Wound Healing In Animal Model Research Articles

Expression and significance of pin1 in the wound healing.

The aim of this study is to delineate the expression patterns of prolyl cis-trans isomerase NIMA-interacting protein 1 (Pin1), Glial cell-derived neurotrophic factor (GDNF), and Angiotensin II (ANG II) during the process of wound repair, and to ascertain the effects of Pin1, GDNF, and ANG II on the healing of wounds in a rat model. A total of 18 rats were allocated into three groups-sham (control), DMSO (vehicle control), and Pin1 inhibitor (treatment with juglone)-with six animals in each group. An animal model of wound healing was established, followed by the intraperitoneal administration of juglone. Tissue samples from the wounds were subsequently collected for histopathological evaluation. Expression levels of Pin1, GDNF, and Ang II were quantified. In addition, an in vitro model of wound healing was created using human umbilical vein endothelial cells (HUVEC), to assess cell proliferation, migration, and tube formation under conditions of juglone pre-treatment. The expression levels of Pin1, GDNF, and ANG II were notably elevated on 7-, and 10- days post-wound compared to those measured on 3-day. Contrastingly, pre-treatment with juglone significantly inhibited the expression of these molecules. Histological analyses, including HE (Hematoxylin and Eosin), Masson's trichrome, and EVG (Elastic van Gieson) staining, demonstrated that vascular angiogenesis, as well as collagen and elastin deposition, were substantially reduced in the juglone pre-treated group when compared to the normal group. Further, immunohistochemical analysis revealed a considerable decrease in CD31 expression in the juglone pre-treatment group relative to the normal control group. Pin1 serves as a pivotal facilitator of wound repair. The findings indicate that the modulation of Pin1, GDNF, and ANG II expression impacts the wound healing process in rats, suggesting potential targets for therapeutic intervention in human wound repair.

Resveratrol-coated chitosan mats promote angiogenesis for enhanced wound healing in animal model.

Growing incidences of chronic wounds recommend the development of optimal therapeutic wound dressings. Electrospun nanofibers have been considered to show potential wound healing properties when accompanied by other wound dressing materials. This study aimed to explore the potential role of Chitosan (CS) nanofibrous mats coated with resveratrol (RS) as an antioxidant and pro-angiogenic agent in rat models of skin wound healing. Electrospun chitosan/polyethylene oxide (PEO) nanofibers were prepared using electrospinning technology and coated by 0.05 and 0.1 mg.ml resveratrol named as (CS/RS 0.05) and (CS/RS 0.1), respectively. The scaffolds were characterized physiochemically such as invitro release study, TGA, FTIR spectroscopy analysis, biodegradability, and human dermal fibroblast seeding assay. The scaffold was subsequently used invivo as a skin substitute on a rat skin wound model. In vitro tests revealed that all scaffolds promoted cell adhesion and proliferation. However, more cell viability was observed in CS/RS 0.1 scaffold. The biocompatibility of the scaffolds was validated by MTT assay, and the results did not show any toxic effects on human dermal fibroblasts. It was observed that RS-coated scaffolds had the ability to release RS in a controlled manner. In invivo tests CS/RS 0.1 scaffold had the greatest impact on the healing process by improving the neodermis formation and modulated inflammation in wound granulation tissue. Histological analysis revealed enhanced vascular endothelial growth factor expression, epithelialization and increased depth of wound granulation tissue. The RS-coated CS/PEO nanofibrous scaffold accelerates wound healing and may be useful as a dressing for cell transfer and clinical skin regeneration.

The opioid growth regulatory system and naltrexone in diabetes: One side makes you taller and the other side makes you smaller

This article provides an overview of research into the inhibitory role of the Opioid Growth Regulatory System (OGRS), which is characterized by its mediator, Opioid Growth Factor (OGF), [Met 5 ]-enkephalin, and its specific receptor (OGFr), in the pathobiology of diabetic complications involving the ocular surface. Additionally, involvement of the OGRS in systemic diabetic complications is illustrated by its role in poor diabetic cutaneous wound healing. The title of this paper is derived from Lewis Carroll’s Alice’s Adventures in Wonderland in which Alice is invited by the caterpillar to eat either side of a mushroom with powerful growth inducing characteristics. In the context of this review, this metaphor highlights the antagonistic relationship between the OGRS and naltrexone (NTX), which blocks the binding of OGF to OGFr thereby preventing or reversing the deleterious effects of the OGRS in the pathobiology of diabetic complications such as dry eye, keratopathy (delayed corneal epithelial wound healing and decreased corneal sensitivity) and delayed cutaneous wound healing in animal models of type 1 and type 2 diabetes. In addition, we will show that topical NTX treatment has been demonstrated to be safe in early phase studies performed in humans. We believe these data support further clinical trials of NTX in the treatment of diabetic ocular surface disease and delayed cutaneous wound healing. Finally, our findings may have implications for the evaluation of the OGRS in the pathobiology of other systemic diabetic complications.

Bimetallic oxide Cu–Fe3O4 nanoclusters with multiple enzymatic activities for wound infection treatment and wound healing

Infections and oxidative stress complicate wound healing. In recent years, nanomaterials with natural enzymatic activities have enabled the development of new antibacterial pathways. In this study, Cu–Fe3O4 nanoclusters with multienzyme properties were synthesized. Interestingly, they exhibited activity similar to that of horseradish peroxidase (POD) in acidic environments but their functions resembled superoxide dismutase and catalase in neutral or weakly alkaline environments. In vitro studies have demonstrated the good free-radical scavenging activity of Cu–Fe3O4 nanoclusters in a neutral environment. Under acidic conditions, Cu–Fe3O4 nanoclusters combined with H2O2 demonstrated good antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli (E. coli). The combination of Cu–Fe3O4 and H2O2 was found to be effective in preventing MRSA infections and promoting wound healing in animal models. RNA sequencing (RNA-seq) technology revealed that chemodynamic therapy (CDT) using nanoparticles can interfere with metabolic processes such as galactose metabolism in MRSA bacteria, destroy the transport system on the surface of MRSA, and affect quorum sensing to hinder the formation of biofilms, thus achieving effective antibacterial efficacy. The use of Cu–Fe3O4 nanoclusters as a novel class of multi-catalytically active nanozymes in the anti-infection of disease-causing pathogens and wound healing has significant potential. Statement of significanceCu–Fe3O4 nanoclusters with multienzyme properties were successfully prepared by a solvothermal method. Cu–Fe3O4 nanoclusters exhibited horseradish peroxidase (POD)-like activity in acidic environments and also showed synergistic effects similar to superoxide dismutase peroxidase in neutral or weakly basic environments. More importantly, these Cu–Fe3O4 nanoclusters showed high biosafety with no apparent in vivo toxicity. Chemodynamic therapy (CDT) using Cu–Fe3O4 nanoclusters was revealed by RNA sequencing (RNA-Seq) technology to interfere with the metabolic processes of MRSA bacteria, such as galactose metabolism, disrupt the MRSA surface transport system, and impede biofilm formation, resulting in effective antibacterial efficacy. The use of Cu–Fe3O4 nanoclusters for anti-infection and wound healing of pathogenic pathogens has significant potential as a novel class of multi-catalytic active nanoclusters.

Facile and eco-friendly fabrication of biocompatible hydrogel containing CuS@Ser NPs with mechanical flexibility and photothermal antibacterial activity to promote infected wound healing

Bacterial infections can significantly impede wound healing and pose a serious threat to the patient’s life. The excessive use of antibiotics to combat bacterial infections has led to the emergence of multi-drug-resistant bacteria. Therefore, there is a pressing need for alternative approaches, such as photothermal therapy (PTT), to address this issue. In this study, for the first time, CuS NPs with photothermal properties were synthesized using sericin as a biological template, named CuS@Ser NPs. This method is simple, green, and does not produce toxic and harmful by-products. These nanoparticles were incorporated into a mixture (XK) of xanthan gum and konjac glucomannan (KGM) to obtain XK/CuS NPs composite hydrogel, which could overcome the limitations of current wound dressings. The composite hydrogel exhibited excellent mechanical flexibility, photothermal response, and biocompatibility. It also demonstrated potent antibacterial properties against both Gram-positive and negative bacteria via antibacterial experiments and accelerated wound healing in animal models. Additionally, it is proved that the hydrogel promoted tissue regeneration by stimulating collagen deposition, angiogenesis, and reducing inflammation. In summary, the XK/CuS NPs composite hydrogel presents a promising alternative for the clinical management of infected wounds, offering a new approach to promote infected wound healing.

Interleukin-6 in Traumatic Brain Injury: A Janus-Faced Player in Damage and Repair.

Traumatic brain injury (TBI) is a common and often devastating illness, with wide-ranging public health implications. In addition to the primary injury, victims of TBI are at risk for secondary neurological injury by numerous mechanisms. Current treatments are limited and do not target the profound immune response associated with injury. This immune response reflects a convergence of peripheral and central nervous system-resident immune cells whose interaction is mediated in part by a disruption in the blood-brain barrier (BBB). The diverse family of cytokines helps to govern this communication and among these, Interleukin (IL)-6 is a notable player in the immune response to acute neurological injury. It is also a well-established pharmacological target in a variety of other disease contexts. In TBI, elevated IL-6 levels are associated with worse outcomes, but the role of IL-6 in response to injury is double-edged. IL-6 promotes neurogenesis and wound healing in animal models of TBI, but it may also contribute to disruptions in the BBB and the progression of cerebral edema. Here, we review IL-6 biology in the context of TBI, with an eye to clarifying its controversial role and understanding its potential as a target for modulating the immune response in this disease.

Mechanical properties and wound healing potential of bacterial cellulose-xyloglucan-dextran hydrogels

Bacterial cellulose (BC) is a promising material for use as an artificial skin in wound healing application, however, its applications are limited due to its poor malleability. Incorporating non-cellulosic polysaccharides such as dextran and xyloglucan (XG) may enhance its respective wound healing and malleability. This study presents a novel in situ biopreparation method to produce BC-based hybrid hydrogels containing dextran (BC-D) and xyloglucan-dextran (BC-XG-D) with unique mechanical and rheological properties. Structural analysis revealed that dextran of different sizes (10 k, 70 k and 2 M of Mw) form micron-sized particles by loosely binding to cellulosic fibres. The addition of xyloglucan resulted acts as a lubricant in mechanical testing. The BC-XG-D hybrid hydrogels showed a reduced Young's modulus of 4 MPa and a higher maximum tensile strain of 53 % compared to native BC. Moreover, they displayed less plastic but more viscous behaviour under large shear strain deformation. The wound healing animal model experiments demonstrated that the BC-XG-D hybrid hydrogels promoted wound healing process and skin maturation. Overall, these findings contribute to the development of functional BC-based medical materials with desired mechanical and rheological properties that have the potential to accelerate wound healing.

In vivo efficiency of the produced recombinant lysostaphin antimicrobial peptide in treatment of methicillin-resistant Staphylococcus aureus (MRSA) skin infection in a mouse model.

Staphylococcus simulans secretes an antimicrobial compound called lysostaphin, which has bactericidal properties. It destroys staphylococci through the hydrolysis of peptidoglycan in the cell wall. Therefore, this unique property indicates the high ability of lysostaphin in the treatment of staphylococcal infections and is considered as an anti-staphylococcal agent. Escherichia coli BL21 (DE3) competent cells were transformed with pET32a-lysostaphin clone and induced by isopropyl-β-D-thio-galactoside (IPTG). The recombinant protein was purified by affinity chromatography. Recombinant lysostaphin -A-based ointment was used for external wound healing in animal model. In vivo activity of ointment was evaluated by clinical evidences and cytological microscopic assessment. Our results showed the recombinant protein was produced exactly. The results of checkerboard tests showed MIC, MBC and antibacterial activity test an acute reduction of cell viability during the use of lysostaphin, and SEM results approved the intense wrecking effects of lysostaphin in combination on bacterial cells. Macroscopic findings and microscopic data showed that the recombinant lysostaphin ointment was effective on excisional wound healing. Our findings proved that the recombinant lysostaphin ointment was effective on wound healing due to Staphylococcus aureus infection.

Bacterial cellulose membrane incorporated with silver nanoparticles for wound healing in animal model

The bacterial cellulose membrane (CM) is a promising biomaterial due to its easy applicability and moist environment. Moreover, nanoscale silver compounds (AgNO3) are synthesized and incorporated into CMs to provide these biomaterials with antimicrobial activity for wound healing. This study aimed to evaluate the cell viability of CM incorporated with nanoscale silver compounds, determine the minimum inhibitory concentration (MIC) for Escherichia coli and Staphylococcus aureus, and its use on in vivo skin lesions. Wistar rats were divided according to treatment: untreated, CM (cellulose membrane), and AgCM (CM incorporated with silver nanoparticles). The euthanasia was performed on the 2nd, 7th, 14th, and 21st days to assess inflammation (myeloperoxidase-neutrophils, N-acetylglucosaminidase-macrophage, IL-1β, IL-10), oxidative stress (NO-nitric oxide, DCF-H2O2), oxidative damage (carbonyl: membrane's damage; sulfhydryl: membrane's integrity), antioxidants (superoxide dismutase; glutathione), angiogenesis, tissue formation (collagen, TGF-β1, smooth muscle α-actin, small decorin, and biglycan proteoglycans). The use of AgCM did not show toxicity, but antibacterial effect in vitro. Moreover, in vivo, AgCM provided balanced oxidative action, modulated the inflammatory profile due to the reduction of IL-1β level and increase in IL-10 level, in addition to increased angiogenesis and collagen formation. The results suggest the use of silver nanoparticles (AgCM) enhanced the CM properties by providing antibacterial properties, modulation the inflammatory phase, and consequently promotes the healing of skin lesions, which can be used clinically to treat injuries.

The Efficacy of Topical Lactoferrin on Wound Healing in an Experimental Animal Model of Nasal Septum Perforation.

The aim of the present experimental animal study was to investigate the efficacy of bovine lactoferrin (LF) on wound healing in an animal model of nasal septum perforation (NSP).Twenty-two, 8 to 10 weeks of age, male Sprague-Dawley rats were separated into two groups. Nasal septum perforation was created in each rat. The saline (control) and 0.05 mg LF (study) groups were delivered locally for 14 days. On the 14th day of the study, after the sacrifice, the cartilage nasal septa of the animals were excised. The degeneration and regeneration observed in the nasal septum epithelium and cartilage, the number of acute inflammatory cells, the number of eosinophils, the amount of new vessel formation, the amount of granulation, and the collagen density were examined microscopically. The microscopic parameters and macroscopic healing of NSPs were analyzed. The epithelium regeneration, the fibroblast number, the granulation tissue formation, the collagen density, and the macroscopic healing were significantly higher in the LF group (p < 0.05). Besides, the acute inflammatory cell count was lower in the LF group (p = 0.034). In conclusion, the topically delivered LF can improve wound healing in an experimental rat model of NSP.

Advanced multilayer composite dressing with co-delivery of gelsevirine and silk fibroin for burn wound healing

Burn is one of the most common types of injuries worldwide, which remains a clinical challenge due to its progressive exacerbation caused by inflammation and edema that impede the growth and differentiation of fibroblast. To solve this problem, in this study, the anti-inflammatory Gelsvirine (Gs), as a specific STING inhibitor for rheumatoid arthritis pain, is used for inflammation control in burn wound healing. Meanwhile, to improve fibroblast migration, proliferation, and differentiation, the natural protein silk fibroin (SF) was used due to its demonstrated capacity to promote the proliferation of epidermal cells and fibroblasts, facilitate collagen synthesis and further improve wound repair. Through our rational design, a functional dressing for the co-delivery of Gs and SF is developed to improve burn wound healing. A multilayer composite dressing of Polycaprolactone(PCL)/Gs-loaded sodium alginate (SA)/SF-gelatin (Gs@SFD) was prepared using the combination of electrospinning and extrusion method, which contained four layers: PCL-dense barrier layer (to prevent infection), SA-hydrogel layer (to load Gs and keep wound moisture), PCL-loosen support layer (to prevent deformation of bioactive layer and to facilitate Gs release into trauma) and SF/gelatin bioactive layer (to contact with trauma and bioactively induce wound healing). Our data showed that the hydrogel layer realized the sustained release of Gs. As a specific inhibitor of STING signaling pathway, the released Gs inhibited the inflammatory response of macrophages and further reduced the fibroblast damage both in vitro and in vivo. In addition, the bioactive layer promoted cell proliferation, facilitated collagen synthesis, and further improved wound healing in animal model of burn trauma. Therefore, this study provides a novel multilayer composite dressing (Gs@SFD) to facilitate burn wound healing via efficient inflammation control with the sustained release of Gs, and improvement on wound healing due to the bioactive components of silk fibroin, which could serve as a potential therapeutic approach in the future. In addition, our multilayer dressing design provides an advanced drug delivery strategy for burn wound healing.

Mongolian Gerbils as an Animal Model of Wound Healing

Mongolian Gerbils As An Animal Model Of Wound Healing - Video. JoVE publishes peer-reviewed scientific video protocols to accelerate biological, medical, chemical and physical research. Watch our scientific video articles. JoVE is the world-leading producer and provider of science videos with the mission to improve scientific research, scientific journals, and education. Millions of scientists, educators and students at thousands of universities, colleges, hospitals and biopharmaceutical companies worldwide use JoVE for their research, teaching and learning.

Mongolian Gerbils as an Animal Model of Wound Healing.

Corneal wound healing studies have been conducted for a long time and have helped to reduce suffering and develop treatments that contribute to improving patients' eye health. Historically, corneal healing has been studied in rodents such as mice and rats, but these models might not completely mimic human disorders. However, information on other rodents such as Mongolian gerbils (Meriones unguiculatus) is scant in corneal research. Here, we describe a technique to develop a novel animal model for studying corneal healing after photorefractive keratectomy. Due to the limited literature available on the cornea of M. unguiculatus, we also describe a histological analysis of the normal cornea. These research techniques can also be employed in the study of eye diseases because of the similarity between the corneas of Mongolian gerbils and humans in terms of genetics, anatomy, and physiology.

The use of occlusive dressings: influence on excisional wound healing in animal model.

To analyze the influence of occlusive dressing on the healing of excisional skin wounds in mice. Pre-clinical, comparative, and translational study. Mice were divided into three experimental groups: wounds occluded with hydrocolloid (HD) dressings, transparent polyurethane film (TF) dressings, and without occlusion (WO), monitored at three, six and 14 days, with eight animals each. Closure rate, infiltration of neutrophils and macrophages, measurement of tumor necrosis factor-α (TNF-α) and vascular endothelial growth factor (VEGF) and, histologically, angiogenesis were evaluated. Wound closure was accelerated in the occlusive groups. There was a decrease in TNF-α levels in the HD group when compared to the WO and TF groups. Neutrophils accumulation decreased in the HD group. Increased dosages of macrophages were evidenced in the HD group, compared to the WO and TF groups. Levels of VEGF were increased in the TF and HD groups. It is suggested that the occlusion of wounds modulates the inflammatory response.

Effective Combination Therapy with Human Amniotic Membrane Mesenchymal Stem Cells and Low-Level Laser Therapy in Wound Healing in Animal Models.

Introduction: Many studies have recognized the importance of new methods in wound healing. This study aims to investigate the healing effects of allograft extra embryonic mesenchymal stem cells (MSCs) with and without low-level diode laser irradiation when grafted into full-thickness skin defects in diabetic animal models. Methods: In this experimental study, in order to make the rats diabetic, we used an intra-peritoneal injection of streptozotocin. Human amniotic membrane derived mesenchymal stem cells (hAMSCs) were irradiated with a low-level diode laser. Two full-thickness excisions were made on the backs of the rats. Next, the rats were divided into the following groups: group 1: low-level laser (LLL) irradiated hAMSCs and group 2: hAMSCs alone transplanted into skin wound. Histopathologic, ultrasound and elasticity evaluations were performed 7, 14 and 21 days after grafting. Results: In the evaluated rats, epithelial formation was on day 7 and increased until day 14. On days 7, 14 and 21, the percentage of epithelial formation in the irradiated cell group was significantly higher than that in the cell group, so that, on day 21, the epithelium in this group completely covered the wound surface while in the control group the wound surface was still not completely covered. In terms of angiogenesis, on day 7, the irradiated cells were significantly lower than the cells. Also, the formation of collagen in the cellular hydrogel group could confirm the effectiveness of amniotic MSCs in collagen production and thus accelerate the wound healing process. In comparison with hAMSCs alone, irradiated hAMSCs increased the thickness and elasticity of the skin. Conclusion: Low-power laser along with MSCs can be effective in improving chronic wound condition in the animal model.

Rock inhibitors and antisense oligonucleotides for Fuchs corneal endothelial dystrophy

AbstractFuchs corneal dystrophy (FECD) is the most common primary cause of corneal endothelial dystrophy. FECD is a complex disease where interaction between multiple genetic and environmental factors results in endothelial cells apoptosis and atypical extracellular matrix deposition. Due to the shortage of donor tissue, and high costs of transplants, a topical therapy for treating corneal endothelial dysfunction is urgently required. The topical treatment of several agents has been investigated as therapies for FECD, by the promotion of endothelial cell proliferation and migration, in experimental models of the disorder. ROCK1 and ROCK2 inhibition promotes cell adhesion, prevents apoptosis, and enhances the proliferation of and human corneal endothelial cells. These therapies have involved the knockdown of connexin by siRNA, the release of cell–cell contact inhibition with EDTA, and inhibition of Rho‐associated protein kinase (ROCK) with Y‐27632. Recently several papers showed that Ripasudil, a rho kinase inhibitor, has been shown to promote corneal endothelial wound healing in animal models and in clinical trials. An antisense oligonucleotide (ASO) has also been developed to target the repetitive RNA. This has been shown to decrease foci formation and reversal of misplacing in ex‐vivo FECD specimens. Antisense oligonucleotides (ASO) reduced the RNA aggregates and their toxic downstream events in patient cells. ASO has to be designed to target a particular genetic mutation. This new medical‐based regenerative therapy may provide a less invasive and more effective method for treating patients with FECD.

Evaluating the Effectiveness of Aqueous Extract of Persian Oak (Quercus castaneifolia C.A.Mey.) Fruit Hull on Dermal Wound Healing in the Rat Model

Background: Persian oak (Quercus castaneifolia C.A.Mey) belongs to the Fagaceae family. This plant is commonly used in Iranian traditional medicine to treat inflammatory and gastric ulcers. Objectives: This study aimed to assess the efficacy of Persian oak fruit aqueous hull extract on wound healing in rats. Methods: Thirty-five male Wistar rats were randomly divided into five groups, then two full-thickness wounds of 10 mm in diameter were created bilaterally on the back of the animals. The negative control group received saline, the positive control group was treated with phenytoin cream, and three treatment groups received 2%, 4%, and 8% Jaft aqueous extract. The animals received these medicines once daily for 15 days. The percentage of wound healing was evaluated using wound contraction ratio, re-epithelialization, tensile strength, vascular endothelial growth factor (VEGF), and platelet-derived growth factor (PDGF) content. Histopathological examination was performed on repaired tissues. Results: In the 2%, 4%, and 8% Jaft extract and the phenytoin groups, the wound closure rate was significantly higher than in the saline group. The treatment groups revealed significant healing improvement (P &lt; 0.05) compared to the control group in wound contraction, tensile strength, epithelialization duration, VEGF, and PDGF plasma level. Histopathological investigations also exhibited development in wound healing with Jaft extract. Conclusions: This study shows that the Persian oak fruit hull aqueous extract was effective in wound healing in animal models. Clinical trials are required to prove the efficacy of Q. castaneifolia fruit hull spray in healing various wounds in humans.

A Rigid Nanoplatform for Precise and Responsive Treatment of Intracellular Multidrug-Resistant Bacteria

Antibiotic treatment failure against life-threatening bacterial pathogens is typically caused by the rapid emergence and dissemination of antibiotic resistance. The current lack of antibiotic discovery and development urgently calls for new strategies to combat multidrug-resistant (MDR) bacteria, especially those that survive in host cells. Functional nanoparticles are promising intracellular drug delivery systems whose advantages include their high biocompatibility and tunable surface modifications. Inspired by the fact that the rigidity of nanoparticles potentiates their cellular uptake, rigidity-functionalized nanoparticles (RFNs) coated with bacteria-responsive phospholipids were fabricated to boost endocytosis, resulting in the increased accumulation of intracellular antibiotics. Precise delivery and high antibacterial efficacy were demonstrated by the clearing of 99% of MDR bacteria in 4 h using methicillin-resistant Staphylococcus aureus (MRSA) and pathogenic Bacillus cereus as models. In addition, the subcellular distribution of the RFNs was modulated by altering the phospholipid composition on the surface, thereby adjusting the electrostatic effects and reprograming the intracellular behavior of the RFNs by causing them to accurately target lysosomes. Finally, the RFNs showed high efficacy against MRSA-associated infections in animal models of wound healing and bacteremia. These findings provide a controllable rigidity-regulated delivery platform with responsive properties for precisely reprograming the accumulation of cytosolic antibiotics, shedding light on precision antimicrobial therapeutics against intracellular bacterial pathogens in the future.

53. Wound Edge Inversion Delays Healing and Contributes to Dystrophic Scar Formation in a Mouse Model

Purpose: Management of dystrophic scars often requires surgical excision in the delayed periods as there are few reliable options to prophylax against the formation off dystrophic scars during physiologic or pathologic wound healing. This is in part because of limitations in the availability of genetically tractable small-animal models which can reliably generate the desired dystrophic tissue architecture. While using small animal models of wound healing is desired, the nature of murine dermal healing through contracture makes it poorly suited to the study of later wound sequalae such as dystrophic scars. We have previously demonstrated that tissue-edge inward folding mimicking the architecture of epibole mitigates contracture, restricts epithelialization, and prolongs wound opening. Here we demonstrate that murine epibolous wounds generate an environment of sustained inflammatory infiltration and proliferative granulation and ultimately generate consistent and reliable dystrophic scars in mice. Methods: Male C57BL/6J control (wt/wt) and diabetic (db/db) mice received bilateral 6mm excisional wounds. Each wound was stratified as either untreated control or chronic model. Chronic wounds were generated by incising skin flaps, which were sutured to the dermis side to create a folded skin edge. A first (acute) cohort was s were maintained for 14-days until all control wounds had closed and/or epithelialized and were harvested for flow cytometry for neutrophils and/or macrophages and/or histology for pan-keratin (epithelium) and alpha-smooth-muscle actin (myofibroblasts). A second (delayed) cohort was maintained until closure up to 63 days. Photographs were taken at time of sacrifice and samples were collected for H&E and Masson’s Trichrome Stain. Results: The epibolous wound environment maintained prolonged neutrophil-dominant inflammatory infiltrate up to 2-weeks with simultaneous enrichment of macrophage/monocyte populations (p<0.05). Epibolous wounds demonstrated reduced frequency of epithelialization as defined by pan-keratin signaling. In epibolous wounds without epithelialization, strong alpha-smooth-muscle actin signal was noted. When allowed to proceed to maturation, scars from epibole injuries remained significantly larger (p<0.05). This was true in both control and diabetic models. All wound-edge inversion injuries demonstrated gross and histologic evidence of dystrophic healing and collagen deposition compared to controls. Conclusion: Previously we demonstrated that wound-edge inversion to mimic epibole prolongs wound opening. Here we demonstrate that this translates to prolongs inflammation and a transition of murine healing to a more human-relevant granulation pattern. Furthermore, the delay of closure results in a consistent dystrophic scar without need for thermal, radiological, chemical or biological interference. Consequently, this simple surgical maneuver enhances our ability to study and intervene in the process of acute and chronic wound development and dystrophic scar formation in a histologically humanized model while retaining access to the genetic tractability of murine stock.

Strategies to Minimize Surgical Scarring: Translation of Lessons Learned from Bedside to Bench and Back.

Significance: An understanding of the physiology of wound healing and scarring is necessary to minimize surgical scar formation. By reducing tension across the healing wound, eliminating excess inflammation and infection, and encouraging perfusion to healing areas, surgeons can support healing and minimize scarring. Recent Advances: Preoperatively, newer techniques focused on incision placement to minimize tension, skin sterilization to minimize infection and inflammation, and control of comorbid factors to promote a healing process with minimal scarring are constantly evolving. Intraoperatively, measures like layered closure, undermining, and tissue expansion can be taken to relieve tension across the healing wound. Appropriate suture technique and selection should be considered, and finally, there are new surgical technologies available to reduce tension across the closure. Postoperatively, the healing process can be supported as proliferation and remodeling take place within the wound. A balance of moisture control, tension reduction, and infection prevention can be achieved with dressings, ointments, and silicone. Vitamins and corticosteroids can also affect the scarring process by modulating the cellular factors involved in healing. Critical Issues: Healing with no or minimal scarring is the ultimate goal of wound healing research. Understanding how mechanical tension, inflammation and infection, and perfusion and hypoxia impact profibrotic pathways allows for the development of therapies that can modulate cytokine response and the wound extracellular microenvironment to reduce fibrosis and scarring. Future Directions: New tension-off loading topical treatments, laser, and dermabrasion devices are under development, and small molecule therapeutics have demonstrated scarless wound healing in animal models, providing a promising new direction for future research aimed to minimize surgical scarring.