Therapeutic Approaches to the Regulation of Wound Angiogenesis

Plant-Derived Exosomes as Novel Nanotherapeutics Contrive Glycolysis Reprogramming-Mediated Angiogenesis for Diabetic Ulcer Healing

Reversal of endothelial cell (EC) dysfunction under high-glucose (HG) conditions to achieve angiogenesis has remained a big challenge in diabetic ulcers. Herein, exosomes derived from medicinal plant ginseng (GExos) were shown as excellent nanotherapeutics with biomimetic cell membrane-like structures to be able to efficiently transfer the encapsulated active substances to ECs, resulting in a marked reprogramming of glycolysis by up-regulating anaerobic glycolysis and down-regulating oxidative stress, which further restore the proliferation, migration, and tubule formation abilities of ECs under HG conditions. In vivo, GExos enhance the angiogenesis and nascent vessel network reconstruction in full-thickness diabetic complicated skin ulcer wounds in mice with high biosafety. GExos were shown as promising nanotherapeutics in stimulating glycolysis reprogramming-mediated angiogenesis in diabetic ulcers, possessing wide application potential for reversing hyperglycemic dysangiogenesis and stimulating vascular regeneration.

A Spatiotemporal Controllable Biomimetic Skin for Accelerating Wound Repair

Skin injury repair is a dynamic process involving a series of interactions over time and space. Linking human physiological processes with materials' changes poses a significant challenge. To match the wound healing process, a spatiotemporal controllable biomimetic skin is developed, which comprises a three-dimensional (3D) printed membrane as the epidermis, a cell-containing hydrogel as the dermis, and a cytokine-laden hydrogel as the hypodermis. In the initial stage of the biomimetic skin repair wound, the membrane frame aids wound closure through pre-tension, while cells proliferate within the hydrogel. Next, as the frame disintegrates over time, cells released from the hydrogel migrate along the residual membrane. Throughout the process, continuous cytokines release from the hypodermis hydrogel ensures comprehensive nourishment. The findings reveal that in the rat full-thickness skin defect model, the biomimetic skin demonstrated a wound closure rate eight times higher than the blank group, and double the collagen content, particularly in the early repair process. Consequently, it is reasonable to infer that this biomimetic skin holds promising potential to accelerate wound closure and repair. This biomimetic skin with mechanobiological effects and spatiotemporal regulation emerges as a promising option for tissue regeneration engineering.

Uterine Cesarean Scar Tissue-An Immunohistochemical Study

Background and Objectives: Wound healing encompasses a multitude of factors and entails the establishment of interactions among components of the basement membrane. The quantification of particle concentrations can serve as valuable biomarkers for assessing biomechanical muscle properties. The objective of this study was to examine the immunoexpression and immunoconcentration of myometrial collagen type VI, elastin, alpha-smooth muscle actin, and smooth muscle myosin heavy chain, as well as the expression of platelets and clusters of differentiation 31 in the uterine scar following a cesarean section (CS). Materials and Methods: A total of 177 biopsies were procured from a cohort of pregnant women who were healthy, specifically during the surgical procedure of CS. The participants were categorized into seven distinct groups. Group 1 consisted of primiparas, with a total of 52 individuals. The subsequent groups were organized based on the duration of time that had elapsed since their previous CS. The analysis focused on the immunoexpression and immunoconcentration of the particles listed. Results: No significant variations were observed in the myometrial immunoconcentration of collagen type VI, elastin, smooth muscle myosin, and endothelial cell cluster of differentiation 31 among the analyzed groups. The concentration of alpha-smooth muscle actin in the myometrium was found to be significantly higher in patients who underwent CS within a period of less than 2 years since their previous CS, compared to those with a longer interval between procedures. Conclusions: Our findings indicate that the immunoconcentration of uterine myometrial scar collagen type VI, elastin, smooth muscle myosin heavy chain, alpha-smooth muscle actin, and endothelial cell marker cluster of differentiation 31 remains consistent regardless of the duration elapsed since the previous CS. The findings indicate that there are no significant alterations in the biomechanical properties of the uterine muscle beyond a period of 13 months following a CS.

Flexible Organic Photovoltaic-Powered Hydrogel Bioelectronic Dressing With Biomimetic Electrical Stimulation for Healing Infected Diabetic Wounds

Electrical stimulation (ES) is proposed as a therapeutic solution for managing chronic wounds. However, its widespread clinical adoption is limited by the requirement of additional extracorporeal devices to power ES-based wound dressings. In this study, a novel sandwich-structured photovoltaic microcurrent hydrogel dressing (PMH dressing) is designed for treating diabetic wounds. This innovative dressing comprises flexible organic photovoltaic (OPV) cells, a flexible micro-electro-mechanical systems (MEMS) electrode, and a multifunctional hydrogel serving as an electrode-tissue interface. The PMH dressing is engineered to administer ES, mimicking the physiological injury current occurring naturally in wounds when exposed to light; thus, facilitating wound healing. In vitro experiments are performed to validate the PMH dressing's exceptional biocompatibility and robust antibacterial properties. In vivo experiments and proteomic analysis reveal that the proposed PMH dressing significantly accelerates the healing of infected diabetic wounds by enhancing extracellular matrix regeneration, eliminating bacteria, regulating inflammatory responses, and modulating vascular functions. Therefore, the PMH dressing is a potent, versatile, and effective solution for diabetic wound care, paving the way for advancements in wireless ES wound dressings.

Ag nanocomposite hydrogels with immune and regenerative microenvironment regulation promote scarless healing of infected wounds

BACKGROUND

Bacterial infection, complex wound microenvironment and persistent inflammation cause delayed wound healing and scar formation, thereby disrupting the normal function and appearance of skin tissue, which is one of the most problematic clinical issues. Although Ag NPs have a strong antibacterial effect, they tend to oxidize and form aggregates in aqueous solution, which reduces their antibacterial efficacy and increases their toxicity to tissues and organs. Current research on scar treatment is limited and mainly relies on growth factors and drugs to reduce inflammation and scar tissue formation. Therefore, there is a need to develop methods that effectively combine drug delivery, antimicrobial and anti-inflammatory agents to modulate the wound microenvironment, promote wound healing, and prevent skin scarring.

RESULTS

Herein, we developed an innovative Ag nanocomposite hydrogel (Ag NCH) by incorporating Ag nanoparticles (Ag NPs) into a matrix formed by linking catechol-modified hyaluronic acid (HA-CA) with 4-arm PEG-SH. The Ag NPs serve dual functions: they act as reservoirs for releasing Ag/Ag+ at the wound site to combat bacterial infections, and they also function as cross-linkers to ensure the sustained release of basic fibroblast growth factor (bFGF). The potent antibacterial effect of the Ag NPs embedded in the hydrogel against S.aureus was validated through comprehensive in vitro and in vivo analyses. The microstructural analysis of the hydrogels and the in vitro release studies confirmed that the Ag NCH possesses smaller pore sizes and facilitates a slower, more sustained release of bFGF. When applied to acute and infected wound sites, the Ag NCH demonstrated remarkable capabilities in reshaping the immune and regenerative microenvironment. It induced a shift from M1 to M2 macrophage polarization, down-regulated the expression of pro-inflammatory factors such as IL-6 and TNF-α, and up-regulated the expression of anti-inflammatory IL-10. Furthermore, the Ag NCH played a crucial role in regulating collagen deposition and alignment, promoting the formation of mature blood vessels, and significantly enhancing tissue reconstruction and scarless wound healing processes.

CONCLUSIONS

We think the designed Ag NCH can provide a promising therapeutic strategy for clinical applications in scarless wound healing and antibacterial therapy.

Topically-applied collagen-binding serum albumin-fused interleukin-4 modulates wound microenvironment in non-healing wounds

Non-healing wounds have a negative impact on quality of life and account for many cases of amputation and even early death among patients. Diabetic patients are the predominate population affected by these non-healing wounds. Despite the significant clinical demand, treatment with biologics has not broadly impacted clinical care. Interleukin-4 (IL-4) is a potent modulator of the immune system, capable of skewing macrophages towards a pro-regeneration phenotype (M2) and promoting angiogenesis, but can be toxic after frequent administration and is limited by its short half-life and low bioavailability. Here, we demonstrate the design and characterization of an engineered recombinant interleukin-4 construct. We utilize this collagen-binding, serum albumin-fused IL-4 variant (CBD-SA-IL-4) delivered in a hyaluronic acid (HA)-based gel for localized application of IL-4 to dermal wounds in a type 2 diabetic mouse model known for poor healing as proof-of-concept for improved tissue repair. Our studies indicate that CBD-SA-IL-4 is retained within the wound and can modulate the wound microenvironment through induction of M2 macrophages and angiogenesis. CBD-SA-IL-4 treatment significantly accelerated wound healing compared to native IL-4 and HA vehicle treatment without inducing systemic side effects. This CBD-SA-IL-4 construct can address the underlying immune dysfunction present in the non-healing wound, leading to more effective tissue healing in the clinic.

Antibacterial and antioxidant double-layered nanofibrous mat promotes wound healing in diabetic rats

Diabetic wounds are problematic to heal owing to microbial infections as well as decreased proliferation and high concentrations of reactive oxygen species. In this study, a double-layered nanofibrous mat containing grape seed extract (GSE) and silver sulfadiazine (SSD) was fabricated. A synthetic biodegradable polymer, e.g., polycaprolactone (PCL), and a natural material (i.e., collagen) were employed as wound dressing substances. The results showed that GSE possesses antioxidant activity which can be helpful in reducing free radicals. The platform exhibited antibacterial activity against gram-positive and -negative bacteria. The double-layered nanofibrous mat containing GSE and SSD not only was not toxic but also amplified the cell proliferation compared to a pure mat, showing the effect of plant extract. After induction of a round wound, the animals were divided into three groups, namely (1) normal group (receiving + GSE/-GSE nanofiber), (2) diabetic group (receiving + GSE/-GSE nanofiber), and (3) control group (receiving gauze). In vivo evaluation demonstrated no significant differences in the healing process of normal rats. Surprisingly, fully repaired skin was observed on day 14 in the double-layered nanofibrous mat containing GSE in the normal and diabetic groups whereas the wound of diabetic rats treated with pure mat was not completely healed. The macroscopic and microscopic results after 14 days showed the following order in wound repair: Normal/ + GES > Diabetic/ + GSE > Normal/-GES > Diabetic/-GSE > control (with gauze) (p < 0.05). Accordingly, the double-layered nanofibrous mat containing GSE and SSD used in the present study could be considered as a suitable wound dressing in order to shorten healing time and prevent infection during the wound healing process.

Molecular mechanism of VEGF and its role in pathological angiogenesis

Over the last seven decades, a significant scientific contribution took place in the delineation of the implications of vascular endothelial-derived growth factor (VEGF) in the processes of angiogenesis. Under pathological conditions, mainly in response to hypoxia or ischemia, elevated VEGF levels promote vascular damage and the growth of abnormal blood vessels. Indeed, the development of VEGF biology has revolutionized our understanding of its role in pathological conditions. Hence, targeting VEGF or VEGF-mediated molecular pathways could be an excellent therapeutic strategy for managing cancers and intraocular neovascular disorders. Although anti-VEGF therapies, such as monoclonal antibodies and small-molecule tyrosine kinase inhibitors, have limited clinical efficacy, they can still significantly improve the overall survival rate. This thus demands further investigation through the development of alternative strategies in the management of VEGF-mediated pathological angiogenesis. This review article focuses on the recent developments toward the delineation of the functional biology of VEGF and the role of anti-VEGF strategies in the management of tumor and eye pathologies. Moreover, therapeutic angiogenesis, an exciting frontier for the treatment of ischemic disorders, is highlighted in this review, including wound healing.

Inhibition of CCL28/CCR10-Mediated eNOS Downregulation Improves Skin Wound Healing in the Obesity-Induced Mouse Model of Type 2 Diabetes

Chronic, nonhealing skin wounds, such as diabetic foot ulcers (DFUs), are common in patients with type 2 diabetes. Here, we investigated the role of chemokine (C-C motif) ligand 28 (CCL28) and its receptor C-C chemokine receptor type 10 (CCR10) in downregulation of endothelial nitric (NO) oxide synthase (eNOS) in association with delayed skin wound healing in the db/db mouse model of type 2 diabetes. We observed reduced eNOS expression and elevated CCL28/CCR10 levels in dorsal skin of db/db mice and subdermal leg biopsy specimens from human subjects with type 2 diabetes. Further interrogation revealed that overexpression of CCR10 reduced eNOS expression, NO bioavailability, and tube formation of human dermal microvascular endothelial cells (HDMVECs) in vitro, which was recapitulated in mouse dorsal skin. In addition, incubation of HDMVECs with CCL28 led to internalization of the CCR10/eNOS complex and colocalization with lysosome-associated membrane protein 1. Finally, topical application of myristoylated CCR10 binding domain 7 amino acid (Myr-CBD7) peptide prevented CCR10-eNOS interaction and subsequent eNOS downregulation, enhanced eNOS/NO levels, eNOS/VEGF-R2+ microvessel density, and blood perfusion, reduced inflammatory cytokine levels, and importantly, decreased wound healing time in db/db mice. Thus, endothelial cell CCR10 activation in genetically obese mice with type 2 diabetes promotes eNOS depletion and endothelial dysfunction, and targeted disruption of CCR10/eNOS interaction improves wound healing.

Angiogenic Effect of a Nanoniosomal Deferoxamine-Loaded Poly(vinyl alcohol)-Egg White Film as a Promising Wound Dressing

Owing to the noticeable increase in the number of patients with impaired wound healing capabilities, developing bioactive wound dressings with supportive physicomechanical and biological properties for clinical wound management has attracted much more attention nowadays. In this regard, engineered dressings with angiogenesis potential are vital for accelerated tissue regeneration. In the current study, nanoniosomal deferoxamine (DFO)-loaded transparent films of egg white-poly(vinyl alcohol) (PVA/EW/ND) were successfully fabricated at three different PVA/EW ratios (1:0, 1:1, and 1:1.5 wt/wt %) through the thin film hydration and solvent casting methods. The developed films' characterizations were carried out using scanning electron microscopy, Fourier transform infrared spectroscopy analysis, uniaxial tensile strength, water uptake, water vapor transmission rate, in vitro degradation, and drug release. The results demonstrated that the various weight ratios of PVA/EW have a significant effect on the microscopic morphology, equilibrium swelling, degradation, and mechanical properties of the films. The drug release profile exhibited a sustained release of DFO with controlled burst-lag phases resembling the Korsmeyer-Peppas pattern. The cytotoxicity and adhesion analysis using human dermal fibroblasts displays the biocompatibility of the developed PVA/EW/ND films and the formation of cellular colonies on the surface. The in vitro angiogenic capability of the developed films evaluated by the scratch wound assay and microbead-assisted tube formation study showed a significant increase in the rate of migration of human umbilical vein endothelial cells and in the number of tube-like structures. Therefore, the achieved results suggest that the presented PVA/EW/ND film has promising potential for effective wound healing applications.

Angiogenic Hydrogels to Accelerate Early Wound Healing

The metabolic disorder diabetes mellitus affects an increasing proportion of the population, a number projected to double by 2060. Non-life-threatening comorbidities contribute to an interrupted healing process which is first delayed, then prolonged, and associated with increased susceptibility to infection and sustained and unresolved inflammation. This leads to chronic non-healing wounds and eventually potential amputation of extremities. Here we examine the use of a bioactive angiogenic peptide-based hydrogel, SLan, to improve early wound healing in diabetic rats, and compare its performance to clinically utilized biosynthetic peptide-based materials such as Puramatrix. Streptozotocin-treated diabetic rats underwent 8 mm biopsy wounding in their dorsum to remove the epithelium, adipose tissues and muscle layer of the skin, and served as a model for diabetic wound healing. Wounds were treated with either Low (1w%) SLan, High (4w%) SLan, PBS, Puramatrix or K2 (an unfunctionalized non-bioactive control sequentially similar to SLan), covered with Tegaderm and monitored on days 0, 3, 7, 10, 14, 17, 21, 28; animals were sacrificed for histomorphic analyses and immunostaining. An LC/MS method developed to detect SLan in plasma allows pharmacokinetic analysis showing no trafficking of peptides from the wound site into the circulation. Low and High SLan groups show similar final outcomes of wound contraction as control groups (Puramatrix, PBS and K2). SLan-treated rats, however, show marked improvement in healing in earlier time points, including increased deposition of new mature blood vessels. Additionally, rats in the Low SLan treatment groups showed significantly improved wound contraction over other groups and significantly improved healing in early time points. Altogether our results suggest this material can be used to "jumpstart" the diabetic wound healing process. This article is protected by copyright. All rights reserved.

Molecular Mechanisms and Physiological Changes behind Benign Tracheal and Subglottic Stenosis in Adults

Laryngotracheal stenosis (LTS) is a complex and heterogeneous disease whose pathogenesis remains unclear. LTS is considered to be the result of aberrant wound-healing process that leads to fibrotic scarring, originating from different aetiology. Although iatrogenic aetiology is the main cause of subglottic or tracheal stenosis, also autoimmune and infectious diseases may be involved in causing LTS. Furthermore, fibrotic obstruction in the anatomic region under the glottis can also be diagnosed without apparent aetiology after a comprehensive workup; in this case, the pathological process is called idiopathic subglottic stenosis (iSGS). So far, the laryngotracheal scar resulting from airway injury due to different diseases was considered as inert tissue requiring surgical removal to restore airway patency. However, this assumption has recently been revised by regarding the tracheal scarring process as a fibroinflammatory event due to immunological alteration, similar to other fibrotic diseases. Recent acquisitions suggest that different factors, such as growth factors, cytokines, altered fibroblast function and genetic susceptibility, can all interact in a complex way leading to aberrant and fibrotic wound healing after an insult that acts as a trigger. However, also physiological derangement due to LTS could play a role in promoting dysregulated response to laryngo-tracheal mucosal injury, through biomechanical stress and mechanotransduction activation. The aim of this narrative review is to present the state-of-the-art knowledge regarding molecular mechanisms, as well as mechanical and physio-pathological features behind LTS.

ST2 deletion accelerates inflammatory-angiogenesis and remodeling in subcutaneous implants in mice

Implantation of biomedical/synthetic devices to replace and/or repair biological tissues very often induces an adverse healing response (scarce angiogenesis, excessive collagen deposition) which is detrimental to implant functionality and integration to host tissue. Interleukin-33/ST2 axis (IL-33/ST2) has been shown to modulate angiogenic and remodeling processes in several types of injuries. However, its effects on these processes after implantation of synthetic matrix have not been reported. Using synthetic matrix of polyether-polyurethane implanted subcutaneously in mice lacking ST2 receptor (ST2/KO), we characterized neovascularization and matrix remodeling in the fibrovascular tissue induced by the implants. Tissue accumulation was increased inside and around the implants in KO implants relative to the wild type (WT). More intense proliferative activity, using CDC 47 marker, was observed in KO implants compared with that of WT implants. Angiogenesis, using two endothelial cell markers, Von Willebrand Factor (VWF) and vascular endothelial cell VE cadherin and hemoglobin content, increased in implants of KO mice relative to control WT. Remodeling of the newly formed fibrovascular tissue (soluble collagen and PicroSirius Red-stained histological sections) showed predominance of type 1 collagen in ST2-KO implants versus type 3 in control implants. The number of positive cells for caspase-3, apoptotic marker, decreased in ST2 group. Our findings evidenced a role of IL-33/ST2 axis in restraining blood vessel formation and regulating the pattern of matrix remodeling in the fibrovascular tissue induced by synthetic implants. Intervention in this cytokine complex holds potential to accelerate integration of biomaterial and host tissue by improving blood supply and matrix remodeling.

Inhibition of Notch signaling pathway reduces angiogenesis in hypertrophic scar

OBJECTIVES

Hypertrophic scar (HS) is the most common pathological scar in clinical practice. During its formation, angiogenesis-related factors show dynamic expression. Modern studies have found that Notch signaling pathway has an extremely important role in maintaining the construction and remodeling of vascular endothelial cells and vascular network. The correlation between Notch signaling pathway and angiogenesis in hypertrophic scar has been rarely reported. This study aims to investigate correlation between Notch signaling pathway and the expression of angiogenic factors in a proliferative scar model.

METHODS

A total of 81 Sprague Dawley rats (SPF grade) were randomly assigned into a blank control group, a model group, and a blocker group. In the blocker group, a 2 cm diameter circular scald head was placed on the back of the rats for 10 s at 75 ℃ by using a constant temperature and pressure electrothermal scalding apparatus to form a rat deep II° burn model, and a hyperplastic scar model rat was obtained after natural healing of the wound skin (21 to 23 day epithelialization). A syringe was used to inject a needle from the normal skin around the scar at the 1st, 3rd, 5th, 7th, and 14th days after modeling. The γ-secretase inhibitor was injected locally at 2 mg/kg in a dilution of 0.1 mL at the base of the scar. The rats in the model group was injected with the same amount of saline after modeling; the rats in the blank control group was injected with the same amount of saline. Nine rats in each group was randomly killed by air embolization at the 21st, 28th, and 35th days, respectively. The protein expressions of collagen type I (COL-I) and collagen type III (COL-III) were detected by immunohistochemistry. The protein expressions of vascular endothelial growth factor (VEGF), angiopoietin 1 (Ang1), transforming growth factor-β1 (TGF-β1), and matrix metalloproteinase-2 (MMP-2) were detected by Western blotting.

RESULTS

Immunohistochemical results showed that, at the 21st,28th, and 35th days, the protein expressions of COL-I and COL-III in the model group were up-regulated compared with the blank control group (all P<0.05) and the protein expressions of COL-I and COL-III in the blocker group were decreased compared with the model group (all P<0.05). Western blotting showed that, at the 21st, 28th, and 35th days, the protein expressions of VEGF, Ang1, TGF-β1, and MMP-2 in the model group were significantly higher than those in the blank control group (all P<0.05). Except for the 21st day, the protein expressions of VEGF, Ang1, TGF-β1, and MMP-2 in the blocker group were lower than those in the model group at the 28th and 35th days (all P<0.05).

CONCLUSIONS

In the Sprague Dawley rat proliferative scar model, inhibition of Notch signaling pathway could attenuate the expressions of COL-I and COL-III, reduce traumatic scar proliferation, down-regulate the expressions of VEGF, Ang1, TGF-β1, and MMP-2, and inhibit angiogenesis. The expressions of angiogenesis-related factors appeare to be up-regulated during the formation of proliferative scar. When the Notch signaling pathway is inhibited, the up-regulated angiogenic factors show a decreasing trend and the proliferative scar is alleviated, which suggests that Notch signaling pathway may affect the formation of hyperplastic scar by regulating the expression of angiogenic factors.

The Potential Use of Cannabis in Tissue Fibrosis

Fibrosis is a condition characterized by thickening or/and scarring of various tissues. Fibrosis may develop in almost all tissues and organs, and it may be one of the leading causes of morbidity and mortality. It provokes excessive scarring that excels the usual wound healing response to trauma in numerous organs. Currently, very little can be done to prevent tissue fibrosis, and it is almost impossible to reverse it. Anti-inflammatory and immunosuppressive drugs are among the few treatments that may be efficient in preventing fibrosis. Numerous publications suggest that cannabinoids and extracts of Cannabis sativa have potent anti-inflammatory and anti-fibrogenic properties. In this review, we describe the types and mechanisms of fibrosis in various tissues and discuss various strategies for prevention and dealing with tissue fibrosis. We further introduce cannabinoids and their potential for the prevention and treatment of fibrosis, and therefore for extending healthy lifespan.

Oral wound healing models and emerging regenerative therapies

Following injury, the oral mucosa undergoes complex sequences of biological healing processes to restore homeostasis. While general similarities exist, there are marked differences in the genomics and kinetics of wound healing between the oral cavity and cutaneous epithelium. The lack of successful therapy for oral mucosal wounds has influenced clinicians to explore alternative treatments and potential autotherapies to enhance intraoral healing. The present in-depth review discusses current gold standards for oral mucosal wound healing and compares endogenous factors that dictate the quality of tissue remodeling. We conducted a review of the literature on in vivo oral wound healing models and emerging regenerative therapies published during the past twenty years. Studies were evaluated by injury models, therapy interventions, and outcome measures. The success of therapeutic approaches was assessed, and research outcomes were compared based on current hallmarks of oral wound healing. By leveraging therapeutic advancements, particularly within in cell-based biomaterials and immunoregulation, there is great potential for translational therapy in oral tissue regeneration.

The Role of miR-181c in Mechanisms of Diabetes-Impaired Angiogenesis: An Emerging Therapeutic Target for Diabetic Vascular Complications

Diabetes mellitus is estimated to affect up to 700 million people by the year 2045, contributing to an immense health and economic burden. People living with diabetes have a higher risk of developing numerous debilitating vascular complications, leading to an increased need for medical care, a reduced quality of life and increased risk of early death. Current treatments are not satisfactory for many patients who suffer from impaired angiogenesis in response to ischaemia, increasing their risk of ischaemic cardiovascular conditions. These vascular pathologies are characterised by endothelial dysfunction and abnormal angiogenesis, amongst a host of impaired signaling pathways. Therapeutic stimulation of angiogenesis holds promise for the treatment of diabetic vascular complications that stem from impaired ischaemic responses. However, despite significant effort and research, there are no established therapies that directly stimulate angiogenesis to improve ischaemic complications such as ischaemic heart disease and peripheral artery disease, highlighting the immense unmet need. However, despite significant effort and research, there are no established therapies that directly stimulate angiogenesis in a clinical setting, highlighting the immense unmet need. MicroRNAs (miRNAs) are emerging as powerful targets for multifaceted diseases including diabetes and cardiovascular disease. This review highlights the potential role of microRNAs as therapeutic targets for rescuing diabetes-impaired angiogenesis, with a specific focus on miR-181c, which we have previously identified as an important angiogenic regulator. Here we summarise the pathways currently known to be regulated by miR-181c, which include the classical angiogenesis pathways that are dysregulated in diabetes, mitochondrial function and axonal guidance, and describe how these relate both directly and indirectly to angiogenesis. The pleiotropic actions of miR-181c across multiple key angiogenic signaling pathways and critical cellular processes highlight its therapeutic potential as a novel target for treating diabetic vascular complications.

Evaluation of 4% stabilized Sodium Hypochlorite activity in the repair of cutaneous excisional wounds in mice

Wounds are conditions largely present in the clinical routine, and even though frequent, their complete resolution can be challenging. Several solutions can aid or stimulate the healing process, and for this reason, this work used a stabilized solution of 4% sodium hypochlorite for the treatment of excisional wounds in mice. This study was carried out in two distinct stages: in the first stage, the optimal concentration of the chlorinated solution was determined by using the sponge implantation technique in mouse subcutaneous tissue to evaluate the dose-response curve; and in the second phase, this concentration was tested in an experimental model of excisional skin wounds in mice. Soluble collagen, hemoglobin, myeloperoxidase (MPO) and N-acetyl-β-D-glycosaminidase (NAG) activity were assessed, and total, type I and type III collagen deposition were quantified in both stages. Based on the results presented in the sponge implantation study, the chlorinated solution at 150 ppm (0.015%) was chosen for use in a preclinical trial of skin healing in mice. At 1, 3, 7 and 14 days of treatment, the % wound area repair in the group treated with 150 ppm chlorinated solution was higher when compared to the control group, with statistical differences at all time points (*p≤ 0.05 and **p≤ 0.01). 150 ppm chlorinated solution obtained from a stabilized 4% sodium hypochlorite solution was effective in accelerating cutaneous excision wound repair in mice, showing a positive influence on tissue repair.

Mathematical Model Predicts that Acceleration of Diabetic Wound Healing is Dependent on Spatial Distribution of VEGF-A mRNA (AZD8601)

Introduction

Pharmacologic approaches for promoting angiogenesis have been utilized to accelerate healing of chronic wounds in diabetic patients with varying degrees of success. We hypothesize that the distribution of proangiogenic drugs in the wound area critically impacts the rate of closure of diabetic wounds. To evaluate this hypothesis, we developed a mathematical model that predicts how spatial distribution of VEGF-A produced by delivery of a modified mRNA (AZD8601) accelerates diabetic wound healing.

Methods

We modified a previously published model of cutaneous wound healing based on coupled partial differential equations that describe the density of sprouting capillary tips, chemoattractant concentration, and density of blood vessels in a circular wound. Key model parameters identified by a sensitivity analysis were fit to data obtained from an in vivo wound healing study performed in the dorsum of diabetic mice, and a pharmacokinetic model was used to simulate mRNA and VEGF-A distribution following injections with AZD8601. Due to the limited availability of data regarding the spatial distribution of AZD8601 in the wound bed, we performed simulations with perturbations to the location of injections and diffusion coefficient of mRNA to understand the impact of these spatial parameters on wound healing.

Results

When simulating injections delivered at the wound border, the model predicted that injections delivered on day 0 were more effective in accelerating wound healing than injections delivered at later time points. When the location of the injection was varied throughout the wound space, the model predicted that healing could be accelerated by delivering injections a distance of 1–2 mm inside the wound bed when compared to injections delivered on the same day at the wound border. Perturbations to the diffusivity of mRNA predicted that restricting diffusion of mRNA delayed wound healing by creating an accumulation of VEGF-A at the wound border. Alternatively, a high mRNA diffusivity had no effect on wound healing compared to a simulation with vehicle injection due to the rapid loss of mRNA at the wound border to surrounding tissue.

Conclusions

These findings highlight the critical need to consider the location of drug delivery and diffusivity of the drug, parameters not typically explored in pre-clinical experiments, when designing and testing drugs for treating diabetic wounds.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12195-021-00678-9.

Endoscopic endoclip papilloplasty preserves sphincter of oddi function

BACKGROUND

Endoscopic sphincterotomy (EST) can destroy sphincter of Oddi (SO) structure and function. The purpose of this study was to assess the feasibility of endoscopic endoclip papilloplasty (EEPP) in restoring SO function after EST.

METHODS

Seven 26-week-old domestic pigs were divided into control and EEPP groups. Necropsy and haematoxylin-eosin staining plus anti-α-smooth muscle actin (α-SMA) staining of papilla and sphincter of Oddi manometry (SOM) were conducted in animals at three independent time points.

RESULTS

EST and EEPP were safely performed in all 7 pigs without serious adverse events. For primary outcome, compared to the controls, EEPP generated smaller dilation and less inflammation. Fibrous repair of the papilla was observed at 24 weeks after EEPP. For secondary outcome, in the control group, SO basal pressure (17.25 ± 18.14 to 5.50 ± 0.71 mmHg), SO contraction amplitude (46.00 ± 19.20 to 34.50 ± 48.79 mmHg), peak (4.50 ± 4.04 to 1.50 ± 2.12) and frequency (3.05 ± 3.29 to 1.41 ± 2.19/min) were reduced after EST. Further reductions to almost 0 of these SOM parameters were observed 3 weeks later, including common bile duct pressure and SO contraction period. In contrast, in the EEPP group, these manometric data were recovered to pre-EST levels, including CBD pressure (11.5 ± 7.31 vs 11 ± 2.16 mmHg), SO pressure (17.50 ± 17.75 vs 18.20 ± 21.39 mmHg) and SO contraction amplitude (53.67 ± 21.54 vs 60.00 ± 36.08 mmHg). However, no significant differences were observed between control and EEPP groups by Student t test.

CONCLUSIONS

In this porcine study, EEPP accelerated and improved papillary healing after EST, further preserved SO function.

GPR43 regulates sodium butyrate-induced angiogenesis and matrix remodeling

Butyrate is a short-chain fatty acid (SCFA) derived from microbiota and is involved in a range of cell processes in a concentration-dependent manner. Low concentrations of sodium butyrate (NaBu) were shown to be proangiogenic. However, the mechanisms associated with these effects are not yet fully known. Here, we investigated the contribution of the SCFA receptor GPR43 in the proangiogenic effects of local treatment with NaBu and its effects on matrix remodeling using the sponge-induced fibrovascular tissue model in mice lacking the Gpr43 gene (Gpr43-KO) and the wild-type (WT) mice. We demonstrated that NaBu (0.2 mM intraimplant) treatment enhanced the neovascularization process, blood flow, and VEGF levels in a GPR43-dependent manner in the implants. Moreover, NaBu was able to modulate matrix remodeling aspects of the granulation tissue such as proteoglycan production, collagen deposition, and α-smooth muscle actin (α-SMA) expression in vivo, besides increasing transforming growth factor (TGF)-β1 levels in the fibrovascular tissue, in a GPR43-dependent manner. Interestingly, NaBu directly stimulated L929 murine fibroblast migration and TGF-β1 and collagen production in vitro. GPR43 was found to be expressed in human dermal fibroblasts, myofibroblasts, and endothelial cells. Overall, our findings evidence that the metabolite-sensing receptor GPR43 contributes to the effects of low dose of NaBu in inducing angiogenesis and matrix remodeling during granulation tissue formation. These data provide important insights for the proposition of new therapeutic approaches based on NaBu, beyond the highly explored intestinal, anti-inflammatory, and anticancer purposes, as a local treatment to improve tissue repair, particularly, by modulating granulation tissue components.NEW & NOTEWORTHY Our data show the contribution of the metabolite-sensing receptor GPR43 in the effects of low dose of sodium butyrate (NaBu) on stimulating angiogenesis and extracellular matrix remodeling in a model of granulation tissue formation in mice. We also show that human dermal fibroblasts, myofibroblasts, and endothelial cells express the receptor GPR43. These data provide important insights for the use of NaBu in local therapeutic approaches applicable to tissue repair in sites other than the intestine.

Synthetic peptide SVVYGLR upregulates cell motility and facilitates oral mucosal wound healing

Osteopontin-derived SVVYGLR (SV) 7-amino-acid sequence is a multifunctional and synthetic SV peptide implicated in angiogenesis, production of collagen III, and fibroblast differentiation into myofibroblasts. This study investigated the effect of the SV peptide on mucosal wound healing activity. Normal human-derived gingival fibroblasts (NHGF) and human oral mucosa keratinocytes (HOMK) were used for in vitro experiments. In addition, an oral punch wound was prepared at the buccal mucosa in male rats aged 11 weeks, and we evaluated the effect of local injection of SV peptide on wound healing. The synthetic SV peptide showed no influence on the proliferation and adhesion properties of NHGF and HOMK, but it enhanced the cell motility and migration activities. TGF-β1 receptor inhibitor, SB431542 or SB505124, substantially suppressed the SV peptide-induced migration activity, suggesting an involvement of TGF-β1 receptor activation. Furthermore, SV peptide accelerated the healing process of an in vivo oral wound model, compared with control groups. Further immunohistological staining of wound tissue revealed that an increase in capillary growth and the greater number of fibroblasts and myofibroblasts that migrated into the wound area might contribute to the facilitation of the healing process produced by the SV peptide. The SV peptide has beneficial effects on oral wound healing through enhancement of the earlier phase consisting of angiogenesis and remodeling with granulation tissue. The synthetic SV peptide can be a useful treatment option, particularly for intractable mucosal wounds caused by trauma or surgery for progressive lesions such as oral cancer.

Skin wound healing assisted by angiogenic targeted tissue engineering: A comprehensive review of bioengineered approaches

Skin injuries and in particular, chronic wounds, are one of the major prevalent medical problems, worldwide. Due to the pivotal role of angiogenesis in tissue regeneration, impaired angiogenesis can cause several complications during the wound healing process and skin regeneration. Therefore, induction or promotion of angiogenesis can be considered as a promising approach to accelerate wound healing. This article presents a comprehensive overview of current and emerging angiogenesis induction methods applied in several studies for skin regeneration, which are classified into the cell, growth factor, scaffold, and biological/chemical compound-based strategies. In addition, the advantages and disadvantages of these angiogenic strategies along with related research examples are discussed in order to demonstrate their potential in the treatment of wounds.

Allicin can suppress the activity of vascular endothelial cells probably by regulating JAK2/STAT3 pathway

Whether allicin can suppress the angiogenesis via inhibiting the activity of vascular endothelial cells (VECs) in preventing epidural hypertrophic scars remains unknown. VECs were treated by allicin at a gradient of concentrations. Cell activity was measured by CCK-8 assay, scratch assay and flow cytometry. Reverse-transcription PCR and Western Blot were used to measure the expression levels of relevant genes and proteins. After treated with allicin at concentrations of 0, 25, 50 and 100 mg/L, the viability of VECs significantly decreased at 24 h (p < 0.001*) and 48 h (p < 0.001*), and migration rate significantly decreased in scratch assay (p = 0.017*) and in Transwell assay (p = 0.021*). As the concentrations of allicin increased, the apoptosis rate of VECs rose up (p = 0.018*). There was no significant difference on cell numbers at S phase (p = 0.25), but cell numbers at G1 phase decreased (p = 0.039*) and at G2 phase increased (p = 0.047*). With the increase of allicin concentrations, the ability of tube formation for VECs significantly decreased (p < 0.001*). Comparing with control group, the expression of PCNA and BCL-2 decreased (p < 0.001*), while the expression of BAX increased significantly (p < 0.001*). Regarding to JAK2/STAT3 pathway, the expression levels of JAK3 and STAT3 decreased significantly with the increase of allicin concentrations (p < 0.001*). Allicin can suppress the activity of VECs probably by regulating JAK2/STAT3 pathway.

Ticks and the effects of their saliva on growth factors involved in skin wound healing

Ticks are unique hematophagous arthropods and possess an astounding array of salivary molecules that ensure their unnoticed and prolonged attachment to the host skin. Furthermore, ticks are very effective vectors of a diverse spectrum of pathogens. In order to feed, tick chelicerae cut the host epidermis and their hypostome penetrates through the layers of the skin. As a result of laceration of the skin and rupturing blood vessels, a pool of blood is formed in the dermis, serving for intermittent blood sucking and secretion of saliva. Cutaneous injury caused by tick mouthparts should normally elicit wound healing, a complex biological process coordinated by interaction among different host cells, numerous signalling pathways and by a variety of soluble factors including growth factors. Growth factors, endogenous signalling proteins involved in various biological events, are key players in all phases of the skin repair process. Maintaining feeding site integrity by overcoming sequential phases of wound healing is particularly important for ixodid ticks and is governed by bioactive molecules in their saliva. Tick saliva is a complex mixture of proteins, peptides, and non-peptide molecules and its composition depends on the feeding phase, tick developmental stage, gender and/or the presence/absence of microbial agents. In addition to already demonstrated anti-haemostatic, anti-cytokine and anti-chemokine activities, anti-growth factors activities were also detected in saliva of some tick species. In consequence of counteracting host defences by ticks, tick-borne pathogens can be transmitted to and disseminated in the host. Elucidation of the complex interplay between ticks - pathogens - host cutaneous immunity could lead to improved vector and pathogens control strategies. Additionally, tick saliva bioactive molecules have a promising therapeutic perspective to cure some human diseases associated with dysregulation of specific cytokines/growth factors and alterations in their signalling pathways.

CCL28-induced CCR10/eNOS interaction in angiogenesis and skin wound healing

Chemokines and their receptors play important roles in vascular homeostasis, development, and angiogenesis. Little is known regarding the molecular signaling mechanisms activated by CCL28 chemokine via its primary receptor CCR10 in endothelial cells (ECs). Here, we test the hypothesis that CCL28/CCR10 signaling plays an important role in regulating skin wound angiogenesis through endothelial nitric oxide synthase (eNOS)-dependent Src, PI3K, and MAPK signaling. We observed nitric oxide (NO) production in human primary ECs stimulated with exogenous CCL28, which also induced direct binding of CCR10 and eNOS resulting in inhibition of eNOS activity. Knockdown of CCR10 with siRNA lead to reduced eNOS expression and tube formation suggesting the involvement of CCR10 in EC angiogenesis. Based on this interaction, we engineered a myristoylated 7 amino acid CCR10-binding domain (Myr-CBD7) peptide and showed that this can block eNOS interaction with CCR10, but not with calmodulin, resulting in upregulation of eNOS activity. Importantly, topical administration of Myr-CBD7 peptide on mouse dermal wounds not only blocked CCR10-eNOS interaction, but also enhanced expression of eNOS, CD31, and IL-4 with reduction of CCL28 and IL-6 levels associated with improved wound healing. These results point to a potential therapeutic strategy to upregulate NO bioavailability, enhance angiogenesis, and improve wound healing by disrupting CCL28-activated CCR10-eNOS interaction.

Optimized Modeled Myofascial Release Enhances Wound Healing in 3-Dimensional Bioengineered Tendons: Key Roles for Fibroblast Proliferation and Collagen Remodeling

OBJECTIVE

The purpose of this study was to evaluate the mechanisms of action of optimized myofascial release (MFR) on wound healing using a 3-dimensional human tissue construct.

METHODS

Bioengineered tendons were cultured on a deformable matrix, wounded using a steel cutting tip, then strained in an acyclic manner with a modeled MFR paradigm at 103% magnitude for 5 minutes. Imaging and measurements of the width and wound size were performed daily, and the average tissue width of the entire bioengineered tendon was measured, and wound size and major and minor axes of the elliptical wound were additionally measured. Assessments of actin and collagen were performed by immunofluorescence, and Gomori's trichrome staining and fibroblast nuclei deposition was quantified using the CellProfiler analysis software.

RESULTS

Optimized modeled MFR treatment significantly reduced the wound size and increased both collagen density and cell deposition at the wound site. All measures of wound healing improvements required the presence of proliferating fibroblasts.

CONCLUSION

Myofascial release-induced cell deposition and collagen density at wound sites required actively proliferating fibroblasts. If clinically translatable, our results support a mechanism by which MFR improves patient wound healing.

Limiting angiogenesis to modulate scar formation

Angiogenesis, the process of new blood vessel formation from existing blood vessels, is a key aspect of virtually every repair process. During wound healing an extensive, but immature and leaky vascular plexus forms which is subsequently reduced by regression of non-functional vessels. More recent studies indicate that uncontrolled vessel growth or impaired vessel regression as a consequence of an excessive inflammatory response can impair wound healing, resulting in scarring and dysfunction. However, in order to elucidate targetable factors to promote functional tissue regeneration we need to understand the molecular and cellular underpinnings of physiological angiogenesis, ranging from induction to resolution of blood vessels. Especially for avascular tissues (e.g. cornea, tendon, ligament, cartilage, etc.), limiting rather than boosting vessel growth during wound repair potentially is beneficial to restore full tissue function and may result in favourable long-term healing outcomes.

Predictive Approach Identifies Molecular Targets and Interventions to Restore Angiogenesis in Wounds With Delayed Healing

Impaired angiogenesis is a hallmark of wounds with delayed healing, and currently used therapies to restore angiogenesis have limited efficacy. Here, we employ a computational simulation-based approach to identify influential molecular and cellular processes, as well as protein targets, whose modulation may stimulate angiogenesis in wounds. We developed a mathematical model that captures the time courses for platelets, 9 cell types, 29 proteins, and oxygen, which are involved in inflammation, proliferation, and angiogenesis during wound healing. We validated our model using previously published experimental data. By performing global sensitivity analysis on thousands of simulated wound-healing scenarios, we identified six processes (among the 133 modeled in total) whose modulation may improve angiogenesis in wounds. By simulating knockouts of 25 modeled proteins and by simulating different wound-oxygenation levels, we identified four proteins [namely, transforming growth factor (TGF)-β, vascular endothelial growth factor (VEGF), fibroblast growth factor-2 (FGF-2), and angiopoietin-2 (ANG-2)], as well as oxygen, as therapeutic targets for stimulating angiogenesis in wounds. Our modeling results indicated that simultaneous inhibition of TGF-β and supplementation of either FGF-2 or ANG-2 could be more effective in stimulating wound angiogenesis than the modulation of either protein alone. Our findings suggest experimentally testable intervention strategies to restore angiogenesis in wounds with delayed healing.

Establishment of a three-dimensional model to study human uterine angiogenesis

STUDY QUESTION

Can primary human uterine microvascular endothelial cells (UtMVECs) be used as a model to study uterine angiogenic responses in vitro that are relevant in pregnancy?

SUMMARY ANSWER

UtMVECs demonstrated angiogenic responses when stimulated with proangiogenic factors, including sphingosine 1-phosphate (S1P), vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), physiological levels of wall shear stress (WSS), human chorionic gonadotropin (hCG) and various combinations of estrogen and progesterone.

WHAT IS KNOWN ALREADY

During sprouting angiogenesis, signaling from growth factors and cytokines induces a monolayer of quiescent endothelial cells (ECs) lining the vasculature to degrade the extracellular matrix and invade the surrounding tissue to form new capillaries. During pregnancy and the female reproductive cycle, the uterine endothelium becomes activated and undergoes sprouting angiogenesis to increase the size and number of blood vessels in the endometrium.

STUDY DESIGN, SIZE, DURATION

The study was designed to examine the angiogenic potential of primary human UtMVECs using the well-characterized human umbilical vein EC (HUVEC) line as a control to compare angiogenic potential. ECs were seeded onto three-dimensional (3D) collagen matrices, supplemented with known proangiogenic stimuli relevant to pregnancy and allowed to invade for 24 h. Sprouting responses were analyzed using manual and automated methods for quantification.

PARTICIPANTS/MATERIALS, SETTING, METHODS

RT-PCR, Western blot analysis and immunostaining were used to characterize UtMVECs. Angiogenic responses were examined using 3D invasion assays. Western blotting was used to confirm signaling responses after proangiogenic lipid, pharmacological inhibitor, and recombinant lentiviral treatments. All experiments were repeated at least three times.

MAIN RESULTS AND THE ROLE OF CHANCE

After ensuring that UtMVECs expressed the proper endothelial markers, we found that UtMVECs invade 3D collagen matrices dose-dependently in response to known proangiogenic stimuli (e.g. S1P, VEGF, bFGF, hCG, estrogen, progesterone and WSS) present during early pregnancy. Invasion responses were positively correlated with phosphorylation of phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) and p42/p44 mitogen-activated protein kinase (ERK). Inhibition of these second messengers significantly impaired sprouting (P < 0.01). Gene silencing of membrane type 1-matrix metalloproteinase using multiple approaches completely abrogated sprouting (P < 0.001). Finally, UtMVECs displayed a unique ability to undergo sprouting in response to hCG, and combined estrogen and progesterone treatment.

LARGE SCALE DATA

Not applicable.

LIMITATIONS, REASONS FOR CAUTION

The study of uterine angiogenesis in vitro has limitations and any findings many not fully represent the in vivo state. However, these experiments do provide evidence for the ability of UtMVECs to be used in functional sprouting assays in a 3D environment, stimulated by physiological factors that are produced locally within the uterus during early pregnancy.

WIDER IMPLICATIONS OF THE FINDINGS

We show that UtMVECs can be used reliably to investigate how growth factors, hormones, lipids and other factors, such as flow, affect angiogenesis in the uterus.

STUDY FUNDING/COMPETING INTERESTS

This work was supported by NIH award HL095786 to K.J.B. The authors have no conflicts of interest.

An In Vitro Model of Angiogenesis during Wound Healing Provides Insights into the Complex Role of Cells and Factors in the Inflammatory and Proliferation Phase

Successful vascularization is essential in wound healing, the histo-integration of biomaterials, and other aspects of regenerative medicine. We developed a functional in vitro assay to dissect the complex processes directing angiogenesis during wound healing, whereby vascular cell spheroids were induced to sprout in the presence of classically (M1) or alternatively (M2) activated macrophages. This simulated a microenvironment, in which sprouting cells were exposed to the inflammatory or proliferation phases of wound healing, respectively. We showed that M1 macrophages induced single-cell migration of endothelial cells and pericytes. In contrast, M2 macrophages augmented endothelial sprouting, suggesting that vascular cells infiltrate the wound bed during the inflammatory phase and extensive angiogenesis is initiated upon a switch to a predominance of M2. Interestingly, M1 and M2 shared a pro-angiogenic secretome, whereas pro-inflammatory cytokines were solely secreted by M1. These results suggested that acute inflammatory factors act as key inducers of vascular cell infiltration and as key negative regulators of angiogenesis, whereas pro-angiogenic factors are present throughout early wound healing. This points to inflammatory factors as key targets to modulate angiogenesis. The here-established wound healing assay represents a useful tool to investigate the effect of biomaterials and factors on angiogenesis during wound healing.

Effects of the antagomiRs 15b and 200b on the altered healing pattern of diabetic mice

BACKGROUND AND PURPOSE

Diabetic patients with non-healing ulcers have a reduced expression of VEGF. Genetically diabetic mice have an altered expression pattern of VEGF and its receptor, VEGF receptor 2 (VEGFR-2). In diabetic wounds, the microRNAs, miR15b and miR200b, which respectively inhibit VEGF and VEGF-R2 mRNAs, are up-regulated, further affecting the impaired angiogenesis. We investigated whether anti-miRs directed toward miR15b and miR200b could improve wound repair in genetically diabetic mice.

EXPERIMENTAL APPROACH

Skin wounds were produced on the backs of female diabetic mice. The anti-miRs (antimiR15b, antimiR200b or antimiR15b/200b) at 10 mg·kg^-1 , or vehicle were applied to the wound edge. Mice were killed on days 7, 14 and at time of complete wound closure. Levels of mRNA and protein of angiogenic mediators and their receptors were measured with RT-qPCR and Western blotting. Wounds were examined by histological and immunochemical methods.

KEY RESULTS

mRNA expression of VEGF, VEGFR-2, angiopoietin-1 and its receptor TEK were evaluated after 7 and 14 days. Protein levels of VEGF and transglutaminase II were measured at day 7, while VEGFR-2 and Angiopoietin-1 were measured at day 14. Histological features and the time to achieve a complete wound closure were also examined. Treatment with the anti-miRs improved the analysed parameters and the co-treatment resulted the most effective.

CONCLUSION AND IMPLICATIONS

The results suggest that the inhibition of miR15b and miR200b may have a potential application in diabetes-related wound disorders.

Ts14 from Tityus serrulatus boosts angiogenesis and attenuates inflammation and collagen deposition in sponge-induced granulation tissue in mice

We have previously described a 25mer anti-hypertensive peptide, previously named TsHpt-I (Tityus serrulatus Hypotensin-I), now Ts14, as an agonist of B2 kinin receptor. Bradykinin is known to play physiological roles in angiogenic, inflammatory, and fibrogenic processes, mostly mediated by B2 receptor. Therefore, we investigated whether Ts14 could modulate key events (neovascularization, inflammatory cell recruitment, and extracellular matrix deposition) of the fibrovascular tissue, induced by polyether-polyurethane sponge implants in mice. Sponges were implanted in the dorsum of 7-week-old C57Bl/6 male mice that received daily intrasponge treatment with Ts14 (27.25μg/sponge/day in 10μL PBS) or vehicle (10μL PBS/sponge/day) and were assessed on day 7 after surgery. Hemoglobin content, blood flow (laser Doppler perfusion imaging), and VEGF levels in the implants, used as indices of vascularization, indicated that Ts14 enhanced angiogenesis in implants relative to the PBS-treated group. Interestingly, Ts14 reduced TNF-α levels and neutrophil infiltration, although stimulated macrophage infiltration into implants, as determined by myeloperoxidase (MPO) and N-acetyl-β-d-glucosaminidase (NAG) enzyme activities, respectively. Regarding the fibrogenic component (soluble collagen content and Sirius-red histological staining), we observed that Ts14 inhibited collagen deposition in the implants. Overall, our results suggest that Ts14 exerts proangiogenic, anti-inflammatory, and anti-fibrogenic activities. These effects may indicate a therapeutical potential of this peptide in conditions where angiogenesis, inflammation, and fibrogenesis contribute to disease progression and chronicity.

Fibroblasts: Diverse Cells Critical to Biomaterials Integration

Fibroblasts are key participants in wound healing and inflammation, and are capable of driving the progression of tissue repair to fully functional tissue or pathologic scar, or fibrosis, depending on the specific mechanical and biochemical cues with which they are presented. Thus, understanding and modulating the fibroblastic response to implanted materials is paramount to achieving desirable outcomes, such as long-term implant function or tissue regeneration. However, fibroblasts are remarkably heterogeneous and can differ vastly in their contributions to regeneration and fibrosis. This heterogeneity exists between tissues and within tissues, down to the level of individual cells. This review will discuss the role of fibroblasts, the pitfalls of describing them as a collective, the specifics of their function, and potential future directions to better understand and organize their highly variable biology.

Chromolaena odorata: A neglected weed with a wide spectrum of pharmacological activities (Review)

The study of wound‑healing plants has acquired an interdisciplinary nature with a systematic investigational approach. Several biochemicals are involved in the healing process of the body, including antioxidants and cytokines. Although several pharmaceutical preparations and formulations are available for wound care and management, it remains necessary to search for efficacious treatments, as certain current formulations cause adverse effects or lack efficacy. Phytochemicals or biomarkers from numerous plants suggest they have positive effects on different stages of the wound healing process via various mechanisms. Several herbal medicines have displayed marked activity in the management of wounds and various natural compounds have verified in vivo wound healing potential, and can, therefore, be considered as potential drugs of natural origin. Chromolaena odorata (L.) R.M. King and H. Robinson is considered a tropical weed. However, it exhibits anti‑inflammatory, antipyretic, analgesic, antimicrobial, cytotoxic and numerous other relevant medicinal properties on an appreciable scale, and is known in some parts of the world as a traditional medicine used to treat various ailments. To understand its specific role as nature's gift for healing wounds and its contribution to affordable healthcare, this plant must be scientifically assessed based on the available literature. This review aims to summarize the role of C. odorata and its biomarkers in the wound healing activities of biological systems, which are crucial to its potential future drug design, development and application for the treatment of wounds.

5-Aminolaevulinic Acid-Based Photodynamic Therapy Restrains Pathological Hyperplasia of Fibroblasts

Background

This study aimed to explore whether 5-aminolaevulinic acid-based photodynamic therapy (ALA-PDT) restrains pathological hyperplasia of fibroblasts from hyperplastic scar tissues, and to investigate the potential mechanism.

Material/Methods

We used MTT assay, flow cytometry, and terminal-deoxynucleotidyl transferase mediated nick-end labeling (TUNEL) to examine the effects of ALA-PDT on proliferation, cell cycle, and apoptosis of fibroblasts isolated from hyperplastic scar tissues. The growth-promoting effect of fibroblasts on vascular endothelial cells was measured by cell co-culture. Real-time PCR and Western blot analysis were performed to detect the expression levels of transforming growth factor-β1 (TGF-β1), α-smooth muscle actin (α-SMA), Collagen I, Collagen III, vascular endothelial growth factor-A (VEGFA), and basic fibroblast growth factor (bFGF).

Results

ALA-PDT inhibited proliferation delayed cell cycle progress, promoted apoptosis of fibroblasts, and suppressed its growth-promoting effect on vascular endothelial cells, and decreased expression of TGF-β1, α-SMA, Collagen I, Collagen III, VEGFA, and bFGF.

Conclusions

ALA-PDT effectively restrained pathological hyperplasia of fibroblasts from hyperplastic scar tissues, which may provide a research basis for clinical therapy of hyperplastic scars.

A Comparative Study of Three Different Types of Stem Cells for Treatment of Rat Spinal Cord Injury

Three different sources of human stem cells-bone marrow-derived mesenchymal stem cells (BM-MSCs), neural progenitors (NPs) derived from immortalized spinal fetal cell line (SPC-01), and induced pluripotent stem cells (iPSCs)-were compared in the treatment of a balloon-induced spinal cord compression lesion in rats. One week after lesioning, the rats received either BM-MSCs (intrathecally) or NPs (SPC-01 cells or iPSC-NPs, both intraspinally), or saline. The rats were assessed for their locomotor skills (BBB, flat beam test, and rotarod). Morphometric analyses of spared white and gray matter, axonal sprouting, and glial scar formation, as well as qPCR and Luminex assay, were conducted to detect endogenous gene expression, while inflammatory cytokine levels were performed to evaluate the host tissue response to stem cell therapy. The highest locomotor recovery was observed in iPSC-NP-grafted animals, which also displayed the highest amount of preserved white and gray matter. Grafted iPSC-NPs and SPC-01 cells significantly increased the number of growth-associated protein 43 (GAP43+) axons, reduced astrogliosis, downregulated Casp3 expression, and increased IL-6 and IL-12 levels. hMSCs transiently decreased levels of inflammatory IL-2 and TNF-α. These findings correlate with the short survival of hMSCs, while NPs survived for 2 months and matured slowly into glia- and tissue-specific neuronal precursors. SPC-01 cells differentiated more in astroglial phenotypes with a dense structure of the implant, whereas iPSC-NPs displayed a more neuronal phenotype with a loose structure of the graft. We concluded that the BBB scores of iPSC-NP- and hMSC-injected rats were superior to the SPC-01-treated group. The iPSC-NP treatment of spinal cord injury (SCI) provided the highest recovery of locomotor function due to robust graft survival and its effect on tissue sparing, reduction of glial scarring, and increased axonal sprouting.

Esophageal anastomosis - how the granulation phase of wound healing improves the incidence of anastomotic leakage

A two-stage esophagectomy with an interval for reconstruction of the esophagus creates an opportunity for the esophageal stump to recover from vessel injury and allows the formation of granulation tissue rich in proangiogenic factors, including transforming growth factor β (TGF-β) and vascular endothelial growth factor A (VEGF-A), which may have an impact on anastomosis healing. The present study comprised 25 patients (27 in total, 2 succumbed to complications following surgery) who underwent two-stage esophagectomy for squamous cell carcinoma in the Department of Gastrointestinal and General Surgery, Wrocław Medical University (Wrocław, Poland) between January 2007 and December 2012. Immunohistochemical staining for VEGF-A and TGF-β was performed to evaluate esophageal wall specimens at the time of esophagostomy construction and prior to anastomosis, in which the cervical esophagus was connected with the colon or ileum. At the time of reconstructive surgery, a significant increase in microvessel density was observed in all esophageal specimens (P<0.03). Significant differences were also identified in the immunohistochemical staining intensity of TGF-β and VEGF-A in the epithelium of all esophageal specimens between biopsies obtained from normal esophageal tissues at the time of esophagectomy and during reconstructive surgery. Delayed anastomosis construction provides an advantage for the esophageal stump to accumulate proangiogenic growth factors, which overlap with the subsequent proliferative stage of the anastomosed tissue and thus supports its recovery, creating an optimal environment for the healing of any fistulas.

Maggot debridement therapy promotes diabetic foot wound healing by up-regulating endothelial cell activity

To determine the role of maggot debridement therapy (MDT) on diabetic foot wound healing, we compared growth related factors in wounds before and after treatment. Furthermore, we utilized human umbilical vein endothelial cells (HUVECs) to explore responses to maggot excretions/secretions on markers of angiogenesis and proliferation. The results showed that there was neo-granulation and angiogenesis in diabetic foot wounds after MDT. Moreover, significant elevation in CD34 and CD68 levels was also observed in treated wounds. In vitro, ES increased HUVEC proliferation, improved tube formation, and increased expression of vascular endothelial growth factor receptor 2 in a dose dependent manner. These results demonstrate that MDT and maggot ES can promote diabetic foot wound healing by up-regulating endothelial cell activity.

Complement Activation in Placental Malaria

Sixty percent of all pregnancies worldwide occur in malaria endemic regions. Pregnant women are at greater risk of malaria infection than their non-pregnant counterparts and have a higher risk of adverse birth outcomes including low birth weight resulting from intrauterine growth restriction and/or preterm birth. The complement system plays an essential role in placental and fetal development as well as the host innate immune response to malaria infection. Excessive or dysregulated complement activation has been associated with the pathobiology of severe malaria and with poor pregnancy outcomes, dependent and independent of infection. Here we review the role of complement in malaria and pregnancy and discuss its part in mediating altered placental angiogenesis, malaria-induced adverse birth outcomes, and disruptions to the in utero environment with possible consequences on fetal neurodevelopment. A detailed understanding of the mechanisms underlying adverse birth outcomes, and the impact of maternal malaria infection on fetal neurodevelopment, may lead to biomarkers to identify at-risk pregnancies and novel therapeutic interventions to prevent these complications.

Bone morphogenetic proteins in tumour associated angiogenesis and implication in cancer therapies

Bone morphogenetic protein (BMP) belongs to transforming growth factor-β superfamily. To date, more than 20 BMPs have been identified in humans. BMPs play a critical role in embryonic and postnatal development, and also in maintaining homeostasis in different organs and tissues by regulating cell differentiation, proliferation, survival and motility. They play important roles in the development and progression of certain malignancies, including prostate cancer, breast cancer, lung cancer, etc. Recently, more evidence shows that BMPs are also involved in tumour associated angiogenesis. For example BMP can either directly regulate the functions of vascular endothelial cells or indirectly influence the angiogenesis via regulation of angiogenic factors, such as vascular endothelial growth factor (VEGF). Such crosstalk can also be reflected in the interaction with other angiogenic factors, like hepatocyte growth factor (HGF) and basic fibroblast growth factor (bFGF). All these factors are involved in the orchestration of the angiogenic process during tumour development and progression. Review of the relevant studies will provide a comprehensive prospective on current understanding and shed light on the corresponding therapeutic opportunity.

Leukocytes: The Double-Edged Sword in Fibrosis

Skin tissue scar formation and fibrosis are often characterized by the increased production and deposition of extracellular matrix components, accompanied by the accumulation of a vast number of myofibroblasts. Scaring is strongly associated with inflammation and wound healing to regain tissue integrity in response to skin tissue injury. However, increased and uncontrolled inflammation, repetitive injury, and individual predisposition might lead to fibrosis, a severe disorder resulting in the formation of dense and stiff tissue that loses the physical properties and physiological functions of normal tissue. Fibrosis is an extremely complicated and multistage process in which bone marrow-derived leukocytes act as both pro- and antifibrotic agents, and therefore, few, if any, effective therapies are available for the most severe and lethal forms of fibrosis. Herein, we discuss the current knowledge on the multidimensional impact of leukocytes on the induction of fibrosis, focusing on skin fibrosis.

Topical fentanyl stimulates healing of ischemic wounds in diabetic rats

BACKGROUND

Topically applied opioids promote angiogenesis and healing of ischemic wounds in rats. We examined if topical fentanyl stimulates wound healing in diabetic rats by stimulating growth-promoting signaling, angiogenesis, lymphangiogenesis and nerve regeneration.

METHODS

We used Zucker diabetic fatty rats that develop obesity and diabetes on a high fat diet due to a mutation in the Leptin receptor. Fentanyl blended with hydrocream was applied topically on ischemic wounds twice daily, and wound closure was analyzed regularly. Wound histology was analyzed by hematoxylin and eosin staining. Angiogenesis, lymphangiogenesis, nerve fibers and phospho-platelet derived growth factor receptor-β (PDGFR-β) were visualized by CD31-, lymphatic vessel endothelium-1, protein gene product 9.5- and anti-phospho PDGFR-β-immunoreactivity, respectively. Nitric oxide synthase (NOS) and PDGFR-β signaling were analyzed using Western immunoblotting.

RESULTS

Fentanyl significantly promoted wound closure as compared to phosphate-buffered saline (PBS). Histology scores were significantly higher in fentanyl-treated wounds, indicative of increased granulation tissue formation, reduced edema and inflammation, and increased matrix deposition. Fentanyl treatment resulted in increased wound angiogenesis, lymphatic vasculature, nerve fibers, nitric oxide, NOS and PDGFR-β signaling as compared to PBS. Phospho-PDGFR-β co-localized with CD31 co-staining for vasculature.

CONCLUSIONS

Topically applied fentanyl promotes closure of ischemic wounds in diabetic rats. Increased angiogenesis, lymphangiogenesis, peripheral nerve regeneration, NO and PDGFR-β signaling are associated with fentanyl-induced tissue remodeling and wound healing.

Post-transcriptional control of Amblyomin-X on secretion of vascular endothelial growth factor and expression of adhesion molecules in endothelial cells

Angiogenesis is a pivotal process of homeostasis and tissue repair, but it also favours neovascularisation syndromes and cancer nutrition. The chemical mediation of angiogenesis is complex, involving a balance between serine proteases and their inhibitors. We addressed the mechanisms of action of a Kunitz serine protease inhibitor (KPI) on spontaneous angiogenesis, using Amblyomin-X, a KPI designed from the cDNA library of the Amblyomma cajennense tick. Amblyomin-X treatment (10-1000 ng/10 μL; each 48 h; 3 times) reduced the number of vessels in the subcutaneous dorsal tissue of male Swiss mice, as measured by intravital microscopy, haematoxylin-eosin staining, and PECAM-1 immunofluorescence labeling. Incubation of Amblyomin-X with t-End endothelial cells, a murine endothelial microvascular lineage, did not alter cell proliferation, cell-cycle phases, necrosis and apoptosis, and the production of nitric oxide and prostaglandin E2. Nevertheless, Amblyomin-X treatment reduced t-End migration and adhesion to Matrigel(®), and inhibited the VEGF-A secretion and VCAM-1 and β3 integrin expressions by posttranscriptional pathways. Together, data herein outline novel posttranscriptional mechanisms of KPIs on endothelial cells during angiogenesis and point out the possible application of Amblyomin-X as a local inhibitor to undesired neovascularisation process.

FKBPL is a critical antiangiogenic regulator of developmental and pathological angiogenesis

OBJECTIVE

The antitumor effects of FK506-binding protein like (FKBPL) and its extracellular role in angiogenesis are well characterized; however, its role in physiological/developmental angiogenesis and the effect of FKBPL ablation has not been evaluated. This is important as effects of some angiogenic proteins are dosage dependent. Here we evaluate the regulation of FKBPL secretion under angiogenic stimuli, as well as the effect of FKBPL ablation in angiogenesis using mouse and zebrafish models.

APPROACH AND RESULTS

FKBPL is secreted maximally by human microvascular endothelial cells and fibroblasts, and this was specifically downregulated by proangiogenic hypoxic signals, but not by the angiogenic cytokines, VEGF or IL8. FKBPL's critical role in angiogenesis was supported by our inability to generate an Fkbpl knockout mouse, with embryonic lethality occurring before E8.5. However, whilst Fkbpl heterozygotic embryos showed some vasculature irregularities, the mice developed normally. In murine angiogenesis models, including the ex vivo aortic ring assay, in vivo sponge assay, and tumor growth assay, Fkbpl(+/-) mice exhibited increased sprouting, enhanced vessel recruitment, and faster tumor growth, respectively, supporting the antiangiogenic function of FKBPL. In zebrafish, knockdown of zFkbpl using morpholinos disrupted the vasculature, and the phenotype was rescued with hFKBPL. Interestingly, this vessel disruption was ineffective when zcd44 was knocked-down, supporting the dependency of zFkbpl on zCd44 in zebrafish.

CONCLUSIONS

FKBPL is an important regulator of angiogenesis, having an essential role in murine and zebrafish blood vessel development. Mouse models of angiogenesis demonstrated a proangiogenic phenotype in Fkbpl heterozygotes.

Chitosan-aluminum monostearate composite sponge dressing containing asiaticoside for wound healing and angiogenesis promotion in chronic wound

There are many factors that delay healing in chronic wounds including lowering level of growth factors and increasing exudate level comprising high amount of tissue destructive enzymes. Asiaticoside possesses interesting wound healing and angiogenic activities that are employed to stimulate tissue regeneration in wound healing application. This study attempted to develop chitosan-aluminum monostearate (Alst) composite sponge containing asiaticoside for use as an absorbent medical dressing in chronic wound. N-methyl-2-pyrrolidone (NMP) was used to enhance homogeneity of asiaticoside in the polymer composite matrix. The sponge dressings were prepared by lyophilization and dehydrothermal treatment (DHT). Functional group interaction, crystallinity, and morphology of the prepared sponges were investigated using FT-IR, PXRD, and SEM, respectively. Physicochemical properties, porosity, hydrophilic/hydrophobic properties and mechanical property, were evaluated. Wound dressing properties, water vapor transmission rate (WVTR), fluid absorbency, oxygen permeation (OP), and bio-adhesive property, were investigated. In vitro asiaticoside release study was conducted using immersion method. Cytotoxicity was studied in normal human dermal fibroblast (NHDF) and normal human epidermal keratinocyte (NHEK). Angiogenic activity of asiaticoside was evaluated using chick-chorioallantoic membrane (CAM) assay. FT-IR and PXRD results revealed the amidation after DHT to enhance the crystallinity of the prepared sponges. The prepared sponges had high porosity comprising high Alst-loaded amount that exhibited more compact structure. Alst enhanced hydrophobicity therefore it reduced the fluid absorption and WVTR together with bio-adhesion of the prepared sponge dressings. Porosity of all sponges was more than 85% therefore resulting in their high OP. Enhancing hydrophobicity of the material by Alst and more homogeneity caused by NMP eventually retarded the asiaticoside release for 7 days. The sponge extractions were non-toxic to the cells moreover they promoted NHDF and NHEK cell proliferation. Asiaticoside and asiaticoside-contained dressings exhibited dose-dependent angiogenic activity in CAM model.