which provides a new strategy for the management of chronic wounds.

Composite Hydrogel Dressings with Enhanced Mechanical Properties and Anti-Inflammatory Ability for Effectively Promoting Wound Repair.

Hydrogel dressings have been used as a crucial method to keep the wound wet and hasten the healing process. Due to safety concerns regarding the gel components, low mechanical adhesiveness, and unsatisfactory anti-inflammatory capacity qualities for practical uses in vivo, leading to the clinical translation of wound dressings is still difficult. A type of composite hydrogel (acrylamide/polyethylene glycol diacrylate/tannic acid, ie, AM/PEGDA/TA) by double bond crosslinking, Schiff base, and hydrogen bond interaction is proposed. The mechanical characteristics, adhesiveness, and biocompatibility of the hydrogel system were all thoroughly examined. Additionally, a full-thickness cutaneous wound model was employed to assess the in vivo wound healing capacity of resulting hydrogel dressings. Benefiting the mechanism of multiple crosslinking, the designed composite hydrogels showed significant mechanical strength, outstanding adhesive capability, and good cytocompatibility. Moreover, the hydrogel system also had excellent shape adaptability, and they can be perfectly integrated into the irregularly shaped wounds through a fast in situ forming approach. Additional in vivo tests supported the findings that the full-thickness wound treated with the composite hydrogels showed quicker epithelial tissue regeneration, fewer inflammatory cells, more collagen deposition, and greater levels of platelet endothelial cell adhesion molecule (CD31) expression. These above results might offer a practical and affordable product or method of skin wound therapy in a medical context.

Deferoxamine-loaded Janus electrospun nanofiber dressing with spatially designed structure for diabetic wound healing

Diabetic wound treatment poses significant global challenges in clinical work and research, alternative treatment approaches need to be developed urgently. Exudate management and angiogenic function are critical to improve diabetic wound healing. In this work, a Janus bilayer electrospun dressing is fabricated via modified electrospinning technologies. The outer layer of dressing is hydrophilic deferoxamine (DFO)-loaded polycaprolactone (PCL) and polyethylene glycol (PEG) random nanofiber, while the inner layer is hydrophobic PCL nanofiber with mesh-like structure and patterns, and the bilayer layers are fabricated via layer-by-layer assembly. The mechanical properties, wettability, and drug release performance of the Janus dressing were studied. Difference in wettability between the two layers enables excess biological fluid to drain away from the wound, and simultaneously trigger the cascade release of DFO in the outer layer. The in vitro data evidenced that the Janus dressing had good biocompatibility. The mesh-like inner surface is considered favorable for attachment and proliferation of fibroblast, and the controlled release of DFO significantly enhanced tube formation. In vivo results from a diabetic full-thickness cutaneous wound model showed that the Janus dressing created a unique microenvironment that accelerates the wound healing process through effective biofluid draining and stimulation of angiogenesis process. The findings indicated that the Janus dressing presented a potentially valuable method for the management and treatment of diabetic wound in clinical applications.

Nonreleasing AgNP Colloids Composite Hydrogel with Potent Hemostatic, Photodynamic Bactericidal and Wound Healing-Promoting Properties.

Reactive oxygen species (ROS) produced by noble metallic nanoparticles under visible light is an effective way to combat drug-resistant bacteria colonized on the wound. However, the photocatalytic efficiency of noble metallic nanoparticles is limited by its self-aggregation in water media. Moreover, the fast release of noble metallic ions from nanoparticles might engender cellular toxicity and hazardous environmental issues. Herein, we chose AgNPs, the most common plasmonic noble metallic nanoparticles, as an example, modifying the surface of AgNPs with oleic acid and n-butylamine and imbedded them into calcium alginate (CA) hydrogel that holds tissue adhesion, rapid hemostatic, sunlight-sensitive antibacterial and anti-inflammatory abilities, and thus effectively promotes the healing of wounds. Unlike conventional AgNP-based materials, the constrain of colloids and hydrogel networks hinders the leach of Ag+. Nonetheless, the CA/Ag hydrogels exhibit on-demand photodynamic antibacterial efficacy due to the generation of ROS under visible light. In addition, the CA/Ag hydrogel can effectively stop the hemorrhage in a mouse liver bleeding model due to their skin-adaptive flexibility and tissue adhesiveness. The potent sunlight-responsive antibacterial activity of the CA/Ag hydrogel can effectively kill multidrug-resistant bacteria both in vitro (>99.999%) and in vivo (>99.9%), while the diminished Ag+ release guarantees its biocompatibility. The CA/Ag hydrogel significantly promotes the wound healing process by the downregulation of proinflammatory cytokines (TNF-α and IL-6) in a rodent full-thickness cutaneous wound model. Overall, the proposed multifunctional CA/Ag nanocomposite hydrogel has excellent prospects as an advanced wound dressing.

Multiple Coordination-Derived Bioactive Hydrogel with Proangiogenic Hemostatic Capacity for Wound Repair.

Bioactive hydrogels with multifunctional properties have shown promising potential in promoting wound repair and skin tissue regeneration. The regulation on different stages of skin wound healing (hemostasis and inflammation) is important for wound repair. Herein, a multiple coordination-derived bioactive hydrogel (SGPA) with anti-inflammatory proangiogenic hemostatic capacity for wound repair is reported. The SGPA is prepared through a facile multiple metal coordination action based on the sodium alginate, metal ions (Gd3+ ), and bisphosphate functionalized polycitrate. The SGPA exhibits a large porous structure, good injectability, and self-healing performance, as well as controlled biodegradation. Furthermore, the SGPA has good cytocompatibility and hemocompatibility, and can further promote the migration of endothelial cells. The SGPA hydrogel presents good hemostasis capacity in a liver hemorrhage model in vivo. The full-thickness cutaneous wound model demonstrates that the SGPA hydrogel can effectively accelerate the wound repair through down-regulating the inflammatory factors and stimulating the angiogenesis around the wound beds. This work suggests that the multiple metal-organic coordination may be a good strategy to construct the multifunctional bioactive hydrogel for wound repair.

Total alkaloid fraction of Leonurus japonicus Houtt. Promotes angiogenesis and wound healing through SRC/MEK/ERK signaling pathway

Ethnopharmacological relevanceLeonurus japonicus Houtt., also known as motherwort, is a traditional Chinese medicine that was first identified in Shennong Bencao Jing, the first and essential pharmacy monograph in China. L. japonicus has been regarded as a good gynecological medicine since ancient times. It has been widely used in clinical settings for treatment of gynecological diseases and postnatal rehabilitation with good efficacy and low adverse effects. Aim of the studyThe main purpose of this study was to determine the angiogenic and wound healing effects of total alkaloid fraction from L. japonicus Houtt. (TALH) in vivo and in vitro. In addition, the main bioactive components of total alkaloids were to be identified and analyzed in this study. Materials and methodsFirst, the UHPLC/Q-TOF-MS method was used to identify and quantify the major components in the TALH extract. The wound healing activity was evaluated in vivo using a rat full-thickness cutaneous wound model. Histological study of wound healing in rat model was performed via immunohistochemistry and immunofluorescence. Cell proliferation was determined by MTT assay. Wound healing and transwell assays were used for detection of cell migration. The effect on tube formation was determined by tube formation assay in HUVECs. Western blot and RT-PCR were used to detect the expressions of relative proteins and genes respectively. Knock-down of SRC by siRNA was done to verify the crucial role of SRC in promotion of angiogenesis induced by TALH. ResultsSeven characteristic peaks were recognized in the UHPLC/Q-TOF-MS spectrum, while four of the main components were quantified. The wound model in rats showed that treatment of TALH promoted wound healing by stimulating cellular proliferation and collagen deposition. In vitro experiments showed that co-treatment of TALH and VEGF increased cell proliferation, migration and tube formation in HUVECs. Mechanistic studies suggested that the co-treatment increased gene expressions of SRC, MEK1/2 and ERK1/2, as well as the phosphorylation levels of these proteins. Furthermore, the effect of co-treatment was attenuated after SRC knockdown, suggesting that SRC plays an important role in angiogenesis and wound healing induced by TALH and VEGF co-treatment. ConclusionOur results showed that TALH was one of the main active components of L. japonicus that promoted angiogenesis and wound healing by regulating the SRC/MEK/ERK pathway. Our study provided scientific basis for better clinical application of L. japonicas.

Urolithin A Promotes Angiogenesis and Tissue Regeneration in a Full-Thickness Cutaneous Wound Model

The treatment of chronic wound is an important topic of current clinical issue. Neovascularization plays a crucial role in skin wound healing by delivering fresh nutrients and oxygen to the wound area. The aim of this study was to investigate the mechanisms of urolithin A (UA) in angiogenesis during wound healing. The results of in vitro experiments showed that treatment with UA (5–20 μM) promoted the proliferation, migration, and angiogenic capacity of HUVECs. Furthermore, we investigated the effect of UA in vivo using a full-thickness skin wound model. Subsequently, we found that UA promoted the regeneration of new blood vessels, which is consistent with the results of accelerated angiogenesis in vitro experiments. After UA treatment, the blood vessels in the wound are rapidly formed, and the deposition and remodeling process of the collagen matrix is also accelerated, which ultimately promotes the effective wound healing. Mechanistic studies have shown that UA promotes angiogenesis by inhibiting the PI3K/AKT pathway. Our study provides evidence that UA can promote angiogenesis and skin regeneration in chronic wounds, especially ischemic wounds.

Transplantation of decellularised human amniotic membranes seeded with mesenchymal stem cell-educated macrophages into animal models.

The reconstruction of chronic skin wounds remains a public health challenge in dermatology. Precisely controlling and monitoring the wound-healing process should result in enhanced outcomes for the patient. Cell-based therapies have shown great potential in medicine due to their immunomodulatory and healing properties. Herein, we produced activated macrophages by treating circulating monocytes with mesenchymal stem cell (MSC) supernatant. We also demonstrated the critical role of activated macrophages transplantation using amniotic membranes in accelerating wound healing in an animal wound model. The activated macrophages not only exhibited immunomodulatory cytokines like transforming growth factorβ (TGFβ) and interleukin 10 (and IL10) secretion but also showed attachment and proliferation ability on the amniotic membrane scaffold. Moreover, MSCs supernatant-treated cells also displayed significant ARG1, CD206, and IL 10 genes expression. Inspired by the in vitro results, we examined the in vivo therapeutic efficacy of the activated macrophage transplantation using an acellular amniotic membrane carrier in a full-thickness cutaneous wound model. The wound healing rate was significant in the group treated with macrophages generated via mesenchymal cell therapy seeded human amniotic membrane. There was less scarring in the wound sites after placing cell-scaffold constructs in the wound sites in the animal models. Overall, macrophages stimulated with mesenchymal cells' supernatant exhibited improved healing processes in incisional wounds by decreasing the inflammatory phase, increasing angiogenesis, and reducing scar tissue development.

Copper metal-organic framework embedded carboxymethyl chitosan-g-glutathione/polyacrylamide hydrogels for killing bacteria and promoting wound healing

Bacterial infection and its induced oxidative stress as major clinical challenge during wound healing call for an urgent response for the development of medical dressings with multi-functions, such as antioxidant and antibacterial. To meet this demand, copper metal organic framework nanoparticles (HKUST NPs) and carboxymethyl chitosan-g-glutathione (CMCs-GSH) were synthesized and characterized. By embedding HKUST NPs into PAM/CMCs-GSH hydrogel (AOH), we developed a novel hydrogel dressing (HKUST-Hs) with dual effects of antibacterial and antioxidant. The morphology, swelling behavior, oxidation resistance and antibacterial properties of HKUST-Hs were investigated as well as the slow-release behavior of copper ions. Full-thickness cutaneous wound model of rats was created to assess the promoting effect of HKUST-Hs on wound healing. We found that HKUST NPs could be well dispersed in HKUST-Hs by shielding the positive charge of copper ions, and thus copper ions released were uniformly distributed and chelated with CMCs-GSH to promote the swelling stability of HKUST-Hs. Also, HKUST-Hs exhibited good free radical scavenging ability in vitro antioxidant assay. Meanwhile, a gradient sustained-release system of copper ions was formed in HKUST-Hs owing to the inhibition of HKUST NPs to copper release and the chelation of CMCs-GSH, which effectively inhibited the explosive release of copper ions and prolonged the release period, thereby reducing cytotoxicity. In vitro antibacterial test demonstrated there was synergistic antibacterial effect between the slow-released copper ions and CMCs-GSH, which improved the antibacterial activity and antibacterial persistence of HKUST-Hs. Finally, HKUST-Hs accelerated wound healing in vivo by continuously killing bacteria and inhibiting oxidative stress.

Curcumin-loaded, alginate-gelatin composite fibers for wound healing applications.

The wound healing process is characterized by varied biological and molecular cascades including inflammation, tissue proliferation, and remodeling phase. To augment and maintain these cascades, an all-natural matrix system is proposed. Biocompatible biopolymers, sodium alginate and gelatin, were employed to prepare microfibers via extrusion-gelation into a physical crosslinking solution. Curcumin, an anti-inflammatory, anti-oxidant and wound healing agent, was loaded into the fibers as a natural bioactive compound. Curcumin-loaded composite microfibers and blank microfibers were fabricated using biopolymers such as sodium alginate and gelatin. The formulation batches were coded as A1G9-A10G0 according to the varied concentrations of sodium alginate and gelatin. The molecular transitions within the composite microfibers were characterized using FTIR and were further corroborated using molecular mechanics analysis. In mechanical properties tensile strength and elongation-at-break (extensibility) were ranging between 1.08 ± 0.01 to 3.53 ± 0.41N/mm2 and 3.89 ± 0.18 to 0.61 ± 0.03%. The morphological analysis confirmed the formation and fabrication of the microfibers. In addition, physical evaluation including matrix degradation and entrapment efficiency was performed to give a comparative account of various formulations. The water uptake capacity of the blank and curcumin-loaded composite fibers was found to be in the range of 30.77 ± 2.17 to 100.00 ± 5.99 and 22.34 ± 1.11 to 56.34 ± 4.68, respectively. Composite microfibers presented a cumulative release of 85% in 72h, confirming the prolonged release potential of the composite fibers. The drug release followed an anomalous (non-Fickian) release behavior asserting the role of degradation and diffusion. In an in vivo full-thickness cutaneous wound model, the composite microfibers provided higher degree of contraction 96.89 ± 3.76% as compared to the marketed formulation (Vicco turmeric cream). In conclusion, this all-natural, alginate-gelatin-curcumin composite has the potential to be explored as a cost-effective wound healing platform.

Antioxidant and anti-inflammatory activities of Prussian blue nanozyme promotes full-thickness skin wound healing

Excessive reactive oxygen species (ROS) and unresolved inflammations are the major causes of impaired wound healing as they overwhelm the cellular antioxidant system and impede the healing process. In this study, we examined the application of Prussian blue (PB) nanozyme as a novel material for cutaneous wound healing through the alleviation of excessive ROS and inflammation modulation. The PB nanoparticles not only exhibited hydrogen peroxide (H2O2) degradation activity but also showed strong superoxide scavenging ability. PB nanozyme mitigated the intracellular ROS at a high oxidative stress environment, resulting in a pronounced cytoprotective effect. Moreover, PB nanozyme also displayed significant anti-inflammatory activity, as evident from the suppression of inflammatory mediators in the lipopolysaccharide (LPS) induced macrophage cells. Encouraged by the in vitro results, we evaluated the in vivo therapeutic efficacy of PB nanozyme in a full-thickness cutaneous wound model combined with LPS treatment to mimic bacterial infection. The beneficial effects of topically applied PB nanozyme on wound healing and tissue regeneration were evident compared to the control. The periodical administration of a low amount (50 μg × 4) of PB nanoparticles exhibited faster wound closure as well as collagen deposition, maturation, and organization. Moreover, the PB treatment effectively induced the differentiation of keratinocytes, enhanced the neovascularization, and reduced macrophage burden in the entire wound site. Thus, PB nanozyme not only accelerated the healing process in an infection-mimicking cutaneous wound model but also exhibited tissue regeneration characteristics owing to the synergistic effect of ROS-scavenging and anti-inflammatory activities.

Highly Water-Preserving Zwitterionic Betaine-Incorporated Collagen Sponges With Anti-oxidation and Anti-inflammation for Wound Regeneration.

A core problem in wound healing – with both fundamental and technological significance – concerns the rational design of bioactive and moist microenvironments. Here, we design a new class of zwitterionic betaine-incorporated collagen sponges (BET@COL) with integrated anti-oxidation and anti-inflammatory properties for promoting wound healing in a full-thickness wound model. The presence of zwitterionic betaine in a 3D network structure of collagen enables tightly bound and locked water molecules inside sponges via ionic solvation and confinement effect, while the integration of this amino acid also empowers the sponge with anti-oxidation and anti-inflammatory functions. In vitro results demonstrated that BET@COL collagen sponges strongly preserved water content up to 33.78 ± 0.78% at the 80th min at 37°C (only 0.44 ± 0.18% in control), and also exhibited high cell biocompatibility. Further, BET@COL collagen sponges with different betaine contents were applied to a full-thickness cutaneous wound model in mice, followed by a systematical evaluation and comparison of the effect of preserved water on wound healing efficiency in vivo. The optimal BET@COL collagen sponges were able to maintain high water content (e.g., moist microenvironment), suppress oxidative stress, improve anti-inflammation, all of which impose synergetic healing effects to promote wound closure, granulation formation, re-epithelization, collagen deposition and angiogenesis. This work demonstrates a new material as a promising candidate for wound dressing.

Injectable melatonin-loaded carboxymethyl chitosan (CMCS)-based hydrogel accelerates wound healing by reducing inflammation and promoting angiogenesis and collagen deposition

Carboxymethyl chitosan (CMCS)-based hydrogels have antibacterial activity, and have shown the abilities of preventing wound infection, promoting cell proliferation, accelerating collagen deposition, and stimulating hyaluronic acid formation during wound healing. As a hormone produced by the pineal gland in humans and animals, melatonin promotes skin wound healing by regulating the release of inflammatory mediators and accelerating the proliferation and migration of cells, angiogenesis, and collagen deposition. However, the combined effects of CMCS and melatonin on wound healing remain unclear. Injectable CMCS-based hydrogels containing melatonin were prepared, and their healing effects were evaluated using a full-thickness cutaneous wound model in rats. Compared with the control and the hydrogel with no melatonin groups, the melatonin-loaded hydrogel significantly increased the percentage of wound closure, promoted the proliferation of granulation tissue and re-epithelialization, and accelerated collagen deposition. Additionally, the melatonin-loaded hydrogel promoted angiogenesis and vascular endothelial growth factor receptor protein expression and increased the expression of cyclooxygenase-2 and inducible nitric oxide synthase. The melatonin-loaded hydrogel also markedly increased the expression of collagen III, α-smooth muscle actin, and transforming growth factor-β1 proteins and reduced collagen I expression. These results suggest that the melatonin-loaded hydrogel promoted granulation tissue formation and accelerated wound healing by reducing inflammation and promoting angiogenesis and collagen deposition.

Paeoniflorin promotes angiogenesis and tissue regeneration in a full-thickness cutaneous wound model through the PI3K/AKT pathway.

The treatment of wounds remains a clinical challenge because of poor angiogenesis under the wound bed, and increasingly, the patients' need for functional and aesthetically pleasing scars. For the wound healing process, new blood vessels which can deliver nutrients and oxygen to the wound area are necessary. In this study, we investigated the pro-angiogenesis ability and mechanism in wound healing of paeoniflorin (PF), which is a traditional Chinese medicine. In our in vitro results, the ability for proliferation, migration and in vitro angiogenesis in human umbilical vein endothelial cells was promoted by coculturing with PF (1.25-5 μM). Meanwhile, molecular docking studies revealed that PF has excellent binding abilities to phosphatidylinositol-3-kinase (PI3K) and protein kinase B (AKT), and consistent with our western blot results, that PF suppressed PI3K and AKT phosphorylation. Furthermore, to investigate the healing effect of PF in vivo, we constructed a full-thickness cutaneous wound model in rats. PF stimulated the cellular proliferation status, collagen matrix deposition and remodeling processes in vitro and new blood vessel formation at the wound bed resulting in efficient wound healing after intragastric administration of 10 mg·kg-1 ·day-1 in vivo. Overall, PF performed the pro-angiogenetic effect in vitro and accelerating wound healing in vivo. In summary, the capacity for angiogenesis in endothelial cells could be enhanced by PF treatment via the PI3K/AKT pathway in vitro and could accelerate the wound healing process in vivo through collagen deposition and angiogenesis in regenerated tissue. This study provides evidence that application of PF represents a novel therapeutic approach for the treatment of cutaneous wounds.

Design and evaluation of an imager for assessing wound inflammatory responses and bioburden in a pig model.

.Our work details the development and characterization of a portable luminescence imaging device for detecting inflammatory responses and infection in skin wounds. The device includes a CCD camera and close-up lens integrated into a customizable 3D printed imaging chamber to create a portable light-tight imager for luminescence imaging. The chamber has an adjustable light portal that permits ample ambient light for white light imaging. This imager was used to quantify in real time the extent of two-dimensional reactive oxygen species (ROS) activity distribution using a porcine wound infection model. The imager was used to successfully visualize ROS-associated luminescent activities in vitro and in vivo. Using a pig full-thickness cutaneous wound model, we further demonstrate that this portable imager can detect the change of ROS activities and their relationship with vasculature in the wound environment. Finally, by analyzing ROS intensity and distribution, an imaging method was developed to distinguish infected from uninfected wounds. We discovered a distinct ROS pattern between bacteria-infected and control wounds corresponding to the microvasculature. The results presented demonstrate that this portable luminescence imager is capable of imaging ROS activities in cutaneous wounds in a large animal model, indicating suitability for future clinical applications.

Efficient Angiogenesis-Based Diabetic Wound Healing/Skin Reconstruction through Bioactive Antibacterial Adhesive Ultraviolet Shielding Nanodressing with Exosome Release.

Diabetic wound healing and angiogenesis remain a worldwide challenge for both clinic and research. The use of adipose stromal cell derived exosomes delivered by bioactive dressing provides a potential strategy for repairing diabetic wounds with less scar formation and fast healing. In this study, we fabricated an injectable adhesive thermosensitive multifunctional polysaccharide-based dressing (FEP) with sustained pH-responsive exosome release for promoting angiogenesis and diabetic wound healing. The FEP dressing possessed multifunctional properties including efficient antibacterial activity/multidrug-resistant bacteria, fast hemostatic ability, self-healing behavior, and tissue-adhesive and good UV-shielding performance. FEP@exosomes (FEP@exo) can significantly enhance the proliferation, migration, and tube formation of endothelial cells in vitro. In vivo results from a diabetic full-thickness cutaneous wound model showed that FEP@exo dressing accelerated the wound healing by stimulating the angiogenesis process of the wound tissue. The enhanced cell proliferation, granulation tissue formation, collagen deposition, remodeling, and re-epithelialization probably lead to the fast healing with less scar tissue formation and skin appendage regeneration. This study showed that combining bioactive molecules into multifunctional dressing should have great potential in achieving satisfactory healing in diabetic and other vascular-impaired related wounds.

Topically injected adrenocorticotropic hormone induces mechanical hypersensitivity on a full-thickness cutaneous wound model in rats.

Cutaneous wound pain causes physical and psychological stress for patients with wounds. Previous studies reported that stress induces hyperalgesia and deteriorates wound healing. However, the effect of the stress response such as in hypothalamic-pituitary-adrenal (HPA) axis on local wound area is unclear. We aimed to investigate the effects of a stress response on the mechanical withdrawal threshold in the local wound area and describe the identification of a wound pain exacerbation. We topically injected adrenocorticotropic hormone (ACTH) into the granulation tissue of full-thickness cutaneous wound model rats on the fifth day postwounding and measured the mechanical withdrawal thresholds, cytochrome P450 2Bs levels and concentration of 5,6-epoxyeicosatrienoic acid in wound exudate. We found that ACTH induced mechanical hypersensitivity at 4 and 6hours after injection (P=.004 and .021, respectively), and increased gene expression of cytochrome P450 2B12 expression (P=.046). Concentration of 5,6-EET in the wound exudate was moderately correlated with the mechanical withdrawal threshold (r=-.630). Finally, the mechanical withdrawal threshold in the 5,6-EET group was significantly lower than that in the control group at 2hours after the injection (P=.015). We propose that 5,6-EET is one of the most promising contributors to the wound pain exacerbation. These findings could guide clinical wound and pain management.

Mussel-Inspired Hydrogel with Potent in Vivo Contact-Active Antimicrobial and Wound Healing Promoting Activities.

Open wounds (e.g., burns and trauma) are always challenged by various opportunistic bacteria. There is an urgent need for developing novel wound dressing that is able to prevent bacterial infection and promote the healing simultaneously. Herein, we developed a new type of antimicrobial hydrogels for the open wound healing through imitating a facile mussel-inspired catechol/polyamine chemistry. This hydrogel was prepared using catechol (CT) and ε-poly-l-lysine (EPL) by oxidative cross-linking directly in the open air at room temperature. This nonleaching CT/EPL hydrogel not only exhibited excellent contact-active antimicrobial activities against Gram-negative bacteria Escherichia coli (E. coli) and Gram-positive "superbug" methicillin-resistant Staphylococcus aureus (MRSA) but also inhibited the biofilm formation in vitro. Moreover, the animal burn wound model study clearly validated the in vivo anti-infective property of CT/EPL hydrogel against MRSA infection. More importantly, the CT/EPL hydrogel possessed low cytotoxicity and enhanced cell migration in vitro. A full-thickness cutaneous wound model study revealed that CT/EPL hydrogel upregulated the expression of vascular endothelial growth factor (VEGF) and reduced the production of the pro-inflammatory cytokines, thus promoted the wound healing. These findings suggested that the CT/EPL hydrogel have great potential as a wound dressing for preventing bacterial infection and accelerating healing of open wounds.

Elucidation of molecular pathways responsible for the accelerated wound healing induced by a novel fibrous chitin dressing.

Fibrous chitin dressing (FCD) prepared from a NaOH-urea aqueous solution of chitin via a physical process was used to study its effect on wound healing using a full-thickness cutaneous wound model in rats and mice. It was demonstrated that wounds in rats covered with the FCD showed faster collagen (especially type I collagen) growth and speedier healing than those with Gauze (12 days versus 16 days). The ability of FCD to promote wound healing was also observed on wild-type (WT) mice. For MyD88-knockout mice, however, FCD displayed no beneficial but an adverse effect on wound healing: the healing time for wounds treated with FCD was even longer than those treated with gauze. Importantly, in vivo studies indicated that FCD-treated mice, compared to gauze-treated ones, exhibited markedly higher expressions of MyD88, IKBα, TGF-β, P-TβR II, TβR II and P-Smad2/3 in wild-type mice. For MyD88 knockout mice, however, the expressions of those molecules were inhibited and lowered in FCD-treated ones than those treated with gauze. In vitro studies confirmed that chitin increased the expression of TGF-β, P-TβRII and P-Smad2/3 while the expressions of those molecules were significantly inhibited with CD14 antibody (p < 0.05). These results indicated that FCD accelerated wound healing through a MyD88-dependent pathway, followed by a TGF-β/Smad pathway. This work not only demonstrated the superior wound healing effect of chitin-derived dressing, but also provided for the first time the underlying molecular mechanism, further establishing chitin as an important biomedical material for potential clinical applications.

Upregulating mTOR/ERK signaling with leonurine for promoting angiogenesis and tissue regeneration in a full-thickness cutaneous wound model.

Wound therapy remains a clinical challenge due to the poor vascularization during the healing process and the high demand to achieve functional and aesthetically satisfactory scars. Newly-formed blood vessels are necessary for wound healing since they can deliver nutrients and oxygen to the wound area. In this study, the role of leonurine (LN), a traditional Chinese medicine isolated from Herba leonuri, in promoting angiogenesis and its function in wound healing have been investigated. The results of co-culture with human umbilical vein endothelial cells (HUVECs) demonstrated that LN treatment (5-20 μM) could promote the proliferation and migration and enhance the ability of in vitro angiogenesis through up-regulating the mTOR/ERK signaling pathway. Furthermore, a full-thickness cutaneous wound model was used to investigate the healing effect of LN in vivo. Intragastric administration of 20 mg per kg per day LN stimulated the regeneration of more blood vessels at the wound sites, which confirmed the in vitro results of promoting angiogenesis. Due to fast vascularization, the collagen matrix deposition and remodeling processes were also accelerated in LN treated wounds, resulting in efficient wound healing. In summary, LN promoted angiogenesis of endothelial cells in vitro by activating the mTOR/ERK pathway, and could efficiently enhance the angiogenesis and collagen deposition of the regenerated tissue, together with facilitating the wound healing process in vivo. This study provides evidence for LN-stimulated angiogenesis and tissue regeneration in skin wounds, especially in ischemic wounds.