Polyphosphate in Chronic Wound Healing: Restoration of Impaired Metabolic Energy State.

Rationale: Tissue regeneration of skin and bone is an energy-intensive, ATP-consuming process that, if impaired, can lead to the development of chronic clinical pictures. ATP levels in the extracellular space including the exudate of wounds, especially chronic wounds, are low. This deficiency can be compensated by inorganic polyphosphate (polyP) supplied via the blood platelets to the regenerating site. Methods: The contribution of the different forms of energy derived from polyP (metabolic energy, mechanical energy and heat) to regeneration processes was dissected and studied both in vitro and in patients. ATP is generated metabolically during the enzymatic cleavage of the energy-rich anhydride bonds between the phosphate units of polyP, involving the two enzymes alkaline phosphatase (ALP) and adenylate kinase (ADK). Exogenous polyP was administered after incorporation into compressed collagen or hydrogel wound coverages to evaluate its regenerative activity for chronic wound healing. Results: In a proof-of-concept study, fast healing of chronic wounds was achieved with the embedded polyP, supporting the crucial regeneration-promoting activity of ATP. In the presence of Ca2+ in the wound exudate, polyP undergoes a coacervation process leading to a conversion of fibroblasts into myofibroblasts, a crucial step supporting cell migration during regenerative tissue repair. During coacervation, a switch from an endothermic to an exothermic, heat-generating process occurs, reflecting a shift from an entropically- to an enthalpically-driven thermodynamic reaction. In addition, mechanical forces cause the appearance of turbulent flows and vortices during liquid-liquid phase separation. These mechanical forces orient the cellular and mineralic (hydroxyapatite crystallite) components, as shown using mineralizing SaOS-2 cells as a model. Conclusion: Here we introduce the energetic triad: metabolic energy (ATP), thermal energy and mechanical energy as a novel theranostic biomarker, which contributes essentially to a successful application of polyP for regeneration processes.

Here, we studied the potential role of inorganic polyphosphate (polyP) as an energy source for ADP and ATP formation in the extracellular space. In SaOS-2 cells, we show that matrix vesicles are released into the extracellular space after incubation with polyP. These vesicles contain both alkaline phosphatase (ALP) and adenylate kinase (AK) activities (mediated by ALPL and AK1 enzymes). Both enzymes translocate to the cell membrane in response to polyP. To distinguish the process(es) of AMP and ADP formation during ALP hydrolysis from the ATP generated via the AK reaction, inhibition studies with the AK inhibitor A(5')P5(5')A were performed. We found that ADP formation in the extracellular space occurs after enzymatic ATP synthesis. After exposure to polyP, a significant increase of the ADP level was observed, which is likely to be been catalyzed by ALP. This increase is not due to an intensified ATP release via exocytosis. The ATP level in the extracellular space of SaOS-2 cells is strongly increased in response to polyP, very likely mediated by the AK. We propose that the ALP and AK enzymes are involved in the extracellular ADP and ATP synthesis.

The adverse impact of chronic wounds is felt worldwide. The concerns for advanced wound care product are progressively increasing due to factors such as value for money spent in wound care products. Acute and Chronic wounds are managed in most health facilities in Ghana with sodium chloride (0.9%) infusion solution and povidone iodine fortified with metronidazole solution. The procedure is usually done by the nurse cleaning the wound with the saline solution wet gauze or cotton and then covered with the povidone iodine wet gauze for acute and chronic wounds. For chronic infected wounds, the wound is usually cleaned with saline solution and covered with wet gauze saline or currently with neomycin wound care spray or powdered antibiotics applied on the wounds. But it is popular as many wounds are covered with povidone iodine after wound cleaning in wound care practices in Ghana. Despite all these efforts, many wounds, especially chronic type wounds take a very long time to heal or sometimes fails to heal which reduce the quality of life of the people suffering from the menace. When it happens in this way, many resort to the use of local remedies to cause the wounds to heal but no avail, especially in Ghana where advanced treatment is scare. It is against this background that focal research in wound care was done in Ghana to come out with an innovative pharmaceutical wound care product effective for chronic and acute wounds healing to improve the quality of life of people as global burden of wounds escalates. In a Blind Observational Study for a period of five years in Ghana to observe the wound care products efficacy to heal wounds especially chronic types, the objective of the study was to examine a new product efficacy in chronic wound healing in the targeted population of patients with wounds. A product that has dual purpose of wound care as a cleaning and application agent, also has unique product pharmaceutical characteristics. A scalable, easy- to- use, multi-purpose, multi-use and cost-effective product, able to address the barriers or problems of wounds healing. The areas of consideration as far as wound care are concerned included: The study also sought to observe the product ability to control wound pains, control wound bleeding, control and prevent wound infection, remove wound debris, remove wound exudates effecting wounds healing at reduced healing time and with minimal scar in varied targeted patients’ population. Again, to observe the product with outcome of which to mitigate the long-term effect of chronic wounds like recurrent hospitalizations, financial burden, amputations, deformity, and frequent visit to hospital for wound care. One product, 9G Wound Solution (a cleaning and application product) manufactured by Pat J Health Company Limited, Ghana, was effective in wounds healing, especially, effective chronic wounds healing. The product was used to subject varied patients’ population with wounds on randomized basis, for wound care, and through observation the direct short, intermedial and long-term outcomes recorded of product effectiveness recorded. The outcome reported included control of wound pains, control of wound odor, control of bleeding, control of wound infection, removal of wounds exudates, removal of wound debris and ultimately reduced wound healing time to prevent wounds complications like amputations. The study was progressively extended across 10 regions in Ghana to cover 500 patient population with varied wounds. Patients’ population included those with Diabetic ulcers, Burns, pressure ulcers, venous ulcers, herpes zoster skin ulcers, Perineum wounds, Surgical abdomen-pelvic wounds, Traumatic wounds, Buruli Ulcers, gas gangrene wounds, and Mouth ulcers. The outcome of using the new wound care product were directly observed for the study period. By this observational study, the new product was observed to be superior to the controls as this product was able to heal 99% patients who had wounds, especially chronic wounds for many years, including 20years-old wound at reduced healing rate with no reoccurrence within the study period. The product scientifically readily released to the wound environment modulators capable to address the problems or barriers of wounds and simultaneously promoting modulators effective for wound healing. The product was not only effective in chronic wound healing at reduced time but also controlled wound pains shortly, controlled wound odor shortly, stopped wound bleeding, fought and controlled wound infection. However, using the product needed change of wound dressing every two days. The long-term effect of the product on target population not conclusively observed within the period of the research. We need to continuously observe the reported long-term effect of the product efficacy.

Surgical infection is one of the most important and important problems of modern medicine. The lack of a universal remedy and method of wound treatment, the difficulty of choosing universal tactics of management of patients with chronic wounds determines the need for further search for new treatments that stimulate reparative processes in chronic wounds, including morphological research methods. The role of cellular regulation in the pathogenesis of the restoration of the morphofunctional state of a chronic wound in the conditions of its damage remains undisclosed. Therefore, the aim of our study was to evaluate the role of myofibroblasts in the healing of chronic purulent-necrotic wounds in the treatment of mesenchymal stem cells using immunohistochemistry. In the experiment we obtained a model of chronic purulent-necrotic wound, which meets all the requirements for quality indicators in the study of morphological changes in chronic wounds and can then be used as a basis for preclinical research. The condition of chronic purulent-necrotic wounds in 120 rats was studied by histological and immunohistochemical methods. Chronic wound was modeled according to the original method of the author: during the formation of a standard skin defect in the interscapular area of the rat with a diameter of 1 cm, the surrounding tissue was superimposed ischemic metal structure to reduce blood flow in the wound area, which significantly slowed the delay. Treatment was started from 28 days from the beginning of wounding, which clinically and histologically corresponded to the chronicity of the wound process. Statistical processing of morphometric parameters was performed using the standard software package “Statistica 6.1”. It was found that the positive dynamics of healing of chronic wounds, using 0.025 % decasan solution, was observed mainly in the early stages (3-7 days), while mesenchymal stem cells (MSC) and MSC cloned in inert gases (MSC-IG) were effective at all stages of the study. The use of MSC and MSC-IG creates favorable conditions for the normal course of regenerative processes and epithelialization of wounds, providing anti-edema and anti-inflammatory effects with activation of myofibroblasts, which increases the healing efficiency of chronic purulent-necrotic wounds. Prospects for the use of MSC in the treatment of chronic wounds are shown.

The physiological polyphosphate as a healing biomaterial for chronic wounds: Crucial roles of its antibacterial and unique metabolic energy supplying properties

High-altitude environments require that animals meet the metabolic O2 demands for locomotion and thermogenesis in O2-thin air, but the degree to which convergent metabolic changes have arisen across independent high-altitude lineages or the speed at which such changes arise is unclear. We examined seven high-altitude waterfowl that have inhabited the Andes (3812–4806 m elevation) over varying evolutionary time scales, to elucidate changes in biochemical pathways of energy metabolism in flight muscle relative to low-altitude sister taxa. Convergent changes across high-altitude taxa included increased hydroxyacyl-coA dehydrogenase and succinate dehydrogenase activities, decreased lactate dehydrogenase, pyruvate kinase, creatine kinase, and cytochrome c oxidase activities, and increased myoglobin content. ATP synthase activity increased in only the longest established high-altitude taxa, whereas hexokinase activity increased in only newly established taxa. Therefore, changes in pathways of lipid oxidation, glycolysis, and mitochondrial oxidative phosphorylation are common strategies to cope with high-altitude hypoxia, but some changes require longer evolutionary time to arise.

Background: Chronic wounds are a growing problem internationally, termed a silent epidemic. To combat this epidemic, it is not sufficient to rely on traditional wound care treatments alone, but to look to innovative and alternative therapies. The indispensable role of oxygen in wound healing is well-discussed in the literature, and in the past two decades the topical application of oxygen has shown promising results in the healing of chronic wounds. However, the toxic effects of oxygen are usually not appreciated and can often lead to wound necrosis and gangrene in wounds with compromised blood supply. While wounds with adequate blood supply contain free radical quenchers (catalase, superoxide dismutase and reduced glutathione) which neutralize the free radicals (reactive oxygen species) released as a by-product of the Krebs cycle, wounds with deficient blood supply are deficient in free radical quenchers and are further damaged by exposure to oxygen as a result of reperfusion injury/oxygen toxicity. Topical hyperbaric oxygen (THOT&#174) uses low oxygen tensions in the hyperbaric range to stimulate angiogenesis, while preventing excessive oxygen toxicity. The result is the induction of marked angiogenesis, with increasing capacity for quenching reactive oxygen species, resulting in wound healing of ischemic wounds. Case Presentation: This case report describes a 95-year-old Caucasian female who presented with a stage IV chronic necrotic ulcer on her lower left leg. Surgical pathology results revealed calcifying vasculopathy, which is thought to be responsible for deficient blood supply to the leg, leading to a necrotic, chronic leg ulcer of her left leg. After traditional wound therapies were unsuccessful, she was considered for leg amputation. The introduction of adjunctive treatment with topical hyperbaric oxygen therapy saw complete healing of the wound within 15 weeks. The wound remained closed, without the presence of scar tissue, with no signs of wound breakdown at three-month and six-month follow-ups. Conclusions: Chronic hypoxic wounds with vascular insufficiency are considered “unlikely to heal” and tend to lead to limb amputation. The use of THOT&#174 technology, with low hyperbaric oxygen tensions to neutralize free radicals released by the Krebs cycle when oxygen contacts the wound, prevents oxygen toxicity and results in angiogenesis necessary for wound healing. In this way, THOT&#174 treatment was able to convert the hypoxic “unlikely to heal” wound considered for limb amputation into one which healed, with limb salvage. The results of this case report demonstrate the potential for complete healing of chronic hypoxic wounds even in complex cases with multiple confounding factors preventing wound healing, using a cost-effective treatment that is easily accessible to patients.

Stalled healing in chronic wounds is a challenging problem for providers and remains multifactorial in etiology. Older adults with insulin-dependent diabetes are at very high risk. In this case report, two patients with large nonhealing wounds were considered for treatment with daily jet lavage irrigation in an attempt to remove the inflammatory products of their respective chronic wounds and eliminate the persisting biofilm bacteria. Several attempts were made to reduce treatments to two to three times per week, and negative-pressure wound therapy was initiated in both cases only to see the return of inflammation and necrosis of the wound bed. In both cases, the daily jet lavage irrigation was successful in creating a granulating wound bed that slowly healed over many months. One patient died with an open sacral pressure injury, and the other patient died 4 months after complete healing of a large heel pressure injury. The interesting observation is the necessity of daily high-intensity wound irrigation to correct the chronic infectious process. Diabetic chronic wounds in high-risk older adults are recalcitrant to standard wound treatments, and providers should consider daily jet lavage wound irrigation to deal with this problem.

Macrophages are immune cells known to have a diverse array of functions dependant on the local tissue environment. This thesis aimed to investigate the role of macrophages in the skin. The first aim was to study if targeting inflammatory cytokines and cellular pathways was able to improve the rate of wound closure in acute and/or chronic wounds. These inflammatorypathways included the IL-17/IL-23 axis, the IL-33/ST2 pathway and the NLRP3 inflammasome. The next aim was to identify the role of macrophages in UV irradiation, specifically neonatal UV and the long-term effects in the skin and on local immune suppression. Finally, we aimed to identify the long-term effects of inflammation in the skin on the resident macrophage populations, studying the kinetics of their self-renewal.Macrophages play a vital role in wound healing, with either excessive or insufficient infiltration both causing to impaired healing responses. Current therapies for chronic wounds have poor prognosis and outcomes, and as such the development of alternative treatments are required. We found IL-17 and IL-23 inhibition improved wound closure in obese, diabetic mice by switching the macrophage phenotype from pro-inflammatory to pro-healing. IL-17 secreted from gamma delta T-cells significantly impaired wound closure, and the inhibition of IL-17 and its upstream regulator IL-23 by blocking antibodies was able to significantly improve chronic wound healing by increasing the percentage of alternatively activated, pro-healing macrophages.IL-33 is a molecule that can function as an alarmin through its receptor, ST2. We used ST2-/- mice to assess the action of IL-33 during wound healing. We found ST2-/- mice had impaired wound closure, reduced angiogenesis and altered collagen deposition/remodelling compared to BALB/C controls. There was increased neutrophilic infiltrate and altered macrophage polarisation in ST2-/- mice wounds. These results indicate that ST2 signalling is important for macrophage differentiation, which may improve wound closure, increase angiogenesis and delay or prevent scarring.The NLRP3 inflammasome has been implicated in a variety of inflammatory diseases. We used MCC950, a water-soluble small molecule inhibitor of NLRP3 in a chronic wound healing mouse model in an attempt to improve wound healing. We failed to identify any significant differences in the rate of wound healing, or angiogenesis in MCC950-treated mice compared to controls. Our results indicated that the NLRP3 inflammasome is not significantly involved in chronic wound healing.UVR has been repeatedly reported to induce immune suppression, one of the driving factors for tumour formation. Delayed-type contact hypersensitivity (CHS) is the leading mechanism for testing UVR-mediated immune suppression. We found the depletion of macrophages in neonates using clodronate liposomes before, during and after insult of a single burning dose of UVR was able to prevent a long-term local immune suppression, mediated by CD4+ regulatory T-cells. We also defined the changing resident myeloid cells in the skin as a response to UV exposure, and opened up new avenues of research to follow on from this work.Langerhans cells are a well-studied resident immune cell in the epidermis, with hundreds of publications identifying their origin, from the yolk-sac/foetal liver and their method of self-renewal under homeostatic conditions, and their ability to be renewed bymonocytes with the presence of chronic inflammation. A lesser studied resident macrophage population in the skin involves the resident dermal macrophages, which have been implicated in conditions such as wound healing and hair follicle cycling. We aimed to use a multicolour, fluorescent lineage-tracing model to investigate the mechanism of renewal of dermal macrophages in homeostasis, and inflammation. Unfortunately, the model chosen for this project was insufficient for this particular study and we were unable to gather any useful information from this project. This thesis has identified a list of molecules and cytokines that are either important or not for macrophage polarisation and the effects on wound healing in both chronic and acute wound healing scenarios. I have also identified a link between phagocytic myeloid cells and UV-induced immunosuppression and subsequent hapten-controlled inflammation in contact-hypersensitivity. Finally, a shift in long-term resident macrophages has also been identified following UV-irradiation, which may play a role in immune suppression and contact hypersensitivity.

Reticular dysgenesis is a human severe combined immunodeficiency that is primarily characterized by profound neutropenia and lymphopenia. The condition is caused by mutations in the adenylate kinase 2 (AK2) gene, resulting in the loss of mitochondrial AK2 protein expression. AK2 regulates the homeostasis of mitochondrial adenine nucleotides (ADP, ATP and AMP) by catalyzing the transfer of high-energy phosphate. Our present results demonstrate that AK2-knocked-down progenitor cells have poor proliferative and survival capacities and are blocked in their differentiation toward lymphoid and granulocyte lineages. We also observed that AK2 deficiency impaired mitochondrial function in general and oxidative phosphorylation in particular – showing that AK2 is critical in the control of energy metabolism. Loss of AK2 disrupts this regulation and leads to a profound block in lymphoid and myeloid cell differentiation.

Reticular Dysgenesis-Associated Adenylate Kinase 2 Deficiency Impairs Hematopoietic Stem and Progenitor Cell Function through Reductive Stress

The emerging translational potential of GDF11 in chronic wound healing

While qualitative aspects of dermal repair differ in wounds of different types, duration, and depths, all wounds must be resurfaced by epidermal keratinocytes before they can be deemed “healed.” Epidermal keratinocytes undergo a series of activation steps in acute wound healing, which are likely to be regulated by autocrine growth control mechanims. The state of epidermal keratinocyte activation in chronic venous wounds is examined in this study in relationship to the correct expression of these changes in acute wound healing. The expression of endogenous growth factor pathways in chronic wounds is presented and changes in the growth activation associated with healing of chronic wounds are studied. The results of this study establish that growth activation of the epidermis is not defective in chronic wounds. The activation of epidermis is likely to be regulated by endogenous keratinocyte cytokine and receptor pathways, suggesting that addition of exogenous epidermal mitogens to chronic wounds is unlikely to further alter epidermal healing. In contrast, some of the therapeutic benefits of hydrocolloid dressings in promoting healing of chronic wounds may be related to their ability to suppress excessive keratinocyte proliferation and activation in chronic wounds.

Apoptotic neutrophil membrane-modified nanoparticles promote wound healing by enhancing efferocytotic capacity of dendritic cells.

Flexible hydrogel sensors have expanded the applications of electronic devices due to their suitable mechanical properties and excellent biocompatibility. However, conventionally synthesized reduced graphene oxide (rGO) encounters limitations in reduction degree and dispersion, restricting the conductivity of graphene hydrogels and impeding the development of high-sensitivity flexible sensors. Moreover, hydrogels are susceptible to inflammation and bacterial infections, jeopardizing sensor stability over time. Thus, the challenge persists in designing conductive hydrogels that encompass high sensitivity, antibacterial efficacy, and anti-oxidative capabilities. In this study, GO was modified and reduced via a heparin-polydopamine (Hep-PDA) complex, yielding well-reduced and uniformly dispersed Hep-PDA-rGO nanosheets. Consequently, a hydrogel utilizing Hep-PDA-rGO was synthesized, showcasing commendable conductivity (3.63 S/m) and sensor performance, effectively applied in real-time motion monitoring. Notably, the hydrogel’s attributes extend to facilitating chronic diabetic wound healing. It maintained a suitable inflammatory environment credited to its potent antibacterial and antioxidative properties, while its inherent conductivity promoted angiogenesis. The multifunctional nature of this hydrogel highlight its potential not only as an epidermal sensor but also as a promising dressing candidate for chronic wound treatment.