Updating on understanding and managing chronic wound

Microbubble enhanced ultrasound with low mechanical index promotes therapeutic angiogenesis in hind limb ischemia mouse model

BACKGROUND

Microbubble enhanced ultrasound (MEUS) can augment tissue perfusion by angiogenesis yet the best treatment ultrasound power in the initial ischemia period is uncertain.

PURPOSE

Considering the mechanical index (MI) is the most commonly used parameter for regulating diagnostic ultrasound power, here, we explored the effects of MEUS mediated by different MI on perfusion and sought to characterize the angiogenesis in the early stage of ischemia.

METHODS

Experiments were conducted on hind limb ischemia mouse model (HLI) and MEUS was administrated in the first week every other day following induction of HLI for four times. MEUS was conducted with a modified diagnostic ultrasound in combination with a lipid microbubble at 3 MHz and 21 cycles employing MI 0.3 (0.8 MPa), 0.7 (1.32 MPa) and 1.3 (2.78 MPa), respectively. Semi-quantitative visual score and blood perfusion quantitation by contrast-enhanced ultrasound were performed before each treatment. Hematoxylin-eosin staining and immunohistochemistry with CD31 were performed after four times treatment.

RESULTS

The results showed HLI mice in MI 0.3 mediated MEUS group longitudinally exhibited more blood perfusion in calf muscle and less visible necrosis compared to other experimental groups in the early stage. Additionally, diffused inflammatory cells with greater number of vessels in calf muscle were observed in MI 0.3 group.

CONCLUSIONS

Low MI mediated MEUS had significantly greater effects on augmenting muscle blood perfusion and reducing necrosis in the initial period after HLI surgery. These effects are most likely mediated by angiogenesis stimulated by low MI mediated MEUS.

Ultrasound and Gold Nanoparticles Improve Tissue Repair for Muscle Injury Caused by Snake Venom

OBJECTIVE

To develop a treatment that enhances recovery from envenomation-induced lesions caused by Bothrops jararaca venom by using ultrasound in combination with gold nanoparticles (GNPs).

METHODS

A total of 108 Swiss mice were arranged into nine groups. The animals underwent necrotic induction with 250 µg B. jararaca venom (BjV) and were treated with ultrasound (U) at 1 MHz frequency at an intensity of 0.8 W/cm² for 5 min, 30 mg/L GNPs, and anti-bothropic serum (AS) in the following combinations: saline solution (SS); BjV; BjV + AS; BjV + AS + U; BjV + GNPs + AS; BjV + GNPs + AS + U; BjV + GNPs; BjV + GNPs + U; and BjV + U. The necrotic area, histology, oxidative stress, oxidative damage, and anti-oxidant system were assessed to evaluate the effects of the treatments.

RESULTS

Treatments that included GNPs, U, and/or AS demonstrated reductions in necrotic area, increases in angiogenesis and fibroblast means, decreases in inflammatory infiltrates, and improvements in collagen synthesis. Additionally, there was an increase in oxidants and oxidant damage within the gastrocnemius muscle, along with an increase in anti-oxidants. Furthermore, systemic effects appear to have been achieved, improving the anti-oxidant system at the cardiovascular and renal levels.

CONCLUSION

The use of GNPs and U may be effective at treating lesions caused by B. jararaca snake venom.

Soy Protein-Based Wound Dressings: A Review of Their Preparation, Properties, and Perspectives

Wound healing is a major challenge worldwide, and people have been researching wound dressings that can promote wound healing for decades. Natural biobased materials, such as polysaccharides and proteins, have been widely used in the development of wound dressings. Among them, soy protein-based materials have attracted the interest of a wide range of researchers due to their safety, biocompatibility, controlled degradation, and ability to be mixed with other materials. However, there has been a lack of comments on these soy protein-based wound dressings. This work reviews various forms of soy protein-based wound dressings, such as hydrogels, films, and others, which could be prepared through physical/chemical cross-linking with synthetic or natural polymers. The important role played by soy protein-based materials in the wound healing phase and their properties will be examined, such as their anti-inflammatory, antioxidant, angiogenesis-promoting, cellular biocompatibility, self-healing ability, adhesion, antimicrobial, and tunable mechanical properties. Additionally, insights into the market prospects and trends for soy protein dressings are provided, clarifying the enormous development potential of soy protein as a new type of wound repair material.

Metformin promotes angiogenesis by enhancing VEGFa secretion by adipose-derived stem cells via the autophagy pathway

Human adipose tissue-derived stem cell (ADSC) derivatives are cell-free, with low immunogenicity and no potential tumourigenicity, making them ideal for aiding wound healing. However, variable quality has impeded their clinical application. Metformin (MET) is a 5' adenosine monophosphate-activated protein kinase activator associated with autophagic activation. In this study, we assessed the potential applicability and underlying mechanisms of MET-treated ADSC derivatives in enhancing angiogenesis. We employed various scientific techniques to evaluate the influence of MET on ADSC, assess angiogenesis and autophagy in MET-treated ADSC in vitro, and examine whether MET-treated ADSC increase angiogenesis. We found that low MET concentrations exerted no appreciable effect on ADSC proliferation. However, MET was observed to enhance the angiogenic capacity and autophagy of ADSC. MET-induced autophagy was associated with increased vascular endothelial growth factor A production and release, which contributed to promoting the therapeutic efficacy of ADSC. In vivo experiments confirmed that in contrast to untreated ADSC, MET-treated ADSC promoted angiogenesis. Our findings thus indicate that the application of MET-treated ADSC would be an effective approach to accelerate wound healing by promoting angiogenesis at wound sites.

Keratin-based wound dressings: From waste to wealth

Keratin is a natural protein with a high content of cysteine residues (7-13%) and is widely found in hair, wool, horns, hooves, and nails. Keratin possesses abundant cell-binding motifs such as leucine-aspartate-valine (LDV), glutamate-aspartate-serine (EDS), and arginine-glycine-aspartate (RGD), which benefit cell attachment and proliferation. It has been confirmed that keratin plays important roles in every stage of wound healing, including hemostasis, inflammation, proliferation, and remodeling, making keratin-based materials good candidates for wound dressings. In combination with synthetic and natural polymers, keratin-based wound dressings in the forms of films, hydrogels, and nanofibers can be achieved with improved mechanical properties. This review focuses on the recent development of keratin-based wound dressings. Firstly, the physicochemical and biological properties of keratin, are systematically discussed. Secondly, the role of keratin in wound healing is proposed. Thirdly, the applications of keratin-based wound dressings are summarized, in terms of the forms and functionalization. Finally, the current challenges and future development of keratin-based wound dressings are presented.

Bidirectional regulation of i-type lysozyme on cutaneous wound healing

OBJECTIVE

This study aimed to assess the effect and mechanism of i-type lysozyme on cutaneous wound healing animal model and Multiple cell models both in vivo and in vitro.

METHODS

Therefore, to evaluate its regenerative efficacy on wound healing process, we daily applied i-type lysozyme on murine full-thickness excisional wounds. After sacrifice on indicated days, skin tissues around surgical defects were harvested and assessed for re-epithelialization, granulation tissue formation, neovascularization and remodeling. To elucidate the underlying mechanisms, i-type lysozyme was analyzed for its tissue regenerative potency on the proliferation, invasion, migration and tube formation against keratinocytes, fibroblasts and endothelial cells. Antioxidant and antimicrobial experiments were also conducted to elucidate protective ability of i-type lysozyme to wound bed.

RESULTS

It displayed excellent bi-directional regulation in wound repair, with significant acceleration of epidermal and dermal regeneration as well as the efficient attenuation of excessive collagen deposition and fibrosis in the surgical lesion. I-type lysozyme treatment augmented the proliferation and migration of HaCaT, NIH 3T3 and HUVECs, enhanced the invasion of HaCaT and HUVECs as well as accelerated tube formation of HUVECs. Additionally, it significantly recovered the proliferation of H₂O₂-damaged cells, whereas represented no microbicidal effect under effective concentration of wound healing.

CONCLUSION

Our findings demonstrate the bi-directional regulation of i-type lysozyme in wound healing process through promoting tissue regeneration while hampering scar formation, implying that it is a promising therapeutic agent for wound repair.

New Treatment of Wound Healing With Allogenic Acellular Human Skin Graft: Preclinical Assessment and In Vitro Study

BACKGROUND

Nonhealing wounds can be a major clinical problem. Impaired wound healing is often related to massive tissue injury, concomitant wound healing deficiencies (chronic wounds), burn injury, or congenital conditions. We propose a novel biological dressing as an alternative surgical approach. The dressing is a form of an allogenic human skin graft equivalent with further use of allogeneic stem cells classified as an advanced therapy medicinal product. This new allogenic acellular human skin graft has been specifically developed to address the clinical indications for dressing wound lesions and promoting tissue repair in specific rare genetic diseases.

METHODS

This case report illustrates the use of an acellular human skin allograft seeded with multipotent stem cells in the treatment of tissue injuries (burns), congenital conditions, and chronic wounds. Donor-tissue processing yields an acellular dermal matrix with integral collagen bundling and organization, as well as an intact basement membrane complex.

RESULTS

Preclinical observations show prolonged viability of acellular human skin grafts with multipotent stem cells. This was confirmed with histological and electron-microscopic evaluation of biopsies, which demonstrated host-cell infiltration and neovascularization of the biological dressing. Moreover, the dressings were characterized by low immunogenicity, as confirmed by histology exam and T-cell proliferation assays in vitro.

CONCLUSION

Our data confirmed the safety and efficacy of the evaluated acellular human skin grafts, which may be used in patients with rare diseases, such as epidermolysis bullosa, burn injuries, and chronic wounds.

Therapeutic strategies for enhancing angiogenesis in wound healing

The enhancement of wound healing has been a goal of medical practitioners for thousands of years. The development of chronic, non-healing wounds is a persistent medical problem that drives patient morbidity and increases healthcare costs. A key aspect of many non-healing wounds is the reduced presence of vessel growth through the process of angiogenesis. This review surveys the creation of new treatments for healing cutaneous wounds through therapeutic angiogenesis. In particular, we discuss the challenges and advancement that have been made in delivering biologic, pharmaceutical and cell-based therapies as enhancers of wound vascularity and healing.

pH and Glucose Dual-Responsive Injectable Hydrogels with Insulin and Fibroblasts as Bioactive Dressings for Diabetic Wound Healing

pH and glucose dual-responsive injectable hydrogels were prepared through the cross-linking of Schiff's base and phenylboronate ester using phenylboronic-modified chitosan, poly(vinyl alcohol) and benzaldehyde-capped poly(ethylene glycol). Protein drugs and live cells could be incorporated into the hydrogels during the in situ cross-linking, displaying sustained and pH/glucose-triggered drug release from the hydrogels and cell viability and proliferation in the three-dimensional hydrogel matrix as well. Hence, the hydrogels with insulin and fibroblasts were considered as bioactive dressings for diabetic wound healing. A streptozotocin-induced diabetic rat model was used to evaluate the efficacy of hydrogel dressings in wound repair. The results revealed that the incorporation of insulin and L929 in the hydrogels could promote neovascularization and collagen deposition and enhance the wound-healing process of diabetic wounds. Thus, the drug- and cell-loaded hydrogels have promising potential in wound healing as a medicated system for various therapeutic proteins and live cells.

Towards a systems approach for chronic diseases, based on health state modeling

Rising pressure from chronic diseases means that we need to learn how to deal with challenges at a different level, including the use of systems approaches that better connect across fragments, such as disciplines, stakeholders, institutions, and technologies. By learning from progress in leading areas of health innovation (including oncology and AIDS), as well as complementary indications (Alzheimer's disease), I try to extract the most enabling innovation paradigms, and discuss their extension to additional areas of application within a systems approach. To facilitate such work, a Precision, P4 or Systems Medicine platform is proposed, which is centered on the representation of health states that enable the definition of time in the vision to provide the right intervention for the right patient at the right time and dose. Modeling of such health states should allow iterative optimization, as longitudinal human data accumulate. This platform is designed to facilitate the discovery of links between opportunities related to a) the modernization of diagnosis, including the increased use of omics profiling, b) patient-centric approaches enabled by technology convergence, including digital health and connected devices, c) increasing understanding of the pathobiological, clinical and health economic aspects of disease progression stages, d) design of new interventions, including therapies as well as preventive measures, including sequential intervention approaches. Probabilistic Markov models of health states, e.g. those used for health economic analysis, are discussed as a simple starting point for the platform. A path towards extension into other indications, data types and uses is discussed, with a focus on regenerative medicine and relevant pathobiology.

A mathematical model for lymphangiogenesis in normal and diabetic wounds

Several studies suggest that one possible cause of impaired wound healing is failed or insufficient lymphangiogenesis, that is the formation of new lymphatic capillaries. Although many mathematical models have been developed to describe the formation of blood capillaries (angiogenesis) very few have been proposed for the regeneration of the lymphatic network. Moreover, lymphangiogenesis is markedly distinct from angiogenesis, occurring at different times and in a different manner. Here a model of five ordinary differential equations is presented to describe the formation of lymphatic capillaries following a skin wound. The variables represent different cell densities and growth factor concentrations, and where possible the parameters are estimated from experimental and clinical data. The system is then solved numerically and the results are compared with the available biological literature. Finally, a parameter sensitivity analysis of the model is taken as a starting point for suggesting new therapeutic approaches targeting the enhancement of lymphangiogenesis in diabetic wounds. The work provides a deeper understanding of the phenomenon in question, clarifying the main factors involved. In particular, the balance between TGF-β and VEGF levels, rather than their absolute values, is identified as crucial to effective lymphangiogenesis. In addition, the results indicate lowering the macrophage-mediated activation of TGF-β and increasing the basal lymphatic endothelial cell growth rate, inter alia, as potential treatments. It is hoped the findings of this paper may be considered in the development of future experiments investigating novel lymphangiogenic therapies.

Glu-Trp-ONa or its acylated analogue (R-Glu-Trp-ONa) administration enhances the wound healing in the model of chronic skin wounds in rabbits

The management of chronic skin wounds represents a major therapeutic challenge. The synthesized dipeptide (Glu-Trp-ONa) and its acylated analogue (R-Glu-Trp-ONa) were assessed in the model of nonhealing dermal wounds in rabbits in relation to their healing properties in wound closure. Following wound modeling, the rabbits received a course of intraperitoneal injections of Glu-Trp-ONa or R-Glu-Trp-ONa. Phosphate-buffered saline and Solcoseryl® were applied as negative and positive control agents, respectively. An injection of Glu-Trp-ONa and R-Glu-Trp-ONa decreased the period of wound healing in animals in comparison to the control and Solcoseryl-treated groups. Acylation of Glu-Trp-ONa proved to be beneficial as related to the healing properties of the dipeptide. Subsequent zymography analyses showed that the applied peptides decreased the proteolytic activity of matrix metalloproteinases MMP-9, MMP-8, and MMP-2 in the early inflammatory phase and reversely increased the activity of MMP-9, MMP-8, and MMP-1 in the remodeling phase. Histological analyses of the wound sections (hematoxylin-eosin, Mallory's staining) confirmed the enhanced formation of granulation tissue and re-epithelialization in the experimental groups. By administering the peptides, wound closures increased significantly through the modulation of the MMPs' activity, indicating their role in wound healing.

Treating the whole not the hole: necessary coupling of technologies for diabetic foot ulcer treatment

Type 2 diabetes is the epidemic of our generation, and diabetic foot ulcers (DFUs) are a major complication. Although DFU formation itself can indicate disease progression, the failure to effectively treat ulcers contributes further to a decay in patient quality of life and increased mortality. Herein we discuss the development of next-generation DFU therapies including: (i) topical growth factors, (ii) scaffolds, and (iii) cellular therapies. Individually these therapies have yielded measurable but modest improvements in DFU repair. Because DFUs arise as a result of multiple biochemical deficiencies, a singular treatment modality is unlikely to be effective. Next-generation DFU technologies must be combined to address effectively the complex underlying pathology and enable reliable DFU repair.