Hyaluronan oligosaccharides promote diabetic wound healing by increasing angiogenesis

Nature-Inspired Scarless Healing: Guiding Biomaterials Design for Advanced Therapies

The use of biomaterials in the treatment of skin wounds has been steadily increasing over the last two decades. The key to the successful application of biomaterials in scar reduction is the up-to-date knowledge of the actors involved in accelerated healing and the cellular factors that can be implemented in bioinspired materials. Natural models of scarless healing such as oral mucosa, fetal skin and the skin of amphibians, fish, and reptiles are a great source of information. By investigating their microenvironments, cellular factors, and inflammatory self-regulatory systems, a general model of scarless healing can be defined. This review introduces the basic and current concepts of skin wound healing and focuses on providing a detailed overview of the main processes of accelerated healing without scarring. The article outlines the common features and key points that develop and promote scar-free healing. The tissues and healing processes of the selected natural models are described individually (tissue organization, structural components, ratios of cellular factors such as Collagen and transforming growth factor and their mechanisms of regulation of inflammation and scar overgrowth). A comparative work of each natural model concerning healing in human skin is included in the discussion. Finally, the patterns identified through the analysis of each model and their differences from normal healing are presented to facilitate the knowledge for the implementation of new treatments.

Enzyme variants in biosynthesis and biological assessment of different molecular weight hyaluronan

In the present study, low- and high-molecular-weight hyaluronic acids (LMW-HA and HMW-HA) were synthesized in vitro by truncated Streptococcus equisimilis hyaluronan synthases (SeHAS). The enzyme kinetic parameters were determined for each enzyme variant. The MW, structure, dispersity, and biological activity of polymers were determined by electrophoresis, FTIR spectroscopy, carbazole, cell proliferation, and cell migration assay, respectively. The specific activities were calculated as 7.5, 6.8, 4.9, and 2.8 µgHA µgenzyme-1 min-1 for SeHAS, HAS123, HAS23, and HASIntra, respectively. The results revealed SeHAS produced a polydisperse HMW-HA (268 kDa), while HAS123 and HAS23 produced a polydisperse LMW-HA (< 30 kDa). Interestingly, HASIntra produced a low-disperse LMW-HA. Kinetics studies revealed the truncated variants displayed increased Km values for two substrates when compared to the wild-type enzyme. Biological assessments indicated all LMW-HAs showed a dose-dependent proliferation activity on endothelial cells (ECs), whereas HMW-HAs exhibited an inhibitory effect. Also, LMW-HAs had the highest cell migration effect at 10 µg/mL, while at 200 µg/mL, both LMW- and HMW-HAs postponed the healing recovery rate. The study elucidated that the transmembrane domains (TMDs) of SeHAS affect the enzyme kinetics, HA-titer, HA-size, and HA-dispersity. These findings open new insight into the rational engineering of SeHAS to produce size-defined HA.

Bioarchitectural Design of Bioactive Biopolymers: Structure-Function Paradigm for Diabetic Wound Healing

Chronic wounds such as diabetic ulcers are a major complication in diabetes caused by hyperglycemia, prolonged inflammation, high oxidative stress, and bacterial bioburden. Bioactive biopolymers have been found to have a biological response in wound tissue microenvironments and are used for developing advanced tissue engineering strategies to enhance wound healing. These biopolymers possess innate bioactivity and are biodegradable, with favourable mechanical properties. However, their bioactivity is highly dependent on their structural properties, which need to be carefully considered while developing wound healing strategies. Biopolymers such as alginate, chitosan, hyaluronic acid, and collagen have previously been used in wound healing solutions but the modulation of structural/physico-chemical properties for differential bioactivity have not been the prime focus. Factors such as molecular weight, degree of polymerization, amino acid sequences, and hierarchical structures can have a spectrum of immunomodulatory, anti-bacterial, and anti-oxidant properties that could determine the fate of the wound. The current narrative review addresses the structure-function relationship in bioactive biopolymers for promoting healing in chronic wounds with emphasis on diabetic ulcers. This review highlights the need for characterization of the biopolymers under research while designing biomaterials to maximize the inherent bioactive potency for better tissue regeneration outcomes, especially in the context of diabetic ulcers.

The role of hyaluronic acid in the design and functionalization of nanoparticles for the treatment of colorectal cancer

Despite advances in new approaches for colorectal cancer (CRC) therapy, intravenous chemotherapy remains one of the main treatment options; however, it has limitations associated with off-target toxicity, tumor cell resistance due to molecular complexity and CRC heterogeneity, which lead to tumor recurrence and metastasis. In oncology, nanoparticle-based strategies have been designed to avoid systemic toxicity and increase drug accumulation at tumor sites. Hyaluronic acid (HA) has obtained significant attention thanks to its ability to target nanoparticles (NPs) to CRC cells through binding to cluster-determinant-44 (CD44) and hyaluronan-mediated motility (RHAMM) receptors, along with its efficient biological properties of mucoadhesion. This review proposes to discuss the state of the art in HA-based nanoparticulate systems intended for localized treatment of CRC, highlighting the importance of the mucoadhesion and active targeting provided by this polymer. In addition, an overview of CRC will be provided, emphasizing the importance of CD44 and RHAMM receptors in this type of cancer and the current challenges related to this disease, and important concepts about the physicochemical and biological properties of HA will also be addressed. Finally, this review aims to contribute to the advancement of accuracy treatment of CRC by the design of new platforms based on by HA.

Local decorin delivery via hyaluronic acid microrods improves cardiac performance, ventricular remodeling after myocardial infarction

Heart failure (HF) remains a global public health burden and often results following myocardial infarction (MI). Following injury, cardiac fibrosis forms in the myocardium which greatly hinders cellular function, survival, and recruitment, thus severely limits tissue regeneration. Here, we leverage biophysical microstructural cues made of hyaluronic acid (HA) loaded with the anti-fibrotic proteoglycan decorin to more robustly attenuate cardiac fibrosis after acute myocardial injury. Microrods showed decorin incorporation throughout the entirety of the hydrogel structures and exhibited first-order release kinetics in vitro. Intramyocardial injections of saline (n = 5), microrods (n = 7), decorin microrods (n = 10), and free decorin (n = 4) were performed in male rat models of ischemia-reperfusion MI to evaluate therapeutic effects on cardiac remodeling and function. Echocardiographic analysis demonstrated that rats treated with decorin microrods (5.21% ± 4.29%) exhibited significantly increased change in ejection fraction (EF) at 8 weeks post-MI compared to rats treated with saline (-4.18% ± 2.78%, p < 0.001) and free decorin (-3.42% ± 1.86%, p < 0.01). Trends in reduced end diastolic volume were also identified in decorin microrod-treated groups compared to those treated with saline, microrods, and free decorin, indicating favorable ventricular remodeling. Quantitative analysis of histology and immunofluorescence staining showed that treatment with decorin microrods reduced cardiac fibrosis (p < 0.05) and cardiomyocyte hypertrophy (p < 0.05) at 8 weeks post-MI compared to saline control. Together, this work aims to contribute important knowledge to guide rationally designed biomaterial development that may be used to successfully treat cardiovascular diseases.

A comparative study of the ameliorative effects of hyaluronic acid oligosaccharides and hyaluronic acid on DSS-induced colitis in mice and research on relevant mechanisms

As a dietary supplement, hyaluronic acid (HA) has exhibited appreciable immunomodulatory activity and an ameliorative effect on rodent colitis. However, its high viscosity is not only refractory to absorb through the gut, but also causes flatulence. In contrast to HA, hyaluronic acid oligosaccharides (o-HAs) can overcome the above-mentioned constraints, but their treatment effect still remains ill-defined contemporarily. Herein, the current study intends to compare the modulatory effects of HA and o-HA on colitis and assess the underlying molecular mechanism. We first showed that o-HA had a better preventive effect than HA in alleviating colitis symptoms, as evidenced by lower body weight loss, lower disease activity index scores, a lower inflammatory response (TNF-α, IL-6, IL-1β, p-NF-κB), and more intact colon epithelial integrity in vivo. The best efficiency was observed in the o-HA treated group with a dosage of 30 mg kg^-1. In an in vitro barrier function assay, o-HA exerted a better protective effect on the transepithelial electrical resistance (TEER), FITC permeability, and wound healing and modulated the expression of tight junction (TJ) proteins (ZO-1, occludin) in lipopolysaccharide (LPS)-stimulated Caco-2 cells. In summary, both HA and o-HA showed the potential to reduce inflammation and ameliorate intestinal damage in DSS-induced colitis and LPS-induced inflammation, but o-HA had improved outcomes. The results also provided a glimpse of the latent mechanism by which HA and o-HA enhanced intestinal barrier function via MLCK/p-MLC signaling pathway suppression.

Local delivery of decorin via hyaluronic acid microrods improves cardiac performance and ventricular remodeling after myocardial infarction

Heart failure (HF) is a global public health burden and associated with significant morbidity and mortality. HF can result as a complication following myocardial infarction (MI), with cardiac fibrosis forming in the myocardium as a response to injury. The dense, avascular scar tissue that develops in the myocardium after injury following MI creates an inhospitable microenvironment that hinders cellular function, survival, and recruitment, thus severely limiting tissue regeneration. We have previously demonstrated the ability of hyaluronic acid (HA) polymer microrods to modulate fibroblast phenotype using discrete biophysical cues and to improve cardiac outcomes after implantation in rodent models of ischemia-reperfusion MI injury. Here, we developed a dual-pronged biochemical and biophysical therapeutic strategy leveraging bioactive microrods to more robustly attenuate cardiac fibrosis after acute myocardial injury. Incorporation of the anti-fibrotic proteoglycan decorin within microrods led to sustained release of decorin over one month in vitro and after implantation, resulted in marked improvement in cardiac function and ventricular remodeling, along with decreased fibrosis and cardiomyocyte hypertrophy. Together, this body of work aims to contribute important knowledge to help develop rationally designed engineered biomaterials that may be used to successfully treat cardiovascular diseases.

Topical gel-based biomaterials for the treatment of diabetic foot ulcers

Diabetic foot ulcers (DFUs) are a devastating ailment for many diabetic patients with increasing prevalence and morbidity. The complex pathophysiology of DFU wound environments has made finding effective treatments difficult. Standard wound care treatments have limited efficacy in healing these types of chronic wounds. Topical biomaterial gels have been developed to implement novel treatment approaches to improve therapeutic effects and are advantageous due to their ease of application, tunability, and ability to improve therapeutic release characteristics. Here, we provide an updated, comprehensive review of novel topical biomaterial gels developed for treating chronic DFUs. This review will examine preclinical data for topical gel treatments in diabetic animal models and clinical applications, focusing on gels with protein/peptides, drug, cellular, herbal/antioxidant, and nano/microparticle approaches. STATEMENT OF SIGNIFICANCE: By 2050, 1 in 3 Americans will develop diabetes, and up to 34% of diabetic patients will develop a diabetic foot ulcer (DFU) in their lifetime. Current treatments for DFUs include debridement, infection control, maintaining a moist wound environment, and pressure offloading. Despite these interventions, a large number of DFUs fail to heal and are associated with a cost that exceeds $31 billion annually. Topical biomaterials have been developed to help target specific impairments associated with DFU with the goal to improve healing. A summary of these approaches is needed to help better understand the current state of the research. This review summarizes recent research and advances in topical biomaterials treatments for DFUs.

Sprayable Hydrogel for Biomedical Applications

Polymeric hydrogels have extraordinary potential to be utilized for biomedical applications. Recently, sprayable hydrogels have received increasing attention for their biocompatibility, degradability, tunable mechanical properties and rapid spray-filming abilities. In...

A functional extracellular matrix biomaterial enriched with VEGFA and bFGF as vehicle of human umbilical cord mesenchymal stem cells in skin wound healing

The construction of microvascular network is one of the greatest challenges for tissue engineering and cell therapy. Endothelial cells are essential for the construction of network of blood vessels. However, their application meets challenges in clinic due to the limited resource of autologous endothelium. Mesenchymal stem cells can effectively promote the angiogenesis in ischemic tissues for their abilities of endothelial differentiation and paracrine, and abundant sources. Extracellular matrix (ECM) has been widely used as an ideal biomaterial to mimic cellular microenvironment for tissue engineering due to its merits of neutrality, good biocompatibility, degradability, and controllability. In this study, a functional cell derived ECM biomaterial enriched with VEGFA and bFGF by expressing the collagen-binding domain fused factor genes in host cells was prepared. This material could induce endothelial differentiation of human umbilical cord mesenchymal stem cells (hUCMSCs) and promote angiogenesis, which may improve the healing effect of skin injury. Our research not only provides a functional ECM material to inducing angiogenesis by inducing endothelial differentiation of hUCMSCs, but also shed light on the ubiquitous approaches to endow ECM materials different functions by enriching different factors. This study will benefit tissue engineering and regenerative medicine researches.

Simvastatin nanoparticles loaded polymeric film as a potential strategy for diabetic wound healing: in vitro and in vivo evaluation

INTRODUCTION

The pleiotropic effects of statins are recently explored for wound healing through angiogenesis and lymph-angiogenesis that could be of great importance in diabetic wounds.

AIM

Aim of the present study is to fabricate nanofilm embedded with simvastatin loaded chitosan nanoparticles (CS-SIM-NPs) has been reported herein to explore the efficacy of SIM in diabetic wound healing.

METHODS

The NPs, prepared via ionic gelation, were 173nm ± 2.645 in size with a zeta potential -0.299 ± 0.009 and PDI 0.051 ± 0.088 with excellent encapsulation efficiency (99.97%). The optimized formulation (CS: TPP, 1:1) that exhibited the highest drug release (91.64%) was incorporated into polymeric nanofilm (HPMC, Sodium alginate, PVA), followed by in vitro characterization. The optimized nanofilm was applied to the wound created on the back of diabetes-induced (with alloxan injection 120 mg/kg) albino rats.

RESULTS

The results showed significant (p < 0.05) improvement in the wound healing process compared to the diabetes-induced non-treated group. The results highlighted the importance of nanofilms loaded with SIM-NPs in diabetic wound healing through angiogenesis promotion at the wound site.

CONCLUSION

Thus, CS-SIM-NPs loaded polymeric nanofilms could be an emerging diabetic wound healing agent in the industry of nanomedicines.

Anti-Angiogenic Property of Free Human Oligosaccharides

Angiogenesis, a fundamental process in human physiology and pathology, has attracted considerable attention owing to its potential as a therapeutic strategy. Vascular endothelial growth factor (VEGF) and its receptor (VEGFR) are deemed major mediators of angiogenesis. To date, inhibition of the VEGF-A/VEGFR-2 axis has been an effective strategy employed in the development of anticancer drugs. However, some limitations, such as low efficacy and side effects, need to be addressed. Several drug candidates have been discovered, including small molecule compounds, recombinant proteins, and oligosaccharides. In this review, we focus on human oligosaccharides as modulators of angiogenesis. In particular, sialylated human milk oligosaccharides (HMOs) play a significant role in the inhibition of VEGFR-2-mediated angiogenesis. We discuss the structural features concerning the interaction between sialylated HMOs and VEGFR-2 as a molecular mechanism of anti-angiogenesis modulation and its effectiveness in vivo experiments. In the current state, extensive clinical trials are required to develop a novel VEGFR-2 inhibitor from sialylated HMOs.

Endothelial angiogenic activity and adipose angiogenesis is controlled by extracellular matrix protein TGFBI

Several studies have suggested that extracellular matrix (ECM) remodeling and the microenvironment are tightly associated with adipogenesis and adipose angiogenesis. In the present study, we demonstrated that transforming growth factor-beta induced (TGFBI) suppresses angiogenesis stimulated by adipocyte-conditioned medium (Ad-CM), both in vitro and in vivo. TGFBI knockout (KO) mice exhibited increased numbers of blood vessels in adipose tissue, and blood vessels from these mice showed enhanced infiltration into Matrigel containing Ad-CM. The treatment of Ad-CM-stimulated SVEC-10 endothelial cells with TGFBI protein reduced migration and tube-forming activity. TGFBI protein suppressed the activation of the Src and extracellular signaling-related kinase signaling pathways of these SVEC-10 endothelial cells. Our findings indicated that TGFBI inhibited adipose angiogenesis by suppressing the activation of Src and ERK signaling pathways, possibly because of the stimulation of the angiogenic activity of endothelial cells.

mTOR inhibitor INK128 promotes wound healing by regulating MDSCs

Background

Skin wounds in diabetic patients hardly recover. Accumulating evidence has shown that mammalian target of rapamycin (mTOR) pathway and myeloid-derived suppressor cells (MDSCs) are involved in inflammatory-related response. INK128 is a novel mTOR kinase inhibitor in clinical development. However, the exact roles of MDSCs and INK128 in healing wound of diabetic patients are unclear.

Methods

Mice models of normal, diabetic, and diabetic+INK128 were constructed. Bone marrow (BM)-derived macrophages and RAW264.7 cell line co-cultured with MDSCs, which were induced at different conditions. Flow cytometry, western blot, quantitative real-time PCR, and immunohistochemical analysis were performed.

Results

Diabetic mice (DM) had a slower recovery rate, thinner epidermis and dermis, and less blood vessels than those of normal mice. MDSCs were abnormally accumulated in DM, mTOR was activated in MDSCs of DM, and the cells were treated with high glucose. Moreover, mTOR signaling inhibitor INK128 could promote wound healing through reducing the MDSCs. MDSC function was disordered in DM and high-glucose environments, while INK128 could help retrieve their function. Furthermore, high glucose and other factors in DM could promote M-MDSC differentiation to M1 pro-inflammatory macrophage cells, thus inhibiting wound healing. The differentiation, which was dependent on mTOR signaling, could be reversed by INK128.

Conclusion

INK128 is potential to be developed as a clinical strategy to promote wound healing of diabetic patients.

Sustained dual release of ciprofloxacin and lidocaine from ionic exchange responding film based on alginate and hyaluronate for wound healing

This study presents a new antibiotic-anesthetic film (AA-film) based on natural polyelectrolytes ionically complexed with lidocaine and ciprofloxacin to manage pain associated with infected wounds. The rational selection of the components resulted in the AA-films being transparent, compatible with wound skin pH and highly water vapor permeable. The drug release properties evaluated in saline solution and water revealed an ionic exchange mechanism for the release of both drugs and showed that ciprofloxacin acts as a cross-linker, as was confirmed by rheological evaluation. The in vitro antimicrobial efficacy against S. aureus and P. aeruginosa was demonstrated. Furthermore, AA-films exhibit a high fluid absorption capacity and act as a physical barrier for microorganisms. This work highlights the great potential of this smart system as an attractive dressing for skin wounds, surpassing currently available treatments.

Role of Hyaluronic Acids and Potential as Regenerative Biomaterials in Wound Healing

The skin can protect the body from external harm, sense environmental changes, and maintain physiological homeostasis. Cutaneous repair and regeneration associated with surgical wounds, acute traumas, and chronic diseases are a central concern of healthcare. Patients may experience the failure of current treatments due to the complexity of the healing process; therefore, emerging strategies are needed. Hyaluronic acids (HAs, also known as hyaluronan), a glycosaminoglycan (GAG) of the extracellular matrix (ECM), play key roles in cell differentiation, proliferation, and migration throughout tissue development and regeneration. Recently, HA derivatives have been developed as regenerative biomaterials for treating skin damage and injury. In this review, the healing process, namely, hemostasis, inflammation, proliferation, and maturation, is described and the role of HAs in the healing process is discussed. This review also provides recent examples in the development of HA derivatives for wound healing.

Hyaluronic acid as a bioactive component for bone tissue regeneration: Fabrication, modification, properties, and biological functions

Hyaluronic acid (HA) is widely distributed in the human body, and it is heavily involved in many physiological functions such as tissue hydration, wound repair, and cell migration. In recent years, HA and its derivatives have been widely used as advanced bioactive polymers for bone regeneration. Many medical products containing HA have been developed because this natural polymer has been proven to be nontoxic, noninflammatory, biodegradable, and biocompatible. Moreover, HA-based composite scaffolds have shown good potential for promoting osteogenesis and mineralization. Recently, many HA-based biomaterials have been fabricated for bone regeneration by combining with electrospinning and 3D printing technology. In this review, the polymer structures, processing, properties, and applications in bone tissue engineering are summarized. The challenges and prospects of HA polymers are also discussed.

Hyaluronic acid with antioxidants improve wound healing in rats

Hyaluronic acid (HA) is found in connective tissue and participates in wound healing. We investigated the efficacy of a HA gel (2% hyaluronic acid; 1% antioxidants, coenzyme Q10 and vitamin E; and 5% benzocaine) on healing of palatal wounds in rats. We established two groups of rats: a control group treated with vehicle and an HA group treated with HA gel. The control group was divided into five subgroups and the HA group was divided into four subgroups according to the day on which animals were sacrificed. Wounds were created by elevating 5 mm diameter full thickness flaps. Healed and unhealed wound areas were measured using photographs. Transforming growth factor (TGF)-β, insulin-like growth factor (IGF), and collagen I and III expressions were determined using immunohistochemistry. The number of fibroblasts increased and inflammatory cells decreased from day 0 to 21 in both groups. The HA group exhibited more fibroblasts by day 7 compared to controls; (TGF)-β and IGF levels were similar between HA and control groups. HA groups exhibited fewer inflammatory cells than controls on days 3 and 7. We found significant differences in TGF-β and IGF levels among HA groups between days 3 and 21, and among control groups between days 0 and 21. Collagen I and III levels were greater for the day 3 HA group compared to controls. We observed improved wound healing in HA treated rats within 7 days.

Rat epidermal stem cells promote the angiogenesis of full-thickness wounds

BACKGROUND

Full-thickness wounds severely affect patients' life quality and become challenging problems for clinicians. Stem cells have great prospects in the treatment of wounds. Our previous study confirmed that autologous basal cell suspension could promote wound healing, and epidermal stem cells (ESCs) were detected in the basal cell suspension. Herein, this study aimed to explore the effect of ESCs on full-thickness wounds.

METHODS

Rat ESCs were isolated and expanded and then were transfected with lentivirus to stably express enhanced green fluorescent protein. The experimental rats were randomly divided into 2 groups: in the ESC group, the rat ESCs were sprayed on the full-thickness wounds of rats; in the control group, phosphate-buffered saline was sprayed the on the wounds. Next, wound healing and neovascularization were evaluated. Colonization, division, and differentiation of ESCs on the wound were analyzed by immunofluorescence.

RESULTS

The rat ESCs colonized, divided, and proliferated in the wound. Additionally, rat ESCs around blood vessels differentiated into vascular endothelial cells and formed a lumen-like structure. Compared with the control group, the ESC group showed enhanced angiogenesis and accelerated wound healing.

CONCLUSIONS

Our study confirmed that rat ESCs are safe and effective for treating full-thickness wounds. Additionally, under certain conditions, ESCs can differentiate into vascular endothelial cells to promote angiogenesis and wound healing.

Hyaluronic acid-Based wound dressings: A review

Hyaluronic acid (HA), a non-sulfated glycosaminoglycan (GAG), is a major component of skin extracellular matrix (ECM) and it is involved in the inflammatory response, angiogenesis, and tissue regeneration process. Due to the intrinsic properties of HA (such as biocompatibility, biodegradability and hydrophilic character), it has been used to produce different wound dressings, namely sponges, films, hydrogels, and electrospun membranes. Herein, an overview of the different HA-based wound dressings that have been produced so far is provided as well as the future directions regarding the strategies aimed to improve the mechanical stability of HA-based wound dressings, along with the incorporation of biomolecules intended to ameliorate their biological performance during the healing process.

Hyaluronic acid and metallic silver treatment of chronic wounds: healing rate and bacterial load control

OBJECTIVE

To confirm the safety and wound healing activity of a topical spray powder containing hyaluronic acid (HA) and metallic silver (Hyalosilver, Fidia Farmaceutici S.p.A., Italy), and investigate its effect on the control of bacterial load in vascular ulcers or category I-II pressure ulcers (PU).

METHODS

This is a single site, prospective, open label study involving patients with a vascular ulcer or category I-II PUs, presenting signs of critical bacterial colonisation. Patients with a wound size of ≤15cm² were enrolled. At baseline, a swab was taken of each wound for a semi-quantitative analysis of bacterial load and the first treatment of topical spray powder was applied. The patient was then requested to self-apply the medication once a day for 28 consecutive days and to return on days one, seven and 28 for clinical and microbiological assessments.

RESULTS

A total of 25 patients were enrolled in the study. Treatment with the topical spray powder enhanced the healing rate of chronic wounds in terms of a reduction of wound area as well as bacterial load (p<0.025) and the overall clinical status of wound (odour, exudate, erythema of periwound skin; p<0.017). Moreover, the spray powder increased overall patient perception of improvement in the wound (p<0.05).

CONCLUSION

The data demonstrated good safety and tolerability of the topical spray powder suggesting that the product is effective not only in reducing wound area, due to the presence of HA, but in keeping the bacterial colonisation under control.

Hyaluronan Fragmentation During Inflammatory Pathologies: A Signal that Empowers Tissue Damage

The mechanisms that modulate the response to tissue injury are not fully understood. Abnormalities in the repair response are associated with a variety of chronic disease states characterized by inflammation, followed subsequently by excessive ECM deposition. As cell-matrix interactions are able to regulate cellular homeostasis, modification of ECM integrity appears to be an unspecific factor in promoting the onset and progression of inflammatory diseases. Evidence is emerging to show that endogenous ECM molecules supply signals to damage tissues and cells in order to promote further ECM degradation and inflammation progression. Several investigations have been confirmed that HA fragments of different molecular sizes exhibit different biological effects and responses. In fact, the increased deposition of HA into the ECM is a strong hallmark of inflammation processes. In the context of inflammatory pathologies, highly polymerized HA is broken down into small components, which are able to exacerbate the inflammatory response by inducing the release of various detrimental mediators such as reactive oxygen species, cytokines, chemokines and destructive enzymes and by facilitating the recruitment of leukocytes. However, strategies involving the modulation of the HA fragment with specific receptors on cell surface could represent different promising effects for therapeutic scope. This review will focus on the inflammation action of small HA fragments in recent years obtained by in vivo reports.

Hydrogel Dressings for Advanced Wound Management

BACKGROUND

Composed in a large extent of water and due to their nonadhesiveness, hydrogels found their way to the wound dressing market as materials that provide a moisture environment for healing while being comfortable to the patient. Hydrogels' exploitation is constantly increasing after evidences of their even broader therapeutic potential due to resemblance to dermal tissue and ability to induce partial skin regeneration. The innovation in advanced wound care is further directed to the development of so-called active dressings, where hydrogels are combined with components that enhance the primary purpose of providing a beneficial environment for wound healing.

OBJECTIVE

The objective of this review is to concisely describe the relevance of hydrogel dressings as platforms for delivery of active molecules for improved management of difficult- to-treat wounds. The emphasis is on the most recent advances in development of stimuli- responsive hydrogels, which allow for control over wound healing efficiency in response to different external modalities. Novel strategies for monitoring of the wound status and healing progress based on incorporation of sensor molecules into the hydrogel platforms are also discussed.

Improving in vitro biocompatibility on biomimetic mineralized collagen bone materials modified with hyaluronic acid oligosaccharide

Hyaluronic acid (HA) has great potential in bone tissue engineering due to its favorable bioactivity and biocompatibility, especially hyaluronic acid oligosaccharides (oHAs) shows a promising result in endothelialization of blood vessel. To improve endothelialized effect and osteogenic performance of bone scaffold, we have created a biomimetic nanofiber network based on collagen modified with hyaluronic acid oligosaccharides (Col/oHAs) and its mineralized product. Biomimetically mineralized Col/oHAs based composite (Col/oHAs/HAP) was prepared via self-assembly at room temperature. The resultant composites were characterized by fourier transform infrared spectroscopy (FT-IR), X-Ray diffractometry (XRD), thermogravimetric analysis (TGA), scanning electron microscope (SEM) and transmission electron microscopy (TEM). They show some characteristics of natural bone both in composition and microstructure. The nanofiber was fabricated as a hybrid network which bionics extracellular matrix (ECM) and was prepared to culture artery endothelial cell (PIEC) and the mouse parietal bone cell (MC3T3-E1). Cells attached tightly to the nanofibers and infiltrated into the materials, forming an interconnected cell community. Moreover, the as-prepared nanofiber was found to noticeably enhance cells adhesion and proliferation and upregulate alkaline phosphatase activity (ALP) and osteocalcin (OCN) expression suggesting positive cellular responses. These results indicated that the Col/oHAs/HAP composite has a promising capacity to direct the osteogenic differentiation by providing an adaptable environment and can be expected as an excellent candidate for bone tissue engineering approaches with improved performance of promoting PIEC proliferation.

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.

Therapeutic strategies for enhancing angiogenesis in wound healing

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

Hyaluronan: molecular size-dependent signaling and biological functions in inflammation and cancer

Hyaluronan (HA) is a linear nonsulfated glycosaminoglycan of the extracellular matrix that plays a pivotal role in a variety of biological processes. High-molecular weight HA exhibits different biological properties than oligomers and low-molecular weight HA. Depending on their molecular size, HA fragments can influence cellular behavior in a different mode of action. This phenomenon is attributed to the different manner of interaction with the HA receptors, especially CD44 and RHAMM. Both receptors can trigger signaling cascades that regulate cell functional properties, such as proliferation migration, angiogenesis, and wound healing. HA fragments are able to enhance or attenuate the HA receptor-mediated signaling pathways, as they compete with the endogenous HA for binding to the receptors. The modulation of these pathways could be crucial for the development of pathological conditions, such as inflammation and cancer. The primary goal of this review is to critically present the importance of HA molecular size on cellular signaling, functional cell properties, and morphology in normal and pathological conditions, including inflammation and cancer. A deeper understanding of these mechanisms could contribute to the development of novel therapeutic strategies.

Differing Roles of Hyaluronan Molecular Weight on Cancer Cell Behavior and Chemotherapy Resistance

Hyaluronan (HA), a glycosaminoglycan located in the extracellular matrix, is important in embryo development, inflammation, wound healing and cancer. There is an extensive body of research demonstrating the role of HA in all stages of cancer, from initiation to relapse and therapy resistance. HA interacts with multiple cell surface receptors, including CD44, receptor for hyaluronan mediated motility (RHAMM) and intracellular signaling pathways, including receptor tyrosine kinase pathways, to promote the survival and proliferation of cancer cells. Additionally, HA promotes the formation of cancer stem cell (CSC) populations, which are hypothesized to be responsible for the initiation of tumors and therapy resistance. Recent studies have identified that the molecular weight of HA plays differing roles on both normal and cancer cell behavior. This review explores the role of HA in cancer progression and therapy resistance and how its molecular weight is important in regulating CSC populations, epithelial to mesenchymal transition (EMT), ATP binding cassette (ABC) transporter expression and receptor tyrosine kinase pathways.

Immunostimulatory activity of low-molecular-weight hyaluronan on dendritic cells stimulated with Aggregatibacter actinomycetemcomitans or Porphyromonas gingivalis

OBJECTIVES

Periodontitis is a chronic inflammatory disease characterized by tooth-supporting tissue destruction, which is elicited by the host's immune response triggered against periodonto-pathogen bacteria. During periodontal tissue destruction, extracellular matrix components are metabolized and fragmented. Some extracellular matrix component-derived fragments, such as low-molecular-weight hyaluronan (LMW-HA), have potent immunogenic potential, playing a role as damage-associated molecular patterns (DAMPs) during activation of immune cells. Dendritic cells (DCs) play a central role in the host's immune response displayed during periodontitis; thus, this study aimed to analyze whether LMW-HA has an immunostimulatory activity on DCs when stimulated with periodonto-pathogen bacteria.

MATERIALS AND METHODS

LMW-HA-treated and non-treated DCs were stimulated with Aggregatibacter actinomycetemcomitans or Porphyromonas gingivalis and the mRNA expression for cytokines tumor necrosis factor-α (TNF-alpha), interleukin-1β (IL-1B), interleukin-6 (IL-6), and interleukin-23 (IL-23A) was quantified by RT-qPCR. In addition, transcription factors interferon regulatory factor 4 (IRF4), interferon regulatory factor 8 (IRF8), neurogenic locus notch homolog protein 2 (NOTCH2), and basic leucine zipper ATF-like transcription factor 3 (BATF3), involved in DC activation, were analyzed.

RESULTS

Higher expression levels of TNF-alpha, IL-1B, IL-6, and IL-23A were detected in LMW-HA-treated DCs after bacterial infection, as compared with non-treated DCs. When LMW-HA-treated DCs were infected with A. actinomycetemcomitans, higher levels of IRF4, NOTCH2, and BATF3 were detected compared with non-treated cells; whereas against P. gingivalis infection, increased levels of IRF4 and NOTCH2 were detected.

CONCLUSION

LMW-HA plays an immunostimulatory role on the immune response triggered by DCs during infection with A. actinomycetemcomitans or P. gingivalis.

CLINICAL RELEVANCE

Detection of extracellular matrix component-derived fragments produced during periodontal tissue destruction, such as LMW-HA, could explain at least partly unsuccessful periodontal treatment and the chronicity of the disease.

Challenges in vascular tissue engineering for diabetic patients

Hyperglycemia and dyslipidemia coexist in diabetes and result in inflammation, degeneration, and impaired tissue remodeling, processes which are not conducive to the desired integration of tissue engineered products into the surrounding tissues. There are several challenges for vascular tissue engineering such as non-thrombogenicity, adequate burst pressure and compliance, suturability, appropriate remodeling responses, and vasoactivity, but, under diabetic conditions, an additional challenge needs to be considered: the aggressive oxidative environment generated by the high glucose and lipid concentrations that lead to the formation of advanced glycation end products (AGEs) in the vascular wall. Extracellular matrix-based scaffolds have adequate physical properties and are biocompatible, however, these scaffolds are altered in diabetes by the formation AGEs and impaired collagen degradation, consequently increasing vascular wall stiffness. In addition, vascular cells detect and respond to altered stimuli from the matrix by pathological remodeling of the vascular wall. Due to the immunomodulatory effects of mesenchymal stem cells (MSCs), they are frequently used in tissue engineering in order to protect the scaffolds from inflammation. MSCs together with antioxidant treatments of the scaffolds are expected to protect the vascular grafts from diabetes-induced alterations. In conclusion, as one of the most daunting environments that could damage the ECM and its interaction with cells is progressively built in diabetes, we recommend that cells and scaffolds used in vascular tissue engineering for diabetic patients are tested in diabetic animal models, in order to obtain valuable results regarding their resistance to diabetic adversities.

STATEMENT OF SIGNIFICANCE

Almost 25 million Americans have diabetes, characterized by high levels of blood sugar that binds to tissues and disturbs the function of cardiovascular structures. Therefore, patients with diabetes have a high risk of cardiovascular diseases. Surgery is required to replace diseased arteries with implants, but these fail after 5-10 years because they are made of non-living materials, not resistant to diabetes. New tissue engineering materials are developed, based on the patients' own stem cells, isolated from fat, and added to extracellular matrix-based scaffolds. Our main concern is that diabetes could damage the tissue-like implants. Thus we review studies related to the effect of diabetes on tissue components and recommend antioxidant treatments to increase the resistance of implants to diabetes.

Local injection of high-molecular hyaluronan promotes wound healing in old rats by increasing angiogenesis

Impaired angiogenesis contributes to delayed wound healing in aging. Hyaluronan (HA) has a close relationship with angiogenesis and wound healing. However, HA content decreases with age. In this study, we used high molecular weight HA (HMW-HA) (1650 kDa), and investigated its effects on wound healing in old rats by local injection. We found that HMW-HA significantly increases proliferation, migration and tube formation in endothelial cells, and protects endothelial cells against apoptosis. Local injection of HMW-HA promotes wound healing by increasing angiogenesis in old rats. HMW-HA increases the phosphorylation of Src, ERK and AKT, leading to increased angiogenesis, suggesting that local injection of HMW-HA promotes wound healing in elderly patients.

Fragments generated upon extracellular matrix remodeling: Biological regulators and potential drugs

The remodeling of the extracellular matrix (ECM) by several protease families releases a number of bioactive fragments, which regulate numerous biological processes such as autophagy, angiogenesis, adipogenesis, fibrosis, tumor growth, metastasis and wound healing. We review here the proteases which generate bioactive ECM fragments, their ECM substrates, the major bioactive ECM fragments, together with their biological properties and their receptors. The translation of ECM fragments into drugs is challenging and would take advantage of an integrative approach to optimize the design of pre-clinical and clinical studies. This could be done by building the contextualized interaction network of the ECM fragment repertoire including their parent proteins, remodeling proteinases, and their receptors, and by using mathematical disease models.

Beneficial effects of a novel shark-skin collagen dressing for the promotion of seawater immersion wound healing

BACKGROUND

Wounded personnel who work at sea often encounter a plethora of difficulties. The most important of these difficulties is seawater immersion. Common medical dressings have little effect when the affected area is immersed in seawater, and only rarely dressings have been reported for the treatment of seawater-immersed wounds. The objective of this study is to develop a new dressing which should be suitable to prevent the wound from seawater immersion and to promote the wound healing.

METHODS

Shark skin collagen (SSC) was purified via ethanol de-sugaring and de-pigmentation and adjusted for pH. A shark skin collagen sponge (SSCS) was prepared by freeze-drying. SSCS was attached to an anti-seawater immersion polyurethane (PU) film (SSCS + PU) to compose a new dressing. The biochemical properties of SSC and physicochemical properties of SSCS were assessed by standard methods. The effects of SSCS and SSCS + PU on the healing of seawater-immersed wounds were studied using a seawater immersion rat model. For the detection of SSCS effects on seawater-immersed wounds, 12 SD rats, with four wounds created in each rat, were divided into four groups: the 3rd day group, 5th day group, 7th day group and 12th day group. In each group, six wounds were treated with SSCS, three wounds treated with chitosan served as the positive control, and three wounds treated with gauze served as the negative control. For the detection of the SSCS + PU effects on seawater-immersed wounds, 36 SD rats were divided into three groups: the gauze (GZ) + PU group, chitosan (CS) + PU group and SSCS + PU group, with 12 rats in each group, and two wounds in each rat. The wound sizes were measured to calculate the healing rate, and histomorphology and the immunohistochemistry of the CD31 and TGF-β expression levels in the wounded tissues were measured by standard methods.

RESULTS

The results of Ultraviolet-visible (UV-vis) spectrum, Fourier-transform infrared (FTIR) spectrum, circular dichroism (CD) spectra, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and amino acid composition analyses of SSC demonstrated that SSC is type I collagen. SSCS had a homogeneous porous structure of approximately 200 μm, porosity rate of 83.57% ± 2.64%, water vapor transmission ratio (WVTR) of 4500 g/m², tensile strength of 1.79 ± 0.41 N/mm, and elongation at break of 4.52% ± 0.01%. SSCS had significant beneficial effects on seawater-immersed wound healing. On the 3rd day, the healing rates in the GZ negative control, CS positive control and SSCS rats were 13.94% ± 5.50%, 29.40% ± 1.10% and 47.24% ± 8.40%, respectively. SSCS also enhanced TGF-β and CD31 expression in the initial stage of the healing period. The SSCS + PU dressing effectively protected wounds from seawater immersion for at least 4 h, and accelerated re-epithelialization, vascularization and granulation formation of seawater-immersed wounds in the earlier stages of wound healing, and as well as significantly promoted wound healing. The SSCS + PU dressing also enhanced expression of TGF-β and CD31. The effects of SSCS and SSCS + PU were superior to those of both the chitosan and gauze dressings.

CONCLUSIONS

SSCS has significant positive effects on the promotion of seawater-immersed wound healing, and a SSCS + PU dressing effectively prevents seawater immersion, and significantly promotes seawater-immersed wound healing.

Minimizing Skin Scarring through Biomaterial Design

Wound healing continues to be a major burden to patients, though research in the field has expanded significantly. Due to an aging population and increasing comorbid conditions, the cost of chronic wounds is expected to increase for patients and the U.S. healthcare system alike. With this knowledge, the number of engineered products to facilitate wound healing has also increased dramatically, with some already in clinical use. In this review, the major biomaterials used to facilitate skin wound healing will be examined, with particular attention allocated to the science behind their development. Experimental therapies will also be evaluated.

Extracellular Matrix, a Hard Player in Angiogenesis

The extracellular matrix (ECM) is a complex network of proteins, glycoproteins, proteoglycans, and polysaccharides. Through multiple interactions with each other and the cell surface receptors, not only the ECM determines the physical and mechanical properties of the tissues, but also profoundly influences cell behavior and many physiological and pathological processes. One of the functions that have been extensively explored is its impingement on angiogenesis. The strong impact of the ECM in this context is both direct and indirect by virtue of its ability to interact and/or store several growth factors and cytokines. The aim of this review is to provide some examples of the complex molecular mechanisms that are elicited by these molecules in promoting or weakening the angiogenic processes. The scenario is intricate, since matrix remodeling often generates fragments displaying opposite effects compared to those exerted by the whole molecules. Thus, the balance will tilt towards angiogenesis or angiostasis depending on the relative expression of pro- or anti-angiogenetic molecules/fragments composing the matrix of a given tissue. One of the vital aspects of this field of research is that, for its endogenous nature, the ECM can be viewed as a reservoir to draw from for the development of new more efficacious therapies to treat angiogenesis-dependent pathologies.