A chemical biological strategy to facilitate diabetic wound healing

Tissue Regeneration and Remodeling in Rat Models after Application of Hypericum perforatum L. Extract-Loaded Bigels

The wound-healing effect of St. John's Wort (SJW) is mainly attributed to hyperforin (HP), but its low stability restricts its topical administration. This study investigates how "free" HP-rich SJW extract (incorporated into a bigel; B/SJW) and extract "protected" by nanostructured lipid carriers (also included in a biphasic semisolid; B/NLC-SJW) affect tissue regeneration in a rat skin excision wound model. Wound diameter, histological changes, and tissue gene expression levels of fibronectin (Fn), matrix metalloproteinase 8 (MMP8), and tumor necrosis factor-alpha (TNF-α) were employed to quantify the healing progress. A significant wound size reduction was achieved after applying both extract-containing semisolids, but after a 21-day application period, the smallest wound size was observed in the B/NLC-SJW-treated animals. However, the inflammatory response was affected more favorably by the bigel containing the "free" SJW extract, as evidenced by histological studies. Moreover, after the application of B/SJW, the expression of Fn, MMP8, and TNF-α was significantly higher than in the positive control. In conclusion, both bigel formulations exhibited beneficial effects on wound healing in rat skin, but B/SJW affected skin restoration processes in a comprehensive and more efficient way.

Investigation of the cellular and molecular effects of dehydrozingerone formulation on various days of diabetic wound repair

Cases of diabetes are significantly increasing year by year, attracting the attention of medical professionals and researchers to focus on diabetes and its underlying complications. One among such are diabetic wounds which are difficult to heal, creating severe implications in the day-to-day chores of not only patients, but also family members. Dehydrozingerone (DHZ) is known to possess various effects like anti-inflammatory, anti-microbial, antioxidant, and wound-healing properties. The effect of DHZ on different phases of diabetic wound healing remains untested. Hence, this study was proposed to find out the effect of oral and topical formulation of DHZ on day 5, 10 and 15 of diabetic wound healing. Excisional wounds were created on the dorsal side of animals using punch biopsy to mimic human diabetic wounds. Topical DHZ gel (100 mg in 1 gm of gel) was prepared using 1% Carbopol 934 and was applied twice a day. The treated groups had increased percentage of wound closure; western blotting suggested that DHZ significantly increased ERK and JNK levels and decreased TNF and MMP 2 and 9 levels. From histopathological studies, it was observed that angiogenesis, collagen formation, granulation tissue formation, and fibroblast proliferation were improved on days 5, 10, and 15 of diabetic wound healing. These findings indicate that DHZ (both systemic and topical) are effective during the early phases of wound healing which gets impaired in diabetic wounds. Dehydrozingerone accelerated diabetic wound healing by regulating the various hallmarks of wound healing process.

A Narrative Review of Diabetic Macroangiopathy: From Molecular Mechanism to Therapeutic Approaches

Diabetic macroangiopathy, a prevalent and severe complication of diabetes mellitus, significantly contributes to the increased morbidity and mortality rates among affected individuals. This complex disorder involves multifaceted molecular mechanisms that lead to the dysfunction and damage of large blood vessels, including atherosclerosis (AS) and peripheral arterial disease. Understanding the intricate pathways underlying the development and progression of diabetic macroangiopathy is crucial for the development of effective therapeutic interventions. This review aims to shed light on the molecular mechanism implicated in the pathogenesis of diabetic macroangiopathy. We delve into the intricate interplay of chronic inflammation, oxidative stress, endothelial dysfunction, and dysregulated angiogenesis, all of which contribute to the vascular complications observed in this disorder. By exploring the molecular mechanism involved in the disease we provide insight into potential therapeutic targets and strategies. Moreover, we discuss the current therapeutic approaches used for treating diabetic macroangiopathy, including glycemic control, lipid-lowering agents, and vascular interventions.

Insights into the mechanisms of diabetic wounds: pathophysiology, molecular targets, and treatment strategies through conventional and alternative therapies

Diabetes mellitus is a prevalent cause of mortality worldwide and can lead to several secondary issues, including DWs, which are caused by hyperglycemia, diabetic neuropathy, anemia, and ischemia. Roughly 15% of diabetic patient's experience complications related to DWs, with 25% at risk of lower limb amputations. A conventional management protocol is currently used for treating diabetic foot syndrome, which involves therapy using various substances, such as bFGF, pDGF, VEGF, EGF, IGF-I, TGF-β, skin substitutes, cytokine stimulators, cytokine inhibitors, MMPs inhibitors, gene and stem cell therapies, ECM, and angiogenesis stimulators. The protocol also includes wound cleaning, laser therapy, antibiotics, skin substitutes, HOTC therapy, and removing dead tissue. It has been observed that treatment with numerous plants and their active constituents, including Globularia Arabica, Rhus coriaria L., Neolamarckia cadamba, Olea europaea, Salvia kronenburgii, Moringa oleifera, Syzygium aromaticum, Combretum molle, and Myrtus communis, has been found to promote wound healing, reduce inflammation, stimulate angiogenesis, and cytokines production, increase growth factors production, promote keratinocyte production, and encourage fibroblast proliferation. These therapies may also reduce the need for amputations. However, there is still limited information on how to prevent and manage DWs, and further research is needed to fully understand the role of alternative treatments in managing complications of DWs. The conventional management protocol for treating diabetic foot syndrome can be expensive and may cause adverse side effects. Alternative therapies, such as medicinal plants and green synthesis of nano-formulations, may provide efficient and affordable treatments for DWs.

Roles and mechanisms of umbilical cord mesenchymal stem cells in the treatment of diabetic foot: A review of preclinical and clinical studies

AIMS

Growing preclinical and clinical evidence has suggested the potential method of umbilical cord mesenchymal stem cell (UCMSC) therapy for diabetic foot. Thus, the authors provided an outline of the application of UCMSCs in the treatment of diabetic foot and further summarized the roles and mechanisms of this therapy.

DATA SYNTHESIS

With no time limitations, the authors searched the Web of Science, Cochrane Central Register of Controlled Trials, and PubMed (MEDLINE) databases. 14 studies were included, including 9 preclinical experiments and 5 clinical trials (3 RCTs and 2 single-arm trials).

CONCLUSIONS

The UCMSCs are of great efficacy and safety, and function mainly by reducing inflammation, regulating immunity, promoting growth factors, and enhancing the functions of vascular endothelial cells, fibroblasts, and keratinocytes. As a result, ulcer healing-related biological processes ensue, which finally lead to diabetic foot ulcer healing and clinical symptom improvement. UCMSC treatment enhances diabetic foot ulcer healing and has a safety profile. They function mainly by modulating immunity, promoting growth factor secretion, and enhancing cellular functions. More well-designed preclinical and clinical studies are needed to provide the most optimal protocol, the comprehensive molecular mechanisms, as well as to further evaluate the efficiency and safety profile of UCMSC treatment in diabetic foot patients.

Analysis of Bulk Transcriptome Sequencing Data and in vitro Experiments Reveal SIN3A as a Potential Target for Diabetic Foot Ulcer

Background

Diabetic foot ulcers (DFUs) represent a severe complication of diabetes associated with reduced quality of life, lower limb amputations, hospitalizations, increased incidence, and mortality. Importantly, a significant number of pathogenic genes remain unexplored in DFUs.

Methods

A series of bioinformatics analyses were performed on publicly available bulk transcriptome sequencing datasets GSE134431 and GSE80178 to explore the transcriptomic changes in DFUs and select core genes for in vitro functional validation. In a focused examination, the differential expression analysis unveiled distinctions in gene expression patterns between DFUs and non-ulcerated diabetic skin tissues. Enriched functional annotations of differentially expressed genes were explored using the DAVID online tool. Protein-protein interaction analysis was conducted to investigate interactions among differentially expressed genes and select core genes. Knockdown or overexpression of core genes in HaCaT keratinocytes was performed to assess their impact on cell proliferation and migration.

Results

Ten core genes were identified. Cell Counting Kit-8 (CCK-8) and scratch assays demonstrated that downregulation of the core gene SIN3A significantly inhibited the migration and proliferation of HaCaT keratinocytes, while overexpression of SIN3A reversed the high-glucose-induced suppression of HaCaT cell viability and migration.

Conclusion

SIN3A expression is downregulated in DFUs. In vitro, SIN3A promotes the proliferation and migration of HaCaT keratinocytes, suggesting it may be a potential therapeutic target for DFUs.

Catechin, epicatechin, curcumin, garlic, pomegranate peel and neem extracts of Indian origin showed enhanced anti-inflammatory potential in human primary acute and chronic wound derived fibroblasts by decreasing TGF-β and TNF-α expression

BACKGROUND

Although chronic wounds are devastating and can cause burden at multiple levels, chronic wound research is still far behind. Chronic wound treatment is often less efficient due to delay in diagnosis and treatment, non-specific treatment mainly due to lack of knowledge of wound healing or healing resistance genes. It's known that chronic wounds do not progress towards healing, because it gets stalled in inflammatory phase of wound healing.

OBJECTIVE

We aimed to use phytoextracts possessing excellent anti-inflammatory properties to regulate the unbalanced levels of cytokines responsible for increased inflammation.

METHODS

Evaluation of anti-inflammatory activity of selected phytoextracts namely, Camellia sinensis (L.) Kuntze, Acacia catechu (L.f) Willd., Curcuma longa (L.), Allium sativum (L.), Punica granatum (L.) and Azadirachta indica A. hereafter, called as catechin, epicatechin, curcumin, garlic, pomegranate and neem extracts, respectively in Acute wound fibroblasts (AWFs) and Chronic wound fibroblasts (CWFs) using flow cytometry.

RESULTS

The phytoextracts exhibited no cytotoxicity below 100 μg/ml on normal Human Dermal fibroblasts (HDFs), while garlic extract showed highest cell viability followed by catechin, epicatechin, curcumin, pomegranate peel and neem based on IC₅₀ value. Garlic, catechin and epicatechin extracts showed highest anti-inflammatory activities for both TGF-β and TNF-α in both AWFs and CWFs treated cells. After treatment of AWFs with catechin, epicatechin and garlic extracts, TGF-β and TNF-α expression was significantly reduced compared to untreated AWFs and reached to almost normal HDFs level. Also, after treatment of CWFs with catechin, epicatechin and garlic extracts, TGF-β and TNF-α expression was significantly reduced compared to untreated CWFs and was lesser than untreated AWFs.

CONCLUSION

The present findings reveal the potential of catechin, epicatechin and garlic extracts for the treatment of acute and chronic wounds with excellent anti-inflammatory properties.

Targeting matrix metalloproteases in diabetic wound healing

Chronic inflammation participates in the progression of multiple chronic diseases, including obesity, diabetes mellitus (DM), and DM related complications. Diabetic ulcer, characterized by chronic wounds that are recalcitrant to healing, is a serious complication of DM tremendously affecting the quality of life of patients and imposing a costly medical burden on society. Matrix metalloproteases (MMPs) are a family of zinc endopeptidases with the capacity of degrading all the components of the extracellular matrix, which play a pivotal part in healing process under various conditions including DM. During diabetic wound healing, the dynamic changes of MMPs in the serum, skin tissues, and wound fluid of patients are in connection with the degree of wound recovery, suggesting that MMPs can function as essential biomarkers for the diagnosis of diabetic ulcer. MMPs participate in various biological processes relevant to diabetic ulcer, such as ECM secretion, granulation tissue configuration, angiogenesis, collagen growth, re-epithelization, inflammatory response, as well as oxidative stress, thus, seeking and developing agents targeting MMPs has emerged as a potential way to treat diabetic ulcer. Natural products especially flavonoids, polysaccharides, alkaloids, polypeptides, and estrogens extracted from herbs, vegetables, as well as animals that have been extensively illustrated to treat diabetic ulcer through targeting MMPs-mediated signaling pathways, are discussed in this review and may contribute to the development of functional foods or drug candidates for diabetic ulcer therapy. This review highlights the regulation of MMPs in diabetic wound healing, and the potential therapeutic ability of natural products for diabetic wound healing by targeting MMPs.

Matrix metalloproteinase profiling and their roles in disease

Matrix metalloproteinases (MMPs) play roles in remodelling of the extracellular matrix that occurs during morphogenesis, repair, and angiogenesis. Dysregulation of extracellular matrix remodelling can lead to cell proliferation, invasion, and tissue fibrosis. Identification of a specific MMP(s) in a disease has been challenging due to the presence of 24 closely-related human MMPs, each existing in three forms, of which only one is active and capable of catalysis. This review focuses on methods for MMP profiling, with particular emphasis on the batimastat affinity resin that binds only to the active forms of MMPs and related ADAMs (a disintegrin and metalloproteinases), which are then identified by mass spectrometry. Use of the batimastat affinity resin has identified targets for intervention in several human diseases.

Antioxidant, Wound Healing Potential and In Silico Assessment of Naringin, Eicosane and Octacosane

1. Diabetic chronic wounds, mainly foot ulcers, constitute one of the most common complications of poorly managed diabetes mellitus. The most typical reasons are insufficient glycemic management, latent neuropathy, peripheral vascular disease, and neglected foot care. In addition, it is a common cause of foot osteomyelitis and amputation of the lower extremities. Patients are admitted in larger numbers attributable to chronic wounds compared to any other diabetic disease. In the United States, diabetes is currently the most common cause of non-traumatic amputations. Approximately five percent of diabetics develop foot ulcers, and one percent require amputation. Therefore, it is necessary to identify sources of lead with wound-healing properties. Redox imbalance due to excessive oxidative stress is one of the causes for the development of diabetic wounds. Antioxidants have been shown to decrease the progression of diabetic neuropathy by scavenging ROS, regenerating endogenous and exogenous antioxidants, and reversing redox imbalance. Matrix metalloproteinases (MMPs) play vital roles in numerous phases of the wound healing process. Antioxidant and fibroblast cell migration activity of Marantodes pumilum (MP) crude extract has previously been reported. Through their antioxidant, epithelialization, collagen synthesis, and fibroblast migration activities, the authors hypothesise that naringin, eicosane and octacosane identified in the MP extract may have wound-healing properties. 2. The present study aims to identify the bioactive components present in the dichloromethane (DCM) extract of M. pumilum and evaluate their antioxidant and wound healing activity. Bioactive components were identified using LCMS, HPTLC and GCMS. Excision wound on STZ-induced diabetic rat model, human dermal fibroblast (HDF) cell line and colorimetric antioxidant assays were used to evaluate wound healing and antioxidant activities, respectively. Molecular docking and pkCMS software would be utilised to predict binding energy and affinity, as well as ADME parameters. 3. Naringin (NAR), eicosane (EIC), and octacosane (OCT) present in MP displayed antioxidant action and wound excision closure. Histological examination HDF cell line demonstrates epithelialization, collagen production, fibroblast migration, polymorphonuclear leukocyte migration (PNML), and fibroblast movement. The results of molecular docking indicate a substantial attraction and contact between MMPs. pkCMS prediction indicates inadequate blood-brain barrier permeability, low toxicity, and absence of hepatotoxicity. 4. Wound healing properties of (NEO) naringin, eicosane and octacosane may be the result of their antioxidant properties and possible interactions with MMP.

Moist exposed burn ointment accelerates diabetes-related wound healing by promoting re-epithelialization

Background

The incidence of diabetes-related wounds is widespread, and the treatment is challenging. We found that Moist Exposed Burn Ointment (MEBO) promotes the healing of diabetes-related wounds, but the mechanism is not clear.

Methods

This study aimed to explore the mechanism of MEBO on diabetic wound healing, which may be related to the promotion of re-epithelialization. A full-thickness skin resection model was established in streptozotocin (STZ)-induced diabetic mice. MEBO and Kangfuxin (KFX) were applied to the wound area, and the wound healing rate was analyzed by photographing. The granulation tissue and epidermal thickness, the collagen remodeling rate, and the expression of cytokeratin 10 (CK10), cytokeratin 14 (CK14), Ki67, Collagen I, and Collagen III in the regenerated skin were detected by H&E staining, Masson staining, and immunofluorescence staining, respectively. MEBO and KFX were applied to human immortalized keratinocytes (HaCaT), mouse dermal fibrolasts (MDF) cells, and cell viability, cell migration, and differentiation were determined by CCK-8, scratching assay, RT-qPCR, and Western blot (WB), respectively.

Results

We found that MEBO significantly promoted the formation of wound granulation tissue and collagen remodeling in diabetic mice. The application of MEBO to diabetic wounds not only promoted the formation of hair follicles and sebaceous glands but also promoted the expression of Ki67, CK10, and CK14 in epidermal cells. MEBO had no significant effect on the differentiation process of keratinocytes.

Conclusion

Our study further proved that MEBO plays a positive role in diabetic wound healing, and its excellent ability to promote re-epithelialization may be an important reason for promoting wound healing.

Treatment Management of Diabetic Wounds Utilizing Herbalism: An Overview

BACKGROUND AND OBJECTIVES

Diabetes Mellitus, commonly known as DM, is a metabolic disorder which is characterized by high blood glucose level, i.e., chronic hyperglycemia. If it is not managed properly, DM can lead to many severe complexities with time and can cause significant damage to the kidneys, heart, eyes, nerves and blood vessels. Diabetic foot ulcers (DFU) are one of those major complexities which affect around 15-25% of the population diagnosed with diabetes. Due to diabetic conditions, the body's natural healing process slows down leading to longer duration for healing of wounds only when taken care of properly. Herbal therapies are one of the approaches for the management and care of diabetic foot ulcer, which utilizes the concept of synergism for better treatment options. With the recent advancement in the field of nanotechnology and natural drug therapy, a lot of opportunities can be seen in combining both technologies and moving towards a more advanced drug delivery system to overcome the limitations of polyherbal formulations.

METHODS

During the writing of this document, the data was derived from existing original research papers gathered from a variety of sources such as PubMed, ScienceDirect, Google Scholar.

CONCLUSION

Hence, this review includes evidence about the current practices and future possibilities of nano-herbal formulation in treatment and management of diabetic wounds.

Mesenchymal Stem Cells Promote Wound Healing and Effects on Expression of Matrix Metalloproteinases-8 and 9 in the Wound Tissue of Diabetic Rats

Diabetic foot ulcer (DFU) is a multifactorial complication of diabetes, mainly manifested as infection, ulcer, or destruction of deep tissue, and there is currently no effective treatment. Several preclinical and clinical studies have proved that the transplantation of mesenchymal stem cells (MSCs) improved wound healing. In this study, we evaluated the therapeutic efficacy of human umbilical cord (hUC-MSCs) in DFU rat model. One dose of hUC-MSCs (1 × 10⁶ cells) was subcutaneously injected around wounds in male Sprague-Dawley rats. Wound healing was evaluated macroscopically (wound closure) every 3 days. In addition, we measured growth factors and specific proteins [matrix metalloproteinases (MMPs)-9 and MMP-8] on Day 14 post hUC-MSC transplantation. Results showed significant differences in the wound healing kinetics of lesions that received hUC-MSCs compared to lesions that received vehicle (phosphate buffered saline; P < 0.05). Enzyme-linked immunosorbent assay analyses indicated that MMP-9 protein contents were significantly upregulated in DFU animals, while MMP-8 was downregulated compared to the diabetic rats (P < 0.05). After MSC treatment, the level of MMP-9 and MMP-8 decreased and increased compared to the vehicle group, respectively. These findings suggest that hUC-MSC transplantation can ameliorate the healing process of DFU rats and a potential mechanism through which MSCs enhance DFU wound healing by decreasing MMP-9 expression and increasing MMP-8 expression. This study represents a promising opportunity to gain insight into how MSCs mediate wound healing.

Recent Advancement of Functional Hydrogels toward Diabetic Wound Management

Wound healing is a dynamic, orchestrated process comprising partially overlapping phases of hemostasis, inflammation, proliferation, and remodeling. This programmed process, dysregulated in diabetic individuals, results in chronic diabetic wounds. The normal process of healing halts at the inflammatory stage, and this prolonged inflammatory phase is characteristic of diabetic wounds. There are a few U.S. Food & Drug Administration approved skin substitutes; dermal matrixes are commercially available to manage diabetic wounds. However, expensiveness and nonresponsiveness in a few instances are the major limitations of such modalities. To address the issues, several treatment strategies have been exploited to treat chronic wounds; among them hydrogel-based systems showed promise due to favorable properties such as excellent absorption capabilities, porous structure, tunable mechanical strength, and biocompatibility. In the past two decades, hydrogels have become one of the most acceptable systems in the field of wound dressing material, offering single functionality to multifunctionality. This review focuses on the advancement of functional hydrogels explored for diabetic wound management. The process of diabetic wound healing is discussed in the light of the normal healing process, and the role of macrophages in the process is explained. This review also discusses the different approaches to treat diabetic wounds using functional hydrogels, along with their future opportunities.

Role of matrix metalloproteinases in diabetic foot ulcers: Potential therapeutic targets

Diabetic foot ulcers (DFUs) are pathological states of tissue destruction of the foot or lower extremity in diabetic patients and are one of the serious chronic complications of diabetes mellitus. Matrix metalloproteinases (MMPs) serve crucial roles in both pathogenesis and wound healing. The primary functions of MMPs are degradation, which involves removing the disrupted extracellular matrix (ECM) during the inflammatory phase, facilitating angiogenesis and cell migration during the proliferation phase, and contracting and rebuilding the tissue during the remodeling phase. Overexpression of MMPs is a feature of DFUs. The upregulated MMPs in DFUs can cause excessive tissue degradation and impaired wound healing. Regulation of MMP levels in wounds could promote wound healing in DFUs. In this review, we talk about the roles of MMPs in DFUs and list potential methods to prevent MMPs from behaving in a manner detrimental to wound healing in DFUs.

Proteomics Identification of Targets for Intervention in Pressure Ulcers

Pressure ulcers (PUs) are chronic wounds that lead to amputations and death. Little is known about why PUs are recalcitrant to healing. Wound healing is mediated by matrix metalloproteinases (MMPs). The 24 MMPs in humans each exist in three forms, of which only one is catalytically competent. We analyzed human PU samples using an affinity resin that exclusively binds to the catalytically competent MMPs. We identified by mass spectrometry the active forms of MMP-1, MMP-8, MMP-9, and MMP-14. Concentrations of MMP-8, MMP-9, and MMP-14 were higher in human PUs compared to the healthy tissue, whereas those for MMP-1 did not change. Decreasing levels of active MMP-9 as the PU improved argued for a detrimental role for this enzyme. In a mouse model of PUs, a highly selective inhibitor for MMP-9 and MMP-14, (R)-ND-336, accelerated wound closure in parallel with significant amelioration of ulcer stage. (R)-ND-336 holds promise as a first-in-class treatment for PUs.

Adaptive Gelatin Microspheres Enhanced Stem Cell Delivery and Integration With Diabetic Wounds to Activate Skin Tissue Regeneration

The delayed and complicated diabetic wound healing raises clinical and social concerns. The application of stem cells along with hydrogels is an attractive therapeutic approach. However, low cell retention and integration hindered the performance. Herein, gelatin microspheres were fabricated for local delivery of adipose-derived stem cells (from rats, rADSCs), and the effect of rADSCs with microspheres on diabetic wound healing was examined. Uniform, well-dispersed microspheres were fabricated using the microfluidic technique. Due to geometry differences, the proteinase degradation rate for microspheres was four times that of the bulk hydrogel. The obtained gelatin microspheres supported cell's adhesion and proliferation and provided a suitable microenvironment for rADSC survival. For in vivo animal tests, rADSCs were labeled with CM-Dil for tracking purposes. Microspheres were well embedded in the regenerated tissue and demonstrated good biocompatibility and an adaptive biodegradation rate. Histological examination revealed rADSC-loaded gelatin microspheres that significantly accelerated wound healing via promoting M2 macrophage polarization, collagen deposition, angiogenesis associated with peripheral nerve recovery, and hair follicle formation. Notably, the relative fluorescence intensity around the hair follicle was 17-fold higher than that of the blank group, indicating rADSC participated in the healing process via exosomes. Taken together, the rADSC-laden gelatin microspheres provided a promising strategy for local stem cell delivery to improve diabetic wound healing.

Pathogenesis and treatment of wound healing in patients with diabetes after tooth extraction

Diabetes mellitus is a common systematic chronic disease amongst dental patients. The elevated glucose microenvironment can prolong the healing of tooth extraction sockets. Therefore, the promotion of healing up tooth extraction sockets is of great clinical importance to the patients with diabetes mellitus. The current evidence indicates the mechanism of the recovery period of extraction sockets in hyperglycaemia conditions from physiological, inflammation, immune, endocrine and neural aspects. New advancements have been made in varied curative approaches and drugs in the management of wound healing of tooth extraction sockets in diabetes. However, most of the interventions are still in the stage of animal experiments, and whether it can be put into clinical application still needs further explorations. Specifically, our work showed topical administration of plasma-rich growth factor, advanced platelet-rich fibrin, leukocyte- and platelet-rich fibrin and hyaluronic acid as well as maxillary immediate complete denture is regarded as a promising approach for clinical management of diabetic patients requiring extractions. Overall, recent studies present a blueprint for new advances in novel and effective approaches for this worldwide health ailment and tooth extraction sockets healing.

Observation of macrophage autophagy in the healing of diabetic ulcers via a lysosome-targeting polarity-specific two-photon probe

As a disease with high incidence, mutilation, and fatality rates, diabetic ulcers (DUs) have become a difficult and complicated disease of widely concern in recent years due to the unclear healing mechanism. The main reason for the delayed healing in DU patients is the unduly long chronic inflammation window, and the polarization state of macrophages plays a key role in this process. Since autophagy is believed to be closely related to the polarization trend of macrophages, recent studies have shown that autophagy is closely related to the healing of DU. To this end, a lysosome-targeting polarity-sensitive probe, XZTU-VIS, was developed to monitor the changes in lysosomal polarity, thereby assessing the autophagy of macrophages in mice suffering from DU. The experimental results showed that under two-photon fluorescence microscopy, the green channel fluorescence signal of XZTU-VIS decreased significantly during autophagy. In the meantime, DU models established using BV-2 cells and mice showed a process that could cause inflammation and the release of ROS, thereby inducing autophagy.

A polarity-dependent two-photon fluorescent probe for evaluation of autophagy in the process of diabetic mouse skin ulcer-induced inflammation was constructed.

The senescence-associated secretory phenotype: Fueling a wound that never heals

Wound healing is impaired with advanced age and certain chronic conditions, such as diabetes and obesity. Moreover, common cancer treatments, including chemotherapy and radiation, can cause unintended tissue damage and impair wound healing. Available wound care treatments are not always effective, as some wounds fail to heal or recur after treatment. Hence, a more thorough understanding of the pathophysiology of chronic, nonhealing wounds may offer new ideas for the development of effective wound care treatments. Cancers are sometimes referred to as wounds that never heal, sharing mechanisms similar to wound healing. We describe in this review how cellular senescence and the senescence-associated secretory phenotype (SASP) contribute to chronic wounds versus cancer.

MiR equal than others: MicroRNA enhancement for cutaneous wound healing

Keratinocyte migration is vital in the re-epithelialisation of the skin during wound healing. Multiple factors conspire to impair closure of chronic wounds such as diabetic foot ulcers, venous leg ulcers and pressure wounds. Despite deep mechanistic understanding of microRNA (miRNA) biogenesis and function, the translational potential of these small genetic molecules has not been exploited to promote wound repair. In this review, I focus on miRNAs whose importance for wound healing stems from their impact on epidermal keratinocyte behaviour. These include miR-21-5p, miR-31-5p, miR-132-3p, miR-19b, miR-20a, miR-184, miR-129-5p and miR-335-5p which regulate diverse aspect of keratinocyte biology such as migration, proliferation, differentiation, inflammation and wound closure. A combinatorial approach where two or more miRNA mimics targeting distinct but complementary wound healing processes is proposed as this may enhance wound repair more effectively than any single miRNA mimic alone.

Strategy for Treatment of Infected Diabetic Foot Ulcers

Diabetic foot ulcers (DFUs) are chronic wounds that develop in 30% of diabetic patients. In DFUs, the normal wound healing process consisting of inflammation, angiogenesis, and extracellular matrix (ECM) remodeling is dysregulated and stalled. Upon injury, neutrophils and monocytes arrive at the wound and secrete matrix metalloproteinase (MMP)-8 and reactive oxygen species (ROS). ROS activates nuclear factor kappa beta (NF-κB), which upregulates MMP-9. Monocytes become macrophages, secreting tumor growth factor (TGF)-β1 and vascular endothelial growth factor (VEGF) for angiogenesis, resulting in remodeling of the ECM. MMP-9 cleaves laminin for keratinocyte migration. MMP-8 is beneficial for remodeling the ECM and healing the wound. In DFUs, the excess unregulated MMP-9 is detrimental, destroying the ECM and preventing the wound from healing. DFUs are typically infected, many with biofilm-producing bacteria that are resistant to antibiotics. Infection increases the time for wound healing and the likelihood for a lower-limb amputation. Despite the use of antibiotics, amputations occur in 24.5% of patients with DFUs. Clearly, new strategies for treatment of DFUs are needed. With the use of an affinity resin that binds exclusively to the active forms of MMPs and proteomics, we identified two proteinases, MMP-8 and MMP-9, in wounds of diabetic mice and diabetic humans. With the use of selective inhibitors, gene ablation of MMP-9, and exogenous application of MMP-8, we demonstrated that MMP-8 is beneficial to wound repair and that MMP-9 prevents the diabetic wound from healing. Our research has shown that infection increases active MMP-9, increasing inflammation and decreasing angiogenesis. As a result, infected diabetic wounds take a longer time to heal than uninfected ones. We found that active MMP-9 and NF-κB increased in human DFUs with wound severity and infection. The best strategy for treatment of DFUs is to selectively inhibit the detrimental proteinase MMP-9 without affecting the beneficial MMP-8 so that the body can repair the wound. Lead optimization of the thiirane class of inhibitors led to the discovery of (R)-ND-336, a potent (19 nM) and selective (450-fold) MMP-9 inhibitor. (R)-ND-336 accelerated wound healing in diabetic mice by decreasing ROS and NF-κB, lowering inflammation, and increasing angiogenesis. (R)-ND-336 in combination with the antibiotic linezolid improved wound healing in infected diabetic mice by inhibiting MMP-9, which mitigated macrophage infiltration and increased angiogenesis, thereby restoring the normal wound healing process.

Selective MMP-9 Inhibitor (R)-ND-336 Alone or in Combination with Linezolid Accelerates Wound Healing in Infected Diabetic Mice

Diabetic foot ulcers (DFUs) are a common complication of diabetes that are recalcitrant to healing due to persistent inflammation. The majority of DFUs have bacterial biofilms, with Staphylococcus epidermidis as a predominant bacterium, requiring infection control with antibiotics before treatment of the wound. Matrix metalloproteinases (MMPs) play roles in the pathology and repair of DFUs. However, defining the roles of the 24 human MMPs has been challenging due to the presence of three forms for each MMP, of which only one is catalytically competent, and the lack of convenient methods to distinguish among the three forms of MMPs. Using an affinity resin that binds only to the active forms of MMPs, with identification and quantification by mass spectrometry, we found that infected wounds in mice had increased levels of active MMP-9 compared to uninfected ones, paralleling infected human DFUs. MMP-9 activity prevents diabetic wounds from healing. We evaluated the efficacy of the selective small-molecule MMP-9 inhibitor, (R)-ND-336, in the infected diabetic mouse model of wound healing and showed that (R)-ND-336 alone or in combination with the antibiotic linezolid improves wound healing by inhibiting the detrimental MMP-9, mitigating macrophage infiltration to diminish inflammation, and increasing angiogenesis to restore the normal wound healing process. An advantage of this strategy is the ability to administer (R)-ND-336 concurrently with an antibiotic.

Limitations of Knockout Mice and Other Tools in Assessment of the Involvement of Matrix Metalloproteinases in Wound Healing and the Means to Overcome Them

Matrix metalloproteinases (MMPs) play important roles in wound healing, but attribution of their functions in repair of wounds has been challenging. Commonly used tools such as MMP-knockout mice and zymography often confound analysis, which is complicated further as these enzymes exist in three distinct forms with only one being catalytically competent. With the use of topical exogenously administered recombinant MMP-8 and MMP-13 to diabetic and nondiabetic mouse wounds, we show that these proteinases facilitate wound repair by upregulating IL-6 and increasing neutrophil trafficking with an early onset of inflammation. Furthermore, by spatiotemporal control in the use of a selective MMP-2 inhibitor, along with immunoprecipitation and Western blotting, we provide definitive demonstration that MMP-2 does not affect wound healing, contrary to reports. MMP-2 is found in wounds complexed with TIMPs, which is catalytically incompetent.

Systematic review and meta-analysis of mouse models of diabetes-associated ulcers

Mouse models are frequently used to study diabetes-associated ulcers, however, whether these models accurately simulate impaired wound healing has not been thoroughly investigated. This systematic review aimed to determine whether wound healing is impaired in mouse models of diabetes and assess the quality of the past research. A systematic literature search was performed of publicly available databases to identify original articles examining wound healing in mouse models of diabetes. A meta-analysis was performed to examine the effect of diabetes on wound healing rate using random effect models. A meta-regression was performed to examine the effect of diabetes duration on wound healing impairment. The quality of the included studies was also assessed using two newly developed tools. 77 studies using eight different models of diabetes within 678 non-diabetic and 720 diabetic mice were included. Meta-analysis showed that wound healing was impaired in all eight models. Meta-regression suggested that longer duration of diabetes prior to wound induction was correlated with greater degree of wound healing impairment. Pairwise comparisons suggested that non-obese diabetic mice exhibited more severe wound healing impairment compared with db/db mice, streptozotocin-induced diabetic mice or high-fat fed mice at an intermediate stage of wound healing (p<0.01). Quality assessment suggested that the prior research frequently lacked incorporation of key clinically relevant characteristics. This systematic review suggested that impaired wound healing can be simulated in many different mouse models of diabetes but these require further refinement to become more clinically relevant.

Imaging in Chronic Wound Diagnostics

Significance: Chronic wounds affect millions of patients worldwide, placing a huge burden on health care resources. Although significant progress has been made in the development of wound treatments, very few advances have been made in wound diagnosis. Recent Advances: Standard imaging methods like computed tomography, single-photon emission computed tomography, magnetic resonance imaging, terahertz imaging, and ultrasound imaging have been widely employed in wound diagnostics. A number of noninvasive optical imaging modalities like optical coherence tomography, near-infrared spectroscopy, laser Doppler imaging, spatial frequency domain imaging, digital camera imaging, and thermal and fluorescence imaging have emerged over the years. Critical Issues: While standard diagnostic wound imaging modalities provide valuable information, they cannot account for dynamic changes in the wound environment. In addition, they lack the capability to predict the healing outcome. Thus, there remains a pressing need for more efficient methods that can not only indicate the current state of the wound but also help determine whether the wound is on track to heal normally. Future Directions: Many imaging probes have been fabricated and shown to provide real-time assessment of tissue microenvironment and inflammatory responses in vivo. These probes have been demonstrated to noninvasively detect various changes in the wound environment, which include tissue pH, reactive oxygen species, fibrin deposition, matrix metalloproteinase production, and macrophage accumulation. This review summarizes the creation of these probes and their potential implications in wound monitoring.

Advances and Impact of Antioxidant Hydrogel in Chronic Wound Healing

The accelerating and thorough treatment of chronic wounds still represents a major unmet medical need owing to the complex symptoms resulting from metabolic disorder of the wound microenvironment. Although numerous strategies and bioactive hydrogels are developed, an effective and widely used method of chronic wound treatment remains a bottleneck. With the aim to accelerate chronic wound healing, many hydrogel dressings with antioxidant functions have emerged and are proven to accelerate wound healing, especially for chronic wound repair. The new strategy in chronic wound treatment brought by antioxidant hydrogels is of great significance to human health. Here, the application of antioxidant hydrogels in the repair of chronic wounds is discussed systematically, aiming to provide an important theoretical reference for the further breakthrough of chronic wound healing.

Arylamide as Potential Selective Inhibitor for Matrix Metalloproteinase 9 (MMP9): Design, Synthesis, Biological Evaluation, and Molecular Modeling

Previous studies have reported that compounds bearing an arylamide linked to a heterocyclic planar ring have successfully inhibited the hemopexin-like domain (PEX9) of matrix metalloproteinase 9 (MMP9). PEX9 has been suggested to be more selectively targeted than MMP9's catalytic domain in a degrading extracellular matrix under some pathologic conditions, especially in cancer. In this study, we aim to synthesize and evaluate 10 arylamide compounds as MMP9 inhibitors through an enzymatic assay as well as a cellular assay. The mechanism of inhibition for the most active compounds was investigated via molecular dynamics simulation (MD). Molecular docking was performed using AutoDock4.0 with PEX9 as the protein model to predict the binding of the designed compounds. The synthesis was carried out by reacting aniline derivatives with 3-bromopropanoyl chloride using pyridine as the catalyst at room temperature. The MMP9 assay was conducted using the FRET-based MMP9 kits protocol and gelatin zymography assay. The cytotoxicity assay was done using the MTT method, and the MD simulation was performed using AMBER16. Assay on MMP9 demonstrated activities of three compounds (2, 7, and 9) with more than 50% inhibition. Further inhibition on MMP9 expressed by 4T1 showed that two compounds (7 and 9) inhibited its gelatinolytic activity more than 50%. The cytotoxicity assay against 4T1 cells results in the inhibition of the cell growth with an EC₅₀ of 125 μM and 132 μM for 7 and 9, respectively. The MD simulation explained a stable interaction of 7 and 9 in PEX9 at 100 ns with a free energy of binding of -8.03 kcal/mol and -6.41 kcal/mol, respectively. Arylamides have potential effects as selective MMP9 inhibitors in inhibiting breast cancer cell progression.

Understanding the multifaceted mechanisms of diabetic wound healing and therapeutic application of stem cells conditioned medium in the healing process

Mesenchymal stem cells (MSCs) transplantation seems to be a promising new therapy for diabetic wound healing (DWH), and currently, arrays of MSCs from various sources ranging from umbilical, adipose to dental sources are available as a treatment modality for this disease. However, it now appears that only a fraction of transplanted cells actually assimilate and survive in host tissues suggesting that the major mechanism by which stem cells participate in tissue repair are most likely related to their secretome level. These include a wide range of growth factors, cytokines, and chemokines, which can be found from the conditioned medium (CM) used to culture the cells. Basic studies and preclinical work confirm that the therapeutic effect of CMs are comparable with the application of stem cells. This review describes in detail the wound healing process in diabetes and the cellular and biological factors that influence the process. Subsequently, through a comprehensive literature search of studies related to wound healing in diabetics, we aim to provide an overview of scientific merits of using MSCs-CM in the treatment of diabetic wound as well as the significant caveats, which restricts its potential use in clinical set-ups. To our best knowledge, this is one of the first review papers that collect the importance of stem cells as an alternative treatment to the DWH. We anticipate that the success of this treatment will have a significant clinical impact on diabetic wounds.

Uncontrolled gelatin degradation in non-healing chronic wounds

OBJECTIVE

To compare matrix metalloproteinase (MMP)-9 and the antiproteinase tissue inhibitor of metalloproteinases (TIMP)-1 in wound fluids and sera from patients with chronic non-healing or acute healing wounds. In addition, the functional consequences on MMP-9 activity and general gelatinase activity were assessed.

METHOD

In this observational study, samples were collected from patients with venous leg ulcers (VLUs), patients with type 2 diabetes with neuropathic foot ulcers (DFUs), and from another cohort of VLU patients with sterile split-thickness skin graft donor sites after autologous skin grafting, serving as healing control wounds. MMP-9 and TIMP-1 concentrations were determined by enzyme-linked immunosorbent assays. MMP-9 and gelatinase activities were determined in wound fluids in subsets of the patients.

RESULTS

A total of 24 patients took part in the study. No significant differences in MMP-9 wound fluid levels were found among the three groups. TIMP-1 levels were markedly and significantly lower in the two chronic wound groups resulting in a severely unbalanced MMP-9/TIMP-1 ratio, especially notable in the VLU group and possibly in the elevated endogenous MMP-9 activity (p<0.01) compared with the acute wound fluids. At least 20% of the chronic wound fluids displayed atypical patterns on gelatin zymography and showed high general gelatinase activity that was not inhibited by either TIMP-1 or by a gelatinase inhibitor (AG3340). MMP-9 levels were higher in the sera of the patients with type 2 diabetes.

CONCLUSION

We hypothesise that non-MMP proteinases contribute to matrix destruction in a significant number of chronic wounds. Blocking the excessive MMP-9 activity may be insufficient to normalise wound healing. The reasons and effects of the very low TIMP-1 levels in chronic wounds need further clarification.

Re-epithelialization of adult skin wounds: Cellular mechanisms and therapeutic strategies

Cutaneous wound healing in adult mammals is a complex multi-step process involving overlapping stages of blood clot formation, inflammation, re-epithelialization, granulation tissue formation, neovascularization, and remodelling. Re-epithelialization describes the resurfacing of a wound with new epithelium. The cellular and molecular processes involved in the initiation, maintenance, and completion of epithelialization are essential for successful wound closure. A variety of modulators are involved, including growth factors, cytokines, matrix metalloproteinases, cellular receptors, and extracellular matrix components. Here, we focus on cellular mechanisms underlying keratinocyte migration and proliferation during epidermal closure. Inability to re-epithelialize is a clear indicator of chronic non-healing wounds, which fail to proceed through the normal phases of wound healing in an orderly and timely manner. This review summarizes the current knowledge regarding the management and treatment of acute and chronic wounds, with a focus on re-epithelialization, offering some insights into novel future therapies.

Targeting MMP-9 in Diabetic Foot Ulcers

Diabetic foot ulcers (DFUs) are significant complications of diabetes and an unmet medical need. Matrix metalloproteinases (MMPs) play important roles in the pathology of wounds and in the wound healing process. However, because of the challenge in distinguishing active MMPs from the two catalytically inactive forms of MMPs and the clinical failure of broad-spectrum MMP inhibitors in cancer, MMPs have not been a target for treatment of DFUs until recently. This review covers the discovery of active MMP-9 as the biochemical culprit in the recalcitrance of diabetic wounds to healing and targeting this proteinase as a novel approach for the treatment of DFUs. Active MMP-8 and MMP-9 were observed in mouse and human diabetic wounds using a batimastat affinity resin and proteomics. MMP-9 was shown to play a detrimental role in diabetic wound healing, whereas MMP-8 was beneficial. A new class of selective MMP-9 inhibitors shows clinical promise for the treatment of DFUs.

Grape Seed-Inspired Smart Hydrogel Scaffolds for Melanoma Therapy and Wound Healing

Grape-seed extracts contain rich flavonoids with oligomeric proanthocyanidins (OPC). In this study, OPC containing hydrogel scaffolds can function as a natural photothermal agent for melanoma therapy and bioactive biomaterial for wound healing. Inspired by grape-seed extracts, OPC were explored as a photothermal agent and endowed the hydrogel scaffolds with excellent and controlled photothermal ability. The rheological property of the hydrogel scaffolds responded to irradiation time of near infrared (NIR) laser, and OPC contents. The compressive mechanical property of the hydrogel scaffolds was well modulated by NIR laser irradiation with different impact durations. The controlled high temperature induced by OPC-containing hydrogel scaffolds under NIR laser irradiation could effectively kill melanoma cells and suppress tumor growth. In addition, OPC-containing hydrogel scaffolds supported the proliferation and migration of human dermal fibroblasts and human umbilical vein endothelial cells, as well as obviously promoted angiogenesis and skin regeneration in both tumor-caused and chronic wounds. Therefore, OPC-containing hydrogel scaffolds possessed controlled photothermal, rheological, and compressive mechanical properties under NIR laser stimuli, as well as excellent biocompatibility and bioactivity for melanoma therapy and wound healing.

Mechanistic insight into diabetic wounds: Pathogenesis, molecular targets and treatment strategies to pace wound healing

Wound management in diabetic patient is of an extreme clinical and social concern. The delayed and impaired healing makes it more critical for research focus. The research on impaired healing process is proceeding hastily evident by new therapeutic approaches other than conventional such as single growth factor, dual growth factor, skin substitutes, cytokine stimulators, cytokine inhibitors, matrix metalloproteinase inhibitors, gene and stem cell therapy, extracellular matrix and angiogenesis stimulators. Although numerous studies are available that support delayed wound healing in diabetes but detailed mechanistic insight including factors involved and their role still needs to be revealed. This review mainly focuses on the molecular cascades of cytokines (with growth factors) and erstwhile factors responsible for delayed wound healing, molecular targets and recent advancements in complete healing and its cure. Present article briefed recent pioneering information on possible molecular targets and treatment strategies including clinical trials to clinicians and researchers working in similar area.

MMP-9 inhibitors impair learning in spontaneously hypertensive rats

Vascular cognitive impairment dementia (VCID) is a major cause of cognitive loss in the elderly. Matrix metalloproteinases (MMPs) are a family of proteases involved in remodeling the extracellular matrix in development, injury and repair. Blood-brain barrier (BBB) disruption due to inflammation mediated by MMPs is a mechanism of white matter injury. Currently there are no treatments besides the control of vascular risk factors. We tested two MMP-9 inhibitors that improved outcome in acute stroke: DP-460 and SB-3CT. We hypothesized that these inhibitors would have a beneficial effect in chronic stroke by reducing edema in white matter and improving behavioral outcomes. Spontaneously hypertensive stroke-prone rats (SHRSPs) with unilateral carotid artery occlusion (UCAO) fed a Japanese Permissive Diet (JPD) were used as a model of VCID. JPD was begun in the 12^th week of life. Rats were treated with DP-460 (500 mg/kg) for 4 weeks, or SB-3CT (10 mg/kg) for 8 weeks, beginning at the UCAO/JPD onset. Rats treated with a dextrose or DMSO solution served as vehicle controls. Naïve SHRSPs on a standard diet served as sham control. Magnetic resonance imaging (MRI) analyses of the corpus callosum, external capsule, hippocampus and Morris water maze behavioral tests were conducted. We found an increase in body weight (p = 0.004) and blood pressure (p = 0.007) at 15 weeks with the DP-460 drug. SB-3CT increased body weight at 14 weeks (p = 0.015) and had significant but variable effects on blood pressure. Neither drug affected imaging parameters. Behavioral studies showed an impaired ability to learn with DP-460 (p<0.001) and no effect on learning with SB-3CT. Unchanged MMP-9 levels were detected in DP-460-treated rats via gel zymography. Our findings suggest that MMPs are not major factors in white matter damage in the SHRSP model of VCID and that drugs that are relatively selective for MMP-9 can interfere with learning.

Expression of active matrix metalloproteinase-9 as a likely contributor to the clinical failure of aclerastide in treatment of diabetic foot ulcers

Chronic wounds are a complication of diabetes. Treatment for diabetic foot ulcers is complex with little clinical recourse, resulting in 108,000 lower-limb amputations annually in the United States alone. Matrix metalloproteinases (MMPs) play important roles in the pathology and in the repair of chronic wounds. We previously identified active MMP-8 and MMP-9 in wounds of diabetic mice and determined that MMP-8 accelerates wound repair, while MMP-9 is the culprit for the diabetic wound being refractory to healing. Aclerastide, a peptide analog of angiotensin II, recently failed in phase III clinical trials for treatment of diabetic foot ulcers. We demonstrate herein that treatment of wounds of diabetic mice with aclerastide results in elevated levels of reactive oxygen species and of active MMP-9, which is likely an important contributor to the failure of aclerastide in clinical trials.

Dysfunctional Wound Healing in Diabetic Foot Ulcers: New Crossroads

PURPOSE OF REVIEW

Diabetic foot ulcerations (DFU) affect 25% of patients with diabetes mellitus during their lifetime and constitute a major health problem as they are often recalcitrant to healing due to a constellation of both intrinsic and extrinsic factors. The purpose of this review is to (1) detail the current mechanistic understanding of DFU formation and (2) highlight future therapeutic targets.

RECENT FINDINGS

From a molecular perspective, DFUs exhibit a chronic inflammatory predisposition. In addition, increased local hypoxic conditions and impaired cellular responses to hypoxia are pathogenic factors that contribute to delayed wound healing. Finally, recent evidence suggests a role for epigenetic alterations, including microRNAs, in delayed DFU healing due to the complex interplay between genes and the environment. In this regard, notable progress has been made in the molecular and genetic understanding of DFU formation. However, further studies are needed to translate preclinical investigations into clinical therapies.

A hydroxamic acid–methacrylated collagen conjugate for the modulation of inflammation-related MMP upregulation

The selective covalent coupling of hydroxamic acid functions on to methacrylated type I collagen led to UV-cured networks with inherent MMP-modulating capability and enhanced proteolytic stability.

Exploitation of Conformational Dynamics in Imparting Selective Inhibition for Related Matrix Metalloproteinases

Matrix metalloproteinases (MMPs) have numerous physiological functions and share a highly similar catalytic domain. Differential dynamical information on the closely related human MMP-8, -13, and -14 was integrated onto the benzoxazinone molecular template. An in silico library of 28,099 benzoxazinones was generated and evaluated in the context of the molecular-dynamics information. This led to experimental evaluation of 19 synthesized compounds and identification of selective inhibitors, which have potential utility in delineating the physiological functions of MMPs. Moreover, the approach serves as an example of how dynamics of closely related active sites may be exploited to achieve selective inhibition by small molecules and should find applications in other enzyme families with similar active sites.

Glycosylation of matrix metalloproteases and tissue inhibitors: present state, challenges and opportunities

Current knowledge about the glycosylation of matrix metalloproteinases (MMPs) and the inhibitors of metalloproteinases (TIMPs) is reviewed. Whereas structural and functional aspects of the glycobiology of many MMPs is unknown, research on MMP-9 and MMP-14 glycosylation reveals important functional implications, such as altered inhibitor binding and cellular localization. This, together with the fact that MMPs contain conserved and many potential attachment sites for N-linked and O-linked oligosaccharides, proves the need for further studies on MMP glycobiology.

Matrix metalloproteases (MMPs) are crucial components of a complex and dynamic network of proteases. With a wide range of potential substrates, their production and activity are tightly controlled by a combination of signalling events, zymogen activation, post-translational modifications and extracellular inhibition. Slight imbalances may result in the initiation or progression of specific disease states, such as cancer and pathological inflammation. As glycosylation modifies the structures and functions of glycoproteins and many MMPs contain N- or O-linked oligosaccharides, we examine, compare and evaluate the evidence for whether glycosylation affects MMP catalytic activity and other functions. It is interesting that the catalytic sites of MMPs do not contain O-linked glycans, but instead possess a conserved N-linked glycosylation site. Both N- and O-linked oligosaccharides, attached to specific protein domains, endow these domains with novel functions such as the binding to lectins, cell-surface receptors and tissue inhibitors of metalloproteases (TIMPs). Validated glycobiological data on N- and O-linked oligosaccharides of gelatinase B/MMP-9 and on O-linked structures of membrane-type 1 MMP/MMP-14 indicate that in-depth research of other MMPs may yield important insights, e.g. about subcellular localizations and functions within macromolecular complexes.

Selective small-molecule inhibitors as chemical tools to define the roles of matrix metalloproteinases in disease

The focus of this article is to highlight novel inhibitors and current examples where the use of selective small-molecule inhibitors has been critical in defining the roles of matrix metalloproteinases (MMPs) in disease. Selective small-molecule inhibitors are surgical chemical tools that can inhibit the targeted enzyme; they are the method of choice to ascertain the roles of MMPs and complement studies with knockout animals. This strategy can identify targets for therapeutic development as exemplified by the use of selective small-molecule MMP inhibitors in diabetic wound healing, spinal cord injury, stroke, traumatic brain injury, cancer metastasis, and viral infection. This article is part of a Special Issue entitled: Matrix Metalloproteinases edited by Rafael Fridman.

A patterned nanocomposite membrane for high-efficiency healing of diabetic wound

A bioactive glass/patterned electrospun membrane (BG/PEM) with uniform nanostructure could stimulate angiogenesis and accelerate diabetic wound healing with high efficiency.