The Role of Matrix Metalloproteinases in Diabetic Wound Healing in relation to Photobiomodulation

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

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

Use of human bone marrow mesenchymal stem cells immortalized by the expression of telomerase in wound healing in diabetic rats

Diabetes mellitus is associated with neural and micro- and macrovascular complications. Therapeutic options for these complications are limited and the delivery of mesenchymal stem cells into lesions have been reported to improve the healing process. In this work, the effects of the administration of a lineage of human bone marrow mesenchymal stem cells immortalized by the expression of telomerase (hBMSC-TERT) as a potential therapeutic tool for wound healing in diabetic rats were investigated. This is the first description of the use of these cells in diabetic wounds. Dorsal cutaneous lesions were made in streptozotocin-induced diabetic rats and hBMSC-TERT were subcutaneously administered around the lesions. The healing process was evaluated macroscopically, histologically, and by birefringence analysis. Diabetic wounded rats infused with hBMSC-TERT (DM-TERT group) and the non-diabetic wounded rats not infused with hBMSC-TERT (CW group) had very similar patterns of fibroblastic response and collagen proliferation indicating improvement of wound healing. The result obtained by birefringence analysis was in accordance with that obtained by the histological analysis. The results indicated that local administration of hBMSC-TERT in diabetic wounds improved the wound healing process and may become a therapeutic option for wounds in individuals with diabetes.

Liquid-type nonthermal atmospheric plasma enhanced regenerative potential of silk-fibrin composite gel in radiation-induced wound failure

Delayed wound healing in heavily irradiated areas is a serious clinical complication that makes widespread therapeutic use of radiation difficult. Efficient treatment strategies are urgently required for addressing radiation-induced wound failure. Herein, we applied liquid-type nonthermal atmospheric plasma (LTP) to a silk-fibrin (SF) composite gel to investigate whether controlled release of LTP from SF hydrogel not only induced favorable cellular events in an irradiated wound bed but also modulated the SF hydrogel microstructure itself, eventually facilitating the development of a regenerative microenvironment. Scanning electron microscopy and Fourier-transform infrared spectroscopy revealed that LTP modulated the microstructures and chemical bindings of the SF gel. Improved cell viability, morphology, and extracellular matrix depositions by the LTP-treated SF hydrogel were identified with wound-healing assays and immunofluorescence staining. An irradiated random-pattern skin-flap animal model was established in six-week-old C57/BL6 mice. Full-thickness skin was flapped from the dorsum and SF hydrogel was placed underneath the raised skin flap. Postoperative histological analysis of the irradiated random-pattern skin-flap mice model suggested that LTP-treated SF hydrogel much improved wound regeneration and the inflammatory response compared to the SF hydrogel- and sham-treated groups. These results support that LTP-treated SF hydrogel significantly enhanced irradiated wound healing. Cellular and tissue reactions to released LTP from the SF hydrogel were favorable for the regenerative process of the wound; furthermore, mechanochemical properties of the SF gel were improved by LTP.

Effect of Photobiomodulation Therapy on Oxidative Stress Markers in Healing Dynamics of Diabetic Neuropathic Wounds in Wistar Rats

Background

Prolonged and overlapping phases of wound healing in diabetes are mainly due to the redox imbalance resulting in the chronicity of the wound. Photobiomodulation therapy works on the principle of absorption of photon energy and its transduction into a biological response in the living tissue. It alleviates the cellular responses, thereby improving the mechanism of wound healing in diabetes.

Objective

To find out the effect of photobiomodulation therapy of dosage 4 J/cm² in the healing dynamics of diabetic neuropathic wounds in Wistar rats and its relation with oxidative stress markers.

Methodology

Diabetes was induced using Streptozotocin of 60 mg/kg of body weight to eighteen female Wistar rats. Neuropathy was induced by the sciatic nerve crush injury followed by an excisional wound of 2 cm² on the back of the animal. Experimental group animals were treated with dosage 4 J/cm² of wavelength 655 and 808 nm, and control group animals were kept unirradiated. The biomechanical, histopathological, and biochemical changes were analysed in both groups.

Results

There was a reduction in mean wound healing time and an increased rate of wound contraction in the experimental group animals compared to its control group. The experimental group showed improved redox status, and histopathological findings revealed better proliferative cells, keratinisation, and epithelialization than un-irradiated controls.

Conclusions

Photobiomodulation therapy of dosage 4 J/cm² enhanced the overall wound healing dynamics of the diabetes-induced neuropathic wound and optimised the oxidative status of the wound, thereby facilitating a faster healing process.

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.

Non-vascular contributing factors of diabetic foot ulcer severity in national referral hospital of Indonesia

PURPOSE

Diabetic foot ulcer (DFU) is a common chronic complication of type 2 diabetes mellitus (T2DM) in Indonesia, with a prevalence of 7.3%. However, the characteristics of these patients remain unclear. We investigated the characteristics of patients with DFU without peripheral arterial disease (PAD) and analyzed non-vascular factors related to severity of DFU in a tertiary care national referral hospital in Indonesia.

METHODS

This was a cross-sectional study including 123 hemodynamically stable DFU patients without PAD recruited from Dr. Cipto Mangunkusumo National General Hospital, Jakarta, Indonesia from 2010-2015.

RESULTS

DFU patients were predominantly over 50 years old (75.6%) and diagnosed with T2DM for 5 years with poor glycemic control (82.7%) and peripheral neuropathy (91.3%). Most patients had anemia (86.7%), leukocytosis (84.6%), and were undernourished, as characterized by a low lipid profile (90.8%) and hypoalbuminemia (83.7%). Most had extensive size of ulcer at the initial visit, with a median size of 16.23 (2.92-60.16) cm2. Ulcers were mostly located of the forefoot (62.5%) and were caused by mechanical trauma (46.2%). Bivariate analysis revealed that significant factors for the development of DFU were related to DFU size, including duration of T2DM (p = 0.04), leukocyte levels (p =  < 0.01), and thrombocyte levels (p =  < 0.01). Multivariate analysis showed leucocyte (p = 0.03) and thrombocyte (p = 0.023) had significantly correlated with DFU severity.

CONCLUSION

Leucocyte and thrombocyte may be the greatest contributing non-vascular factors for severity of DFU in Indonesia.

Self-assembled elastin-like polypeptide fusion protein coacervates as competitive inhibitors of advanced glycation end-products enhance diabetic wound healing

Chronic and non-healing skin wounds are some of the most significant complications in patients with advanced diabetes. A contributing mechanism to this pathology is the non-enzymatic glycation of proteins due to hyperglycemia, leading to the formation of advanced glycation end products (AGEs). AGEs bind to the receptor for AGEs (RAGE), which triggers pro-inflammatory signals that may inhibit the proliferative phase of wound healing. Soluble forms of RAGE (sRAGE) may be used as a competitive inhibitor of AGE-mediated signaling; however, sRAGE is short-lived in the highly proteolytic wound environment. We developed a recombinant fusion protein containing the binding domain of RAGE (vRAGE) linked to elastin-like polypeptides (ELPs) that self-assembles into coacervates at around 30-31 °C. The coacervate size was concentration and temperature-dependent, ranging between 500 and 1600 nm. vRAGE-ELP reversed several AGE-mediated changes in cultured human umbilical vein endothelial cells, including a decrease in viable cell number, an increase in levels of reactive oxygen species (ROS), and an increased expression of the pro-inflammatory marker, intercellular adhesion molecule-1 (ICAM-1). vRAGE-ELP was stable in elastase in vitro for 7 days. When used in a single topical application on full-thickness excisional skin wounds in diabetic mice, wound closure was accelerated, with 90% and 100% wound closure on post-wounding days 28 and 35, respectively, compared to 62% and 85% on the same days in animals treated with vehicle control, consisting of ELP alone. This coacervate system topically delivering a competitive inhibitor of AGEs has potential for the treatment of diabetic wounds.

Monocyte phenotype as a predictive marker for wound healing in diabetes-related foot ulcers

AIMS

Delayed healing of diabetes-related foot ulcers (DRFUs) is associated with increased macrophage and matrix metalloproteinases (MMPs) at the wound site. Whether circulating monocyte phenotype and/or MMPs are altered in association with wound healing outcome is unknown, and was investigated in this study.

METHODS

Blood was obtained from 21 participants with DRFU, at initial visit (V1), week-4 (V2), and week-8 (V3) for measurement of monocyte number (CD14⁺), phenotype (CD16, CD163) and chemokine receptors (CCRs) by flow cytometry, and circulating MMPs and TIMP-1 by ELISA.

RESULTS

Six wounds healed during the study. At V1, non-classical CD16⁺⁺ monocytes and MMP-3 were higher in healed vs unhealed (both p < 0.05). At V3, the increased %CD16⁺⁺ persisted and %CCR2⁺ was decreased in healed, but no other monocyte markers nor MMP/TIMP differed between groups. Increased wound closure rate (WCR) at V3 correlated with increased %CD16⁺⁺ monocytes and decreased MMP-2 at V1 or V1 + V2. Receiver operating characteristic (ROC) curves yielded an area-under-the-curve of %CD16⁺⁺ at V1 of 0.78 to predict ulcer healing at V3.

CONCLUSIONS

These results indicate that circulating monocyte phenotype and MMPs alter as DRFUs heal. The relationship of %CD16⁺⁺ monocytes with WCR and ROC curve suggest a predictive role of %CD16⁺⁺ monocytes for ulcer healing.

Regulatory Role of Nrf2 Signaling Pathway in Wound Healing Process

Wound healing involves a series of cellular events in damaged cells and tissues initiated with hemostasis and finally culminating with the formation of a fibrin clot. However, delay in the normal wound healing process during pathological conditions due to reactive oxygen species, inflammation and immune suppression at the wound site represents a medical challenge. So far, many therapeutic strategies have been developed to improve cellular homeostasis and chronic wounds in order to accelerate wound repair. In this context, the role of Nuclear factor erythroid 2-related factor 2 (Nrf2) during the wound healing process has been a stimulating research topic for therapeutic perspectives. Nrf2 is the main regulator of intracellular redox homeostasis. It increases cytoprotective gene expression and the antioxidant capacity of mammalian cells. It has been reported that some bioactive compounds attenuate cellular stress and thus accelerate cell proliferation, neovascularization and repair of damaged tissues by promoting Nrf2 activation. This review highlights the importance of the Nrf2 signaling pathway in wound healing strategies and the role of bioactive compounds that support wound repair through the modulation of this crucial transcription factor.

Photobiomodulation induces microvesicle release in human keratinocytes: PI3 kinase-dependent pathway role

Microvesicles (MVs, 100-1000 nm diameter) are released into the extracellular environment by mammalian cells. MVs interact with near or remote cells through different mechanisms; in particular, MVs from human keratinocytes accelerate wound healing. Photobiomodulation by laser improves wound healing, but no information is available about its effects on MV release from human keratinocyte. Human-immortalized keratinocytes (human adult low-calcium high-temperature, HaCaT) were starved for 24 h and then irradiated using a 980-nm energy density of 0, 16.2, 32.5, and 48.7 J/cm². After 24 h, MVs released in the conditioned medium were isolated, stained, and quantified using flow cytometry. MVs were distinguished from exosomes on the basis of their volume (forward scatter signals). In some experiments, phosphatidylinositol 3-kinase (PI-3K) activity, involved in MV release and stimulated by laser light, was inhibited by pre-treating cells with Wortmannin (WRT, 10 μg/mL). MVs were observed in HaCaT-conditioned medium both in basal- and laser-stimulated conditions. Photobiomodulation therapy, also known as PBMT, was able to increase MV release from human keratinocytes reaching a maximum effect at 32.5 J/cm² with a stimulation of (148.6 ±15.1)% of basal (p<0.001). PI-3K activity inhibition strongly reduced both basal- and laser-induced MV release; but PBMT by laser still increased MV release, compared to basal values in the presence of WRT. In vitro near infrared photobiomodulation increased the releasing of MVs from human keratinocytes, while Wortmannin, a PI-3K inhibitor, negatively affects both basal- and laser-induced releasing. Laser-induced MV release could be a new effect of biostimulation on the wound healing process.

Immunomodulatory biomaterials and their application in therapies for chronic inflammation-related diseases

The degree of tissue injuries such as the level of scarring or organ dysfunction, and the immune response against them primarily determine the outcome and speed of healing process. The successful regeneration of functional tissues requires proper modulation of inflammation-producing immune cells and bioactive factors existing in the damaged microenvironment. In the tissue repair and regeneration processes, different types of biomaterials are implanted either alone or by combined with other bioactive factors, which will interact with the immune systems including immune cells, cytokines and chemokines etc. to achieve different results highly depending on this interplay. In this review article, the influences of different types of biomaterials such as nanoparticles, hydrogels and scaffolds on the immune cells and the modification of immune-responsive factors such as reactive oxygen species (ROS), cytokines, chemokines, enzymes, and metalloproteinases in tissue microenvironment are summarized. In addition, the recent advances of immune-responsive biomaterials in therapy of inflammation-associated diseases such as myocardial infarction, spinal cord injury, osteoarthritis, inflammatory bowel disease and diabetic ulcer are discussed.

Highly Porous and Superabsorbent Biomaterial Made of Marine-Derived Polysaccharides and Ascorbic Acid as an Optimal Dressing for Exuding Wound Management

There are many modern wound dressings that have promising properties for repairing skin damage. However, due to various types of wounds and the problems they cause, there is still a great demand for new, effective healing strategies. The aim of this study was to create superabsorbent wound dressing made of marine-derived polysaccharides (agarose and chitosan) using the freeze-drying method. The secondary goal was its comprehensive evaluation for potential use as an external superabsorbent bandage for wounds with high exudation. Due to the well-known positive effect of ascorbic acid (vitamin C) on the healing process, biomaterial enriched with vitamin C was prepared and compared to the variant without the addition of ascorbic acid. It was shown that the produced foam-like wound dressing had a very porous structure, which was characterized by hydrophilicity, allowing a large amount of human fluids to be absorbed. According to in vitro tests on human fibroblasts, biomaterial was nontoxic and supportive to cell proliferation. Vitamin C-enriched dressing also had the ability to significantly reduce matrix metalloproteinase-2 production and to promote platelet-derived growth factor-BB synthesis by fibroblasts, which is desired during chronic wound treatment. The material has features of the eco-friendly wound care product since it was made of naturally-derived polysaccharides and was proved to be biodegradable. Importantly, despite degradable character, it was stable in the chronic and infected wound microenvironment, maintaining high integrity after 8-week incubation in the enzymatic solutions containing lysozyme and collagenases. The obtained results clearly showed that developed biomaterial possesses all necessary features of the external dressing for the management of exudate from both acute and chronic non-healing wounds.

Magnetic fields as a potential therapy for diabetic wounds based on animal experiments and clinical trials

Diabetes mellitus (DM) is a chronic metabolic disorder with various complications that poses a huge worldwide healthcare burden. Wounds in diabetes, especially diabetic foot ulcers (DFUs), are difficult to manage, often leading to prolonged wound repair and even amputation. Wound management in people with diabetes is an extremely clinical and social concern. Nowadays, physical interventions gain much attention and have been widely developed in the fields of tissue regeneration and wound healing. Magnetic fields (MFs)-based devices are translated into clinical practice for the treatment of bone diseases and neurodegenerative disorder. This review attempts to give insight into the mechanisms and applications of MFs in wound care, especially in improving the healing outcomes of diabetic wounds. First, we discuss the pathological conditions associated with chronic diabetic wounds. Next, the mechanisms involved in MFs' effects on wounds are explored. At last, studies and reports regarding the effects of MFs on diabetic wounds from both animal experiments and clinical trials are reviewed. MFs exhibit great potential in promoting wound healing and have been practised in the management of diabetic wounds. Further studies on the exact mechanism of MFs on diabetic wounds and the development of suitable MF-based devices could lead to their increased applications into clinical practice.

Berberine accelerated wound healing by restoring TrxR1/JNK in diabetes

The high disability, mortality and morbidity of diabetic ulcers make it urgent to explore effective strategies for diabetic wound repair. TrxR1 plays a vital role in regulating redox homeostasis in various pathologies. In the present study, the effect of berberine (BBR) on diabetic wounds was investigated in streptozotocin (STZ)-induced diabetic rats and a high glucose (HG)-induced cell model, and the mechanism of BBR on TrxR1 was elucidated. BBR treatment remarkably accelerated wound healing and enhanced extracellular matrix (ECM) synthesis and significantly inhibited HG-induced HaCaT cell damage. Further analysis indicated that BBR activated TrxR1, suppressed its downstream JNK signaling, thereby inhibiting oxidative stress and apoptosis, promoted cell proliferation, down-regulated matrix metalloproteinase (MMP) 9 (MMP9) and up-regulated transforming growth factor-β1 (TGF-β1) and tissue inhibitors of MMP 1 (TIMP1), resulting in accelerated wound healing. Importantly, the enhancement of BBR on wound repair was further abolished by TrxR1 inhibitor. Moreover, in diabetic wounds induced by a combination of STZ injection and high-fat diet, BBR significantly increased wound closure rate and TrxR1 expression, and this was reversed by TrxR1 inhibitor. These data indicated that topical BBR treatment accelerated diabetic wound healing by activating TrxR1. Targeting TrxR1 may be a novel, effective strategy for restoring redox homeostasis and promoting diabetic wound healing.

Lightwave-reinforced stem cells with enhanced wound healing efficacy

Comprehensive research has led to significant preclinical outcomes in modified human adipose-derived mesenchymal stem cells (hADSCs). Photobiomodulation (PBM), a technique to enhance the cellular capacity of stem cells, has attracted considerable attention owing to its effectiveness and safety. Here, we suggest a red organic light-emitting diode (OLED)-based PBM strategy to augment the therapeutic efficacy of hADSCs. In vitro assessments revealed that hADSCs basked in red OLED light exhibited enhanced angiogenesis, cell adhesion, and migration compared to naïve hADSCs. We demonstrated that the enhancement of cellular capacity was due to an increased level of intracellular reactive oxygen species. Furthermore, accelerated healing and regulated inflammatory response was observed in mice transplanted with red light-basked hADSCs. Overall, our findings suggest that OLED-based PBM may be an easily accessible and attractive approach for tissue regeneration that can be applied to various clinical stem cell therapies.

Effect of photobiomodulation therapy on inflammatory cytokines in healing dynamics of diabetic wounds: a systematic review of preclinical studies

CONTEXT

Delayed wound healing in diabetes mellitus (DM) is due to the overlapping phases of the healing process. The prolonged inflammation and altered levels of inflammatory cytokines lead to deformed cell proliferation. Photobiomodulation alleviates the expression of inflammatory cytokines and promotes tissue repair, thereby restoring the wound healing process.

OBJECTIVE

To find out the effect of photobiomodulation therapy (PBMT) in the healing dynamics of diabetic wounds with particular emphasis on interleukin-6, interleukin-1β, and tumour necrosis factor-α.

METHODS

Scientific databases searched using keywords of the population: DM, intervention: PBMT, and outcomes: inflammatory cytokines.

RESULTS

We have included five preclinical studies in the present systematic review for qualitative analysis. These studies evaluated the effect of PBMT at different wavelengths, dosage, and time on wound healing in DM.

CONCLUSIONS

The systematic review concludes that PBMT regulates inflammatory cytokines levels, enhances cell proliferation, and migration, thereby improving the wound healing properties.

Improving Chronic Diabetic Wound Healing through an Injectable and Self-Healing Hydrogel with Platelet-Rich Plasma Release

Diabetic skin ulcer is one of the severe complications of diabetes mellitus, which has a high incidence and may cause death or disability. Platelet-rich plasma (PRP) is widely used in the treatment of diabetic wounds due to the effect of growth factors (GFs) derived from it. However, the relatively short half-life of GFs limits their applications in clinics. In addition, the presence of a large amount of proteases in the diabetic wound microenvironment results in the degradation of GFs, which further impedes angiogenesis and diabetic wound healing. In our study, we fabricated a self-healing and injectable hydrogel with a composite of chitosan, silk fibroin, and PRP (CBPGCTS-SF@PRP) for promoting diabetic wound healing. CBPGCTS-SF@PRP could protect PRP from enzymatic hydrolysis, release PRP sustainably, and enhance the chemotaxis of mesenchymal stem cells. The results showed that it could promote the proliferation of repair cells in vitro. Moreover, it could enhance wound healing by expediting collagen deposition, angiogenesis, and nerve repair in a type 2 diabetic rat model and a rat skin defect model. We hope that this study will offer a new treatment for diabetic nonhealing wounds in clinics.

Cryptotanshinone enhances wound healing in type 2 diabetes with modulatory effects on inflammation, angiogenesis and extracellular matrix remodelling

CONTEXT

Cryptotanshinone (CT) is a diterpene quinone compound from Salvia miltiorrhiza Bge. Labiatae has been widely used in cardio-cerebral vascular diseases, which could be potentially effective in treating diabetic wounds.

OBJECTIVE

This study evaluates the wound healing activity of CT by employing an excisional wound splinting model in db/db mice.

MATERIALS AND METHODS

Wounds were induced at the dorsum of non-diabetic (db/+) and diabetic (db/db) mice and treated with sodium carboxymethyl cellulose (CMC-Na) or 300 mg/kg/d CT for 16 days. Wound closure was measured every two days. Body weight, fasting blood glucose, re-epithelialization, granulation, leukocyte infiltration, capillary density, collagen deposition and expressions of CXCL1, CXCL2, VEGF, Ang-1, p-eNOS, eNOS, α-SMA, MMP2 and MMP9 were analysed. Expression of VEGF and tube formation was measured in vitro with human umbilical vein endothelial cells (HUVECs).

RESULTS

CT significantly accelerated rate of wound closure, as the contraction ratio increased from 68% (non-treated group) to 83% (CT-treated group) at days 16 post-injury. A significant increase was observed in re-epithelialization and granulation tissue formation. Mechanistically, CT suppressed leukocyte infiltration and CXCL1 and CXCL2 expression. CT treatment also increased blood vessel density and expression level of VEGF, Ang-1 and p-eNOS. In vitro, CT boosted expression of VEGF and tube formation of endothelial cells. Moreover, extracellular matrix (ECM) remodelling was enhanced by CT via promoting fibroblast transformation and inhibiting MMP2 and MMP9.

CONCLUSIONS

Our study provides evidence that CT could be developed as a potential therapeutic agent for the treatment of chronic diabetic wound healing.

Designing Enzyme-responsive Biomaterials

Enzymes are a class of protein that catalyze a wide range of chemical reactions, including the cleavage of specific peptide bonds. They are expressed in all cell types, play vital roles in tissue development and homeostasis, and in many diseases, such as cancer. Enzymatic activity is tightly controlled through the use of inactive pro-enzymes, endogenous inhibitors and spatial localization. Since the presence of specific enzymes is often correlated with biological processes, and these proteins can directly modify biomolecules, they are an ideal biological input for cell-responsive biomaterials. These materials include both natural and synthetic polymers, cross-linked hydrogels and self-assembled peptide nanostructures. Within these systems enzymatic activity has been used to induce biodegradation, release therapeutic agents and for disease diagnosis. As technological advancements increase our ability to quantify the expression and nanoscale organization of proteins in cells and tissues, as well as the synthesis of increasingly complex and well-defined biomaterials, enzyme-responsive biomaterials are poised to play vital roles in the future of biomedicine.

Agar-Iodine Transdermal Patches for Infected Diabetic Wounds

In the present work, we have tested the potency of iodine-loaded agar transdermal patches (5 mg/cm²) for the treatment of infected diabetic wounds in the Wistar rat model. The rats were treated with the newly developed agar-iodine-potassium iodide (KI)-glycerol (AKIG) patch along with two other commercial dressings Iodoflex and Tegaderm as controls. Animals that received treatment with AKIG patches and Iodoflex showed better infection containment as compared to that with Tegaderm-covered control and exhibited complete healing. The antimicrobial property of all the patches was tested on three bacterial species-Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa-found in infected wounds. P. aeruginosa exhibited the highest minimum inhibitory concentration and minimum bactericidal concentration values among the three bacterial species for all the patches. The patch showed values of tensile strength, elongation, water vapor transmission rate, and swelling in the range of 34 ± 5 MPa, 51% ± 5, 2700 ± 110 g/m²/day, and 250% ± 25, respectively, for the agar-KI-iodine patch. The release kinetics of iodine through the agar matrix was found to follow the first-order drug release kinetics.

Effect of photobiomodulation therapy on the proliferation phase and wound healing in rats fed with an experimental hypoproteic diet

Photobiomodulation therapy (PBMT) has been indicated for enforcement on healing skin wounds. This study evaluated the effects of PBMT on the healing of skin wounds during the proliferation phase in rats with a hypoproteic diet. Rats were randomized to one of the following groups (n = 10 per group): (i) injured normoproteic (25% protein) not subjected to PBMT; (ii) injured normoproteic who received PBMT; (iii) injured hypoproteic (8% protein) not subjected to PBMT; and (iv) injured hypoproteic who received PBMT. Rats were submitted to skin wounds and then treated with PBMT (low-level laser therapy: 660 nm, 50 mW, 1.07 W/cm², 0.028 cm², 72 J/cm², 2 J). Analyses were performed at 7 and 14 days of follow-up: semi-quantitative histopathologic analysis, collagen type I and III expressions, immunohistochemical marking for matrix metalloproteinases-3 (MMP-3) and (matrix metalloproteinases-9) MMP-9, and mechanical resistance test. There were significant differences between the normoproteic groups and their respective treated groups (p < 0.05), as well as to treated and untreated hypoproteic groups in histopathologic analysis semi-quantitatively and immunohistochemistry for MMP-3 and 9, in which PBMT was able to decrease immunostaining. Moreover, there was a decrease in collagen deposition with the statistical difference (p < 0.05) for both collagen types III and I. In conclusion, PBMT application was proved effective in the treatment of cutaneous wounds in rats submitted to a hypoproteic diet. These alterations were more salient in the proliferation stage with the reduction of metalloproteinases providing better mechanical resistance of the injured area in the remodeling phase with an intensification of type I collagen.

Transcriptomic analysis of adhesive capsulitis of the shoulder

Adhesive capsulitis (AC) is a disabling condition of the shoulder joint affecting 2 to 5% of the general population. Our understanding of the molecular mechanisms is limited. The present study aimed to determine potential biomarkers of AC through transcriptomic analysis. This multi-centre study investigated patients undergoing arthroscopic capsulotomy surgery for resistant AC compared to those undergoing arthroscopic stabilization surgery for glenohumeral instability (control). Tissue samples were harvested from the anterior capsule during surgery. Total RNA was extracted and RNA-sequencing-based transcriptomics were performed. A number of genes deemed differentially expressed in RNA-sequencing analysis were validated using real-time reverse transcription polymerase chain reaction (RT-PCR). Baseline characteristics of the AC group (n = 22) were; mean age 52.7 years (SD: 10.2), 73% female, and Oxford Shoulder Score 19.6 (SD: 8.0), compared with the control group (n = 26), average age 23.9 years (SD: 5.2), 15% female, and Oxford Shoulder Score 39.0 (SD: 7.4). Transcriptomic analysis with false discovery rate correction and log₂ fold change cut-off of ±1.5 revealed 545 differentially expressed genes in AC relative to control. Bioinformatic analyses were carried out to identify biological processes and pathways enriched in this dataset. Real-time RT-PCR using two different normalization processes confirmed increased expression of matrix metallopeptidase 13 (MMP13) and platelet-derived growth factor subunit B (PDGFB), in patients with AC, while tumor necrosis factor α (TNFA) expression was reduced. These findings provide a comprehensive assessment of transcriptional changes associated with AC that give insights into the aetiology of the disease and provides a resource for molecular targets to better diagnose and treat this condition.

Antibacterial-Integrated Collagen Wound Dressing for Diabetes-Related Foot Ulcers: An Evidence-Based Review of Clinical Studies

Diabetic foot ulcer (DFU) is a chronic wound frequently delayed from severe infection. Wound dressing provides an essential barrier between the ulcer and the external environment. This review aimed to analyse the effectiveness of antibacterial collagen-based dressing for DFU treatment in a clinical setting. An electronic search in four databases, namely, Scopus, PubMed, Ovid MEDLINE(R), and ISI Web of Science, was performed to obtain relevant articles published within the last ten years. The published studies were included if they reported evidence of (1) collagen-based antibacterial dressing or (2) wound healing for diabetic ulcers, and (3) were written in English. Both randomised and non-randomised clinical trials were included. The search for relevant clinical studies (n) identified eight related references discussing the effectiveness of collagen-based antibacterial wound dressings for DFU comprising collagen impregnated with polyhexamethylene biguanide (n = 2), gentamicin (n = 3), combined-cellulose and silver (n = 1), gentian violet/methylene blue mixed (n = 1), and silver (n = 1). The clinical data were limited by small sample sizes and multiple aetiologies of chronic wounds. The evidence was not robust enough for a conclusive statement, although most of the studies reported positive outcomes for the use of collagen dressings loaded with antibacterial properties for DFU wound healing. This study emphasises the importance of having standardised clinical trials, larger sample sizes, and accurate reporting for reliable statistical evidence confirming DFU treatment efficiency.

Skin well-being in diabetes: Role of macrophages

Macrophages are key players in wound healing- along with mediating the acute inflammatory response, macrophages activate cutaneous epithelial cells and promote tissue repair. Diabetes complications, including diabetic chronic wounds, are accompanied by persistent inflammation and macrophage malfunction. Several studies indicate that hyperglycemia induces various alterations that affect macrophage function in wound healing including epigenetic changes, imbalance between pro- and anti-inflammatory modulators, and insensitivity to proliferative stimuli. In this review, we briefly summarize recent studies regarding those alterations and their implications on skin well-being in diabetes.

Immunochemical analysis on polypropylene mesh: does mesh size make a difference?

INTRODUCTION AND HYPOTHESIS

The aim of the study is to demonstrate the impact of the size of implanted mesh in relation to its immunohistochemical reaction implanted into animal models.

METHODS

An experimental study utilizing 54 female Sprague Dawley (SD) rats was divided into five groups: control, sham, and study groups (mesh-small [M-S], mesh-medium [M-M], mesh-large [M-L]). The M-S group used a mesh size of 0.2 × 0.2 cm, the M-M group a mesh size of 0.5 × 0.5 cm, and the M-L a mesh size of 0.7 × 1.0 cm. The sham group underwent vaginal dissection with no mesh implantation. The rats were sacrificed using isoflurane overdose on days 7 and 30. The mesh with the surrounding vaginal and bladder wall tissues were removed and processed for histochemical and western blot analysis.

RESULTS

There is a significant increase in IL-1 and TNF-α immunoreactivity in the M-M and M-L groups on day 7 when compared with the sham group with p values of 0.001 and < 0.001 respectively. M-L showed significantly higher immunoreactivity to TNF-α persisting until day 30. All study groups presented a significantly higher immunoreactivity to MMP-2 and NGF on day 7. However, reactivity to NGF does not persist to day 30 in all groups. Immunoreactivity to CD 31 on days 7 and 30 appears significantly greater in the M-M and M-L groups, with the reaction in the M-L group continuing until day 30.

CONCLUSION

Mesh size is directly proportional to the inflammatory reaction in the host tissue. The prolonged inflammatory process leads to delayed tissue remodeling and angiogenesis, which could delay mesh-tissue integration.

Practical context of enzymatic treatment for wound healing: A secreted protease approach (Review)

Skin wounds have been extensively studied as their healing represents a critical step towards achieving homeostasis following a traumatic event. Dependent on the severity of the damage, wounds are categorized as either acute or chronic. To date, chronic wounds have the highest economic impact as long term increases wound care costs. Chronic wounds affect 6.5 million patients in the United States with an annual estimated expense of $25 billion for the health care system. Among wound treatment categories, active wound care represents the fastest-growing category due to its specific actions and lower costs. Within this category, proteases from various sources have been used as successful agents in debridement wound care. The wound healing process is predominantly mediated by matrix metalloproteinases (MMPs) that, when dysregulated, result in defective wound healing. Therapeutic activity has been described for animal secretions including fish epithelial mucus, maggot secretory products and snake venom, which contain secreted proteases (SPs). No further alternatives for use, sources or types of proteases used for wound healing have been found in the literature to date. Through the present review, the context of enzymatic wound care alternatives will be discussed. In addition, substrate homology of SPs and human MMPs will be compared and contrasted. The purpose of these discussions is to identify and propose the stages of wound healing in which SPs may be used as therapeutic agents to improve the wound healing process.

Nanoparticle-Based Therapeutic Approach for Diabetic Wound Healing

Diabetes mellitus (DM) is a common endocrine disease characterized by a state of hyperglycemia (higher level of glucose in the blood than usual). DM and its complications can lead to diabetic foot ulcer (DFU). DFU is associated with impaired wound healing, due to inappropriate cellular and cytokines response, infection, poor vascularization, and neuropathy. Effective therapeutic strategies for the management of impaired wound could be attained through a better insight of molecular mechanism and pathophysiology of diabetic wound healing. Nanotherapeutics-based agents engineered within 1-100 nm levels, which include nanoparticles and nanoscaffolds, are recent promising treatment strategies for accelerating diabetic wound healing. Nanoparticles are smaller in size and have high surface area to volume ratio that increases the likelihood of biological interaction and penetration at wound site. They are ideal for topical delivery of drugs in a sustained manner, eliciting cell-to-cell interactions, cell proliferation, vascularization, cell signaling, and elaboration of biomolecules necessary for effective wound healing. Furthermore, nanoparticles have the ability to deliver one or more therapeutic drug molecules, such as growth factors, nucleic acids, antibiotics, and antioxidants, which can be released in a sustained manner within the target tissue. This review focuses on recent approaches in the development of nanoparticle-based therapeutics for enhancing diabetic wound healing.

Application of Easy Wet Healing Therapy for Chronic Noninfectious Wounds in Limbs

Chronic wounds in limbs without infection are common. This study was to identify an economical, simple, and useful wet healing therapy for patients with chronic noninfectious wounds in the limbs, especially for low-income patients. In total, 56 patients with chronic limb wounds without infection from April 2018 to March 2019 were included. They underwent wound cleaning by iodine and wound covering by recombinant human epidermal growth factor gel, zinc oxide ointment, and erythromycin eye ointment at a 1:1:1 ratio and thickness of 0.8 cm. After applying the drug, a slight-pressure dressing was applied to the wound with a cotton pad and bandage, and the dressing was changed every 3 days. All the wounds completely healed within 12 to 45 days (26.2 ± 11.9 days). The healing time showed a positive correlation with the area of the wound (r = 0.328, P < .05) and the course of disease (r = 0.485, P < .01). The healing time of deep second-degree wounds was 17.2 ± 3.3 days, which was shorter than that of deep third-degree wounds (34.8 ± 8.4 days; P < .05). There was no significant difference in the healing time according to sex. Upper limb wounds healed faster than lower limb wounds (16 ± 2.7 days versus 31.7 ± 9.7 days, P < .05). The simple therapy required a low cost of 0.07 dollars per square centimeter for each dressing change. This wet healing therapy is easy, effective, relatively safe, and affordable, with no obvious side effects.

Nanomedicine in Healing Chronic Wounds: Opportunities and Challenges

The poor healing associated with chronic wounds affects millions of people worldwide through high mortality rates and associated costs. Chronic wounds present three main problems: First, the absence of a suitable environment to facilitate cell migration, proliferation, and angiogenesis; second, bacterial infection; and third, unbalanced and prolonged inflammation. Unfortunately, current therapeutic approaches have not been able to overcome these main issues and, therefore, have limited clinical success. Over the past decade, incorporating the unique advantages of nanomedicine into wound healing approaches has yielded promising outcomes. Nanomedicine is capable of stimulating various cellular and molecular mechanisms involved in the wound microenvironment via antibacterial, anti-inflammatory, and angiogenetic effects, potentially reversing the wound microenvironment from nonhealing to healing. This review briefly discusses wound healing mechanisms and pathophysiology and then highlights recent findings regarding the opportunities and challenges of using nanomedicine in chronic wound management.

Manipulation of living cells with 450 nm laser photobiomodulation

Increasing studies demonstrated that photobiomodulation (PBM) influenced specific biological effects in cells, tissues and organs, and these effects rely on the production of light irradiation. In this study, we aimed to precisely manipulate the spatial arrangement of adhesion cells in a traditional culture condition with 450 nm low intensity laser. Through 450 nm laser PBM, the adhesion of the cultured cells was significantly improved and resisted the digestion of 0.1% trypsin. Combined with a computer aided design system (CAD) and computer numerical control (CNC) system, the designed laser irradiation pattern induced the specific cell micropattern in the culture dish. RNA sequencing and biochemical experiments confirmed that the 450 nm laser prompted low-density lipoprotein (LDL) bonding to the cell surface and induced lipid peroxidation, which crosslinked and modified the protein molecules on the irradiated cell surface. In this way, the peroxidation product-modified proteins resisted trypsin proteolysis, ultimately leading to a differential detachment between the irradiated and non-irradiated cells under trypsin treatment. This convenient method did not require special biomaterial processing, has no impact on cell viability and functions, and required no changes to the conventional cell culture conditions. The photo-induced cell capturing is a great complement to existing tools by providing spatial resolution.

Alterted Adipogenesis of Human Mesenchymal Stem Cells by Photobiomodulation Using 1064 nm Laser Light

BACKGROUND AND OBJECTIVES

Photobiomodulation (PBM) describes the influence of light irradiation on biological tissues. Laser light in the near-infrared (NIR) spectrum has been shown to mitigate pain, reduce inflammation, and promote wound healing. The cellular mechanism that mediates PBM's effects is generally accepted to be at the site of the mitochondria, leading to an increased flux through the electron transport chain and adenosine triphosphate (ATP) production. Moreover, PBM has been demonstrated to reduce oxidative stress through an increased production of reactive oxygen species (ROS)-sequestering enzymes. The aim of the study is to determine whether these PBM-induced effects expedite or interfere with the intended stem cell differentiation to the adipogenic lineage.

STUDY DESIGN/MATERIALS AND METHODS

To determine the effects of 1064 nm laser irradiation (fluence of 8.8-26.4 J/cm² ) on human mesenchymal stem cells (hMSCs) undergoing adipogenic differentiation, the ATP and ROS levels, and adipogenic markers were quantitatively measured.

RESULTS

At a low fluence (8.8 J/cm² ) the ATP increase was essentially negligible, whereas a higher fluence induced a significant increase. In the laser-stimulated cells, PBM over time decreased the ROS level compared with the non-treated control group and significantly reduced the extent of adipogenesis. A reduction in the ROS level was correlated with a diminished lipid accumulation, reduced production of adipose-specific genetic markers, and delayed the chemically intended adipogenesis.

CONCLUSION

We characterized the use of NIR light exposure to modulate adipogenesis. Both the ATP and ROS levels in hMSCs responded to different energy densities. The current study is expected to contribute significantly to the growing field of PBM as well as stem cell tissue engineering by demonstrating the wavelength-dependent responses of hMSC differentiation. Lasers Surg. Med. © 2020 Wiley Periodicals LLC.

Matrix Metalloproteinases as Biomarkers of Atherosclerotic Plaque Instability

Matrix metalloproteinases (MMPs) are a family of zinc-dependent endopeptidases responsible for tissue remodeling and degradation of extracellular matrix (ECM) proteins. MMPs may modulate various cellular and signaling pathways in atherosclerosis responsible for progression and rupture of atherosclerotic plaques. The effect of MMPs polymorphisms and the expression of MMPs in both the atherosclerotic plaque and plasma was shown. They are independent predictors of atherosclerotic plaque instability in stable coronary heart disease (CHD) patients. Increased levels of MMPs in patients with advanced cardiovascular disease (CAD) and acute coronary syndrome (ACS) was associated with future risk of cardiovascular events. These data confirm that MMPs may be biomarkers in plaque instability as they target in potential drug therapies for atherosclerosis. They provide important prognostic information, independent of traditional risk factors, and may turn out to be useful in improving risk stratification.

Huangbai Liniment Accelerated Wound Healing by Activating Nrf2 Signaling in Diabetes

As a serious complication of diabetes, nonhealing skin ulcer leads to high mortality and disability in diabetic patients. However, limited therapy is available in managing diabetic wounds. In this study, RNA-seq technology was used to systematically investigate the effect of Huangbai (HB) liniment, a traditional Chinese medicine, on the streptozotocin- (STZ-) induced diabetic wound. HB liniment significantly accelerated the wound closure and enhanced the generation of extracellular matrix in diabetic rats, and oxidative stress was identified to play a vital role in HB-mediated wound healing. Importantly, HB liniment activated nuclear factor erythroid-derived 2-like 2 (Nrf2) and its downstream antioxidant genes (e.g., genes involved in glutathione system, thioredoxin system, and GAPDH generation as well as other antioxidant genes), which inhibited oxidative damage and apoptosis. By associating drug targets of HB liniment with Nrf2 and its downstream genes, 54 components in HB liniment were screened out, and the majority was from Cortex Phellodendri and Forsythia suspensa. Additionally, HB liniment enhanced TGF-β1 and reduced MMP9 level, accelerating wound healing in diabetes. The in vitro experiment showed HB facilitated cell proliferation and inhibited oxidative damage in high glucose-induced HaCaT cells. Our findings provided the experimental evidence for the treatment of diabetic wound with HB, clarified the potential mechanism of HB, and improved our understanding of diabetic wound healing.

Cellular Response to Vitamin C-Enriched Chitosan/Agarose Film with Potential Application as Artificial Skin Substitute for Chronic Wound Treatment

The treatment of chronic wounds is still a meaningful challenge to physicians. The aim of this work was to produce vitamin C-enriched chitosan/agarose (CHN/A) film that could serve as potential artificial skin substitute for chronic wound treatment. The biomaterial was fabricated by a newly developed and simplified method via mixing acidic chitosan solution with alkaline agarose solution that allowed to obtain slightly acidic pH (5.97) of the resultant material, which is known to support skin regeneration. Vitamin C was immobilized within the matrix of the film by entrapment method during production process. Produced films (CHN/A and CHN/A + vit C) were subjected to comprehensive evaluation of cellular response with the use of human skin fibroblasts, epidermal keratinocytes, and macrophages. It was demonstrated that novel biomaterials support adhesion and growth of human skin fibroblasts and keratinocytes, have ability to slightly reduce transforming growth factor-beta 1 (TGF-β1) (known to be present at augmented levels in the epidermis of chronic wounds), and increase platelet-derived growth factor-BB (PDGF-BB) secretion by the cells. Nevertheless, addition of vitamin C to the biomaterial formulation does not significantly improve its biological properties due to burst vitamin release profile. Obtained results clearly demonstrated that produced CHN/A film has great potential to be used as cellular dermal, epidermal, or dermo-epidermal graft pre-seeded with human skin cells for chronic wound treatment.

Matrix metalloproteinase 9 induces keratinocyte apoptosis through FasL/Fas pathway in diabetic wound

Apoptosis is a mechanism to remove unwanted cells in the tissue. In diabetic wound, which is characterized by delayed healing process, excessive apoptosis is documented and plays a crucial role. Matrix metalloproteinase 9 (MMP9), which is elevated in non-healed diabetic wound, is necessary for healing process but its abnormality resulted in a delayed healing. The classical function of MMP9 is the degradation of extracellular matrix (ECM). However, there is some literature evidence that MMP9 triggers cell apoptosis. Whether the excessive MMP9 contributes to epidermis cell apoptosis in delayed healing diabetic wound and the underlying mechanisms is not clear. In this study, we aimed to explore whether MMP9 induced keratinocyte apoptosis and investigate the plausible mechanisms. Our in vitro study showed that advanced glycation end products (AGEs) induced keratinocyte apoptosis and enhanced MMP9 level. Besides, MMP9, both intra-cellular expressions and extra-cellular supplement, promoted cell apoptosis. Further, MMP9 resulted in an increased expression of FasL, other than Fas and p53. These findings identified a novel effect that MMP9 exerted in delayed diabetic wound healing, owing to a pro-apoptotic effect on keratinocyte, which was mediated by an increase of FasL expression. This study increases understanding of elevated MMP9 which is involved in diabetic wound repair and offers some insights into novel future therapies.

Treatment of Full-Thickness Skin Wounds with Blood-Derived CD34+ Precursor Cells Enhances Healing with Hair Follicle Regeneration

Objective: Epidermal CD34⁺ stem cells located in the hair follicle (HF) bulge area are capable of inducing HF neogenesis and enhancing wound healing after transplantation. In this study, we observed CD34⁺ cells derived from blood directly participate in dermal regeneration during full-thickness excisional wound healing. Approach: We isolated and in vitro expanded a subset of hematopoietic stem cell (HSC)-like precursor cells from the peripheral blood of adult mice with the surface markers: CD34⁺, leucine rich repeat containing G protein-coupled receptor 5 (LGR5)⁺, CD44⁺, c-kit⁺, lineage negative (lin^-), and E-cadherin^-. These blood-derived precursor cells (BDPCs), can be further differentiated into epithelial-like cells (eBDPCs) and secret fibroblast growth factor 9 (Fgf9) protein. Result: When transplanted into full-thickness skin wounds, eBDPC treatment produced accelerated healing and enhanced skin structure regeneration with less dermal scar formation. Also, HF neogenesis (HFN) was observed with incorporation of labeled BDPCs in the wound area. Innovation:Nondermal-derived CD34⁺ cells (BDPCs) from the adult unmobilized peripheral blood are capable of in vitro expansion and differentiation.Successful establishment of an in vitro technical platform for BDPCs expansion and differentiation.The in vitro expanded and differentiated epithelial-like cells (eBDPCs) enhance wound healing and directly contribute to skin regeneration and HFN. Conclusion: BDPCs isolated and expanded from adult peripheral blood may provide a possible new cell-based treatment strategy for HF neogenesis and skin wound regeneration.

Tear biomarkers and corneal sensitivity as an indicator of neuropathy in type 2 diabetes

AIMS

Explore potential of 31 tear biomarkers involved in screening for diabetic peripheral neuropathy (DPN). Assess the utility of aesthesiometry for measuring corneal damage in DPN and determine optimal cutoff point for detecting DPN.

METHODS

Screening test pilot study recruited 90 participants from a tertiary hospital in Lima, Peru. Participants were grouped by diabetes and neuropathy status. Tears collected on Schirmer strips, and proteins measured by both ELISA and multiplex-bead assay. Corneal sensitivity was measured by aesthesiometry, and DPN by vibration perception threshold testing.

RESULTS

There were 89 participants included in the analysis. The mean age was 55.7 ± 1.46, and 58.4% were female. MMP-9 and TGF-alpha concentrations were higher in participants with DPN versus diabetes alone, though not significant. Aesthesiometry was decreased in individuals with DPN when compared to participants with diabetes alone (p < 0.01) and normal controls (p < 0.01). Optimal cutoff point for aesthesiometry was found to be 5.8 cm, with 79% sensitivity and 75% specificity.

CONCLUSIONS

Tears are an insufficient standalone tool for detecting DPN based on the biomarkers analyzed. Aesthesiometry is a simple, inexpensive, and accurate method to assess corneal damage associated with moderate-severe DPN, and its integration into screening practices has potential to improve detection of DPN in poor-resource settings.

Topical administration of mangiferin promotes healing of the wound of streptozotocin-nicotinamide-induced type-2 diabetic male rats

Purpose: This study identifies the potential use of mangiferin gel to promote wound healing in diabetes mellitus (DM).Materials and methods: Male rats were rendered diabetes mellitus via intraperitoneal injection of streptozotocin and nicotinamide. Following diabetes development, wound was created at the back of the neck. 1% and 2% mangiferin gel and 1% silver sulphurdiazine (SS) gel (positive control) were applied to the wound for twenty-one (21) days. Fasting blood glucose (FBG) levels were weekly monitored. At the end of the treatment, rats were sacrificed and wound was excised and subjected for histopathological and molecular biological analysis.Results: No changes to serum FBG levels was noted throughout the period of mangiferin treatment. Albeit, a significant decrease in the size of the wound with increased in the skin thickness of surrounding the wound were observed. Increased expression and distribution of EGF, FGF, TGF-β, VEGF, PI3K, MMP and Nrf2 and decreased expression and distribution of TNFα and NF-κB p65 were observed in diabetic wound treated with topical mangiferin.Conclusions: Mangiferin has potential to be used as an agent to promote wound healing in diabetic condition.

Naturally-occurring bacterial cellulose-hyperbranched cationic polysaccharide derivative/MMP-9 siRNA composite dressing for wound healing enhancement in diabetic rats

The anomalous high expression of matrix metalloproteinase 9 (MMP-9) is one important factor that impedes diabetic wound healing. Therefore, inhibition of MMP-9 expression in a diabetic wound could be a feasible method to promote wound healing. In this study, we studied the possibility of self-therapy using wound dressings that contain bacterial cellulose-hyperbranched cationic polysaccharide (BC-HCP) derivatives that encapsulate siRNA (BC-HCP/siMMP-9) and have controlled release properties. Herein, we used four HCPs (Gly-DMAPA, Gly-D4, Amyp-DMAPA, Amyp-D4) as gene carriers. Our results showed that all HCP derivatives were minimally toxic to cells in vitro, while the cationic properties of HCP could be used as a complexation agent for MMP-9 siRNA (siMMP-9). Upon exposure to bacterial cellulose (BC), the BC slowly released HCP/siMMP-9. The released siMMP-9 effectively reduced the gene expression and protein levels of MMP-9 in a human immortalized epithelial cell line (HaCAT) and in diabetic rat wounds. Inhibition of MMP-9 in the wounds of diabetic rats resulted in a significant enhancement of wound healing, suggesting that the BC-HCP/siMMP-9 composite dressing could be used as a safe and effective dressing to promote wound healing in diabetic rats. STATEMENT OF SIGNIFICANCE: In this work, we evaluated the possibility of using bacterial cellulose-hyperbranched cationic polysaccharide derivatives (BC-HCP) as a self-therapeutic wound dressing with siRNA encapsulated and controlled release properties. Our results showed that the BC-HCP/siMMP-9 composite dressing slowly released HCP/siMMP-9. The released siMMP-9 effectively reduced the gene expression and protein level of MMP-9 in human immortalized epithelial cell line and in the wound of diabetic rats. The BC-HCP/siMMP-9 composite dressing promoted diabetic wound healing by the unique nanostructure of BC and by releasing siMMP-9 for specific MMP-9 inhibition. Therefore, it could be used as a safe and effective dressing to promote wound healing in diabetic rats. This is the first evidence on the study of using BC as a dressing composite by encapsulating HCP/siRNA complexes for efficient RNAi gene silencing for better wound healing in diabetic rats.

Bioengineered Platforms for Chronic Wound Infection Studies: How Can We Make Them More Human-Relevant?

Chronic wound infections are an important cause of delayed wound healing, posing a significant healthcare burden with consequences that include hospitalization, amputation, and death. These infections most often take the form of three-dimensional biofilm communities, which are notoriously recalcitrant to antibiotics and immune clearance, contributing to the chronic wound state. In the chronic wound microenvironment, microbial biofilms interact closely with other key components, including host cellular and matrix elements, immune cells, inflammatory factors, signaling components, and mechanical cues. Intricate relationships between these contributing factors not only orchestrate the development and progression of wound infections but also influence the therapeutic outcome. Current medical treatment for chronic wound infections relies heavily on long-term usage of antibiotics; however, their efficacy and reasons for failure remain uncertain. To develop effective therapeutic approaches, it is essential to better understand the complex pathophysiology of the chronic wound infection microenvironment, including dynamic interactions between various key factors. For this, it is critical to develop bioengineered platforms or model systems that not only include key components of the chronic wound infection microenvironment but also recapitulate interactions between these factors, thereby simulating the infection state. In doing so, these platforms will enable the testing of novel therapeutics, alone and in combinations, providing insights toward composite treatment strategies. In the first section of this review, we discuss the key components and interactions in the chronic wound infection microenvironment, which would be critical to recapitulate in a bioengineered platform. In the next section, we summarize the key features and relevance of current bioengineered chronic wound infection platforms. These are categorized and discussed based on the microenvironmental components included and their ability to recapitulate the architecture, interactions, and outcomes of the infection microenvironment. While these platforms have advanced our understanding of the underlying pathophysiology of chronic wound infections and provided insights into therapeutics, they possess certain insufficiencies that limit their clinical relevance. In the final section, we propose approaches that can be incorporated into these existing model systems or developed into future platforms developed, thus enhancing their biomimetic and translational capabilities, and thereby their human-relevance.

Effect of ethanol extract from Lactobacillus plantarum TWK10-fermented soymilk on wound healing in streptozotocin-induced diabetic rat

Wound healing is a highly dynamic phenomenon comprising numerous coordinated steps including homeostasis/coagulation, inflammation, migration, proliferation, and remodeling. Diabetes mellitus (DM) is a multisystem chronic epidemic that prolongs inflammation in wounds and is associated with impaired healing. This study aimed to investigate the effect of an ethanol extract from Lactobacillus plantarum TWK10 (TWK10)-fermented soymilk on wound healing. The anti-inflammatory effects of the ethanol extract of TWK10-fermented soymilk on lipopolysaccharide-stimulated RAW264.7 macrophage cells were examined. The ethanol extract of TWK10-fermented soymilk (100 µg/mL) significantly decreased nitric oxide production from 11.34 ± 0.74 μM to 8.24 ± 2.02 µM (p < 0.05) and enhanced proliferation in Detroit 551 cells cultured in high-glucose medium; the cell number peaked at 128.44 ± 7.67% (compared to the untreated control) at 600 µg/mL. An ethanol extract of TWK10-fermented soymilk + vaseline-treated rat model of streptozotocin-induced diabetic wounds was generated herein, and the following groups were formed herein: normal control (NC), blank control (BC), low dose group (LD, 0.24 mg/wound), intermediate dose (MD, 0.48 mg/wound), and high dose (HD, 2.40 mg/wound). On day 14 after wound infliction, the wound area in the LD, MD, and HD groups was significantly decreased to 10.2, 8.4, and 8.5% respectively (p < 0.05). Moreover, in the LD, MD, and, HD groups, tumor necrosis factor-α, interleukin 6, and matrix metalloproteinase-9 were downregulated in the wounded skin. These results show that the topical application of the ethanol extract of TWK10-fermented soymilk is beneficial for enhancing wound healing and for the closure of diabetic wounds.

GnRH impairs diabetic wound healing through enhanced NETosis

It has been reported that neutrophil extracellular traps (NETs) impair wound healing in diabetes and that inhibiting NET generation (NETosis) improves wound healing in diabetic mice. Gonadotropin-releasing hormone (GnRH) agonists are associated with a greater risk of diabetes. However, the role of GnRH in diabetic wound healing is unclear. We determined whether GnRH-promoted NETosis and induced more severe and delayed diabetic wound healing. A mouse model of diabetes was established using five injections with streptozotocin. Mice with blood glucose levels >250 mg/dL were then used in the experiments. GnRH agonist treatment induced delayed wound healing and increased NETosis at the skin wounds of diabetic mice. In contrast, GnRH antagonist treatment inhibited GnRH agonist-induced delayed wound healing. The expression of NETosis markers PAD4 and citrullinated histone H3 were increased in the GnRH-treated diabetic skin wounds in diabetic mice and patients. In vitro experiments also showed that neutrophils expressed a GnRH receptor and that GnRH agonist treatment increased NETosis markers and promoted phorbol myristate acetate (PMA)-induced NETosis in mouse and human neutrophils. Furthermore, GnRH antagonist treatment suppressed the expression of NETosis markers and PMA-induced NETosis, which were increased by GnRH treatment. These results indicated that GnRH-promoted NETosis and that increased NETosis induced delayed wound healing in diabetic skin wounds. Thus, inhibition of GnRH might be a novel treatment of diabetic foot ulcers.

Role of growth factors and cytokines in diabetic foot ulcer healing: A detailed review

The aim of the review is to examine the role of growth factors and cytokines in the management of Diabetic Foot Ulcers, such as platelet derived growth factor (PDGF), vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF) and Insulin like growth factor (IGF). Taking this a step further, the role of Hypoxia-inducible factors (HIFs), Transforming growth factor beta 1 (TGF-β-1) and other growth factors have also been examined, with regard to the treatment of diabetic foot ulcers. The roles of these above-mentioned growth cytokines have been analyzed by studying various scholastic articles. The complete process of wound healing is implemented and regulated by numerous cytokines and human growth factors. The findings of the study indicate that wound healing of diabetic foot ulcers is a complex and extremely challenging biological and molecular process that involves coordinated efforts of multiple cell types. The therapeutic effects of various growth factors in the clinical management of wounds are chronic venous ulcers, pressure ulcers, and diabetic foot ulcers. It has been concluded that altercations of various cytokines are found in patients enduring diabetic foot ulcers. In a similar way, changes in the level of cytokines are also found in patients suffering from other diabetic complications such as diabetic nephropathy, retinopathy, and neuropathy. Subsequently, the diabetic wound healing process can be accelerated by regulating the levels of the cytokines.

Effect of photobiomodulation and exercise on early remodeling of the Achilles tendon in streptozotocin-induced diabetic rats

The aim of this study was to compare the treatment effects of laser photobiomodulation (LPBM) therapy and aerobic exercise on the biomechanical properties, tissue morphology and the expression of tendon matrix molecules during early remodeling of Achilles tendon (AT) injury in diabetic rats. Animals were randomly assigned to five groups: injured non diabetic (I, n = 15), injured diabetic (ID, n = 15), injured diabetic plus LPBM (IDL, n = 16), injured diabetic plus aerobic exercise (IDE, n = 16) and injured diabetic plus aerobic exercise and LPBM (IDEAL, n = 17). Type 1 diabetes was induced via a single intravenous injection of Streptozotocin at a dose of 40 mg/kg. A partial tenotomy was performed in the right AT. LPBM was performed with an indium-gallium-aluminum-phosphide 660 nm 10 mW laser device (spot size 0.04 cm2, power density 250 mW/cm2, irradiation duration 16 s, energy 0.16 J, energy density 4 J/cm2) on alternate days for a total of 9 sessions over 3 weeks (total energy 1.44 J), using a stationary contact technique to a single point over the dorsal aspect of the AT. Moderate aerobic exercise was performed on a motorized treadmill (velocity 9 m/min for 60 minutes). At 3 weeks post-injury, biomechanical analyzes as well as assessment of fibroblast number and orientation were performed. Collagen 1 (Col1) and 3 (Col3) and matrix metalloproteinases (MMPs) -3 and 13 protein distributions were studied by immunohistochemistry; while Col1 and Col3 and MMP-2 and 9 gene expression were assessed by quantitative RT-PCR (qRT-PCR). IDEAL exhibited significant increases in several biomechanical parameters in comparison to the other groups. Moreover, IDEAL presented stronger Col1 immunoreactivity when compared to ID, and weaker Col3 immunoreactivity than IDE. Both IDL and IDEAL demonstrated weaker expression of MMP-3 in comparison to I, while IDL presented no expression of MMP-13 when compared to ID. ID, IDL and IDE showed an increased number of fibroblasts in comparison to I, while IDEAL decreased the number of these cells in comparison to ID and IDE. IDL and IDEAL groups exhibited decreased angular dispersion among the fibroblasts when compared to I. The gene expression results showed that IDE demonstrated a downregulation in Col1 mRNA expression in comparison to I and ID. IDEAL demonstrated upregulation of Col1 mRNA expression when compared to IDL or IDE alone and increased MMP-2 expression when compared to IDL and IDE. MMP-9 expression was upregulated in IDEAL when compared to I, IDL and IDE. Our results suggest a beneficial interaction of combining both treatment strategies i.e., aerobic exercise and LPBM, on the biomechanical properties, tissue morphology and the expression of matrix molecules in diabetic tendons.

Improvement of diabetic wound healing by topical application of Vicenin-2 hydrocolloid film on Sprague Dawley rats

Background

Impaired wound healing is a debilitating complication of diabetes that leads to significant morbidity, particularly foot ulcers. The risk of developing diabetic foot ulcers for diabetic patients is 15% over their lifetime and approximately 85% of limb amputations is caused by non–healing ulcers. Unhealed, gangrenous wounds destroy the structural integrity of the skin, which acts as a protective barrier that prevents the invasion of external noxious agents into the body. Vicenin-2 (VCN-2) has been reported to contain prospective anti-oxidant and anti-inflammatory properties that enhance cell proliferation and migration. Sodium Alginate (SA) is a natural polysaccharide that possesses gel forming properties and has biodegradable and biocompatible characteristics. Therefore, the objective of this study is to evaluate the effect of SA wound dressings containing VCN-2 on diabetic wounds.

Methods

Wounds were inflicted in type-1 diabetic-streptozotocin (STZ) induced male Sprague Dawley rats. Subsequently, relevant groups were topically treated with the indicated concentrations (12.5, 25 and 50 μM) of VCN-2 hydrocolloid film over the study duration (14 days). The control group was treated with vehicle dressing (blank or allantoin). Wounded tissues and blood serum were collected on 0, 7 and 14 days prior to sacrifice. Appropriate wound assessments such as histological tests, nitric oxide assays, enzyme-linked immunosorbent assays (ELISA) and immunoblotting assays were conducted to confirm wound healing efficacy in the in vivo model. One-way Analysis of Variance (ANOVA) was used for statistical analysis.

Results

Results showed that hydrocolloid film was recapitulated with VCN-2 enhanced diabetic wound healing in a dose-dependent manner. VCN-2 reduced pro-inflammatory cytokines (IL-1β, IL-6 and TNF-α), mediators (iNOS and COX-2), and nitric oxide (NO) via the NF-κB pathway. Data suggests that the VCN-2 film facilitated healing in hyperglycemic conditions by releasing growth factors such as (VEGF and TGF-β) to enhance cell proliferation, migration, and wound contraction via the VEGF and TGF-β mechanism pathways.

Conclusions

This study’s findings suggest that VCN-2 may possess wound healing potential since topical treatment with VCN-2 hydrocolloid films effectively enhanced wound healing in hyperglycemic conditions.

Effect of Horse-chestnut seed extract on matrix metalloproteinase-1 and -9 during diabetic wound healing

The effects of aqueous-ethanol extract of Horse chestnut (HCE) on MMP-1 and MMP-9 expressions during cutaneous wound healing in diabetic rats were investigated in this study. The expressions of MMP-1 and MMP-9, wound closure, myeloperoxidase (MPO) activity, hydroxyproline, and malondialdehyde (MDA) levels in wound tissue were measured. Quercetin glucuronide in HCE was identified as main compound using a LC-MS/MS. The hydroxyproline level was significantly increased in the treated group versus control after the 3rd and 7th days (p < 0.05). The MDA level and MPO activity were significantly lower in the treatment group (p < 0.05). MMP-1 gene expression level in treated rats was increased in the 7th day while it was reduced in 14th day. MMP-9 gene expression level in treated rats was decreased in 7th, and 14th days compared to control (p < 0.05). These results show that HCE accelerated the cutaneous wound-healing process in diabetic rats via MMP-1 and MMP-9 regulation. PRACTICAL APPLICATIONS: The main function of MMPs is to degrade and deposite the various components of the extracellular matrix. Also, they participate physiological processes such as inflammation, angiogenesis, and tissue remodeling. Horse chestnut seeds (HC) are known to be rich in saponins and flavonoids. HC are used for the treatment of abdominal pain, stomach ache, cold, hemorrhoids, arterial stiffness, rheumatism, oedema, diarrhea, chronic venous insufficiency and also as an antihemorrhagic and antipyretic in traditional medicine. It has been shown that HC has anti-inflammatory, antioedema, vessel protective, and free radical scavenging properties. This study indicates that HCE could be an effective agent for wound healing in diabetic wound model via its ability to suppress the MMP-9 gene expression and regulates MMP-1 gene expression besides its antioxidative, anti-inflammatory effects.

Aster koraiensis extract improves impaired skin wound healing during hyperglycemia

Background

Diabetes mellitus (DM) is one of the most common diseases found across the world. Aster koraiensis extract (AKE) has a protective effect on diabetic complications such as diabetic retinopathy. However, the effects of AKE on hyperglycemia-linked impairment of wound healing during DM have not been elucidated. In this study, we investigated the effects of AKE on delayed wound healing induced by DM.

Methods

DM was induced by intraperitoneal administration of streptozotocin (STZ; 75 mg/kg) to Sprague Dawley (SD) rats. Next, a wound was induced on the back of rats after administration of STZ. Further, AKE was prepared using an alcoholic extraction of A. koraiensis and orally administered daily for 18 days. Wound healing was evaluated using an in vitro migration assay and measuring the wound area in vivo. Skin tissue thickness was evaluated using hematoxylin and eosin staining. Matrix metalloprotease (MMP) activity and expression were detected using zymography and immunohistochemistry.

Results

AKE administration improved the delayed migration of keratinocytes in hyperglycemic animals. It also attenuated an increase in keratinocyte MMP-2/9 activity induced by hyperglycemia. AKE protected against DM-induced impaired wound healing in rats and prevented the degradation of skin tissue induced by DM. In addition, AKE attenuated DM-induced increase in MMP-2/9 expression in skin tissue.

Conclusions

In conclusion, AKE may promote wound healing by re-epithelization via promotion of keratinocyte migration and by attenuating the disruption of the skin tissue layer via MMP-2/9 inhibition during hyperglycemia.