Mechanisms Of Impaired Wound Healing Research Articles

Glycosaminoglycan-Based Hydrogel Delivery System Regulates the Wound Microenvironment to Rescue Chronic Wound Healing.

Chronic wounds cannot proceed through the normal, orderly, and timely sequence of repair. The adverse cycle between excess reactive oxide species (ROS) and a persistent inflammatory response is an important mechanism of impaired wound healing. Herein, by combining the intrinsic bioactivities of natural polysaccharides and natural drugs, a glycosaminoglycan-based hydrogel delivery system is proposed to regulate the wound microenvironment. Dynamic supramolecular cross-linking enables the hydrogel to easily encapsulate the drug and fully fill the wound area. As the backbone of the hydrogel, heparin captures inflammatory chemokines at the wound site, while hyaluronic acid mimics the function of ECM. The hydrophobic drug curcumin has been ingeniously encapsulated in the hydrogel through micellization, thereby exerting good ROS scavenging ability and anti-inflammatory activity. Evaluations in diabetic mice showed that this antioxidant and anti-inflammatory hydrogel was effective in reducing the influx of immune cells at the wound site and in down-regulating the inflammatory response. Accelerated wound healing was also observed, as evidenced by faster re-epithelialization and better ECM remodeling. The proposed hydrogel can regulate the microenvironment of wounds from multiple aspects and thereby achieve regression of wound repair, which may provide a new therapeutic strategy for chronic wounds.

EFFECT OF THE ENZYME-CONTAINING POLYMERIC NANOPARTICLES ON MMP-2 ACTIVITY DURING BURN WOUND HEALING IN RATS WITH STREPTOZOTOCIN-INDUCED DIABETES

Relevance. Diabetic foot syndrome is a common complication that is characterized by the development of chronic ulcers. Among the mechanisms of impaired wound healing, the leading role is played by disturbance of extracellular matrix homeostasis: chronic hyperglycemia, on the one hand, promotes the formation of so-called advanced glycation end products (AGEs), which mediate pro-inflammatory activation of immune cells, and on the other hand, inhibits fibroblasts proliferation and collagen production, disrupts the migration of keratinocytes and endothelial cells. Therefore, the elimination of AGEs is a pathogenetic approach in diabetic wound treatment. For this purpose, a composite consisting of polyspecific microbial proteinases fixed on polymeric porous nanoparticles was developed. The activity of matrix metalloproteinase-2 (MMP-2) was chosen as a prognostic indicator of chronic wound healing.
 Objective: to study the activity of MMP-2 in the tissues of the burn wound of rats with simulated diabetes mellitus under the influence of enzyme-containing nanoparticles.
 Materials and methods. N = 48 Wistar rats were used in the experiment. Diabetes mellitus was induced by administration of 50 mg/kg of streptozotocin. To model the wound in rats, a standard animal model of thermal burns by Walker and Mason was used. Thermal damage corresponded to the II-IIIA degree of burns, and occupied 19±1.6% of the total area of ​​animal skin. Rats were divided into two groups of 24 animals each: the DM group did not receive any treatment, and rats from the DM+T group were daily applied to the burn wound with the mentioned composite (enzyme-containing nanoparticles). Animals were removed from the experiment on days 3, 7, 14 and 21 of observation. The activity of MMP-2 in the tissues of the burn wound of diabetic rats was studied by gelatin zymography, expressed in arbitrary units (AU). Statistical data processing was performed in the software package SPSS Statistics Base, v.22 with Student and Scheffe tests.
 Results. The level of activity of MMP-2 in the tissues of the burn wound of rats in the DM group on the 3rd day of the study was 4.9 ± 1.3 AU, increased by 7 days (p <0.01) and reached a maximum level of 52.55 ± 3.06 AU at day 14 (p <0.01). On day 21, the activity of the test enzyme decreased by 8.5 AU (p <0.01), compared to day 14.
 On day 3 of the study in the DM+T group, the activity of MMP-2 in the diabetic wound was 15.93 ± 2.68 AU and gradually decreased (p <0.01) to 5.67 ± 2.67 AU on day 14. However, on day 21, the second peak (p <0.01) of the activity of the studied enzyme was observed - 33.64 ± 4.1 AU.
 When comparing the two groups (DmM and DM+T) on day 3 of the study, the activity of MMP-2 in the tissues of the burn wound of rats in the DM+T group was three times higher (p <0.01) than in the DM group. But from the 7th day the activity of MMP-2 in the DM group was higher than the DM+T group. On day 21 of the study, the level of MMP-2 in the DM group remained higher (p <0.01) than in the DM+T group.
 Conclusions. The use of enzyme-containing nanoparticles provides effective degradation of glycosylated components of the extracellular matrix (AGEs), thereby reducing the inflammatory process and activity of MMP-2, and promoting wound healing in rats with streptozotocin-induced diabetes.

A new rabbit model of impaired wound healing in an X-ray-irradiated field.

Radiation is an important therapy for cancer with many benefits; however, its side effects, such as impaired wound healing, are a major problem. While many attempts have been made to overcome this particular disadvantage, there are few effective treatments for impaired wound healing in an X-ray-irradiated field. One reason for this deficiency is the lack of experimental models, especially animal models. We have previously reported a mouse model of impaired wound healing in which the irradiation area was restricted to the hindlimbs. In this mouse model, due to the size of the animal, a diameter of five millimeters was considered the largest wound size suitable for the model. In addition, the transplanted cells had to be harvested from other inbred animals. To investigate larger wounds and the impact of autologous specimen delivery, a rabbit model was developed. Rabbits were kept in a special apparatus to shield the body and hindlimbs while the irradiation field was exposed to radiation. Six weeks after irradiation, a 2 x 2 cm, full-thickness skin defect was made inside the irradiation field. Then, the wound area was observed over time. The wound area after irradiation was larger than that without irradiation at all time points. Both angiogenesis and collagen formation were reduced. For further study, as an example of using this model, the effect of autologous platelet-rich plasma (PRP) was observed. Autologous PRP from peripheral blood (pb-PRP) and bone marrow aspirate (bm-PRP) was processed and injected into the wounds in the irradiated field. Two weeks later, the wounds treated with bm-PRP were significantly smaller than those treated with phosphate buffer vehicle controls. In contrast, the wounds treated with pb-PRP were not significantly different from the controls. This rabbit model is useful for investigating the mechanism of impaired wound healing in an X-ray-irradiated field.

Hydrogen sulfide improves diabetic wound healing in ob/ob mice via attenuating inflammation

BackgroundThe proposed mechanisms of impaired wound healing in diabetes involve sustained inflammation, excess oxidative stress and compromised agiogenesis. Hydrogen sulfide (H2S) has been reported to have multiple biological activities. We aim to investigate the role of H2S in impaired wound healing in ob/ob mice and explore the possible mechanisms involved. ProceduresFull-thickness skin dorsal wounds were created on ob/ob mice and C57BL/6 mice. Cystathionine-γ-lyase (CSE) expression and H2S production were determined in granulation tissues of the wounds. Effects of NaHS on wound healing were evaluated. Inflammation and angiogenesis in granulation tissues of the wounds were examined. ResultsCSE expression, and H2S content were significantly reduced in granulation tissues of wounds in ob/ob mice compared with control mice. NaHS treatment significantly improved wound healing in ob/ob mice, which was associated with reduced neutrophil and macrophage infiltration, decreased production of tumor necrosis factor (TNF)-α, interleukin (IL)-6. NaHS treatment decreased metalloproteinase (MMP)-9, whereas increased collagen deposition and vascular-like structures in granulation tissues of wounds in ob/ob mice. ConclusionCSE down-regulation may play a role in the pathogenesis of diabetic impaired wound healing. Exogenous H2S could be a potential agent to improve diabetic impaired wound healing by attenuating inflammation and increasing angiogenesis.

Xanthine Oxidoreductase: A Novel Therapeutic Target for the Treatment of Chronic Wounds?

Significance: Chronic wounds are a major burden to patients and to healthcare systems worldwide. These wounds are difficult to heal and treatment is often lengthy and expensive. This has led to research efforts focussed on the wound environment attempting to understand the underlying pathological mechanisms of impaired wound healing. While some of this research has translated to advancements in wound therapies and implementation of new treatment options, chronic wounds remain a significant challenge to treat. Thus, identification of effective, low-cost, advanced wound therapies that enhance healing rates of these problematic wounds is still essential. Recent Advances and Critical Issues: Xanthine oxidoreductase (XOR), a molybdoflavin enzyme, is emerging as an important source of reactive oxygen species (ROS) in various pathologies, including diabetes and chronic wounds. XOR has recently been shown to be upregulated in chronic wounds, stimulating the overproduction of ROS during dysfunctional wound healing. XOR-induced ROS can amplify and potentiate inflammation in the wound environment further delaying wound closure. Future Directions: The detrimental role of XOR in impaired healing indicates it may be a therapeutic target. Targeted inhibition of XOR has been shown to reduce the expression and activity of this enzyme in diabetic wound models. In turn, this resulted in a significant decrease in ROS levels in the wound environment and improved wound healing. Therefore, repurposing existing XOR inhibitors that are approved for human use may be able to restore homeostasis at the wound site and enable damaged tissue to return to normal healing.

Pseudosyndactyly - an inflammatory and fibrotic wound healing disorder in recessive dystrophic epidermolysis bullosa.

A genetic blistering skin disease, recessive dystrophic epidermolysis bullosa (RDEB), is marked by severe wound healing defects and finger contractures. The purpose of this investigation was to elucidate the mechanisms of impaired wound healing and pseudosyndactyly occurring in RDEB patients by studying the role of known inflammation and fibrosis markers in RDEB pseudosyndactyly tissue. We studied the expression of the fibrosis and/or inflammation markers tenascin-C, α-smooth muscle actin, transforming growth factor-β1, interleukin-1β, and interleukin-6 in scarring and nonscarring tissue from healthy donors and RDEB patients by semiquantitative real time-PCR and, where applicable, by immunoblots. Furthermore, the distribution pattern of α-smooth muscle actin and tenascin-C were assessed by immunofluorescence microscopy. Based on mRNA and protein analysis, we found upregulation of tenascin-C, interleukin-1β, and interleukin-6 - but not of transforming growth factor-β1 - in recessive dystrophic epidermolysis bullosa scar samples taken from pseudosyndactyly hands. Unexpectedly, α-smooth muscle actin was not upregulated. Our results confirm inflammation and fibrosis in recessive dystrophic epidermolysis bullosa, especially in scars, suggesting major roles for these processes in pseudosyndactyly. Our data therefore suggests the potential use of antiinflammatory and antifibrotic drugs in the prevention of pseudosyndactyly.

Propolis and bee venom in diabetic wounds; a potential approach that warrants clinical investigation

Background: Wound healing in diabetes mellitus is a complex multi-stage process that requires the proper function of multiple systems. The mechanisms of impaired wound healing of diabetic wounds are still poorly understood. Therefore, various interventions are being used for wound management without great success. Bee products have various properties that make them an important addition to the diabetic wound management.Methods: This review summarized previous and recently published papers of the effects of two bee products, propolis and bee venom, on the wound healing. The main results were obtained from preclinical experimentation.Results: Diabetes mellitus compromises immune system, increases infections, impairs wound healing, and affects cells and factors involved in the wound healing. There is an increasing interest in natural products in modern medicine as part of disease management. Bee products are natural substances that others and we have explored some of their biological activities and applications in the treatment of various diseases. Some of these products are bee venom and propolis. These products have analgesic, antioxidant, antimicrobial, and anti-inflammatory properties. In addition, both propolis and bee venom contain considerable amounts of antioxidants that have a great role in accelerating wound healing.Conclusion: There is sound rationality and scientific data for using propolis and bee venom in diabetic wound healing. We believe that topical application of propolis in addition to bee venom might have a place in repairing damaged tissues and accelerating the healing of diabetic wounds.Keywords: Honey, propolis, wound, cytokines, healing, diabetes, antioxidants, inflammation

PROPOLIS AND BEE VENOM IN DIABETIC WOUNDS; A POTENTIAL APPROACH THAT WARRANTS CLINICAL INVESTIGATION

Background: Wound healing in diabetes mellitus is a complex multi-stage process that requires the proper function of multiple systems. The
 mechanisms of impaired wound healing of diabetic wounds are still poorly understood. Therefore, various interventions are being used for wound
 management without great success. Bee products have various properties that make them an important addition to the diabetic wound management.
 Methods: This review summarized previous and recently published papers of the effects of two bee products, propolis and bee venom, on the wound
 healing. The main results were obtained from preclinical experimentation.
 Results: Diabetes mellitus compromises immune system, increases infections, impairs wound healing, and affects cells and factors involved in the
 wound healing. There is an increasing interest in natural products in modern medicine as part of disease management. Bee products are natural
 substances that others and we have explored some of their biological activities and applications in the treatment of various diseases. Some of these
 products are bee venom and propolis. These products have analgesic, antioxidant, antimicrobial, and anti-inflammatory properties. In addition, both
 propolis and bee venom contain considerable amounts of antioxidants that have a great role in accelerating wound healing.
 Conclusion: There is sound rationality and scientific data for using propolis and bee venom in diabetic wound healing. We believe that topical
 application of propolis in addition to bee venom might have a place in repairing damaged tissues and accelerating the healing of diabetic wounds.

KdPT: Novel protective role against impaired wound healing in diabetes?

Diabetic ulcers are a major and therapeutic challenging complication in diabetes. Not only increased morbidity of affected patients but also extremely high costs on health care systems make the development of new therapeutic strategies an urgent necessity. Our group works on the pluripotent protective effects of melanocortin peptides in various inflammatory models. In this work, the effects of high glucose on keratinocytes and the protective effects of KdPT, a melanocortin derivative, against glucotoxicity, were investigated. High glucose adversely affected various vital cell functions, e.g. proliferation, metabolic activity, viability and migration. No significant induction of apoptosis or autophagy was observed. Using atomic force microscopy studies we showed that high glucose profoundly changes the cells’ biomechanical properties (diameter, elasticity). Induction of intracellular oxidative stress and endoplasmic reticulum stress mediated glucotoxicity. KdPT, a truncated tripeptide of alpha-MSH, significantly attenuated high glucose induced oxidative stress and antagonised the toxic effects of glucose on cell viability, metabolic activity and migration. Finally, using an ex vivo model of skin organ cultures we validated our in vitro generated data in a more physiological environment. In summary, our work creates a basis for better understanding the mechanisms of impaired wound healing in diabetes and possibly points towards novel therapies for diabetic ulcers.

Comparative analysis of angiogenic gene expression in normal and impaired wound healing in diabetic mice: effects of extracorporeal shock wave therapy

Impaired wound healing is a persistent clinical problem which has been treated with mixed results. Studies aimed at elucidating the mechanism of impaired wound healing have focused on small cohorts of genes which leave an incomplete picture of the wound healing process. We aimed to investigate impaired wound healing via a comprehensive panel of angiogenic/inflammation-related genes and wound closure kinetics with and without the application of extracorporeal shock wave therapy (ESWT), which has been demonstrated to improve wound healing. Full-thickness skin from the dorsal surface of "normal" (BALB/c) and "impaired" (db (+)/db (+)) mice was excised, and wound margin tissue was harvested 2, 7, and 10 days post injury. A separate, but identical wound model was established over 40 days in order to measure wound closure kinetics. Over time, the normal non-ESWT treated wounds exhibited varying patterns of elevated expression of 25-30 genes, whereas wounds with impaired healing displayed prolonged elevated expression of only a few genes (CXCL2, CXCL5, CSF3, MMP9, TGF-α). In response to ESWT, gene expression was augmented in both types of wounds, especially in the expression of PECAM-1; however, ESWT had no effect on wound closure in either model. In addition, multiple doses of ESWT exacerbated the delayed wound healing, and actually caused the wounds to initially increase in size. These data provide a more complete picture of impaired wound healing, and a way to evaluate various promising treatments.

The Mechanism of Protracted Wound Healing on Oral Mucosa in Diabetes. Review

Diabetic patients increase their body's susceptibility to infection and diabetes is a risk factor for periodontal diseases and oral infection. Although many studies showed the mechanism of impaired wound healing in diabetes, there are still arguments to shed light on what kind of factors, including local and systemic factors are involved in the protracted wound healing. This review article summarizes reports on the wound healing in diabetes and discusses the mechanism of the protracted wound healing of the oral mucosa in diabetes. Delayed vascularization, reduction in blood flow, decline in innate immunity, decreases in growth factor production, and psychological stresses may be involved in the protracted wound healing of the oral mucosa in diabetics.

Apoptosis down-regulates inflammation under the advancing epithelial wound edge: Delayed patterns in diabetes and improvement with topical growth factors

Background . Wound healing is involved in many aspects of care, ranging from anastomoses and skin incisions to foot ulcers and decubitus. Clinical healing failures are a major challenge to the physician and cause significant morbidity and mortality in select patient populations. As we are starting to understand more fully the mechanisms of impaired wound healing, the diabetic mouse (C5 7BL/KsJ-db/db) has been a good model for research. The diabetic wound exhibits significant delays in healing, previously identified as impaired cellular infiltration and granulation tissue formation. Apoptosis, or programmed cell death, is intimately involved in the regulation of inflammation and ultimately should play a role in the inflammatory phase of wound healing. Methods . To examine its role in wound healing, patterns of apoptosis in large, full-thickness cutaneous wounds were compared between groups of diabetic and nondiabetic mice. Results . Initially apoptosis was mainly limited to the wound edge and followed the advancing epithelial edge toward the center of the wound as healing progressed. Significant delays in the appearance of the apoptotic pattern were noted in the diabetic mice. Wounds in diabetic mice were then treated with topical application of growth factors. The delay in apoptotic pattern was reversed after treatment with the combination of insulin-like growth factor—II and platelet-derived growth factor, approaching levels in nondiabetic animals. Conclusions . Apoptosis appears concurrently with reepithelialization of the wound and may signal the end of the inflammatory phase of healing at that site in the wound. One can speculate that a signal for apoptosis and down-regulation of inflammation in the wound is derived from the epithelium.

Phagocytosis in riboflavin- or pyridoxine-deficient rats

The effect of riboflavin or pyridoxine deficiency on phagocytosis was examined in rats to elucidate the mechanism of impaired wound healing in these deficiencies reported earlier. Phagocytic ingestion by peritoneal leukocytes was 60.4% and 68%, respectively, in riboflavin- or pyridoxine-deficient rats compared with weight-matched control animals. Lactate production, which is a measure of glycolytic activity and exocytic degranulation, were also reduced to 74% and 65%, respectively, in riboflavin deficiency but were unaltered in pyridoxine deficiency. Food restriction per se increased production of superoxide anion by leukocytes by two fold, and it was further increased by 1.5 fold during particle uptake only in pyridoxine deficiency. However, postphagocytic digestive events, as judged by the activities of acid phosphatase and collagenase in the incised wound, were not affected in either deficiency. Thus, impaired phagocytosis other than reduced collagenization (reported earlier) may contribute to the adverse effects of vitamins B 2 or B 6 deficiencies on wound healing.