Inflammation and neuropeptides: the connection in diabetic wound healing

Co-Delivery of Valsartan and Metformin from a Thermosensitive Hydrogel-Nanoparticle System Promotes Collagen Production in Proliferating and Senescent Primary Human Dermal Fibroblasts

Aging negatively impacts skin health, notably through the senescent cell phenotype, which reduces collagen production and leads to thinner, more fragile skin prone to injuries and chronic wounds. We designed a drug delivery system that addresses these age-related issues using a hybrid hydrogel-nanoparticle system that utilizes a poly(δ-valerolactone-co-lactide)-b-poly(ethylene-glycol)-b-poly(δ-valerolactone-co-lactide) (PVLA-PEG-PVLA) hydrogel. This hydrogel allows for the local, extended release of therapeutics targeting both proliferating and senescent cells. The PVLA-PEG-PVLA hydrogel entrapped valsartan, and metformin-loaded liposomes functionalized with a fibronectin-mimetic peptide, PR_b. Metformin acts as a senomorphic, reversing aspects of cellular senescence, and valsartan, an angiotensin receptor blocker, promotes collagen production. This combination treatment partially reversed the senescent phenotype and improved collagen production in senescent dermal fibroblasts from both young and old adults. Our codelivery hydrogel-nanoparticle system offers a promising treatment for improving age-related dermal pathologies.

Tear neuropeptide Y as a non-invasive marker of peripheral microvascular complications in type 1 diabetes

AIMS

To investigate tear neuropeptide Y (NPY) and substance P concentrations in individuals with type 1 diabetes, comparing those with and without both diabetic retinopathy (DR) and peripheral neuropathy.

METHODS

This cross-sectional study involved 41 participants with type 1 diabetes and none to moderate DR, and 22 healthy controls. Assessments included clinical ocular surface parameters, quantification of corneal nerve attributes (based on in vivo confocal microscopy imaging), DR grading, and evaluation for small and large fibre neuropathy. Concentrations of NPY and substance P in tear samples were measured using enzyme-linked immunosorbent assay.

RESULTS

Mean (± standard deviation) tear NPY concentrations in participants with type 1 diabetes and length-dependent small fibre neuropathy (SFN) was lower than in controls (10.84 ± 4.10 ng/mL vs 14.72 ± 3.12 ng/mL; p=0.004), but not significantly different from type 1 diabetes participants without SFN (13.39 ± 4.66 ng/mL; p=0.11). Tear NPY levels were lower in individuals with type 1 diabetes and mild/moderate non-proliferative DR (10.44 ± 3.46 ng/mL) compared to none/minimal DR (13.79 ± 4.76 ng/mL; p=0.0005) and controls. In separate linear regression models, both the presence of SFN (β = -0.75, p=0.02) and the presence of mild/moderate DR (β = -0.84, p=0.009) were significantly associated with tear NPY levels relative to controls, after adjusting for participant age, sex, and dry eye disease. There were no inter-group differences for tear substance P concentrations.

CONCLUSIONS

Tear NPY has potential utility as an indicator of peripheral microvascular complications associated with type 1 diabetes.

Effect of Using Photobiomodulation (660 Nanometers) for the Treatment of Diabetic Ulcers: Protocol for a Randomized Controlled Trial

Diabetic foot ulcers (DFUs) result in tissue damage or impairment of deeper structures that affect quality of life. The impacts are numerous, and even after a long treatment period, 65% of patients experience recurrence. Among the interventions used to accelerate the healing process of DFUs, photobiomodulation therapy (PBMT) is a painless, noninvasive, and low-cost treatment. To achieve effective therapeutic results optimal PBMT parameters are necessary. The positive effect of PBMT on diabetic cells may be dependent on fluence (J/cm2) and wavelength (nm). This double-blind, randomized clinical trial will be conducted at the University Clinic of Physical Therapy. One hundred patients will be randomly placed in 4 groups. A Laserpulse Ibramed (Helium-Neon, HeNe, 660 nm) with 20 W power will be used (continuous mode), with doses stipulated for each treatment group (GL1, 4 J/cm2; GL2, 8 J/cm2; GL3, 12 J/cm2) and Endophoton KLD GaAs 904 nm (ST, 10 J/cm2) for 2 nonconsecutive days per week for 10 weeks, for a total of 20 sessions. The primary outcomes will be ulcer healing rate and University of Texas classification scores. Patients' DFUs will be assessed on the 1st day, 5 weeks, and 10 weeks of treatment then 1 month after the end of treatment. This study may aid effective clinical decision-making for the management of DFUs.

Translational application of human keratinocyte-fibroblast cell sheets for accelerated wound healing in a clinically relevant type 2 diabetic rat model

BACKGROUND AIMS

Despite advancements in wound care, wound healing remains a challenge, especially in individuals with type 2 diabetes. Cell sheet technology has emerged as an efficient and promising therapy for tissue regeneration and wound repair. Among these, bilayered human keratinocyte-fibroblast cell sheets constructed using temperature-responsive culture surfaces have been shown to mimic a normal tissue-like structure and secrete essential cytokines and growth factors that regulate the wound healing process.

METHODS

This study aimed to evaluate the safety and therapeutic potential of human skin cell sheets to treat full-thickness skin defects in a rat model of type 2 diabetes.

RESULTS

Our findings demonstrate that diabetic wounds transplanted with bilayered cell sheets resulted in accelerated re-epithelialization, increased angiogenesis, enhanced macrophage polarization and regeneration of tissue that closely resembled healthy skin. In contrast, the control group that did not receive cell sheet transplantation presented characteristic symptoms of impaired and delayed wound healing associated with type 2 diabetes.

CONCLUSIONS

The secretory cytokines and the upregulation of Nrf2 expression in response to cell sheet transplantation are believed to have played a key role in the improved wound healing observed in diabetic rats. Our study suggests that human keratinocyte-fibroblast cell sheets hold great potential as a therapeutic alternative for diabetic ulcers.

Gut microbiota in relationship to diabetes mellitus and its late complications with a focus on diabetic foot syndrome: A review

Diabetes mellitus is a chronic disease affecting glucose metabolism. The pathophysiological reactions underpinning the disease can lead to the development of late diabetes complications. The gut microbiota plays important roles in weight regulation and the maintenance of a healthy digestive system. Obesity, diabetes mellitus, diabetic retinopathy, diabetic nephropathy and diabetic neuropathy are all associated with a microbial imbalance in the gut. Modern technical equipment and advanced diagnostic procedures, including xmolecular methods, are commonly used to detect both quantitative and qualitative changes in the gut microbiota. This review summarises collective knowledge on the role of the gut microbiota in both types of diabetes mellitus and their late complications, with a particular focus on diabetic foot syndrome.

The efficacy of electroacupuncture in among early diabetic patients with lower limb arteriosclerotic wounds

Diabetic foot ulcers are the prevalent complication of diabetes mellitus, frequently culminating in arteriosclerosis of the lower extremities and consequent development of chronic wounds. The effectiveness of electroacupuncture (EA) as therapeutic intervention for promoting wound healing in this particular group of patients has been comprehensively assessed in this study. A randomized controlled trial involving 380 early diabetic patients with arteriosclerotic lesions of the lower limbs was conducted. Standard wound care plus EA was administered to the treatment group, while standard wound care alone was administered to the control group. The principal outcome assessed was the reduction in lesion size following the 8-week treatment period. Pain scores, recuperation time, and quality of life (QoL) evaluations constituted secondary outcomes. In comparison to the control group, the treatment group exhibited a significantly greater reduction in wound size (p < 0.05). The treatment group exhibited significantly reduced pain scores and significantly higher QoL scores (p < 0.05). The duration of recovery did not vary substantially among the groups (p > 0.05). Electroacupuncture thus appeared to be an effective adjunctive treatment for early diabetic patients with lower limb arteriosclerotic lesions, promoting pain relief and quality of life. Additional investigation is necessary to validate these results and delve into the underlying mechanisms of action.

CGRP sensory neurons promote tissue healing via neutrophils and macrophages

The immune system has a critical role in orchestrating tissue healing. As a result, regenerative strategies that control immune components have proved effective1,2. This is particularly relevant when immune dysregulation that results from conditions such as diabetes or advanced age impairs tissue healing following injury2,3. Nociceptive sensory neurons have a crucial role as immunoregulators and exert both protective and harmful effects depending on the context4-12. However, how neuro-immune interactions affect tissue repair and regeneration following acute injury is unclear. Here we show that ablation of the NaV1.8 nociceptor impairs skin wound repair and muscle regeneration after acute tissue injury. Nociceptor endings grow into injured skin and muscle tissues and signal to immune cells through the neuropeptide calcitonin gene-related peptide (CGRP) during the healing process. CGRP acts via receptor activity-modifying protein 1 (RAMP1) on neutrophils, monocytes and macrophages to inhibit recruitment, accelerate death, enhance efferocytosis and polarize macrophages towards a pro-repair phenotype. The effects of CGRP on neutrophils and macrophages are mediated via thrombospondin-1 release and its subsequent autocrine and/or paracrine effects. In mice without nociceptors and diabetic mice with peripheral neuropathies, delivery of an engineered version of CGRP accelerated wound healing and promoted muscle regeneration. Harnessing neuro-immune interactions has potential to treat non-healing tissues in which dysregulated neuro-immune interactions impair tissue healing.

The response of salivary proinflammatory biomarkers to tooth extraction in individuals with type II diabetes mellitus

PURPOSE

This study investigated the levels of salivary proinflammatory cytokines in the saliva of patients living with type II diabetes mellitus (DM) compared to those in healthy individuals three times: before tooth extraction and at 2 hours and 2 days after tooth extraction.

METHODS

The study included 27 participants. Among them, 20 (n = 20; 74%) had type II DM, and seven (n = 7; 26%) were healthy control subjects. Saliva samples were collected at three time intervals: before tooth extraction and 2 hours and 2 days after tooth extraction. The salivary biomarkers were investigated using a Luminex multiplex assay. These salivary biomarkers included tumor necrosis factor-alpha (TNF-α), interleukin 6 (IL-6), interleukin 1-beta (IL-1β), and interferon-gamma (IFN-γ).

RESULTS

At baseline, patients with type II DM had significantly lower levels of IL-1β (P = 0.016). Moreover, 2 hours after extraction, patients with type II DM had significantly lower levels of IL-1β and TNF-α than did healthy control subjects (P = 0.046 and P = 0.020, respectively). In addition, 2 days after tooth extraction, the DM group had significantly greater IL-6 levels (P = 0.010) than the control group.

CONCLUSIONS

In patients with type II DM, salivary proinflammatory biomarker levels are generally comparable or lower than those in healthy control subjects. Proinflammatory cytokines manifest differently in patients with type II DM after tooth extraction than in normal healthy individuals. There is generally a delayed early response of salivary proinflammatory markers in patients living with type II DM who undergo tooth extraction.

Fibroblasts in Diabetic Foot Ulcers

Fibroblasts are stromal cells ubiquitously distributed in the body of nearly every organ tissue. These cells were previously considered to be "passive cells", solely responsible for ensuring the turnover of the extracellular matrix (ECM). However, their versatility, including their ability to switch phenotypes in response to tissue injury and dynamic activity in the maintenance of tissue specific homeostasis and integrity have been recently revealed by the innovation of technological tools such as genetically modified mouse models and single cell analysis. These highly plastic and heterogeneous cells equipped with multifaceted functions including the regulation of angiogenesis, inflammation as well as their innate stemness characteristics, play a central role in the delicately regulated process of wound healing. Fibroblast dysregulation underlies many chronic conditions, including cardiovascular diseases, cancer, inflammatory diseases, and diabetes mellitus (DM), which represent the current major causes of morbidity and mortality worldwide. Diabetic foot ulcer (DFU), one of the most severe complications of DM affects 40 to 60 million people. Chronic non-healing DFU wounds expose patients to substantial sequelae including infections, gangrene, amputation, and death. A complete understanding of the pathophysiology of DFU and targeting pathways involved in the dysregulation of fibroblasts are required for the development of innovative new therapeutic treatments, critically needed for these patients.

Topical Anti-ulcerogenic Effect of the Beta-adrenergic Blockers on Diabetic Foot Ulcers: Recent Advances and Future Prospectives

BACKGROUND

Patients with diabetes suffer from major complications like Diabetic Retinopathy, Diabetic Coronary Artery Disease, and Diabetic Foot ulcers (DFUs). Diabetes complications are a group of ailments whose recovery time is especially delayed, irrespective of the underlying reason. The longer duration of wound healing enhances the probability of problems like sepsis and amputation. The delayed healing makes it more critical for research focus. By understanding the molecular pathogenesis of diabetic wounds, it is quite easy to target the molecules involved in the healing of wounds. Recent research on beta-adrenergic blocking drugs has revealed that these classes of drugs possess therapeutic potential in the healing of DFUs. However, because the order of events in defective healing is adequately defined, it is possible to recognize moieties that are currently in the market that are recognized to aim at one or several identified molecular processes.

OBJECTIVE

The aim of this study was to explore some molecules with different therapeutic categories that have demonstrated favorable effects in improving diabetic wound healing, also called the repurposing of drugs.

METHOD

Various databases like PubMed/Medline, Google Scholar and Web of Science (WoS) of all English language articles were searched, and relevant information was collected regarding the role of beta-adrenergic blockers in diabetic wounds or diabetic foot ulcers (DFUs) using the relevant keywords for the literature review.

RESULT

The potential beta-blocking agents and their mechanism of action in diabetic foot ulcers were studied, and it was found that these drugs have a profound effect on diabetic foot ulcer healing as per reported literatures.

CONCLUSION

There is a need to move forward from preclinical studies to clinical studies to analyze clinical findings to determine the effectiveness and safety of some beta-antagonists in diabetic foot ulcer treatment.

Diabetic Foot Ulcer Management and Treatment: An Overview of Published Patents

BACKGROUND

One of the most challenging effects of diabetes is diabetic foot ulceration (DFU). DFU may occur in up to one-third of individuals with diabetes mellitus (D.M.) at some point in their lives. The major cause of morbidity in D.M. patients is DFU. The length of treatment is difficult, and DFU recurrence is common.

OBJECTIVE

The most crucial element for the treatment and prevention of DFUs require a multidisciplinary approach. Patients who are at risk should be identified, depending on the type of risk, prophylactic actions etc. It is imperative to identify at-risk patients and take preventative measures accordingly.

METHOD

The at-risk diabetes-related foot ulcer was identified based on the risk category classification, while the foot ulcers were evaluated using Wagner's classification system.

RESULTS

Literature reported that patients with lower limb vascular insufficiency, loss of vibratory sensation, or protective sensation loss have an increased risk of developing foot ulcers. Proper categorization and therapeutic measures will be implemented after the DFU has been formed. The appropriate assessment and management of general health status should include glycemic control, the diagnosis and treatment of vascular disease, standard care for wounds, diagnosis, and infection treatments.

CONCLUSION

The review reflects the updated awareness of the treatment and management of DFU based on the current and past literature and patent analysis.

Upregulation of circ_0080968 in diabetic foot ulcer inhibits wound healing via repressing the migration and promoting proliferation of keratinocytes

BACKGROUND

Diabetic foot ulcer (DFU) is a serious chronic complication of diabetes mellitus whose pathogenesis remains unclear. Circular RNA (circRNA) refers to a group of covalently closed non-coding RNAs that are reported to be dysregulated in patients with DFU. However, the mechanism whereby dysregulation in circRNAs contributes to DFU remains unclear. In this study, we investigated the role of dysregulated circRNAs in DFU.

MATERIALS AND METHODS

A gene expression dataset was downloaded from the Gene Expression Omnibus portal and analyzed by the limma package of R. The levels of 24 upregulated circRNAs were detected in two independent cohorts by RT-qPCR. Interactions between miRNAs and circRNAs were predicted through bioinformatics and confirmed using a dual luciferase assay. The circularity and subcellular localization of circRNA-080968 was examined by northern blotting after digestion with RNase-R and in situ hybridization. Cell migration and proliferation were examined using Transwell and MTT assays. The apoptotic cells were detected by flow cytometry.

RESULTS

The level of circRNA-080968 was upregulated in DFU tissues compared to that of non-DFU samples and normal human wounds. CircRNA-080968 was mainly localized in the cytoplasm and its overexpression inhibited the migration and promoted the proliferation of keratinocytes. MiR-326 and miR-766-3p were identified to interact with and be negatively correlated with circRNA-080968 levels. Increased glucose upregulated circRNA-080968, and its overexpression accelerated the degradation of both miR-326 and miR-766-3p. Reduced levels of miR-326 and miR-766-3p upregulated the expression of several genes controlling cell adhesion and proliferation which are related to the pathogenesis of DFU.

CONCLUSIONS

The upregulation of circRNA-080968 in DFU induced the degradation of miR-326 and miR-766-3p, which further repressed the migration and increased the proliferation of keratinocytes.

Oriented artificial niche provides physical-biochemical stimulations for rapid nerve regeneration

Skin wound is always accompanied with nerve damage, leading to significant sensory function loss. Currently, the functional matrix material based stem cell transplantation and in situ nerve regeneration are thought to be effective strategies, of which, how to recruit stem cells, retard senescence, and promote neural differentiation has been obstacle to be overcome. However, the therapeutic efficiency of the reported systems has yet to be improved and side effect reduced. Herein, a conduit matrix with three-dimensional ordered porous structures, regular porosity, appropriate mechanical strength, and conductive features was prepared by orienting the freezing technique, which was further filled with neural-directing exosomes to form a neural-stimulating matrix for providing hybrid physical-biochemical stimulations. This neural-stimulating matrix was then compacted with methacrylate gelatin (GelMA) hydrogel thin coat that loaded with chemokines and anti-senescence drugs, forming a multi-functional artificial niche (termed as GCr-CSL) that promotes MSCs recruitment, anti-senescence, and neural differentiation. GCr-CSL was shown to rapidly enhances in situ nerve regeneration in skin wound therapy, and with great potential in promoting sensory function recovery. This study demonstrates proof-of-concept in building a biomimetic niche to organize endogenous MSCs recruitment, differentiation, and functionalization for fast neurological and sensory recovery.

Neuropeptide Y Promotes the Treatment of Adipose Stem Cells on Type 2 Diabetic Wounds

BACKGROUND

Type 2 diabetes (T2D) is a common metabolic disorder. Due to insufficient insulin secretion or insulin resistance, increased blood glucose often leads to impaired wound healing in T2D patients. Our previous research showed that adipose-derived stem cells (ASCs) from normal mice and T2D mice improved the cutaneous wound healing of diabetic mice. We also found that the expression of neuropeptide Y (NPY) in T2D ASCs was significantly decreased.

METHODS

In order to explore the effects of NPY on ASCs and diabetic wound healing, we investigated the effects of NPY on ASCs proliferation and growth factors expression and secretion, the effects of NPY on skin fibroblasts, and the effects of NPY combined with ASCs on T2D wound healing.

RESULTS

The results showed that a certain concentration of NPY could promote the proliferation and the growth factors expression and secretion of ASCs, and promote the proliferation and migration of fibroblasts. At the same time, NPY and ASCs have a synergistic effect, which can promote wound healing and decrease inflammation in T2D wounds. NPY may regulate ASCs through the ERK pathway. These results are conducive to promoting ASCs and NPY in the treatment of diabetic wounds.

CONCLUSIONS

NPY can promote the effect of ASCs in the treatment of diabetic wounds.

Bio-evaluation of Untapped Alkaloids from Vinca minor Enriched by Methyl-jasmonate-induced Stress: an Integrated Approach

The low amount of metabolites isolated from natural products is one of the challenges preventing their biological evaluation. The modulation of biosynthetic pathways by stimulating stress-induced responses in plants was proven to be a valuable tool for diversification of already known natural products. Recently, we reported the dramatic effect of methyl jasmonate (MeJA) on Vinca minor alkaloids distribution. In this study, three compounds identified as 9-methoxyvincamine, minovincinine, and minovincine are successfully isolated in good yield and subjected to several bioassays based on a network pharmacology study. The extracts and isolated compounds show weak to moderate antimicrobial and cytotoxic activities. Also, they are found to significantly promote wound healing in scratch assay, and transforming growth factor-β (TGF-β) modulation is suggested to be the potential pathway based on bioinformatic analysis. Hence, Western blotting is used to assess the expression of several markers related to this pathway and wound healing. The extracts and isolated compounds are able to increase the expression of Smad3 and Phosphatidylinositol-3-kinase (PI3K), while downregulating the levels of cyclin D1 and the mammalian target of rapamycin (mTOR) except for minovincine, which increases the mTOR expression, inferring that it might act through a different mechanism. Molecular docking is used to give insights on the ability of isolated compounds to bind with different active sites in mTOR. Collectively, the integrated phytochemical, in silico, and molecular biology approach reveal that V. minor and its metabolite could be repurposed for the management of dermatological disorders where these markers are dysregulated, which opens the gate to develop new therapeutics in the future.

Exploring the contribution of pro-inflammatory cytokines to impaired wound healing in diabetes

Background

Impaired wound healing is the most common and significant complication of Diabetes. While most other complications of Diabetes have better treatment options, diabetic wounds remain a burden as they can cause pain and suffering in patients. Wound closure and repair are orchestrated by a sequence of events aided by the release of pro-inflammatory cytokines, which are dysregulated in cases of Diabetes, making the wound environment unfavorable for healing and delaying the wound healing processes. This concise review provides an overview of the dysregulation of pro-inflammatory cytokines and offers insights into better therapeutic outcomes.

Purpose of review

Although many therapeutic approaches have been lined up nowadays to treat Diabetes, there are no proper treatment modalities proposed yet in treating diabetic wounds due to the lack of understanding about the role of inflammatory mediators, especially Pro-inflammatory mediators- Cytokines, in the process of Wound healing which we mainly focus on this review.

Recent findings

Although complications of Diabetes mellitus are most reported after years of diagnosis, the most severe critical complication is impaired Wound Healing among Diabetes patients. Even though Trauma, Peripheral Artery Disease, and Peripheral Neuropathy are the leading triggering factors for the development of ulcerations, the most significant issue contributing to the development of complicated cutaneous wounds is wound healing impairment. It may even end up with amputation. Newer therapeutic approaches such as incorporating the additives in the present dressing materials, which include antimicrobial molecules and immunomodulatory cytokines is of better therapeutic value.

Summary

The adoption of these technologies and the establishment of novel therapeutic interventions is difficult since there is a gap in terms of a complete understanding of the pathophysiological mechanisms at the cellular and molecular level and the lack of data in terms of the assessment of safety and bioavailability differences in the individuals' patients. The target-specific pro-inflammatory cytokines-based therapies, either by upregulation or downregulation of them, will be helpful in the wound healing process and thereby enhances the Quality of life in patients, which is the goal of drug therapy.

Adiponectin as a therapeutic target for diabetic foot ulcer

The global burden of diabetic foot ulcers (DFUs) is a significant public health concern, affecting millions of people worldwide. These wounds cause considerable suffering and have a high economic cost. Therefore, there is a need for effective strategies to prevent and treat DFUs. One promising therapeutic approach is the use of adiponectin, a hormone primarily produced and secreted by adipose tissue. Adiponectin has demonstrated anti-inflammatory and anti-atherogenic properties, and researchers have suggested its potential therapeutic applications in the treatment of DFUs. Studies have indicated that adiponectin can inhibit the production of pro-inflammatory cytokines, increase the production of vascular endothelial growth factor, a key mediator of angiogenesis, and inhibit the activation of the intrinsic apoptotic pathway. Additionally, adiponectin has been found to possess antioxidant properties and impact glucose metabolism, the immune system, extracellular matrix remodeling, and nerve function. The objective of this review is to summarize the current state of research on the potential role of adiponectin in the treatment of DFUs and to identify areas where further research is needed in order to fully understand the effects of adiponectin on DFUs and to establish its safety and efficacy as a treatment for DFUs in the clinical setting. This will provide a deeper understanding of the underlying mechanisms of DFUs that can aid in the development of new and more effective treatment strategies.

Mesenchymal Stem Cell Derived Exosomes Therapy in Diabetic Wound Repair

Nowadays, refractory diabetic wounds cause a worldwide medical burden. Mesenchymal stem cells derived exosomes (MSC-Exos) show promise as a solid alternative to existing therapeutics in the latest researches, since MSC-Exos share similar biologic activity but less immunogenicity when compared with MSCs. To facilitate further understanding and application, it is essential to summarize the current progress and limitations of MSC-Exos in the treatment of diabetic wounds. In this review, we introduce the effects of different MSC-Exos on diabetic wounds according to their origins and contents and discuss the specific experimental conditions, target wound cells/pathways, and specific mechanisms. In addition, this paper focuses on the combination of MSC-Exos and biomaterials, which improves the efficacy and utilization of MSC-Exos therapy. Together, exosome therapy has high clinical value and application prospects, both in its role and in combination with biomaterials, while novel drugs or molecules loaded into exosomes as carriers targeting wound cells will be development trends.

Recent trends in diabetic wound healing with nanofibrous scaffolds

There is an emphasis in this review on nanofibrous scaffolds (NFSs) in diabetic wound healing, as well as their mechanisms and recent advancements. Diabetes-related complex wounds pose an important problem to humanity, due to the fact that their chronic nature can lead to serious complications including sepsis and amputations. Despite the fact that there are certain therapy options available for diabetic wound healing, these options are either ineffective or intrusive, making clinical intervention difficult. Clinical research is also challenged by the emergence of bacterial resistance to standard antibiotics. However, research into nanotechnology, in particular NFSs, is growing swiftly and has a positive impact on the treatment of diabetic wounds. For instance, SpinCare™, developed by Nanomedic Technologies Ltd, has successfully finished clinical testing and can re-epithelialize second-degree burns and chronic diabetic wounds in 7 and 14 days, respectively. In this review, we discussed homologous studies as well as other recent research studies on diabetic wound healing using NFSs.

The Potential of Topical Therapy for Diabetic Wounds: A Narrative Review

The rising prevalence of diabetes mellitus brings with it a rise in the occurrence of several complications of the disease such as chronic non-healing wounds. Diabetics are more prone to developing chronic wounds due to complications like peripheral neuropathy, poor foot care, hyperglycaemia and peripheral vascular diseases. The aim of this review is to discuss the various imbalances in the cytokine environment of diabetic wounds and to explore the developments in their management with an emphasis on agents that may be used topically to aid the healing process of chronic wounds. A systematic search was conducted on Scopus, PubMed and Google Scholar and relevant articles were shortlisted. We conclude that increased blood sugar impairs most phases of wound healing in several ways. Supplementary therapy with either topical or systemic cytokines is shown to promote wound healing in a diabetic wound.

Pharmacological blockade of HDAC3 accelerates diabetic wound healing by regulating macrophage activation

AIMS

Here, we report the effect of histone deacetylase 3 (HDAC3) inhibition associated with macrophage activation, IL-1β expression, angiogenesis and wound healing in diabetic mice.

MAIN METHODS

To determine the expression of HDAC3 in diabetic mice wounds, hyperglycemia was induced in C57BL/6 mice with streptozotocin followed by induction of 6 mm wounds. To understand the effect of HDAC3 selective inhibitor, BG45, wound tissues were isolated for analysing M1/M2 markers expression, immune cells infiltration, angiogenesis and healing factors expression. CD11b⁺F4/80⁺ cells were sorted from the wound tissues and analysed for the expression of M1/M2 markers using RT-qPCR and flow cytometer. In cell based assays, HDAC3 expression was measured in macrophages stimulated with high glucose (HG) plus LPS. Macrophages treated with BG45 and HG + LPS were analysed for the expression of pro-IL-1β, mature IL-1β, oxidative stress and pro-inflammatory (M1) and anti-inflammatory (M2) factors.

KEY FINDINGS

HDAC3 was found to be upregulated in impaired diabetic mice wounds and in macrophages stimulated with HG + LPS. Topical application of BG45 loaded gel accelerated the wound healing in diabetic mice and was evident by improved expression of Collagen-1A, IL-10, TGF-β, and angiogenesis (CD31, VEGF). BG45 treatment decreased the expression of IL-1β, TNF-α, and IL-6 (M1 phenotype), reduced oxidative stress and promoted the expression of Arginase-1 and YM1/2 (M2 phenotype) in macrophages treated with HG + LPS. BG45 also improved the expression of CD11b⁺F4/80⁺CD206⁺ cells in wound tissues and reduced expression of inflammatory markers.

SIGNIFICANCE

HDAC3 is upregulated in diabetic mice wounds and HDAC3 selective inhibitor promotes the wound healing by regulating macrophage activation, angiogenesis and IL-1β.

Development of Neuropeptide Hemokinin-1 Analogues with Antimicrobial and Wound-Healing Activity

Wound healing is a complex process that can be delayed in some pathological conditions, such as infection and diabetes. Following skin injury, the neuropeptide substance P (SP) is released from peripheral neurons to promote wound healing by multiple mechanisms. Human hemokinin-1 (hHK-1) has been identified as an SP-like tachykinin peptide. Surprisingly, hHK-1 shares similar structural features with antimicrobial peptides (AMPs), but it does not display efficient antimicrobial activity. Therefore, a series of hHK-1 analogues were designed and synthesized. Among these analogues, AH-4 was found to display the greatest antimicrobial activity against a broad spectrum of bacteria. Furthermore, AH-4 rapidly killed bacteria by membrane disruption, similar to most AMPs. More importantly, AH-4 showed favorable healing activity in all tested mouse full-thickness excisional wound models. Overall, this study suggests that the neuropeptide hHK-1 can be used as a desirable template for developing promising therapeutics with multiple functions for wound healing.

Polylactic Acid/Poly(vinylpyrrolidone) Co-Electrospun Fibrous Membrane as a Tunable Quercetin Delivery Platform for Diabetic Wounds

Diabetic wound infections (DWI) represent one of the most costly and disruptive complications in diabetic mellitus. The hyperglycemic state induces a persistent inflammation with immunological and biochemical impairments that promotes delayed wound healing processes and wound infection that often results in extended hospitalization and limb amputations. Currently, the available therapeutic options for the management of DWI are excruciating and expensive. Hence, it is essential to develop and improve DWI-specific therapies able to intervene on multiple fronts. Quercetin (QUE) exhibits excellent anti-inflammatory, antioxidant, antimicrobial and wound healing properties, which makes it a promising molecule for the management of diabetic wounds. In the present study, Poly-lactic acid/poly(vinylpyrrolidone) (PP) co-electrospun fibers loaded with QUE were developed. The results demonstrated a bimodal diameter distribution with contact angle starting from 120°/127° and go to 0° in less than 5 s indicating the hydrophilic nature of fabricated samples. The release QUE kinetics, analyzed in simulated wound fluid (SWF), revealed a strong initial burst release, followed by a constant and continuous QUE release. Moreover, QUE-loaded membranes present excellent antibiofilm and anti-inflammatory capacity and significantly reduce the gene expression of M1 markers tumor necrosis factor (TNF)-α, and IL-1β in differentiated macrophages. In conclusion, the results suggested that the prepared mats loaded with QUE could be a hopeful drug-delivery system for the effective treatment of diabetic wound infections.

nWASP Inhibition Increases Wound Healing via TrKb/PLCγ Signalling

(1) Background: Chronic wounds represent a major burden to patients and healthcare systems and identifying new therapeutic targets to encourage wound healing is a significant challenge. This study evaluated nWASP as a new therapeutic target in human wound healing and determined how this can be regulated. (2) Methods: Clinical cohorts from patients with chronic wounds were tested for the expression of nWASP and cell models were employed to evaluate the influence of nWASP on cellular functions that are key to the healing process following knockdown and/or the use of nWASP-specific inhibitors. (3) Results: nWASP was significantly elevated at transcript levels in human non-healing chronic wounds versus healing tissues. nWASP inhibitors, wiskostatin and 187-1, along with the knockdown of nWASP, modified both HaCaT and HECV cell behaviour. We then identified two signalling pathways affected by nWASP inhibition: TrkB signalling and downstream PLCγ1 phosphorylation were impaired by nWASP inhibition in HaCaT cells. The healing of wounds in a diabetic murine model was significantly improved with an nWASP inhibitor treatment. (4) Conclusions: This study showed that nWASP activity was related to the non-healing behaviour of chronic wounds and together with the findings in the in vivo models, it strongly suggested nWASP as a therapeutic target in non-healing wounds that are regulated via TrkB and PLCγ1 signalling.

Review: Research progress of adipose-derived stem cells in the treatment of chronic wounds

Although methods are used to treat wounds clinically, there are still many challenges in the treatment of chronic wounds due to excessive inflammatory response, difficulties in epithelialization, vascularization, and other factors. With the increasing research on adipose-derived stem cells (ADSCs) in recent years, accumulating evidence has shown that ADSCs scan promotes the healing of chronic wounds by regulating macrophage function and cellular immunity and promoting angiogenesis and epithelialization. The present study reviewed the difficulties in the treatment of chronic wounds, as well as the advantages and the mechanism of ADSCs in promoting the healing of chronic wounds, to provide a reference for the stem cell therapy of chronic wounds.

Neuroepithelial Interactions in Cancer

Nerves not only regulate the homeostasis and energetic metabolism of normal epithelial cells but also are critical for cancer, as cancer recapitulates the biology of neural regulation of epithelial tissues. Cancer cells rarely develop in denervated organs, and denervation affects tumorigenesis, in vivo and in humans. Axonogenesis occurs to supply the new malignant epithelial growth with nerves. Neurogenesis happens later, first in ganglia around organs or the spinal column and subsequently through recruitment of neuroblasts from the central nervous system. The hallmark of this stage is regulation of homeostasis and energetic metabolism. Perineural invasion is the most efficient interaction between cancer cells and nerves. The hallmark of this stage is increased proliferation and decreased apoptosis. Finally, carcinoma cells transdifferentiate into a neuronal profile in search of neural independence. The latter is the last stage in neuroepithelial interactions. Treatments for cancer must address the biology of neural regulation of cancer.

Sympathetic System in Wound Healing: Multistage Control in Normal and Diabetic Skin

In this review, we discuss sympathetic regulation in normal and diabetic wound healing. Experimental denervation studies have confirmed that sympathetic nerve endings in skin have an important and complex role in wound healing. Vasoconstrictor neurons secrete norepinephrine (NE) and neuropeptide Y (NPY). Both mediators decrease blood flow and interact with inflammatory cells and keratinocytes. NE acts in an ambiguous way depending on receptor type. Beta2-adrenoceptors could be activated near sympathetic endings; they suppress inflammation and re-epithelialization. Alpha1- and alpha2-adrenoceptors induce inflammation and activate keratinocytes. Sudomotor neurons secrete acetylcholine (ACh) and vasoactive intestinal peptide (VIP). Both induce vasodilatation, angiogenesis, inflammation, keratinocytes proliferation and migration. In healthy skin, all effects are important for successful healing. In treatment of diabetic ulcers, mediator balance could be shifted in different ways. Beta2-adrenoceptors blockade and nicotinic ACh receptors activation are the most promising directions in treatment of diabetic ulcers with neuropathy, but they require further research.

The neuropeptide substance P/neurokinin-1 receptor system and diabetes: From mechanism to therapy

Diabetes is a significant public health issue known as the world's fastest-growing disease condition. It is characterized by persistent hyperglycemia and subsequent chronic complications leading to organ dysfunction and, ultimately, the failure of target organs. Substance P (SP) is an undecapeptide that belongs to the family of tachykinin (TK) peptides. The SP-mediated activation of the neurokinin 1 receptor (NK1R) regulates many pathophysiological processes in the body. There is also a relation between the SP/NK1R system and diabetic processes. Importantly, deregulated expression of SP has been reported in diabetes and diabetes-associated chronic complications. SP can induce both diabetogenic and antidiabetogenic effects and thus affect the pathology of diabetes destructively or protectively. Here, we review the current knowledge of the functional relevance of the SP/NK1R system in diabetes pathogenesis and its exploitation for diabetes therapy. A comprehensive understanding of the role of the SP/NK1R system in diabetes is expected to shed further light on developing new therapeutic possibilities for diabetes and its associated chronic conditions.

A Review of Immunomodulatory Reprogramming by Probiotics in Combating Chronic and Acute Diabetic Foot Ulcers (DFUs)

Diabetic foot ulcers (DFUs) are characterized by a lack of angiogenesis and distal limb diabetic neuropathy. This makes it possible for opportunistic pathogens to protect the biofilm-encased micro-communities, causing a delay in wound healing. The acute and chronic phases of DFU-associated infections are distinguished by the differential expression of innate proinflammatory cytokines and tumor necrosis factors (TNF-α and -β). Efforts are being made to reduce the microbial bioburden of wounds by using therapies such as debridement, hyperbaric oxygen therapy, shock wave therapy, and empirical antibiotic treatment. However, the constant evolution of pathogens limits the effectiveness of these therapies. In the wound-healing process, continuous homeostasis and remodeling processes by commensal microbes undoubtedly provide a protective barrier against diverse pathogens. Among commensal microbes, probiotics are beneficial microbes that should be administered orally or topically to regulate gut-skin interaction and to activate inflammation and proinflammatory cytokine production. The goal of this review is to bridge the gap between the role of probiotics in managing the innate immune response and the function of proinflammatory mediators in diabetic wound healing. We also highlight probiotic encapsulation or nanoformulations with prebiotics and extracellular vesicles (EVs) as innovative ways to tackle target DFUs.

A Biocompatible Self-Powered Piezoelectric Poly(vinyl alcohol)-Based Hydrogel for Diabetic Wound Repair

Acute and chronic wounds, caused by trauma, tumors, diabetic foot ulcers, etc., are usually difficult to heal, while applying exogenous electrical stimulation to enhance the endogenous electric field in the wound has been proven to significantly accelerate wound healing. However, traditional electrical stimulation devices require an additional external power supply, making them poor in portability and comfort. In this work, a self-powered piezoelectric poly(vinyl alcohol) (PVA)/polyvinylidene fluoride (PVDF) composite hydrogel is constructed by establishing a distinctive preparation process of freezing/thawing-solvent replacement-annealing-swelling. The hydrogen bonding in the hydrogel is remarkably enhanced by the annealing-swelling process, which is stronger between PVA/PVDF molecules than that between PVA molecules, promoting transformation of the α-phase into the electroactive β-phase PVDF and facilitating formation of a much more crystalline structure with high cross-linking density. Hence, an obvious piezoelectric response with high piezoelectric coefficient and electrical signal output with superior stability and sensitivity and excellent mechanical strength and stretchability was achieved for hydrogels. PVA/PVDF composite hydrogels with good cytocompatibility significantly promote proliferation, migration, and secretion of extracellular matrix proteins and growth factors of fibroblasts, possibly through activating the AKT and ERK1/2 signaling pathways. In a wound model of diabetic rats, piezoelectric hydrogels could not only rapidly attract wound exudate and maintain the wet environment of the wound bed but also convert the mechanical energy generated by rats' physical activities into electrical energy, so as to provide local piezoelectric stimulation to the wound bed evenly and symmetrically in real time. Such an effect significantly promotes re-epithelialization and collagen deposition and increases angiogenesis and secretion of growth factors in wound tissue. Besides, it regulates the macrophage phenotype from the M1 subtype (pro-inflammatory subtype) to the M2 subtype (anti-inflammatory subtype) and reduces the expression levels of inflammatory factors, thus accelerating wound healing. The development of such a novel piezoelectric hydrogel provides new therapeutic strategies for chronic wound healing.

Increased synovial expression of calcitonin gene-related peptide and its potential roles in Charcot Neuroarthropathy

OBJECTIVE

Joint destruction in Charcot neuroarthropathy (CNA) is accompanied with abundant hyperplastic synovium. This study aimed to characterize the expression patterns of a group of neuropeptides in the CNA synovium.

METHODS

Synovial specimens were collected during surgery from the CNA (n = 6) and non-CNA joints (n = 14). Tissue samples were processed for protein extraction and western blot for vasoactive intestinal peptide (VIP), galanin, and calcitonin gene-related peptide (CGRP). Immunohistochemistry was performed to localize CGRP in the CNA synovium. Additionally, CGRP was applied to fibroblast-like synoviocytes (FLS) isolated from CNA synovium for its effects on cell proliferation and collagenolysis in vitro.

RESULTS

Western blot detected light bands of VIP in the CNA samples but abundant galanin in both CNA and non-CNA samples. Most of the CNA samples (5/6) increased expression of CGRP, with an average band density about 2 times that in the non-CNA group (p < .05). Immunohistochemistry of CGRP demonstrated intense staining in the intimal layer of the CNA synovium. In tissue culture, adding CGRP (10 nM) in the medium promoted FLS proliferation. In combination with TNF-α, CGRP enhanced FLS-mediated collagenolysis in vitro.

CONCLUSION

This study revealed an increased expression of CGRP in the CNA synovium and demonstrated that CGRP regulates FLS proliferation and collagenolytic activity, suggesting CGRP may contribute to the bone and cartilage destruction in CNA.

Characterisation of key biomarkers in diabetic ulcers via systems bioinformatics

Diabetic ulcers (DUs) are characterised by a high incidence and disability rate. However, its pathogenesis remains elusive. Thus, a deep understanding of the underlying mechanisms for the pathogenesis of DUs has vital implications. The weighted gene co-expression network analysis was performed on the main data from the Gene Expression Omnibus database. Gene Ontology (GO) terms, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were adopted to analyse the potential biological function of the most relevant module. Furthermore, we utilised CytoHubba and protein-protein interaction network to identify the hub genes. Finally, the hub genes were validated by animal experiments in diabetic ulcer mice models. The expression of genes from the turquoise module was found to be strongly related to DUs. GO terms, KEGG analysis showed that biological functions are closely related to immune response. The hub genes included IFI35, IFIT2, MX2, OASL, RSAD2, and XAF1, which were higher in wounds of DUs mice than that in normal lesions. Additionally, we also demonstrated that the expression of hub genes was correlated with the immune response using immune checkpoint, immune cell infiltration, and immune scores. These data suggests that IFI35, IFIT2, MX2, OASL, RSAD2, and XAF1 are crucial for DUs.

Scaffold-based delivery of mesenchymal stromal cells to diabetic wounds

Foot ulceration is a major complication of diabetes mellitus, which results in significant human suffering and a major burden on healthcare systems. The cause of impaired wound healing in diabetic patients is multifactorial with contributions from hyperglycaemia, impaired vascularization and neuropathy. Patients with non-healing diabetic ulcers may require amputation, creating an urgent need for new reparative treatments. Delivery of stem cells may be a promising approach to enhance wound healing because of their paracrine properties, including the secretion of angiogenic, immunomodulatory and anti-inflammatory factors. While a number of different cell types have been studied, the therapeutic use of mesenchymal stromal cells (MSCs) has been widely reported to improve delayed wound healing. However, topical administration of MSCs via direct injection has several disadvantages, including low cell viability and poor cell localization at the wound bed. To this end, various biomaterial conformations have emerged as MSC delivery vehicles to enhance cell viability and persistence at the site of implantation. This paper discusses biomaterial-based MSCs therapies in diabetic wound healing and highlights the low conversion rate to clinical trials and commercially available therapeutic products.

Fibroblasts: Immunomodulatory factors in refractory diabetic wound healing

Diabetes is a systemic disease in which patients with diabetes may develop peripheral neuropathy of the lower extremities and peripheral vascular disease due to long-term continuous exposure to high glucose. Delayed wound healing in diabetes is one of the major complications of diabetes. Slow wound healing in diabetic patients is associated with high glucose toxicity. When the condition deteriorates, the patient needs to be amputated, which seriously affects the quality of life and even endangers the life of the patient. In general, the delayed healing of diabetes wound is due to the lack of chemokines, abnormal inflammatory response, lack of angiogenesis and epithelial formation, and fibroblast dysfunction. The incidence of several chronic debilitating conditions is increasing in patients with diabetes, such as chronic renal insufficiency, heart failure, and hepatic insufficiency. Fibrosis is an inappropriate deposition of extracellular matrix (ECM) proteins. It is common in diabetic patients causing organ dysfunction. The fibrotic mechanism of diabetic fibroblasts may involve direct activation of permanent fibroblasts. It may also involve the degeneration of fibers after hyperglycemia stimulates immune cells, vascular cells, or organ-specific parenchymal cells. Numerous studies confirm that fibroblasts play an essential role in treating diabetes and its complications. The primary function of fibroblasts in wound healing is to construct and reshape the ECM. Nowadays, with the widespread use of single-cell RNA sequencing (scRNA-seq), an increasing number of studies have found that fibroblasts have become the critical immune sentinel cells, which can detect not only the activation and regulation of immune response but also the molecular pattern related to the injury. By exploring the heterogeneity and functional changes of fibroblasts in diabetes, the manuscript discusses that fibroblasts may be used as immunomodulatory factors in refractory diabetic wound healing, providing new ideas for the treatment of refractory diabetic wound healing.

Exosomes Derived From Umbilical Cord Mesenchymal Stem Cells Treat Cutaneous Nerve Damage and Promote Wound Healing

Wound repair is a key step in the treatment of skin injury caused by burn, surgery, and trauma. Various stem cells have been proven to promote wound healing and skin regeneration as candidate seed cells. Therefore, exosomes derived from stem cells are emerging as a promising method for wound repair. However, the mechanism by which exosomes promote wound repair is still unclear. In this study, we reported that exosomes derived from umbilical cord mesenchymal stem cells (UC-MSCs) promote wound healing and skin regeneration by treating cutaneous nerve damage. The results revealed that UC-MSCs exosomes (UC-MSC-Exo) promote the growth and migration of dermal fibroblast cells. In in vitro culture, dermal fibroblasts could promote to nerve cells and secrete nerve growth factors when stimulated by exosomes. During the repair process UC-MSC-Exo accelerated the recruitment of fibroblasts at the site of trauma and significantly enhanced cutaneous nerve regeneration in vivo. Interestingly, it was found that UC-MSC-Exo could promote wound healing and skin regeneration by recruiting fibroblasts, stimulating them to secrete nerve growth factors (NGFs) and promoting skin nerve regeneration. Therefore, we concluded that UC-MSC-Exo promote cutaneous nerve repair, which may play an important role in wound repair and skin regeneration.

Polyherbal formulation exerts wound healing, anti-inflammatory, angiogenic and antimicrobial properties: Potential role in the treatment of diabetic foot ulcers

Diabetic foot ulcer (DFU) is a common and devastating complication in diabetic patients and is associated with an elevated risk of amputation and mortality. DFU remains a major therapeutic challenge due to poor understanding of its underlying pathogenesis. This complication is characterized by impaired wound healing; however, mechanisms causing this impairment are complicated and involve interactions between many different cell types and infections. In addition to other conventional DFU treatments, herbal foot baths are also common, although little is known about their mechanisms of action, and they contain a wide variety of herbal ingredients. In this study, we aimed to examine the effects of three polyherbal formulations consisting of medicinal plants used in traditional Thai herbal foot baths on wound healing, anti-inflammation, angiogenesis, and extracellular matrix modulation using high-concentration glucose-treated human keratinocytes, in addition to antibacterial evaluation. Our results showed that formulation 3 (F3) possessed the greatest potential to restore the impairment of keratinocytes caused by high glucose concentrations. We found that F3 could inhibit the growth of Staphylococcus aureus, accelerate wound healing, and upregulate the expression of TIMP-1, VEGF, and TGF-β, and downregulate the expression of TNF-α, IL-6, and MMP-9. Collectively, these data support the potential of F3 for therapeutic development in the treatment of DFU.

Fluoxetine Ecofriendly Nanoemulsion Enhances Wound Healing in Diabetic Rats: In Vivo Efficacy Assessment

Impaired diabetic wound healing is a major concern for health care professionals worldwide, imposing an intense financial burden and reducing the quality of life of patients. A dysregulation of this process can be responsible for the development of intractable ulcers and the formation of excessive scars. Therefore, the identification of novel pharmacological strategies able to promote wound healing and restore the mechanical integrity of injured tissue becomes essential. In the present study, fluoxetine ecofriendly nanoemulsion (FLX-EFNE) was prepared and its potential efficacy in enhancing wound healing was tested in diabetic rats. The Box-Behnken response surface design was used to select the optimized formulation that was prepared by the high-shear homogenization-based technique. A Zetasizer was used for the characterization of the optimized formulation, providing a FLX-EFNE with a globule size of 199 nm. For the in vivo study, a wound was induced by surgical methods, and diabetic rats (streptozotocin-induced) were divided into five groups: untreated control, vehicle-treated, FLX, FLX-EFNE, and positive control receiving a commercially available formula. The treatment continued from the day of wound induction to day 21. Then, the animals were sacrificed and skin tissues were collected at the site of wounding and used for biochemical, histopathological, immunohistochemical, and mRNA expression assessments. In the FLX-EFNE treated group, the rate of wound contraction and signs of healing were significantly higher compared to all other groups. In addition, angiogenesis, proliferation, and collagen deposition were enhanced, while oxidative stress and inflammation decreased. The present data highlight the enhanced wound healing activity of the optimized FLX-EFNE formulation.

Astragalus Polysaccharides/PVA Nanofiber Membranes Containing Astragaloside IV-Loaded Liposomes and Their Potential Use for Wound Healing

Delayed wound healing is a common and serious complication in diabetic patients, especially the slow healing of foot ulcers, which seriously affects the quality of life of patients and is also the most important risk factor for lower limb amputation. The multifunctional novel dressing prepared by loading the polymer nanofibers with anti-inflammatory and prohealing plant extracts can promote the wound repair of these ulcers by electrospinning technology. Liposomes are nanoparticles prepared from phospholipids and have been widely used as drug delivery systems. Liposomes can be combined with electrospun nanofibrous webs to facilitate local and sustained delivery of loaded bioactive substances. In this study, liposomes were prepared with astragaloside IV (AS) by employing a modified ethanol injection method and conducting the physical and chemical characterization (e.g., the particle size, polydispersity index, zeta potential, and entrapment efficiency). Astragalus polysaccharides were extracted from Astragalus membranaceus. Subsequently, we prepared the electrospun polyvinyl alcohol (PVA)/astragalus polysaccharide (APS)/astragaloside IV (AS) nanofibers. The morphology of the produced ASL/APS/PVA, APS/PVA, and PVA nanofibers were analyzed by scanning electron microscopy (SEM), and it turns out that the addition of astragalus extract made the fiber diameter smaller and the fibers arranged neatly with no dripping. An induced diabetic rat model was built, and a diabetic ulcer model was built by total cortical resection to assess the prorepair ability of the prepared nanofibers. According to in vivo animal experiments, the nanofibrous membrane loaded with APS and ASL was reported to inhibit the occurrence of wound inflammation, enhance the deposition of collagen fibers (P < 0.05) and the repair of regenerated epithelium (P < 0.05), and effectively strengthen the wound healing of diabetic rats (P < 0.05). In brief, PVA-loaded APS/ASL nanofibrous membranes refer to a prominent wound healing dressing material, which can effectively facilitate the healing of diabetic wounds, and they are demonstrated to be highly promising for application in diabetic wound dressings and tissue engineering.

Role of neurotransmitters in the regulation of cutaneous wound healing

Wound healing is a highly coordinated and dynamic process of tissue repair after injury. The global burden of disease associated with wounds, both acute and chronic, is a significantly rising health concern. Upon skin wounding, neurons have the ability to sense the disruption to mediate the release of neurotransmitters into the wound microenvironment. Serotonin that has long been recognised as a potential vasoconstrictor is now also being contemplated to play a role in re-epithelialisation of wounds. While the role of neuropeptides in stimulating diabetic wound healing is being increasingly emphasised, on the other hand, dopamine is being widely studied for its dual role in mediating both pro- and antiangiogenic effects at the site of the wounds. Similarly, epinephrine levels that are known to be elevated during stress is now recognised as a contributing factor towards delayed wound closure, thereby serving as an inhibitor of wound healing. Thus, each neurotransmitter regulates wound repair and their active regeneration in a typical way. Strengthening our understanding of the molecular pathways via which the neurotransmitter modulates the immune system to control wound healing can yield potential therapeutic measures. Further investigations regarding the safety, efficacy, and cost-effectiveness of these processes are a prerequisite for their possible translation into clinical trials.

The Healing Capability of Clove Flower Extract (CFE) in Streptozotocin-Induced (STZ-Induced) Diabetic Rat Wounds Infected with Multidrug Resistant Bacteria

Treatment of diabetic foot ulcer (DFU) is of great challenge as it is shown to be infected by multidrug resistant bacteria (MDR bacteria). Sixty four bacterial isolates were isolated from DFU cases; antibiotic susceptibility tests were carried out for all of them. One bacterial isolate (number 11) was shown to resist the action of 8 out of 12 antibiotics used and was identified by both a Vitek-2 system and 16S rRNA fingerprints as belonging to Proteus mirabilis, and was designated Proteus mirabilis LC587231 (P. mirabilis). Clove flower extract (CFE) inhibited distinctively the P. mirabilis bacterium obtained. GC-MS spectroscopy showed that this CFE contained nine bioactive compounds. The effect of CFE on wound healing of Type 1 diabetic albino rats (Rattus norvegicus) was studied. The results indicated that topical application of CFE hydrogel improved wound size, wound index, mRNA expression of the wound healing markers (Coli1, MMP9, Fibronectin, PCNA, and TGFβ), growth factor signaling pathways (PPAR-α, PGC1-α, GLP-1, GLPr-1, EGF-β, EGF-βr, VEGF-β, and FGF-β), inflammatory cytokine expression (IL8, TNFα, NFKβ, IL1β, and MCP1), as well as anti-inflammatory cytokines (IL4 & IL10), pro-apoptotic markers (FAS, FAS-L, BAX, BAX/BCL-2, Caspase-3, P53, P38), as well as an antiapoptotic one (BCL2). Furthermore, it improved the wound oxidative state and reduced the wound microbial load, as the cefepime therapy improved the wound healing parameters. Based on the previous notions, it could be concluded that CFE represents a valid antibiotics alternative for DFU therapy since it improves diabetic wound healing and exerts antibacterial activity either in vitro or in vivo.

The Gut-Skin Microbiota Axis and Its Role in Diabetic Wound Healing-A Review Based on Current Literature

Diabetic foot ulcers (DFU) are a growing concern worldwide as they pose complications in routine clinical practices such as diagnosis and management. Bacterial interactions on the skin surface are vital to the pathophysiology of DFU and may control delayed wound healing. The microbiota from our skin directly regulates cutaneous health and disease by interacting with the numerous cells involved in the wound healing mechanism. Commensal microbiota, in particular, interact with wound-repairing skin cells to enhance barrier regeneration. The observed microbes in DFU include Staphylococcus, Streptococcus, Corynebacterium, Pseudomonas, and several anaerobes. Skin commensal microbes, namely S. epidermidis, can regulate the gamma delta T cells and induce Perforin-2 expression. The increased expression of Perforin-2 by skin cells destroyed S. aureus within the cells, facilitating wound healing. Possible crosstalk between the human commensal microbiome and different cell types involved in cutaneous wound healing promotes the immune response and helps to maintain the barrier function in humans. Wound healing is a highly well-coordinated, complex mechanism; it can be devastating if interrupted. Skin microbiomes are being studied in relation to the gut-skin axis along with their effects on dermatologic conditions. The gut-skin axis illustrates the connection wherein the gut can impact skin health due to its immunological and metabolic properties. The precise mechanism underlying gut-skin microbial interactions is still unidentified, but the immune and endocrine systems are likely to be involved. Next-generation sequencing and the development of bioinformatics pipelines may considerably improve the understanding of the microbiome-skin axis involved in diabetic wound healing in a much more sophisticated way. We endeavor to shed light on the importance of these pathways in the pathomechanisms of the most prevalent inflammatory conditions including the diabetes wound healing, as well as how probiotics may intervene in the gut-skin axis.

Decellularized Tissues for Wound Healing: Towards Closing the Gap Between Scaffold Design and Effective Extracellular Matrix Remodeling

The absence or damage of a tissue is the main cause of most acute or chronic diseases and are one of the appealing challenges that novel therapeutic alternatives have, in order to recover lost functions through tissue regeneration. Chronic cutaneous lesions are the most frequent cause of wounds, being a massive area of regenerative medicine and tissue engineering to have efforts to develop new bioactive medical products that not only allow an appropriate and rapid healing, but also avoid severe complications such as bacterial infections. In tissue repair and regeneration processes, there are several overlapping stages that involve the synergy of cells, the extracellular matrix (ECM) and biomolecules, which coordinate processes of ECM remodeling as well as cell proliferation and differentiation. Although these three components play a crucial role in the wound healing process, the ECM has the function of acting as a biological platform to permit the correct interaction between them. In particular, ECM is a mixture of crosslinked proteins that contain bioactive domains that cells recognize in order to promote migration, proliferation and differentiation. Currently, tissue engineering has employed several synthetic polymers to design bioactive scaffolds to mimic the native ECM, by combining biopolymers with growth factors including collagen and fibrinogen. Among these, decellularized tissues have been proposed as an alternative for reconstructing cutaneous lesions since they maintain the complex protein conformation, providing the required functional domains for cell differentiation. In this review, we present an in-depth discussion of different natural matrixes recently employed for designing novel therapeutic alternatives for treating cutaneous injuries, and overview some future perspectives in this area.

The Regenerative Potential of Substance P

Wound healing is a highly coordinated process which leads to the repair and regeneration of damaged tissue. Still, numerous diseases such as diabetes, venous insufficiencies or autoimmune diseases could disturb proper wound healing and lead to chronic and non-healing wounds, which are still a great challenge for medicine. For many years, research has been carried out on finding new therapeutics which improve the healing of chronic wounds. One of the most extensively studied active substances that has been widely tested in the treatment of different types of wounds was Substance P (SP). SP is one of the main neuropeptides released by nervous fibers in responses to injury. This review provides a thorough overview of the application of SP in different types of wound models and assesses its efficacy in wound healing.

A pH-responsiveness injectable hyaluronic acid hydrogel towards regulation of inflammation and remodeling of extracellular matrix for diabetic wound

Diabetes is a universal disease in the world. A critical mediator of proper wound healing is the production, assembly, and remodeling of the ECM by fibroblasts, but in the wound...

Novel topical esmolol hydrochloride improves wound healing in diabetes by inhibiting aldose reductase, generation of advanced glycation end products, and facilitating the migration of fibroblasts

AIMS/OBJECTIVES

Wound healing in people with diabetes is delayed secondary to impaired nitric oxide generation, advanced glycation end products (AGE), and poor migration of epithelial cells. We developed a novel topical esmolol hydrochloride (Galnobax) and assessed its efficacy for wound healing in streptozocin-induced diabetic hairless rat.

METHODS

All experiments were performed at an animal laboratory and tertiary-care research facility. Ex vivo aldose reductase inhibition was assessed from enzymes obtained from a bacterial culture (spectrophotometer), sorbitol content in homogenized red blood cells, and AGE in glucose and bovine serum by fluorometry following the addition of esmolol in varying concentrations. A scratch assay of human fibroblasts, endothelial cells, and keratinocytes was assessed under a high-glucose environment and after esmolol by phase-contrast microscopy. The efficacy evaluation of the topical application of Galnobax (14 and 20%) or vehicle was conducted in streptozotocin-induced diabetic hairless rats, and endogenous nitrite and hydroxyproline from homogenized wound tissue were measured along with pharmacokinetic and dermal toxicity in Hanford miniature swine.

RESULTS

Esmolol inhibited the formation of sorbitol by 59% in erythrocytes in comparison to glucose-induced sorbitol levels. AGE generation in bovine serum albumin was reduced at 1 mM esmolol concentrations (2.6 ± 1.7) compared with control (p < 0.05) and similar to that of diclofenac (2.5 ± 1.3). Esmolol at 1 and 10 µM enhanced the migration of fibroblasts, epithelial cells, and keratinocytes compared with control. The nitric oxide levels (day 7) were 44 and 112% higher with Galnobax (14%) than those of the diabetic group (p < 0.05) and the vehicle control group (p < 0.05), respectively. The days 7 and 14 hydroxyproline in the wound was higher by 22 and 44% following Galnobax (14%) compared with the diabetic and vehicle control groups. The wound area exhibited better reduction with Galnobax at 14% up to day 10 follow-up compared with the controls. The pharmacokinetic and dermal toxicity in miniature swine suggested no significant adverse event with Galnobax.

CONCLUSIONS

Topical esmolol hydrochloride is a novel, safe, and effective treatment modality that acts through pleotropic mechanisms to hasten wound healing in diabetes.

The role of keratinocyte function on the defected diabetic wound healing

Non-healing wounds are a major complication of diabetes that can lead to limb amputation and disability in patients. The normal process of wound repair progresses through well-defined stages including hemostasis, inflammation, proliferative, and remodeling, which may be impaired in diabetic wounds. In recent years, it has been reported that keratinocytes, a major cell type in human skin, play a key role in the healing process of wounds. In this overview, firstly, a summary of the wound healing process is provided and the role of keratinocytes in wound healing is briefly reviewed. Then, a set of evidence about the impaired keratinocytes activities in diabetic wounds and clinical trials focused mainly on improving keratinocytes in the context of diabetic wound therapeutics are summarized. Keratinocytes can produce signaling molecules that act in a paracrine and autocrine way, causing pleiotropic effects on various cell types. The affected cells respond to keratinocytes by creating several signaling molecules, which also adjust keratinocyte activation through wound healing. In diabetic wounds, disruption of various biological mechanisms leads to dysfunction of keratinocytes including impaired migration, adhesion, and proliferation. The function of abnormal keratinocytes can lead to poor diabetic wound healing. Taken together, clarification of molecular and functional disturbances of keratinocyte cells and applying them in diabetic wounds can contribute to enhanced treatment of diabetic wounds. Based on the location of keratinocytes in the epidermis and the central role of keratinocytes in the diabetic wound healing process, applying keratinocytes has great potential for the treatment of diabetic burn wounds.

Altered human alveolar bone gene expression in type 2 diabetes-A cross-sectional study

OBJECTIVE

The objective of this cross-sectional study is to investigate alveolar bone gene expression in health and diabetes through ribonucleic acid (RNA) sequencing and bioinformatics analysis.

BACKGROUND

It is relatively unknown how type 2 diabetes modulates gene expression in alveolar bone in humans. Clinical concern regarding increased implant failure rate in patients with diabetes has been discussed in the literature. Previous studies in animal models and humans have suggested an imbalance between the genes regulating bone formation with data suggesting bone resorption in diabetes. However, there is lack of data regarding a comprehensive gene expression from human alveolar bone in diabetes.

METHODS

Alveolar bone was collected from healthy and type 2 diabetic subjects undergoing periodontal and implant surgeries. The homogenized RNA sample was then extracted and analyzed for quantity and quality. RNA samples were further purified using ribosomal RNA depletion technique and processed for RNA sequencing and analysis. Expression levels for mRNAs were performed by calculating FPKM ([total_exon_fragments/mapped reads (millions) × exon length (kB)]), and differentially expressed mRNAs were selected with log₂ (fold change) >1 or log₂ (fold change) ≤1 and with a parametric F test comparing nested linear models.

RESULTS

Eighteen bone samples (10 healthy, 8 patients with diabetes) were analyzed for gene expression. The mean age and HbA1c% of healthy versus diabetic subjects were as follows: age (55.3 ± 17.5 vs 63.9 ± 8.7 years) and HbA1c% (5.6 ± 0.29 vs 7.3 ± 2.4), respectively. Sequencing analysis showed that expression of genes that regulate bone turnover like TGFB1, LTBP4, IGF1, BMP2, BMP4, BMP6, SMAD1, RUNX2, MCSF, and THRA was significantly downregulated in diabetes samples compared with healthy controls with overall reduced expression of genes in the bone regulation pathway in patients with diabetes. Bioinformatics analysis for the altered genes highlighted several pathways related to bone homeostasis and inflammation in diabetes. Periodontitis did not affect the gene expression pattern based on diabetes status.

CONCLUSIONS

Altered expression of genes due to downregulation of certain pathways that are involved in bone turnover and inflammation suggests that overall wound healing and bone homeostasis may be compromised in type 2 diabetes.

Neuropeptide Y: a potential theranostic biomarker for diabetic peripheral neuropathy in patients with type-2 diabetes

Background:

Diabetic peripheral neuropathy (DPN), the most common microvascular complication of type-2 diabetes mellitus (T2DM), results in nontraumatic lower-limb amputations. When DPN is not detected early, disease progression is irreversible. Thus, biomarkers for diagnosing DPN are needed.

Methods:

We analyzed three data sets of T2DM DPN: two for mouse models (GSE70852 and GSE34889) and one for a human model (GSE24290). We found common differentially expressed genes (DEGs) in the two mouse data sets and validated them in the human data set. To identify the phenotypic function of the DEGs, we overexpressed them in zebrafish embryos. Clinical information and serum samples of T2DM patients with and without DPN were obtained from the Korea Biobank Network. To assess the plausibility of DEGs as biomarkers of DPN, we performed an enzyme-linked immunosorbent assay.

Results:

Among the DEGs, only NPY and SLPI were validated in the human data set. As npy is conserved in zebrafish, its mRNA was injected into zebrafish embryos, and it was observed that the branches of the central nervous system became thicker and the number of dendritic branches increased. Baseline characteristics between T2DM patients with and without DPN did not differ, except for the sex ratio. The mean serum NPY level was higher in T2DM patients with DPN than in those without DPN (p = 0.0328), whereas serum SLPI levels did not differ (p = 0.9651).

Conclusion:

In the pathogenesis of DPN, NPY may play a protective role in the peripheral nervous system and may be useful as a biomarker for detecting T2DM DPN.

Cutaneous innervation in impaired diabetic wound healing

Type 2 diabetes is associated with several potential comorbidities, among them impaired wound healing, chronic ulcerations, and the requirement for lower extremity amputation. Disease-associated abnormal cellular responses, infection, immunological and microvascular dysfunction, and peripheral neuropathy are implicated in the pathogenesis of the wound healing impairment and the diabetic foot ulcer. The skin houses a dense network of sensory nerve afferents and nerve-derived modulators, which communicate with epidermal keratinocytes and dermal fibroblasts bidirectionally to effect normal wound healing after trauma. However, the mechanisms through which cutaneous innervation modulates wound healing are poorly understood, especially in humans. Better understanding of these mechanisms may provide the basis for targeted treatments for chronic diabetic wounds. This review provides an overview of wound healing pathophysiology with a focus on neural involvement in normal and diabetic wound healing, as well as future therapeutic perspectives to address the unmet needs of diabetic patients with chronic wounds.