Hyperglycaemic conditions decrease cultured keratinocyte mobility: implications for impaired wound healing in patients with diabetes

Bioengineered MSCCxcr2 transdifferentiated keratinocyte-like cell-derived organoid potentiates skin regeneration through ERK1/2 and STAT3 signaling in diabetic wound

Skin regeneration is severely compromised in diabetic foot ulcers. Allogeneic mesenchymal stem cell (MSC) transplantation is limited due to the poor engraftment, mitogenic, and differentiation potential in the harsh wound microenvironment. Thus, to improve the efficacy of cell therapy, the chemokine receptor Cxcr2 was overexpressed in MSCs (MSCCxcr2). CXCL2/CXCR2 axis induction led to the enhanced proliferation of MSCs through the activation of STAT3 and ERK1/2 signaling. Transcriptional upregulation of FGFR2IIIb (KGF Receptor) promoter by the activated STAT3 and ERK1/2 suggested trans-differentiation of MSCs into keratinocytes. These stable MSCCxcr2 in 2D and 3D (spheroid) cell cultures efficiently transdifferentiated into keratinocyte-like cells (KLCs). An in vivo therapeutic potential of MSCCxcr2 transplantation and its keratinocyte-specific cell fate was observed by accelerated skin tissue regeneration in an excisional splinting wound healing murine model of streptozotocin-induced type 1 diabetes. Finally, 3D skin organoids generated using MSCCxcr2-derived KLCs upon grafting in a relatively avascular and non-healing wounds of type 2 diabetic db/db transgenic old mice resulted in a significant enhancement in the rate of wound closure by increased epithelialization (epidermal layer) and endothelialization (dermal layer). Our findings emphasize the therapeutic role of the CXCL2/CXCR2 axis in inducing trans-differentiation of the MSCs toward KLCs through the activation of ERK1/2 and STAT3 signaling and enhanced skin regeneration potential of 3D organoids grafting in chronic diabetic wounds.

One-Step Synthesis of Hydrogel Adhesive with Acid-Responsive Tannin Release for Diabetic Oral Mucosa Defects Healing

The complex preparation, weak wet tissue adhesion, and limited biological activity of traditional oral wound dressings usually impede their efficient treatment and healing for diabetic oral mucosal defects. To overcome these problems, a novel hydrogel adhesive (named CFT hydrogel) is rapidly constructed using a one-step method based on dual-dynamic covalent cross-linking. Compared with the commercial oral patches, the CFT hydrogel shows superior in vivo (rat tongue) wet tissue adhesion performance. Additionally, the CFT hydrogel exhibits unique acid-responsive properties, thereby facilitating the release of bioactive molecule tannic acid in the acidic diabetic wound microenvironment. And a series of in vitro experiments substantiate the favorable biocompatibility and bioactivity properties (including antibacterial, antioxidative, anti-inflammatory, and angiogenetic effects) exhibited by CFT hydrogel. Moreover, in vivo experiments conducted on a diabetic rat model with oral mucosal defects demonstrate that the CFT hydrogel exhibits significant efficacy in protecting against mucosal wounds, alleviating inflammatory reactions, thereby facilitating the wound-healing process. Taken together, this study provides a promising and comprehensive therapeutic option with great potential for the clinical management of oral mucosa defects in diabetic patients.

Diabetic Foot Ulcer Management and Treatment: An Overview of Published Patents

BACKGROUND

One of the most challenging effects of diabetes is diabetic foot ulceration (DFU). DFU may occur in up to one-third of individuals with diabetes mellitus (D.M.) at some point in their lives. The major cause of morbidity in D.M. patients is DFU. The length of treatment is difficult, and DFU recurrence is common.

OBJECTIVE

The most crucial element for the treatment and prevention of DFUs require a multidisciplinary approach. Patients who are at risk should be identified, depending on the type of risk, prophylactic actions etc. It is imperative to identify at-risk patients and take preventative measures accordingly.

METHOD

The at-risk diabetes-related foot ulcer was identified based on the risk category classification, while the foot ulcers were evaluated using Wagner's classification system.

RESULTS

Literature reported that patients with lower limb vascular insufficiency, loss of vibratory sensation, or protective sensation loss have an increased risk of developing foot ulcers. Proper categorization and therapeutic measures will be implemented after the DFU has been formed. The appropriate assessment and management of general health status should include glycemic control, the diagnosis and treatment of vascular disease, standard care for wounds, diagnosis, and infection treatments.

CONCLUSION

The review reflects the updated awareness of the treatment and management of DFU based on the current and past literature and patent analysis.

Panthenol Citrate Biomaterials Accelerate Wound Healing and Restore Tissue Integrity

Impaired wound healing is a common complication for diabetic patients and effective diabetic wound management remains a clinical challenge. Furthermore, a significant problem that contributes to patient morbidity is the suboptimal quality of healed skin, which often leads to reoccurring chronic skin wounds. Herein, a novel compound and biomaterial building block, panthenol citrate (PC), is developed. It has interesting fluorescence and absorbance properties, and it is shown that PC can be used in soluble form as a wash solution and as a hydrogel dressing to address impaired wound healing in diabetes. PC exhibits antioxidant, antibacterial, anti-inflammatory, and pro-angiogenic properties, and promotes keratinocyte and dermal fibroblast migration and proliferation. When applied in a splinted excisional wound diabetic rodent model, PC improves re-epithelialization, granulation tissue formation, and neovascularization. It also reduces inflammation and oxidative stress in the wound environment. Most importantly, it improves the regenerated tissue quality with enhanced mechanical strength and electrical properties. Therefore, PC could potentially improve wound care management for diabetic patients and play a beneficial role in other tissue regeneration applications.

Biomimetic human skin model patterned with rete ridges

Rete ridges consist of undulations between the epidermis and dermis that enhance the mechanical properties and biological function of human skin. However, most human skin models are fabricated with a flat interface between the epidermal and dermal layers. Here, we report a micro-stamping method for producing human skin models patterned with rete ridges of controlled geometry. To mitigate keratinocyte-induced matrix degradation, telocollagen-fibrin matrices with and without crosslinks enable these micropatterned features to persist during longitudinal culture. Our human skin model exhibits an epidermis that includes the following markers: cytokeratin 14, p63, and Ki67 in the basal layer, cytokeratin 10 in the suprabasal layer, and laminin and collagen IV in the basement membrane. We demonstrated that two keratinocyte cell lines, one from a neonatal donor and another from an adult diabetic donor, are compatible with this model. We tested this model using an irritation test and showed that the epidermis prevents rapid penetration of sodium dodecyl sulfate. Gene expression analysis revealed differences in keratinocytes obtained from the two donors as well as between 2D (control) and 3D culture conditions. Our human skin model may find potential application for drug and cosmetic testing, disease and wound healing modeling, and aging studies.

Cutaneous changes in diabetic patients: Primed for aberrant healing?

Cutaneous manifestations affect most patients with diabetes mellitus, clinically presenting with numerous dermatologic diseases from xerosis to diabetic foot ulcers (DFUs). Skin conditions not only impose a significantly impaired quality of life on individuals with diabetes but also predispose patients to further complications. Knowledge of cutaneous biology and the wound healing process under diabetic conditions is largely limited to animal models, and studies focusing on biology of the human condition of DFUs remain limited. In this review, we discuss the critical molecular, cellular, and structural changes to the skin in the hyperglycaemic and insulin-resistant environment of diabetes with a focus specifically on human-derived data. Elucidating the breadth of the cutaneous manifestations coupled with effective diabetes management is important for improving patient quality of life and averting future complications including wound healing disorders.

Incubation with porcine urinary bladder matrix yields a late-stage wound transcriptome in endothelial cells and keratinocytes isolated from both diabetic and non-diabetic subjects

Proper wound closure requires the functional coordination of endothelial cells (ECs) and keratinocytes. In the late stages of wound healing, keratinocytes become activated and ECs promote the maturation of nascent blood vessels. In diabetes mellitus, decreased keratinocyte activation and impaired angiogenic action of ECs delay wound healing. Porcine urinary bladder matrix (UBM) improves the rate of wound healing, but the effect of exposure to UBM under diabetic conditions remains unclear. We hypothesized that keratinocytes and ECs isolated from both diabetic and non-diabetic donors would exhibit a similar transcriptome representative of the later stages of wound healing following incubation with UBM. Human keratinocytes and dermal ECs isolated from non-diabetic and diabetic donors were incubated with and without UBM particulate. RNA-Seq analysis was performed to identify changes in the transcriptome of these cells associated with exposure to UBM. While diabetic and non-diabetic cells exhibited different transcriptomes, these differences were minimized following incubation with UBM. ECs exposed to UBM exhibited changes in the expression of transcripts suggesting an increase in the endothelial-mesenchymal transition (EndoMT) associated with vessel maturation. Keratinocytes incubated with UBM demonstrated an increase in markers of activation. Comparison of the whole transcriptomes with public datasets suggested increased EndoMT and keratinocyte activation following UBM exposure. Both cell types exhibited loss of pro-inflammatory cytokines and adhesion molecules. These data suggest that application of UBM may accelerate healing by promoting a transition to the later stages of wound healing. This healing phenotype is achieved in cells isolated from both diabetic and non-diabetic donors.

Adiponectin as a therapeutic target for diabetic foot ulcer

The global burden of diabetic foot ulcers (DFUs) is a significant public health concern, affecting millions of people worldwide. These wounds cause considerable suffering and have a high economic cost. Therefore, there is a need for effective strategies to prevent and treat DFUs. One promising therapeutic approach is the use of adiponectin, a hormone primarily produced and secreted by adipose tissue. Adiponectin has demonstrated anti-inflammatory and anti-atherogenic properties, and researchers have suggested its potential therapeutic applications in the treatment of DFUs. Studies have indicated that adiponectin can inhibit the production of pro-inflammatory cytokines, increase the production of vascular endothelial growth factor, a key mediator of angiogenesis, and inhibit the activation of the intrinsic apoptotic pathway. Additionally, adiponectin has been found to possess antioxidant properties and impact glucose metabolism, the immune system, extracellular matrix remodeling, and nerve function. The objective of this review is to summarize the current state of research on the potential role of adiponectin in the treatment of DFUs and to identify areas where further research is needed in order to fully understand the effects of adiponectin on DFUs and to establish its safety and efficacy as a treatment for DFUs in the clinical setting. This will provide a deeper understanding of the underlying mechanisms of DFUs that can aid in the development of new and more effective treatment strategies.

Various effects of 11,12 EET rescue wound healing in a combined model of diabetes and ischemia

Chronic non healing wounds in diabetic patients still impose a major problem in modern medicine. Especially additional peripheral vascular disease complicates treatment success in these patients. Thus, we analyzed the effects of 11,12 epoxyeicosatrienoic acid (EET) in a combined model of hyperglycemia and ischemia in mice. Hyperglycemia was induced by Streptozotozin 2 weeks prior to wounding. 3 days before wound creation 2 of the 3 suppling vessels of the moue ear were cautherized for ischemia. Either 11,12 EET or solvent for control was applied. Wound closure as well as TNF-α, TGF-β, SDF-1α, VEGF, CD31, and Ki67 were measured. The wounds closed on day 14.4 ± 0.4 standard deviation (SD). 11,12 EET treatment enhanced healing to 9.8 ± 0.6 SD. TNF-α level was augmented on day 9 compared to control and receded on day 18. TGF-β seemed to be elevated all days observed after 11,12 EET treatment. SDF-1α was enhanced on day 6 and 9 by 11,12 EET, and VEGF on day 6 and 18 as well as CD13 on day 3, 6, and 18. 11,12 EET did not alter Ki67. 11,12 EET are able to rescue deteriorated wound healing in a combined model of hyperglycamia and ischemia by resolution of inflammation, augmentation of neovascularization and increasing expression of TGF-β as well as SDF-1α.

Infected Diabetic Wound Regeneration Using Peptide-Modified Chiral Dressing to Target Revascularization

Revascularization plays a critical role in the healing of diabetic wounds. Accumulation of advanced glycation end products (AGEs) and refractory multidrug resistant bacterial infection are the two major barriers to revascularization, directly leading to impaired healing of diabetic wounds. Here, an artfully designed chiral gel dressing is fabricated (named as HA-LM2-RMR), which consists of l-phenylalanine and cationic hexapeptide coassembled helical nanofibers cross-linked with hyaluronic acid via hydrogen bonding. This chiral gel possesses abundant chiral and cationic sites, not only effectively reducing AGEs via stereoselective interaction but also specifically killing multidrug resistant bacteria rather than host cells since cationic hexapeptides selectively interact with negatively charged microbial membrane. Surprisingly, the HA-LM2-RMR fibers present an attractive ability to activate sprouted angiogenesis of Human Umbilical Vein Endothelial Cells by upregulating VEGF and OPA1 expression. In comparison with clinical Prontosan Wound Gel, the HA-LM2-RMR gel presents superior healing efficiency in the infected diabetic wound with respect to angiogenesis and re-epithelialization, shortening the healing period from 21 days to 14 days. These findings for chiral wound dressing provide insights for the design and construction of diabetic wound dressings that target revascularization, which holds great potential to be utilized in tissue regenerative medicine.

Mechanisms of Nrf2 and NF-κB pathways in diabetic wound and potential treatment strategies

The issue of delayed wound healing or nonhealing in diabetic patients presents a challenge for modern medicine. A number of attempts have been made to understand the mechanisms behind diabetic wound. In a hyperglycemic environment, increased intracellular reactive oxygen species (ROS) disturb the balance between oxidation and antioxidant, causing the wound environment to deteriorate. It has been established that the nuclear factor E2-related factor 2 (Nrf2) and nuclear factor-kappa B (NF-κB) pathways play an important role in regulating inflammation and oxidative stress. Several potential treatment strategies involving Nrf2 and/or NF-κB pathways have been explored in previous studies. Hence, we analyzed mechanisms and changes in Nrf2 and NF-κB pathways in response to oxidative stress and inflammation in diabetic environment. Additionally, we reviewed potential treatment strategies from the past five years for diabetic wound by Nrf2 and/or NF-κB pathways, including receptor agonists, vitamins, hormones, exosomes, drugs, plants, and biomaterials. It may be useful to develop drugs to promote diabetic wound healing.

Acceleration of Oral Wound Healing under Diabetes Mellitus Conditions Using Bioadhesive Hydrogel

Oral wounds under diabetic conditions display a significant delay during the healing process, mainly due to oxidative stress-induced inflammatory status and abnormal immune responses. Besides, the wet and complicated dynamic environment of the oral cavity impedes stable treatment of oral wounds. To overcome these, a biomimetic hydrogel adhesive was innovatively developed based on a mussel-inspired multifunctional structure. The adhesive displays efficient adhesion and mechanical harmony on the oral mucosa through enhanced bonding in an acidic proinflammatory environment. The bioadhesive hydrogel exhibits excellent antioxidative properties by mimicking antioxidative enzymatic activities to reverse reactive oxygen species (ROS)-mediated immune disorders. Experiments on oral wounds of diabetic rats showed that this hydrogel adhesive could effectively protect against mucosal wounds and obviously shorten the inflammatory phase, thus promoting the wound-healing process. Therefore, this study offers a promising therapeutic choice with the potential to advance the clinical treatment of diabetic oral wounds.

Mapping intellectual structure and research hotspots in the field of fibroblast-associated DFUs: a bibliometric analysis

Background

Diabetic foot ulcers (DFUs) are one of the most popular and severe complications of diabetes. The persistent non-healing of DFUs may eventually contribute to severe complications such as amputation, which presents patients with significant physical and psychological challenges. Fibroblasts are critical cells in wound healing and perform essential roles in all phases of wound healing. In diabetic foot patients, the disruption of fibroblast function exacerbates the non-healing of the wound. This study aimed to summarize the hotspots and evaluate the global research trends on fibroblast-related DFUs through bibliometric analysis.

Methods

Scientific publications on the study of fibroblast-related DFUs from January 1, 2000 to April 27, 2022 were retrieved from the Web of Science Core Collection (WoSCC). Biblioshiny software was primarily performed for the visual analysis of the literature, CiteSpace software and VOSviewer software were used to validate the results.

Results

A total of 479 articles on fibroblast-related DFUs were retrieved. The most published countries, institutions, journals, and authors in this field were the USA, The Chinese University of Hong Kong, Wound Repair and Regeneration, and Seung-Kyu Han. In addition, keyword co-occurrence networks, historical direct citation networks, thematic map, and the trend topics map summarize the research hotspots and trends in this field.

Conclusion

Current studies indicated that research on fibroblast-related DFUs is attracting increasing concern and have clinical implications. The cellular and molecular mechanisms of the DFU pathophysiological process, the molecular mechanisms and therapeutic targets associated with DFUs angiogenesis, and the measures to promote DFUs wound healing are three worthy research hotspots in this field.

The burden of diabetes on the soft tissue seal surrounding the dental implants

Soft tissue seal around implant prostheses is considered the primary barrier against adverse external stimuli and is a critical factor in maintaining dental implants' stability. Soft tissue seal is formed mainly by the adhesion of epithelial tissue and fibrous connective tissue to the transmembrane portion of the implant. Type 2 diabetes mellitus (T2DM) is one of the risk factors for peri-implant inflammation, and peri-implant disease may be triggered by dysfunction of the soft tissue barrier around dental implants. This is increasingly considered a promising target for disease treatment and management. However, many studies have demonstrated that pathogenic bacterial infestation, gingival immune inflammation, overactive matrix metalloproteinases (MMPs), impaired wound healing processes and excessive oxidative stress may trigger poor peri-implant soft tissue sealing, which may be more severe in the T2DM state. This article reviews the structure of peri-implant soft tissue seal, peri-implant disease and treatment, and moderating mechanisms of impaired soft tissue seal around implants due to T2DM to inform the development of treatment strategies for dental implants in patients with dental defects.

High Glucose Induces Late Differentiation and Death of Human Oral Keratinocytes

Keratinocytes are essential cells for wound repair. Impaired oral wound healing is common in diabetic patients with periodontal disease. High glucose, or hyperglycemia, impairs the cellular function of different cell types. However, it is unknown whether high glucose has a detrimental effect on the functions of oral keratinocytes. In the current study, a human gingival keratinocyte cell line, telomerase immortalized gingival keratinocytes (TIGK), was treated with high glucose (24 and 48 mM) for up to 120 h. Proliferation, migration, cell viability, and production of markers of differentiation, growth factors and enzymatic antioxidants were assessed after high glucose treatment. The results showed that high glucose significantly inhibited TIGK proliferation and migration. High glucose also induced significant cell death through apoptosis and necrosis as determined by flow cytometry, especially at 120 h after high glucose treatment. Necrosis was the dominant form of cell death induced. Real-time PCR showed that high glucose treatment upregulated mRNA expression of late keratinocyte differentiation makers, such as keratin 1, 10, 13 and loricrin, and downregulated enzymatic antioxidants, including superoxide dismutase 1, catalase, nuclear factor erythroid 2 -related factor 2, heme oxygenase 1. In conclusion, high glucose impairs the proliferation and migration of oral keratinocytes and likely induces cell death through the promotion of late cell differentiation and down-regulation of enzymatic antioxidants.

Nephrin expression in human epidermal keratinocytes and its implication in poor wound closure

Nephrin is a type-1 transmembrane protein and a component of the slit diaphragm renal-filtration barrier. It has several functions in actin remodeling and cell-cell adhesion. Nephrin is principally located in the kidney glomerulus, but several studies have reported that nephrin is found in the pancreas, brain, and placenta. However, nephrin expression and its role in human skin have not yet been reported. First, using single-cell RNA sequencing, immunohistochemistry, and immuno-electron microscopy, nephrin expression was confirmed in human-skin epidermal keratinocytes. Nephrin expression colocalized with the expression of zonula occludens-1 in keratinocytes and was closely related to keratinocyte cell density, proliferation, and migration. High glucose treatment decreased nephrin expression and compromised keratinocyte cell migration without yes-associated protein nuclear entry. This reduced cell migration under high glucose conditions was improved in nephrin-overexpressing keratinocytes. Nephrin was highly expressed on the margins of re-epithelized epidermis based on in vivo mice and ex vivo human skin wound models. The results demonstrate that nephrin is expressed in human-skin keratinocytes and functions in cell adhesion, proliferation, and migration. In conclusion, this study suggests that nephrin may have a variety of physiological roles in human skin.

The Gut-Skin Microbiota Axis and Its Role in Diabetic Wound Healing-A Review Based on Current Literature

Diabetic foot ulcers (DFU) are a growing concern worldwide as they pose complications in routine clinical practices such as diagnosis and management. Bacterial interactions on the skin surface are vital to the pathophysiology of DFU and may control delayed wound healing. The microbiota from our skin directly regulates cutaneous health and disease by interacting with the numerous cells involved in the wound healing mechanism. Commensal microbiota, in particular, interact with wound-repairing skin cells to enhance barrier regeneration. The observed microbes in DFU include Staphylococcus, Streptococcus, Corynebacterium, Pseudomonas, and several anaerobes. Skin commensal microbes, namely S. epidermidis, can regulate the gamma delta T cells and induce Perforin-2 expression. The increased expression of Perforin-2 by skin cells destroyed S. aureus within the cells, facilitating wound healing. Possible crosstalk between the human commensal microbiome and different cell types involved in cutaneous wound healing promotes the immune response and helps to maintain the barrier function in humans. Wound healing is a highly well-coordinated, complex mechanism; it can be devastating if interrupted. Skin microbiomes are being studied in relation to the gut-skin axis along with their effects on dermatologic conditions. The gut-skin axis illustrates the connection wherein the gut can impact skin health due to its immunological and metabolic properties. The precise mechanism underlying gut-skin microbial interactions is still unidentified, but the immune and endocrine systems are likely to be involved. Next-generation sequencing and the development of bioinformatics pipelines may considerably improve the understanding of the microbiome-skin axis involved in diabetic wound healing in a much more sophisticated way. We endeavor to shed light on the importance of these pathways in the pathomechanisms of the most prevalent inflammatory conditions including the diabetes wound healing, as well as how probiotics may intervene in the gut-skin axis.

The effects of electrical stimulation on diabetic ulcers of foot and lower limb: A systematic review

Diabetic foot ulcer (DFU) is a life-threatening condition affecting a third of diabetic patients. Many adjuvant therapies aimed at improving the healing rate (HR) and accelerating healing time are currently under investigation. Electrical stimulation (ES) is a physical-based therapy able to increase cells activity and migration into wound bed as well as inhibiting bacterial activity. The aim of this paper was to collect and analyse findings on the effects of ES used in combination with standard wound care (SWC) in the treatment of diabetic foot ulceration compared with SWC alone. A systematic review was performed to synthesise data from quantitative studies from eight databases. Article quality was assessed using the Crowe critical appraisal tool. Seven articles out of 560 publications met the inclusion criteria. A meta-analysis was not performed due to the heterogeneity of the studies and the results were narratively synthetised. Findings showed that HR appears to be higher among diabetic ulcers treated with ES; however, the reliability of these findings is affected by the small sample sizes of the studies. Furthermore, four studies are considered as moderate or high risk of bias. The evidence to suggest the systematic usage of ES in the treatment of DFUs is still insufficient.

Green Synthesis of Silver Nanoparticles by the Cyanobacteria Synechocystis sp.: Characterization, Antimicrobial and Diabetic Wound-Healing Actions

Green nanotechnology is now accepted as an environmentally friendly and cost-effective advance with various biomedical applications. The cyanobacterium Synechocystis sp. is a unicellular spherical cyanobacterium with photo- and hetero-trophic capabilities. This study investigates the ability of this cyanobacterial species to produce silver nanoparticles (AgNPs) and the wound-healing properties of the produced nanoparticles in diabetic animals.

METHODS

UV-visible and FT-IR spectroscopy and and electron microscopy techniques investigated AgNPs' producibility by Synechocystis sp. when supplemented with silver ion source. The produced AgNPs were evaluated for their antimicrobial, anti-oxidative, anti-inflammatory, and diabetic wound healing along with their angiogenesis potential.

RESULTS

The cyanobacterium biosynthesized spherical AgNPs with a diameter range of 10 to 35 nm. The produced AgNPs exhibited wound-healing properties verified with increased contraction percentage, tensile strength and hydroxyproline level in incision diabetic wounded animals. AgNPs treatment decreased epithelialization period, amplified the wound closure percentage, and elevated collagen, hydroxyproline and hexosamine contents, which improved angiogenesis factors' contents (HIF-1α, TGF-β1 and VEGF) in excision wound models. AgNPs intensified catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx) activities, and glutathione (GSH) and nitric oxide content and reduced malondialdehyde (MDA) level. IL-1β, IL-6, TNF-α, and NF-κB (the inflammatory mediators) were decreased with AgNPs' topical application.

CONCLUSION

Biosynthesized AgNPs via Synechocystis sp. exhibited antimicrobial, anti-oxidative, anti-inflammatory, and angiogenesis promoting effects in diabetic wounded animals.

The progress and challenges of circRNA for diabetic foot ulcers: A mini-review

Since the Human Genome Project was successfully completed, humanity has entered a post-genome era, and the second-generation sequencing technology has gradually progressed and become more accurate. Meanwhile, circRNAs plays a crucial role in the regulation of diseases and potential clinical applications has gradually attracted the attention of physicians. However, the mechanisms of circRNAs regulation at the cellular and molecular level of diabetic foot ulcer (DFU) is still not well-understood. With the deepening of research, there have been many recent studies conducted to explore the effect of circRNAs on DFU. In this mini-review, we discuss the potential role of circRNAs as therapeutic targets and diagnostic markers for DFU in order to gain a better understanding of the molecular mechanisms that underlie the development of DFU and to establish a theoretical basis for accurate treatment and effective prevention.

Emerging Role of Epitranscriptomics in Diabetes Mellitus and Its Complications

Diabetes mellitus (DM) and its related complications are among the leading causes of disability and mortality worldwide. Substantial studies have explored epigenetic regulation that is involved in the modifications of DNA and proteins, but RNA modifications in diabetes are still poorly investigated. In recent years, posttranscriptional epigenetic modification of RNA (the so-called 'epitranscriptome') has emerged as an interesting field of research. Numerous modifications, mainly N⁶ -methyladenosine (m⁶A), have been identified in nearly all types of RNAs and have been demonstrated to have an indispensable effect in a variety of human diseases, such as cancer, obesity, and diabetes. Therefore, it is particularly important to understand the molecular basis of RNA modifications, which might provide a new perspective for the pathogenesis of diabetes mellitus and the discovery of new therapeutic targets. In this review, we aim to summarize the recent progress in the epitranscriptomics involved in diabetes and diabetes-related complications. We hope to provide some insights for enriching the understanding of the epitranscriptomic regulatory mechanisms of this disease as well as the development of novel therapeutic targets for future clinical benefit.

A nano phototheranostic approach of toluidine blue conjugated gold silver core shells mediated photodynamic therapy to treat diabetic foot ulcer

Diabetic foot infection caused by multidrug-resistant bacteria, is becoming serious problem. Moreover, polymicrobial biofilms contribute significantly to the persistent infections. In the present study, we investigated the effectiveness of novel toluidine blue conjugated chitosan coated gold-silver core-shell nanoparticles (TBO-chit-Au-AgNPs) mediated photodynamic therapy and demonstrate their use as a nontoxic antibacterial therapy to combat diabetic foot ulcer (DFU) caused by multi-drug resistant strains both in monomicrobial and polymicrobial state of infection. In vitro efficacy of TBO-chit-Au-AgNPs mediated photodynamic therapy (PDT) against polymicrobial biofilms was determined using standard plate count method and compared with that of monomicrobial biofilms of each species. Different anti-biofilm assays and microscopic studies were performed to check the efficacy of TBO-chit-Au-AgNPs mediated PDT, displayed significant decrease in the formation of biofilm. Finally, its therapeutic potential was validated in vivo type-2DFU. Cytokines level was found reduced, using nano-phototheranostic approach, indicating infection control. Expression profile of growth factors confirmed both the pathogenesis and healing of DFU. Hence, we conclude that TBO-chit-Au-AgNPs mediated PDT is a promising anti-bacterial therapeutic approach which leads to a synergistic healing of DFU caused by MDR bacterial strains.

11,12 Epoxyeicosatrienoic Acid Rescues Deteriorated Wound Healing in Diabetes

Epoxyeicosatrienoic acids (EET) facilitate regeneration in different tissues, and their benefit in dermal wound healing has been proven under normal conditions. In this study, we investigated the effect of 11,12 EET on dermal wound healing in diabetes. We induced diabetes by i.p. injection of streptozotocin 2 weeks prior to wound creation on the dorsal side of the mouse ear. 11,12 EET was applied every second day on the wound, whereas the control groups received only solvent. Epithelialization was monitored every second day intravitally up to wound closure. Wounds were stained for VEGF, CD31, TGF-β, TNF-α, SDF-1α, NF-κB, and Ki-67, and fibroblasts were counted after hematoxylin-eosin stain on days 3, 6, 9, and 16 after wounding. After induction of diabetes, wounds closed on day 13.00 ± 2.20 standard deviation (SD). Local 11,12 ETT application improved wound closure significantly to day 8.40 ± 1.39 SD. EET treatment enhanced VEGF and CD31 expression in wounds on day 3. It also seemed to raise TNF-α level on all days investigated as well as TGF-β level on days 3 and 6. A decrease in NF-κB could be observed on days 9 and 16 after EET application. The latter findings were not significant. SDF-1α expression was not influenced by EET application, and Ki-67 was significantly less in the EET group on day 9 after EET application. The number of fibroblasts was significantly increased on day 9 after the 11,12 EET application. 11,12 EET improve deteriorated wound healing in diabetes by enhancing neoangiogenesis, especially in the early phase of wound healing. Furthermore, they contribute to the dissolution of the initial inflammatory reaction, allowing the crucial transition from the inflammatory to proliferative phase in wound healing.

Epigallocatechin Gallate: The Emerging Wound Healing Potential of Multifunctional Biomaterials for Future Precision Medicine Treatment Strategies

Immediate treatment for cutaneous injuries is a realistic approach to improve the healing rate and minimise the risk of complications. Multifunctional biomaterials have been proven to be a potential strategy for chronic skin wound management, especially for future advancements in precision medicine. Hence, antioxidant incorporated biomaterials play a vital role in the new era of tissue engineering. A bibliographic investigation was conducted on articles focusing on in vitro, in vivo, and clinical studies that evaluate the effect and the antioxidants mechanism exerted by epigallocatechin gallate (EGCG) in wound healing and its ability to act as reactive oxygen species (ROS) scavengers. Over the years, EGCG has been proven to be a potent antioxidant efficient for wound healing purposes. Therefore, several novel studies were included in this article to shed light on EGCG incorporated biomaterials over five years of research. However, the related papers under this review's scope are limited in number. All the studies showed that biomaterials with scavenging ability have a great potential to combat chronic wounds and assist the wound healing process against oxidative damage. However, the promising concept has faced challenges extending beyond the trial phase, whereby the implementation of these biomaterials, when exposed to an oxidative stress environment, may disrupt cell proliferation and tissue regeneration after transplantation. Therefore, thorough research should be executed to ensure a successful therapy.

A review of diabetic wound models-Novel insights into diabetic foot ulcer

Diabetic foot ulcer (DFU) is a major debilitating complication of diabetes. Many research investigations have been conducted with the aims to uncover the diabetic wound healing mechanisms, develop novel therapeutics, and screen bioactive wound dressings in order to improve the current management of DFU. These would have not been possible without the utilization of an appropriate wound model, especially in a diabetic wound context. This review focuses on the different in vitro research models used in DFU investigations such as the 2D scratch wound assay, 3D skin model, and 3D angiogenesis model as well as their limitations. The current efforts and challenges to apply the 2D and 3D in vitro models in a hyperglycemic context to provide insights into DFU modeling will be reviewed. Perspectives of utilizing 3D bioprinting and skin-on-the-chip model as a diabetic wound model in the future will also be highlighted. By leveraging knowledge from past experiences and current research, an improved experimental model for DFU is anticipated to be established in near future.

NIR-Triggered Intracellular H+ Transients for Lamellipodia-Collapsed Antimetastasis and Enhanced Chemodynamic Therapy

In solid tumors, tumor invasion and metastasis account for 90 % of cancer-related deaths. Cell migration is steered by the lamellipodia formed at the leading edge. These lamellipodia can drive the cell body forward by its mechanical deformation regulated by cofilin. Inhibiting cofilin activity can cause significant defects in directional lamellipodia formation and the locomotory capacity of cell invasion, thus contributing to antimetastatic treatment. Herein, a near infrared light (NIR)-controlled nanoscale proton supplier was designed with upconversion nanoparticles (UCNPs) as a core coated in MIL-88B for interior photoacids loading; this photoacids loading can boost H⁺ transients in cells, which converts the cofilin to an inactive form. Strikingly, inactive cofilin loses the ability to mediate lamellipodia deformation for cell migration. Additionally, the iron, which serves as a catalyticaly active center in MIL-88B, initiates an enhanced Fenton reaction due to the increased H⁺ in the tumor, ultimately achieving intensive chemodynamic therapy (CDT). This work provides new insight into H⁺ transients in cells, which not only regulates cofilin protonation for antimetastatic treatment but also improves chemodynamic therapy.

Circ_PRKDC knockdown promotes skin wound healing by enhancing keratinocyte migration via miR-31/FBN1 axis

Circular RNA protein kinase, DNA-activated, catalytic subunit (circ_PRKDC) has been found to impede wound healing in diabetic foot ulcers via regulating keratinocyte proliferation and migration. However, the mechanisms underlying circ_PRKDC in skin wound healing remain unclear. The expression of circ_PRKDC, microRNA (miR)-31 and fibrillin 1 (FBN1) was detected using quantitative reverse transcription-polymerase chain reaction and Western blot assays. The migration ability and the changes of matrix metallopeptidase 9 (MMP-9) and MMP2 levels were determined using wound healing, transwell and Western blot assays. The interaction between miR-31 and circ_PRKDC or FBN1 was verified by dual-luciferase reporter assay. The expression of circ_PRKDC was gradually down-regulated in wound edge at 1 and 7 days after injury relative to the unwounded skin. In human epidermal keratinocytes (HEKa), knockdown of circ_PRKDC promoted cell migration partly through up-regulating MMP-2 and MMP9, while circ_PRKDC overexpression showed opposite effects. In a mechanical study, we confirmed that miR-31 was a target of circ_PRKDC, and inhibition of miR-31 reversed the promotive effect of circ_PRKDC knockdown on HEKa migration. Besides that, miR-31 was verified to target FBN1, and ectopic overexpression of miR-31 accelerated HEKa migration via FBN1. Importantly, we also demonstrated that FBN1 overexpression attenuated the effects of circ_PRKDC knockdown on HEKa migration. In all, circ_PRKDC knockdown promoted HEKa migration during wound healing through miR-31/FBN1 axis, suggesting the therapeutic potential for circ_PRKDC on skin wound healing.

Injectable Hydrogels for Chronic Skin Wound Management: A Concise Review

Diabetic foot ulcers (DFU) are a predominant impediment among diabetic patients, increasing morbidity and wound care costs. There are various strategies including using biomaterials have been explored for the management of DFU. This paper will review the injectable hydrogel application as the most studied polymer-based hydrogel based on published journals and articles. The main key factors that will be discussed in chronic wounds focusing on diabetic ulcers include the socioeconomic burden of chronic wounds, biomaterials implicated by the government for DFU management, commercial hydrogel product, mechanism of injectable hydrogel, the current study of novel injectable hydrogel and the future perspectives of injectable hydrogel for the management of DFU.

Association of glycaemic status and outcomes in diabetic foot problems: a retrospective evidence from South India

OBJECTIVES

Emerging shreds of evidence indicates that the risk of diabetic foot ulcer and associated morbidity can be reduced through the intensive glycemic control. There are very few studies which assessed the effects of glycemic control on diabetic foot problems among Indian patients. We aimed to assess the effect of glycemic control on the outcomes of diabetic foot problems among adult type 2 diabetes (T2DM) patients with foot ulcers.

METHODS

A cross sectional study was conducted among the T2DM patients from a tertiary care teaching hospital in South India. The demographic characters, risk factors, treatment characters, glycemic status were collected among the patients and analyzed against the outcomes of diabetic foot ulcers by reviewing their medical records. Descriptive statistics were used to present the data. The Chi-square test and ANOVA were used for was used for the categorical variables and continuous parameters to identify the factors affecting the outcomes, respectively. All analysis was performed in SPSS v21.

RESULTS

Out of the 100 participants included in the study, 70% were male. The majority (78%) were from an age group of 40 to 70 years, and the mean age was found to be 59.91 ± 10.6 years. The mean duration of diabetes was 9.66 years. Only ankle-brachial Index score (p=0.001) was significantly associated with the type of ulcers, whereas other factors not (p>0.05). A high level of average HbA_1c, BMI, ABI index and poor glycemic status was associated with a significant debridement strategy and longer duration of hospitalization; however, it was not substantial.

CONCLUSION

Our study inferred that poor glycemic status is associated with a significant debridement strategy and longer duration of hospitalization. However, these findings need to be strengthened with adequately powered prospective studies.

Fibroblast Growth Factor in Diabetic Foot Ulcer: Progress and Therapeutic Prospects

Diabetic foot ulcer (DFU) is a combination of neuropathy and various degrees of peripheral vasculopathy in diabetic patients resulting in lower extremity infection, ulcer formation, and deep-tissue necrosis. The difficulty of wound healing in diabetic patients is caused by a high glucose environment and various biological factors in the patient. The patients' skin local microenvironment changes and immune chemotactic response dysfunction. Wounds are easy to be damaged and ulcerated repeatedly, but difficult to heal, and eventually develop into chronic ulcers. DFU is a complex biological process in which many cells interact with each other. A variety of growth factors released from wounds are necessary for coordination and promotion of healing. Fibroblast growth factor (FGF) is a family of cell signaling proteins, which can mediate various processes such as angiogenesis, wound healing, metabolic regulation and embryonic development through its specific receptors. FGF can stimulate angiogenesis and proliferation of fibroblasts, and it is a powerful angiogenesis factor. Twenty-three subtypes have been identified and divided into seven subfamilies. Traditional treatments for DFU can only remove necrotic tissue, delay disease progression, and have a limited ability to repair wounds. In recent years, with the increasing understanding of the function of FGF, more and more researchers have been applying FGF-1, FGF-2, FGF-4, FGF-7, FGF-21 and FGF-23 topically to DFU with good therapeutic effects. This review elaborates on the recently developed FGF family members, outlining their mechanisms of action, and describing their potential therapeutics in DFU.

Application of 3D Bioprinting Technologies to the Management and Treatment of Diabetic Foot Ulcers

Diabetes mellitus (DM) is a chronic metabolic disease with increasing prevalence worldwide. Diabetic foot ulcers (DFUs) are a serious complication of DM. It is estimated that 15-25% of DM patients develop DFU at least once in their lifetime. The lack of effective wound dressings and targeted therapy for DFUs often results in prolonged hospitalization and amputations. As the incidence of DM is projected to rise, the demand for specialized DFU wound management will continue to increase. Hence, it is of great interest to improve and develop effective DFU-specific wound dressings and therapies. In the last decade, 3D bioprinting technology has made a great contribution to the healthcare sector, with the development of personalized prosthetics, implants, and bioengineered tissues. In this review, we discuss the challenges faced in DFU wound management and how 3D bioprinting technology can be applied to advance current treatment methods, such as biomanufacturing of composite 3D human skin substitutes for skin grafting and the development of DFU-appropriate wound dressings. Future co-development of 3D bioprinting technologies with novel treatment approaches to mitigate DFU-specific pathophysiological challenges will be key to limiting the healthcare burden associated with the increasing prevalence of DM.

Improved Diabetic Wound Healing by EGF Encapsulation in Gelatin-Alginate Coacervates

Topical imageplication of epidermal growth fctor (EGF) has been used to accelerate diabetic foot ulcers but with limited efficacy. In this study, we selected a complex coacervate (EGF-Coa) composed of the low molecular weight gelatin type A and sodium alginate as a novel delivery system for EGF, based on encapsulation efficiency and protection of EGF from protease. EGF-Coa enhanced in vitro migration of keratinocytes and accelerated wound healing in streptozotocin-induced diabetic mice with increased granulation and re-epithelialization. While diabetic wound sites without treatment showed downward growth of hyperproliferative epidermis along the wound edges with poor matrix formation, EGF-Coa treatment recovered horizontal migration of epidermis over the newly deposited dermal matrix. EGF-Coa treatment also resulted in reduced levels of proinflammatory cytokines IL-1, IL-6, and THF-α. Freeze-dried coacervates packaged in aluminum pouches were stable for up to 4 months at 4 and 25 °C in terms of appearance, purity by RP-HPLC, and in vitro release profiles. There were significant physical and chemical changes in relative humidity above 33% or at 37 °C, suggesting the requirement for moisture-proof packaging and cold chain storage for long term stability. We propose low molecular weight gelatin type A and sodium alginate (LWGA-SA) coacervates as a novel EGF delivery system with enhanced efficacy for chronic wounds.

Does intensive glycaemic control promote healing in diabetic foot ulcers? - a feasibility study

INTRODUCTION

One in four diabetes patients will develop a foot ulcer over their lifetime. The role of glycaemic control in the healing of foot ulcers in diabetes patients is not supported by randomised controlled trial (RCT) data.

OBJECTIVES

To determine the feasibility of an RCT of glycaemic control with intensive insulin therapy in diabetic foot ulcer, by assessing: entry criteria, fasting capillary blood glucose (FCBG) medication satisfaction and sensitivity of different ulcer-healing endpoints to glycaemic control.

DESIGN

Two substudies: one cross-sectional and one single-arm prospective.

SETTING

Single-centre secondary care diabetic foot clinic in New Zealand.

PARTICIPANTS

Substudy 1: 78 participants consisting of all people ≥18 years with a diabetic foot ulcer presenting to the clinic over 35 weeks in 2015.Substudy 2: 15 participants from Substudy 1 consenting to intensive insulin therapy.

INTERVENTION

Substudy 1: None.Substudy 2: Intensive insulin therapy with standard podiatry care over 24 weeks.

OUTCOME

Substudy 1: Proportion of participants satisfying potential RCT entry criteria; medication satisfaction (Diabetes Medication Satisfaction).Substudy 2: FCBG, index ulcer healing time, index ulcer size, health-related quality of life (HRQoL; EuroQol 5 Dimensions 5 Levels and Diabetic Foot Ulcer Scale-Short Form).

RESULTS

Proportion in Substudy 1 satisfying all entry criteria was 31% (95% CI 21 to 42). FCBG values decreased between baseline and study end (difference -3.7 mmol/L, 95% CI -6.5 to -0.8); 83% (95% CI 44 to 95) of ulcers healed by 24 weeks. FCBG correlated negatively with medication satisfaction. Ulcer area logarithm was most sensitive to FCBG changes, displaying significant negative correlation with HRQoL outcomes. Detecting a 30% between-group difference in this outcome (80% power, α=5%) requires 220 participants per arm, achievable within 1 year with 15 centres similar to study setting.

CONCLUSIONS

An adequately powered RCT requires cooperation between a large number of centres. Ulcer area logarithm should be primary endpoint.

TRIAL REGISTRATION NUMBER

ANZCTR ACTRN12617001414303.

Keratinocyte Function in Normal and Diabetic Wounds and Modulation by FOXO1

Diabetes has a significant and negative impact on wound healing, which involves complex interactions between multiple cell types. Keratinocytes play a crucial role in the healing process by rapidly covering dermal and mucosal wound surfaces to reestablish an epithelial barrier with the outside environment. Keratinocytes produce multiple factors to promote reepithelialization and produce factors that enhance connective tissue repair through the elaboration of mediators that stimulate angiogenesis and production of connective tissue matrix. Among the factors that keratinocytes produce to aid healing are transforming growth factor-β (TGF-β), vascular endothelial growth factor-A (VEGF-A), connective tissue growth factor (CTGF), and antioxidants. In a diabetic environment, this program is disrupted, and keratinocytes fail to produce growth factors and instead switch to a program that is detrimental to healing. Changes in keratinocyte behavior have been linked to high glucose and advanced glycation end products that alter the activities of the transcription factor, FOXO1. This review examines reepithelialization and factors produced by keratinocytes that upregulate connective tissue healing and angiogenesis and how they are altered by diabetes.

Improved Wound Closure Rates and Mechanical Properties Resembling Native Skin in Murine Diabetic Wounds Treated with a Tropoelastin and Collagen Wound Healing Device

Chronic wounds in patients suffering from type II diabetes mellitus (DMII) where wounds remain open with a complicated pathophysiology, healing, and recovery process is a public health concern. Normal wound healing plays a critical role in wound closure, restoration of mechanical properties, and the biochemical characteristics of the remodeled tissue. Biological scaffolds provide a tissue substitute to help facilitate wound healing by mimicking the extracellular matrix (ECM) of the dermis. In the current study an electrospun biomimetic scaffold, wound healing device (WHD), containing tropoelastin (TE) and collagen was synthesized to mimic the biochemical and mechanical characteristics of healthy human skin. The WHD was compared to a commercially available porcine small intestinal submucosa (SIS) matrix that has been used in both partial and full-thickness wounds, Oasis^® Wound Matrix. Using a diabetic murine model C57BKS.Cg-m+/+Leprdb/J mice (db/db) wound closure rates, histochemistry (CD31 and CD163), qPCR (GAPDH, TNF-α, NOS2, ARG1 and IL10), and mechanical testing of treated wound sites were evaluated. The WHD in a splinted, full thickness, diabetic murine wound healing model demonstrated skin organ regeneration, an enhanced rate of wound closure, decreased tissue inflammation, and a stronger and more durable remodeled tissue that more closely mimics native unwounded skin compared to the control device.

Evaluation of Serum Vitamin D Levels in Diabetic Foot Infections: A Cross-Sectional Study in a Tertiary Care Center in South India

Background

The impact of diabetic foot infections is enormous in India. Studies on vitamin D levels in diabetes mellitus foot infections are scarce. The primary objective of the present study was to compare the serum vitamin D level between diabetics with foot infections and those without foot infections and the secondary objective was to assess the association between the vitamin D level and the severity of foot infections and outcomes.

Methods

The study included 176 type 2 diabetics who attended Jawaharlal Institute of Postgraduate Medical Education and Research, Pondicherry, India, between September 2012 and June 2014. The serum vitamin D level was measured for 88 diabetics with foot infections (Group 1) and 88 without foot infections (Group 2) using the ELISA 25OH vitamin D DIAsource kit (DIAsource ImmunoAssays S.A., Belgium) and compared. Both groups were followed up for 6 months for outcomes. The qualitative variables were analyzed using the χ2 test and the quantitative variables using the Student t test. The statistical analyses were performed using SPSS, version 17.0. A P value of less than 0.05 was considered significant.

Results

The mean serum vitamin D level was not significantly different between the two groups (P=0.306). Among the patients in Group 1 who either required amputations or died, 97.44% had subnormal vitamin D levels in contrast to 59.18% in those who were grafted or achieved wound healing (P=0.001). Among those who achieved wound healing within 6 months, 78.9% had normal vitamin D levels (P=0.0006).

Conclusion

The study found no significant difference in the serum level of vitamin D between diabetics with and without foot infections. However, vitamin D deficiency was associated with a poor outcome in diabetics with foot infections.

Current Therapeutic Strategies in Diabetic Foot Ulcers

Diabetic foot ulcers (DFUs) are the fastest growing chronic complication of diabetes mellitus, with more than 400 million people diagnosed globally, and the condition is responsible for lower extremity amputation in 85% of people affected, leading to high-cost hospital care and increased mortality risk. Neuropathy and peripheral arterial disease trigger deformities or trauma, and aggravating factors such as infection and edema are the etiological factors for the development of DFUs. DFUs require identifying the etiology and assessing the co-morbidities to provide the correct therapeutic approach, essential to reducing lower-extremity amputation risk. This review focuses on the current treatment strategies for DFUs with a special emphasis on tissue engineering techniques and regenerative medicine that collectively target all components of chronic wound pathology.

[Antidiabetic role of high density lipoproteins]

Disturbance in lipid metabolism can be both a cause and a consequence of the development of diabetes mellitus (DM). One of the most informative indicator of lipid metabolism is the ratio of atherogenic and antiatherogenic fractions of lipoproteins and their protein components. The review summarizes literature data and own results indicating the important role of high-density lipoprotein (HDL) and their main protein component, apolipoprotein A-I (apoA-I), in the pathogenesis of type 2 DM. On the one hand, HDL are involved in the regulation of insulin secretion by b-cells and insulin-independent absorption of glucose. On the other hand, insulin resistance and hyperglycemia lead to a decrease in HDL levels and cause modification of their protein component. In addition, HDL, possessing anti-inflammatory and mitogenic properties, provide anti-diabetic protection through systemic mechanisms. Thus, maintaining a high concentration of HDL and apoA-I in blood plasma and preventing their modification are important issues in the context of prevention and treatment of diabetes.

Crawling wounded: molecular genetic insights into wound healing from Drosophila larvae

For animals, injury is inevitable. Because of this, organisms possess efficient wound healing mechanisms that can repair damaged tissues. However, the molecular and genetic mechanisms by which epidermal repair is accomplished remain poorly defined. Drosophila has become a valuable model to study epidermal wound healing because of the comprehensive genetic toolkit available in this organism and the similarities of wound healing processes between Drosophila and vertebrates. Other reviews in this Special Issue cover wound healing assays and pathways in Drosophila embryos, pupae and adults, as well as regenerative processes that occur in tissues such as imaginal discs and the gut. In this review, we will focus on the molecular/genetic control of wound-induced cellular processes such as inflammation, cell migration and epithelial cell-cell fusion in Drosophila larvae. We will give a brief overview of the three wounding assays, pinch, puncture, and laser ablation, and the cellular responses that ensue following wounding. We will highlight the actin regulators, signaling pathways and transcriptional mediators found so far to be involved in larval epidermal wound closure and what is known about how they act. We will also discuss wound-induced epidermal cell-cell fusion and possible directions for future research in this exciting system.

The Dynamics of the Skin's Immune System

The skin is a complex organ that has devised numerous strategies, such as physical, chemical, and microbiological barriers, to protect the host from external insults. In addition, the skin contains an intricate network of immune cells resident to the tissue, crucial for host defense as well as tissue homeostasis. In the event of an insult, the skin-resident immune cells are crucial not only for prevention of infection but also for tissue reconstruction. Deregulation of immune responses often leads to impaired healing and poor tissue restoration and function. In this review, we will discuss the defensive components of the skin and focus on the function of skin-resident immune cells in homeostasis and their role in wound healing.

Targeting epigenetic mechanisms in diabetic wound healing

Impaired wound healing is a major secondary complication of type 2 diabetes that often results in limb loss and disability. Normal tissue repair progresses through discrete phases including hemostasis, inflammation, proliferation, and remodeling. In diabetes, normal progression through these phases is impaired resulting in a sustained inflammatory state and dysfunctional epithelialization in the wound. Due to their plasticity, macrophages play a critical role in the transition from the inflammation phase to the proliferation phase. Diabetes disrupts macrophage function by impairing monocyte recruitment to the wound, reducing phagocytosis, and prohibiting the transition of inflammatory macrophages to an anti-inflammatory state. Diabetes also impedes keratinocyte and fibroblast function during the later phases resulting in impaired epithelialization of the wound. Several recent studies suggest that altered epigenetic regulation of both immune and structural cells in wounds may influence cell phenotypes and healing, particularly in pathologic states, such as diabetes. Specifically, it has been shown that macrophage plasticity during wound repair is partly regulated epigenetically and that diabetes alters this epigenetic regulation and contributes to a sustained inflammatory state. Epigenetic regulation is also known to regulate keratinocyte and fibroblast function during wound repair. In this review, we provide an introduction to the epigenetic mechanisms that regulate tissue repair and highlight recent findings that demonstrate, how epigenetic events are altered during the course of diabetic wound healing.

High Glucose Suppresses Keratinocyte Migration Through the Inhibition of p38 MAPK/Autophagy Pathway

Wound healing is delayed frequently in patients with diabetes. Proper keratinocyte migration is an essential step during re-epithelialization. Impaired keratinocyte migration is a critical underlying factor responsible for the deficiency of diabetic wound healing, which is mainly attributed to the hyperglycemic state. However, the underlying mechanisms remain largely unknown. Previously, we demonstrated a marked activation of p38/mitogen-activated protein kinase (MAPK) pathway in the regenerated migrating epidermis, which in turn promoted keratinocyte migration. In the present study, we find that p38/MAPK pathway is downregulated and accompanied by inactivation of autophagy under high glucose (HG) environment. In addition, we demonstrate that inactivation of p38/MAPK and autophagy result in the inhibition of keratinocyte migration under HG environment, and the activating p38/MAPK by MKK6(Glu) overexpression rescues cell migration through an autophagy-dependent way. Moreover, diabetic wound epidermis shows a significant inhibition of p38/MAPK and autophagy. Targeting these dysfunctions may provide novel therapeutic approaches.

Excessive localized leukotriene B4 levels dictate poor skin host defense in diabetic mice

Poorly controlled diabetes leads to comorbidities and enhanced susceptibility to infections. While the immune components involved in wound healing in diabetes have been studied, the components involved in susceptibility to skin infections remain unclear. Here, we examined the effects of the inflammatory lipid mediator leukotriene B4 (LTB4) signaling through its receptor B leukotriene receptor 1 (BLT1) in the progression of methicillin-resistant Staphylococcus aureus (MRSA) skin infection in 2 models of diabetes. Diabetic mice produced higher levels of LTB4 in the skin, which correlated with larger nonhealing lesion areas and increased bacterial loads compared with nondiabetic mice. High LTB4 levels were also associated with dysregulated cytokine and chemokine production, excessive neutrophil migration but impaired abscess formation, and uncontrolled collagen deposition. Both genetic deletion and topical pharmacological BLT1 antagonism restored inflammatory response and abscess formation, followed by a reduction in the bacterial load and lesion area in the diabetic mice. Macrophage depletion in diabetic mice limited LTB4 production and improved abscess architecture and skin host defense. These data demonstrate that exaggerated LTB4/BLT1 responses mediate a derailed inflammatory milieu that underlies poor host defense in diabetes. Prevention of LTB4 production/actions could provide a new therapeutic strategy to restore host defense in diabetes.

Keratinocyte Motility Is Affected by UVA Radiation-A Comparison between Normal and Dysplastic Cells

UVA radiation induces multiple and complex changes in the skin, affecting epidermal cell behavior. This study reports the effects of UVA exposure on normal (HaCaT) and dysplastic (DOK) keratinocytes. The adherence, spreading and proliferation were investigated by time-lapse measurement of cell layer impedance on different matrix proteins. Prior to UVA exposure, the time required for adherence and spreading did not differ significantly for HaCaT and DOK cells, while spreading areas were larger for HaCaT cells. Under UVA exposure, HaCaT and DOK cells behavior differed in terms of movement and proliferation. The cells' ability to cover the denuded surface and individual cell trajectories were recorded by time-lapse videomicroscopy, during wound healing experiments. Dysplastic keratinocytes showed more sensitivity to UVA, exhibiting transient deficiencies in directionality of movement and a delay in re-coating the denuded area. The actin cytoskeleton displayed a cortical organization immediately after irradiation, in both cell lines, similar to mock-irradiated cells. Post-irradiation, DOK cells displayed a better organization of stress fibers, persistent filopodia, and new, stronger focal contacts. In conclusion, after UVA exposure HaCaT and DOK cells showed a different behavior in terms of adherence, spreading, motility, proliferation, and actin cytoskeleton dynamics, with the dyplastic keratinocytes being more sensitive.

Gangliosides in Diabetic Wound Healing

An organized series of complicated biological and molecular phenomena is required for normal skin wound healing. These processes depend on normal cellular responses to cytokines, growth factors, and other mediators, such as clotting factors, prostaglandins, free radicals, and nitric oxide. In diabetic ulcers, impaired responses to these molecules lead to abnormalities in vascularization, innervation, matrix reconstruction, and reepithelialization of wounds. keratinocyte migration and proliferation on an extracellular matrix is critical in reepithelialization, but the response to growth factors is blunted in diabetes, including the insulin/IGF-1signaling axis. Ganglioside GM3, a sialylated epidermal glycosphingolipid, has been identified as a key mediator of the inhibition of insulin/IGF-1 signaling in response to factors, such as tumor necrosis factor-alpha (TNF-α) and hyperglycemia. Decreased expression of GM3 and the enzyme required for its synthesis, GM3 synthase (GM3S), leads to increased insulin/IGF-1 receptor signaling and accelerated keratinocyte migration, even in the presence of high glucose levels. GM3 depletion in GM3S knockout diabetic mice and diet-induced diabetic mice treated topically with nanoconstruct-mediated GM3S-targeting gene regulation also accelerates wound healing. These recent observations, coupled with evidence that GM3 depletion reverses distal innervation abnormalities in diabetic mice, suggest that GM3-depleting strategies are a promising new approach for human diabetic wounds.

Ginsenoside Rg3 inhibits keloid fibroblast proliferation, angiogenesis and collagen synthesis in vitro via the TGF‑β/Smad and ERK signaling pathways

A wide range of therapeutic options exists for the treatment of keloids, all of which have their own strengths; however, a high risk of side-effects and frequent recurrence remains. Therefore, the present study aimed to identify improved therapeutic approaches or drugs for the treatment of keloids. Ginsenoside Rg3 (Rg3) has been reported to exert numerous antitumor effects, thus indicating that Rg3 may be a potential therapeutic agent that targets keloids. The present study determined the effects of Rg3 on human keloid fibroblasts (KFs) in vitro, and further explored the associated molecular and cellular mechanisms. Keloid scar specimens were obtained from patients, aged between 22 and 35 years, without systemic diseases and primary cells were isolated from keloid tissues. In each assay, KFs were divided into three groups and were cultured in medium with or without various concentrations of Rg3 (50 or 100 μg/ml). Cell viability assay, flow cytometry, quantitative polymerase chain reaction, cell migration assay, immunofluorescence staining, western blot analysis, Transwell cell invasion assay and immunohistochemical analysis were used to analyze the KFs and keloid explant cultures. The results of the present study demonstrated that Rg3 was able to exert an inhibitory effect on the transforming growth factor-β/Smad and extracellular signal-regulated kinase signaling pathways in KFs. The proliferation, migration, invasion, angiogenesis and collagen synthesis of KFs were markedly suppressed following treatment with Rg3. Furthermore, the results of an ex vivo assay indicated that Rg3 inhibited angiogenesis and reduced collagen accumulation in keloids. Significant statistical differences existed between the control and Rg3-treated groups (P<0.05). All of these experimental results suggested that Rg3 may serve as a reliable drug for the treatment of patients with keloids.

Microbiota of Chronic Diabetic Wounds: Ecology, Impact, and Potential for Innovative Treatment Strategies

World Health Organization considered diabetes as one of the 20th century epidemics, estimating that over 10% of the world population is diabetic or at high risk. Self-assessment studies indicate that diabetic patients consider chronic wounds to affect their quality of life more dramatically than vision loss or renal failure. In addition to being the main reason for diabetic patients' hospitalization, the economic burden of diabetic chronic wounds is close to 1% of United Kingdom and United States health systems budgets, which exceeds the funds allocated to the treatment of some types of cancer in both countries. Among the factors preceding the emergence of chronic diabetic wounds, also designated diabetic foot ulcers (DFUs), hygiene and pressure in specific areas are under patient control, while others are still far from being understood. A triple impairment in the innervation, immune responses, and vascularization associated to DFU has been extensively studied by the scientific community. However, the skin natural microbiota has only recently emerged as having a tremendous impact on DFU emergence and evolution to chronicity. Despite the great inter- and intra-variability of microbial colonizers, ongoing efforts are now focused on deciphering the impact of commensal and pathogenic microbiota on DFU etiology, as well as the mechanisms of interkingdom microbial-host communication. This review summarizes recent work in this context and offers new microbiological perspectives that may hold potential in the prevention and treatment of chronic diabetic wounds.