The role of hyaluronic acid in wound healing: assessment of clinical evidence

Current Insight of Peptide-Based Hydrogels for Chronic Wound Healing Applications: A Concise Review

Chronic wounds present a substantial healthcare obstacle, marked by an extended healing period that can persist for weeks, months, or even years. Typically, they do not progress through the usual phases of healing, which include hemostasis, inflammation, proliferation, and remodeling, within the expected timeframe. Therefore, to address the socioeconomic burden in taking care of chronic wounds, hydrogel-based therapeutic materials have been proposed. Hydrogels are hydrophilic polymer networks with a 3D structure which allows them to become skin substitutes for chronic wounds. Knowing that peptides are abundant in the human body and possess distinct biological functionality, activity, and selectivity, their adaptability as peptide-based hydrogels to individual therapeutic requirements has made them a significant potential biomaterial for the treatment of chronic wounds. Peptide-based hydrogels possess excellent physicochemical and mechanical characteristics such as biodegradability and swelling, and suitable rheological properties as well great biocompatibility. Moreover, they interact with cells, promoting adhesion, migration, and proliferation. These characteristics and cellular interactions have driven peptide-based hydrogels to be applied in chronic wound healing.

Harnessing the potential of hyaluronic acid methacrylate (HAMA) hydrogel for clinical applications in orthopaedic diseases

The treatment of orthopaedic diseases, such as fractures and osteoarthritis, remains a significant challenge due to the complex requirements for mechanical strength and tissue repair. Hydrogels based on hyaluronic acid methacrylate (HAMA) show promise as tissue engineering materials for these conditions. Hyaluronic acid (HA) is a natural component of the extracellular matrix, known for its good compatibility. The mechanical strength of HAMA-based hydrogels can be adjusted through crosslinking and by combining them with other materials. This review provides an overview of recent research on HAMA-based hydrogels for tissue engineering applications in orthopaedic diseases. First, we summarize the techniques for the preparation and characterization of HAMA hydrogels. Next, we offer a detailed review of the use of HAMA-based hydrogels in treating conditions such as cartilage injuries, bone defects, and meniscus injuries. Additionally, we discuss the applications of HAMA-based hydrogels in other diseases related to orthopaedics. Finally, we point out the challenges and propose future directions for the clinical translation of HAMA-based hydrogels.

Translational potential statement

HAMA-based hydrogels show strong translational potential in orthopaedics due to their biocompatibility, adjustable mechanical properties, and regenerative capabilities. With ongoing research, these hydrogels are well-positioned for clinical applications, particularly in cartilage repair, meniscus injuries, and osteoarthritis treatment.

A Systematic Review on Biochemical Perspectives on Natural Products in Wound Healing: Exploring Phytochemicals in Tissue Repair and Scar Prevention

Wound healing is a critical process in tissue repair following injury, and traditional herbal therapies have long been utilized to facilitate this process. This review delves into the mechanistic understanding of the significant contribution of pharmacologically demonstrated natural products in wound healing. Natural products, often perceived as complex yet safely consumed compared to synthetic chemicals, play a crucial role in enhancing the wound-healing process. Drawing upon a comprehensive search strategy utilizing databases such as PubMed, Scopus, Web of Science, and Google Scholar, this review synthesizes evidence on the role of natural products in wound healing. While the exact pharmacological mechanisms of secondary metabolites in wound healing remain to be fully elucidated, compounds from alkaloids, phenols, terpenes, and other sources are explored here to delineate their specific roles in wound repair. Each phytochemical group exerts distinct actions in tissue repair, with some displaying multifaceted roles in various pathways, potentially enhancing their therapeutic value, supported by reported safety profiles. Additionally, these compounds exhibit promise in the prevention of keloids and scars. Their potential alongside economic feasibility may propel them towards pharmaceutical product development. Several isolated compounds, including chlorogenic acid, thymol, and eugenol from natural sources, are undergoing investigation in clinical trials, with many reaching advanced stages. This review provides mechanistic insights into the significant role of pharmacologically demonstrated natural products in wound healing processes.

Hyaluronic Acid in Nanopharmaceuticals: An Overview

Hyaluronic acid (HA) is a naturally occurring, long, unbranched polysaccharide that plays a critical role in maintaining skin structure and hydration. Its unique properties make it a valuable component in the field of nanopharmaceuticals. The combination of HA into nanopharmaceuticals enhances its ability to interact with various therapeutic agents, improving the delivery and efficacy of drugs. HA-based nanoparticles, including solid lipid nanoparticles, and polymeric nanogels, offer controlled release, enhanced stability, and targeted delivery of therapeutic agents. These innovations significantly improve therapeutic outcomes and reduce side effects, making HA an essential tool in modern medicine. In general, HA-modified liposomes enhance drug encapsulation and targeting, while HA-modified solid lipid nanoparticles (SLNs) provide a solid lipid core for drug encapsulation, offering controlled release and stability. This article provides an overview of the potential applications and recent advancements of HA in nanopharmaceuticals, emphasizing its significant impact on the evolving field of targeted drug delivery and advanced therapeutic strategies. By delving into the unique properties of HA and its compatibility with various therapeutic agents, this review underscores the promising potential of HA in revolutionizing nanopharmaceuticals.

The use of supramolecular systems in biomedical applications for antimicrobial properties, biocompatibility, and drug delivery

Supramolecular chemistry is versatile for developing stimuli-responsive, dynamic and multifunctional structures. In the context of biomedical engineering applications, supramolecular assemblies are particularly useful as coatings for they can closely mimic the natural structure and organisation of the extracellular matrix (ECM), they can also fabricate other complex systems like drug delivery systems and bioinks. In the current context of growing medical device-associated complications and the developments in the controlled drug delivery and regenerative medicine fields, supramolecular assemblies are becoming an indispensable part of the biomedical engineering arsenal. This review covers the different supramolecular assemblies in different biomedical applications with a specific focus on antimicrobial coatings, coatings that enhance biocompatibility, surface modifications on implantable medical devices, systems that promote therapeutic efficiency in cancer therapy, and the development of bioinks. The introduced supramolecular systems include multilayer coating by polyelectrolytes, polymers incorporated with nanoparticles, coating simulation of ECM, and drug delivery systems. A perspective on the application of supramolecular systems is also included.

Preparation and characterization of PVA/chitosan nanofibers loaded with Dragon's blood or poly helixan as wound dressings

Nanofibers have been investigated in regenerative medicine. Dragon's blood (DB)- and poly helixan PF (PHPF) are natural materials used in cosmetics. Herein, we generated DB- and PHPF-loaded polyvinyl alcohol/chitosan (PVA/CS/DB and PVA/CS/PHPF, respectively) nanofibers. PVA/CS/DB and PVA/CS/PHPF nanofibers had an average diameter of 547.5 ± 17.13 and 521 ± 24.67 nm, respectively as assessed by SEM, and a degradation rate of 43.1 and 47.6 % after 14 days, respectively. PVA/CS/DB and PVA/CS/PHPF nanofibers had a hemolysis rate of 0.10 and 0.39 %, respectively, and a water vapor transmission rate of ∼2200 g.m-2.day-1. These nanofibers exhibited favorable antimicrobial activity against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Bacillus subtilis in vitro. PVA/CS/DB and PVA/CS/PHPF nanofibers demonstrated a sustained release of 77.91 and 76.55 % over 72 h. PVA/CS/DB and PVA/CS/PHPF nanofibers had a high rate of cytocompatibility and significantly improved the viability of NIH/3T3 cells as compared with free drugs or unloaded nanofibers. Histological inspection via H&E and Verhoeff's staining demonstrated PVA/CS/DB and PVA/CS/PHPF nanofibers enhanced the wound healing and damaged tissue recovery of unsplinted wound models by promoting epithelial layer formation, collagen deposition, and enhancing the presence of fibroblasts. Conclusively, PVA/CS/DB and PVA/CS/PHPF can be introduced as potential wound dressing candidates with favorable properties.

Multiscale Control of Nanofiber-Composite Hydrogel for Complex 3D Cell Culture by Extracellular Matrix Composition and Nanofiber Alignment

In order to manipulate the complex behavior of cells in a 3-dimensional (3D) environment, it is important to provide the microenvironment that can accurately portray the complexity of highly anisotropic tissue structures. However, it is technically challenging to generate a complex microenvironment using conventional biomaterials that are mostly isotropic with limited bioactivity. In this study, the gelatin-hyaluronic acid hydrogel incorporated with aqueous-dispersible, short nanofibers capable of in situ alignment is developed to emulate the native heterogeneous extracellular matrix consisting of fibrous and non-fibrous components. The gelatin nanofibers containing magnetic nanoparticles, which could be aligned by external magnetic field, are dispersed and embedded in gelatin-hyaluronic acid hydrogel encapsulated with dermal fibroblasts. The aligned nanofibers via magnetic field could be safely integrated into the hydrogel, and the process could be repeated to generate larger 3D hydrogels with variable nanofiber alignments. The aligned nanofibers in the hydrogel can more effectively guide the anisotropic morphology (e.g., elongation) of dermal fibroblasts than random nanofibers, whereas myofibroblastic differentiation is more prominent in random nanofibers. At a given nanofiber configuration, the hydrogel composition having intermediate hyaluronic acid content induces myofibroblastic differentiation. These results indicate that modulating the degree of nanofiber alignment and the hyaluronic acid content of the hydrogel are crucial factors that critically influence the fibroblast phenotypes. The nanofiber-composite hydrogel capable of directional nanofiber alignment and tunable material composition can effectively induce a wide array of phenotypic plasticity in 3D cell culture.

Evaluation of the restorative effect of ozone and chitosan-hyaluronic acid with and without mesenchymal stem cells on wound healing in rats

This study evaluated the effect of ozone, chitosan-hyaluronic (Cs-HA) acid and mesenchymal stem cells (MSCs) on wound healing in rats. A total of 64 rats were randomly divided into four groups: control, ozone, Cs-HA + ozone and Cs-HA + ozone + MSCs. A 5 mm full-thickness wound was created on the back of each rat. The wound area was measured macroscopically on days 3, 5, 9 and 14. Tissue sections were prepared for histopathological evaluation of inflammation, collagen arrangement, neovascularization and epithelial tissue rearrangement. Macroscopic assessment showed differences in wound area on days 5, 9 and 14. Histopathological examination showed that the Cs-HA + ozone + MSCs and Cs-HA + ozone groups had significantly higher vascularization on day 3 compared to the ozone-treated and control groups. All treatment groups had significantly better collagen arrangement than the control group. On day 5, no significant difference was observed between different groups. On day 9, the inflammation level in the Cs-HA + ozone + MSCs group was significantly lower than in the other groups. All treatment groups had significantly better vascularization compared to the control group. On day 14, the rate of inflammation was significantly lower in the treatment groups than in the control group. Significantly higher collagen arrangement levels were observed in the Cs-HA + ozone and Cs-HA + ozone + MSCs groups compared to the control and ozone groups. All treatment groups had significantly better epithelial tissue rearrangement than the control group. Overall, the results of this study indicated that treatment with ozone, Cs-HA acid, Cs-HA and MSCs accelerated wound healing in rats. The effect of using Cs-HA acid with mesenchymal cells was better than the other types of treatment. Larger clinical trials are needed to assess these factors for improving chronic wound treatment.

Patterned PCL/PGS Nanofibrous Hyaluronic Acid-Coated Scaffolds Promote Cellular Response and Modulate Gene Expression Profiles

Chronic wounds impose a significant burden on individuals and healthcare systems, necessitating the development of advanced wound management strategies. Tissue engineering, with its ability to create scaffolds that mimic native tissue structures and promote cellular responses, offers a promising approach. Electrospinning, a widely used technique, can fabricate nanofibrous scaffolds for tissue regeneration. In this study, we developed patterned nanofibrous scaffolds using a blend of poly(ε-caprolactone) (PCL) and poly(glycerol sebacate) (PGS), known for their biocompatibility and biodegradability. By employing a mesh collector, we achieved a unique fiber orientation pattern that emulated the natural tissue architecture. The average fiber diameter of PGS/PCL collected on aluminum foil and on mesh was found to be 665.2 ± 4 and 404.8 ± 16 nm, respectively. To enhance the scaffolds' bioactivity and surface properties, it was coated with hyaluronic acid (HA), a key component of the extracellular matrix known for its wound-healing properties. The HA coating improved the scaffold hydrophilicity and surface wettability, facilitating cell attachment, spreading, and migration. Furthermore, the HA-coated scaffold exhibited enhanced biocompatibility, promoting cell viability and proliferation. High-throughput RNA sequencing was performed to analyze the influence of the fabricated scaffold on the gene expression levels of endothelial cells. The top-upregulated biological processes and pathways include cell cycle regulation and cell proliferation. The results revealed significant alterations in gene expression profiles, indicating the scaffold's ability to modulate cellular functions and promote wound healing processes. The developed scaffold holds great promise for advanced wound management and tissue regeneration applications. By harnessing the advantages of aligned nanofibers, biocompatible polymers, and HA coating, this scaffold represents a potential solution for improving wound healing outcomes and improving the quality of life for individuals suffering from chronic wounds.

Immunomodulatory hydrogels for skin wound healing: cellular targets and design strategy

Skin wounds significantly impact the global health care system and represent a significant burden on the economy and society due to their complicated dynamic healing processes, wherein a series of immune events are required to coordinate normal and sequential healing phases, involving multiple immunoregulatory cells such as neutrophils, macrophages, keratinocytes, and fibroblasts, since dysfunction of these cells may impede skin wound healing presenting persisting inflammation, impaired vascularization, and excessive collagen deposition. Therefore, cellular target-based immunomodulation is promising to promote wound healing as cells are the smallest unit of life in immune response. Recently, immunomodulatory hydrogels have become an attractive avenue to promote skin wound healing. However, a detailed and comprehensive review of cellular targets and related hydrogel design strategies remains lacking. In this review, the roles of the main immunoregulatory cells participating in skin wound healing are first discussed, and then we highlight the cellular targets and state-of-the-art design strategies for immunomodulatory hydrogels based on immunoregulatory cells that cover defect, infected, diabetic, burn and tumor wounds and related scar healing. Finally, we discuss the barriers that need to be addressed and future prospects to boost the development and prosperity of immunomodulatory hydrogels.

Accelerated wound healing after topical application of hyaluronic acid cotton to hemorrhoidectomy wounds in a rat model

Purpose

Anal wounds following hemorrhoidectomy can lead to severe pain and postoperative bleeding, impacting patient recovery and quality of life. Hyaluronic acid (HA) stimulates tissue regeneration and wound healing by accelerating cell migration and proliferation. This study aimed to investigate the differences in wound healing rate and completeness of recovery of perianal wounds topically treated with HA-soaked cotton in a murine model.

Methods

Forty-eight 8-week-old Sprague-Dawley rats with perianal wounds created using a biopsy punch were divided into 2 groups: simple dressing with gauze (control) and topical HA-soaked cotton. A single application of HA-soaked cotton was administered after surgery. Wound healing rate and completeness of recovery were evaluated by measuring the healed area and conducting histological analyses.

Results

The HA-cotton group exhibited a shorter complete wound healing duration compared to the control group (13.9 days vs. 16.4 days, P = 0.031). Differences in wound healing area between the 2 groups were greatest on postoperative day 2 (51.6% vs. 28.8%, P < 0.001). The HA-cotton group exhibited fewer cases of granulation tissue (2 vs. 5) or redness (0 vs. 3) upon complete wound healing. Histologically, the HA-cotton group showed accelerated reepithelialization, rapid shift to lymphocyte-dominant inflammation, enhanced fibroblast proliferation, and increased collagen deposition compared to the control group.

Conclusion

Herein, topical application of HA-soaked cotton on perianal wounds in rats resulted in accelerated wound healing, particularly in the initial stages, and improved completeness of recovery, underscoring the potential of the topical application of HA-soaked cotton on hemorrhoidectomy wounds in human patients to improve wound healing.

An Insight into Biodegradable Polymers and their Biomedical Applications for Wound Healing

Biodegradable polymers, encompassing both natural and synthetic polymers, have demonstrated efficacy as carriers for synthetic drugs, natural bioactive molecules, and inorganic metals. This is due to their ability to control the release of these substances. As a result, various advanced materials, such as nanoparticle- loaded hydrogels, nanofibrous scaffolds, and nanocomposites, have been developed. These materials have shown promise in enhancing processes, such as cell proliferation, vascular angiogenesis, hair growth, and wound healing management. Natural polymers, including hyaluronic acid, collagen, chitosan, gelatin, and alginate, as well as synthetic polymers like polylactic acid, polyglycolic acid, polylactic co-glycolic acid, and PCA, have significant potential for promoting wound healing. This study examines the advancements in biodegradable polymers for wound healing, specifically focusing on each polymer and its distinctive formulations. It also discusses the in vitro experiments conducted using different cell lines, as well as the in vivo studies that explore the numerous uses of these polymers in wound healing. The discussion also included the exploration of modifications or combinations of several polymers, as well as surface changes, in order to produce synergistic effects and address the limitations of individual polymers. The goal was to expedite the healing process of different chronic wounds. Due to this, there have been notable advancements in the technological use of polymeric mixes, including biodegradable polymer-based scaffolds, which have accelerated the process of wound healing.

Natural and Synthetic Polymeric Biomaterials for Application in Wound Management

Biomaterials are at the forefront of the future, finding a variety of applications in the biomedical field, especially in wound healing, thanks to their biocompatible and biodegradable properties. Wounds spontaneously try to heal through a series of interconnected processes involving several initiators and mediators such as cytokines, macrophages, and fibroblasts. The combination of biopolymers with wound healing properties may provide opportunities to synthesize matrices that stimulate and trigger target cell responses crucial to the healing process. This review outlines the optimal management and care required for wound treatment with a special focus on biopolymers, drug-delivery systems, and nanotechnologies used for enhanced wound healing applications. Researchers have utilized a range of techniques to produce wound dressings, leading to products with different characteristics. Each method comes with its unique strengths and limitations, which are important to consider. The future trajectory in wound dressing advancement should prioritize economical and eco-friendly methodologies, along with improving the efficacy of constituent materials. The aim of this work is to give researchers the possibility to evaluate the proper materials for wound dressing preparation and to better understand the optimal synthesis conditions as well as the most effective bioactive molecules to load.

Tendon-inspired hybrid hydrogel based on polyvinyl alcohol and gallic acid-lysozyme for promoting wound closure and healing

Noninvasive wound closure remains a challenge in the field of wound healing. In this study, we report the development of a cross-linked P-GL hydrogel constructed from polyvinyl alcohol (PVA) and GL (a hydrogel consisting of gallic acid and lysozyme) that effectively promotes wound closure and healing. The P-GL hydrogel exhibited a unique lamellar and tendon-like fibrous network structure, providing good thermo-sensitivity and tissue adhesiveness up to 60 MPa, as well as retaining autonomous self-healing and acid resistance capacities. In addition, the P-GL hydrogel exhibited sustained release characteristics lasting >100 h, excellent biocompatibility both in vitro and in vivo, as well as good antibacterial activity and mechanical properties. The in vivo full-thickness skin wounds model revealed the positive wound closure and healing therapeutic effects of the P-GL hydrogels were confirmed, showing a promising potential as a noninvasive wound closure and healing bio-adhesive hydrogel.

Hyaluronic acid/alginate-based biomimetic hydrogel membranes for accelerated diabetic wound repair

The study aims to develop a new multifunctional biopolymer-based hydrogel membrane dressing by adopting a solvent casting method for the controlled release of cefotaxime sodium at the wound site. Sodium alginate enhances collagen production in the skin, which provides tensile strength to healing tissue. Moreover, the significance of extracellular molecules such as hyaluronic acid in the wound the healing cascade renders these biopolymers an essential ingredient for the fabrication of hydrogel membranes via physical crosslinking (hydrogen bonding). These membranes were further investigated in terms of their structure, and surface morphology, as well as cell viability analysis. A membrane with the most suitable characteristics was chosen as a candidate for cefotaxime sodium loading and in vivo analysis. Results show that the 3D porous nature of developed membranes allows optimum water vapor and oxygen transmission (>8.21 mg/mL) to divert excessive wound exudate away from the diabetic wound bed, MTT assay confirmed cell viability at more than 80%. In vivo results confirmed that the CTX-HA-Alg-PVA hydrogel group showed rapid wound healing with accelerated re-epithelization and a decreased inflammatory response. Conclusively, these findings indicate that CTX-HA-Alg-PVA hydrogel membranes exhibit a suitable niche for use as dressing membranes for healing of diabetic wounds.

Injectable, self-healing hydrogel adhesives with firm tissue adhesion and on-demand biodegradation for sutureless wound closure

Tissue adhesives have garnered extensive interest as alternatives and supplements to sutures, whereas major challenges still remain, including weak tissue adhesion, inadequate biocompatibility, and uncontrolled biodegradation. Here, injectable and biocompatible hydrogel adhesives are developed via catalyst-free o-phthalaldehyde/amine (hydrazide) cross-linking reaction. The hydrogels demonstrate rapid and firm adhesion to various tissues, and an o-phthalaldehyde-mediated tissue adhesion mechanism is established. The hydrogel adhesives show controlled degradation profiles of 6 to 22 weeks in vivo through the incorporation of disulfide bonds into hydrogel network. In liver and blood vessel injury, the hydrogels effectively seal the incisions and rapidly stop bleeding. In rat and rabbit models of full-thickness skin incision, the hydrogel adhesives quickly close the incisions and accelerate wound healing, which exhibit efficacies superior to those of commercially available fibrin glue and cyanoacrylate glue. Thus, the hydrogel adhesives show great potential for sutureless wound closure, hemostasis sealing, and prevention of leakage in surgical applications.

Recent Advances in Biodegradable and Biocompatible Synthetic Polymers Used in Skin Wound Healing

The treatment of skin wounds caused by trauma and pathophysiological disorders has been a growing healthcare challenge, posing a great economic burden worldwide. The use of appropriate wound dressings can help to facilitate the repair and healing rate of defective skin. Natural polymer biomaterials such as collagen and hyaluronic acid with excellent biocompatibility have been shown to promote wound healing and the restoration of skin. However, the low mechanical properties and fast degradation rate have limited their applications. Skin wound dressings based on biodegradable and biocompatible synthetic polymers can not only overcome the shortcomings of natural polymer biomaterials but also possess favorable properties for applications in the treatment of skin wounds. Herein, we listed several biodegradable and biocompatible synthetic polymers used as wound dressing materials, such as PVA, PCL, PLA, PLGA, PU, and PEO/PEG, focusing on their composition, fabrication techniques, and functions promoting wound healing. Additionally, the future development prospects of synthetic biodegradable polymer-based wound dressings are put forward. Our review aims to provide new insights for the further development of wound dressings using synthetic biodegradable polymers.

Polymeric Based Hydrogel Membranes for Biomedical Applications

The development of biomedical applications is a transdisciplinary field that in recent years has involved researchers from chemistry, pharmacy, medicine, biology, biophysics, and biomechanical engineering. The fabrication of biomedical devices requires the use of biocompatible materials that do not damage living tissues and have some biomechanical characteristics. The use of polymeric membranes, as materials meeting the above-mentioned requirements, has become increasingly popular in recent years, with outstanding results in tissue engineering, for regeneration and replenishment of tissues constituting internal organs, in wound healing dressings, and in the realization of systems for diagnosis and therapy, through the controlled release of active substances. The biomedical application of hydrogel membranes has had little uptake in the past due to the toxicity of cross-linking agents and to the existing limitations regarding gelation under physiological conditions, but now it is proving to be a very promising field This review presents the important technological innovations that the use of membrane hydrogels has promoted, enabling the resolution of recurrent clinical problems, such as post-transplant rejection crises, haemorrhagic crises due to the adhesion of proteins, bacteria, and platelets on biomedical devices in contact with blood, and poor compliance of patients undergoing long-term drug therapies.

Recent Advances in Antimicrobial Peptide Hydrogels

Advances in the number and type of available biomaterials have improved medical devices such as catheters, stents, pacemakers, prosthetic joints, and orthopedic devices. The introduction of a foreign material into the body comes with a risk of microbial colonization and subsequent infection. Infections of surgically implanted devices often lead to device failure, which leads to increased patient morbidity and mortality. The overuse and improper use of antimicrobials has led to an alarming rise and spread of drug-resistant infections. To overcome the problem of drug-resistant infections, novel antimicrobial biomaterials are increasingly being researched and developed. Hydrogels are a class of 3D biomaterials consisting of a hydrated polymer network with tunable functionality. As hydrogels are customizable, many different antimicrobial agents, such as inorganic molecules, metals, and antibiotics have been incorporated or tethered to them. Due to the increased prevalence of antibiotic resistance, antimicrobial peptides (AMPs) are being increasingly explored as alternative agents. AMP-tethered hydrogels are being increasingly examined for antimicrobial properties and practical applications, such as wound-healing. Here, we provide a recent update, from the last 5 years of innovations and discoveries made in the development of photopolymerizable, self-assembling, and AMP-releasing hydrogels.

Multifunctional conductive hyaluronic acid hydrogels for wound care and skin regeneration

Although the main function of skin is to act as a protective barrier against external factors, it is indeed an extremely vulnerable tissue. Skincare, regardless of the wound type, requires effective treatments to prevent bacterial infection and local inflammation. The complex biological roles displayed by hyaluronic acid (HA) during the wound healing process have made this multifaceted polysaccharide an alternative biomaterial to prepare wound dressings. Therefore, herein, we present the most advanced research undertaken to engineer conductive and interactive hydrogels based on HA as wound dressings that enhance skin tissue regeneration either through electrical stimulation (ES) or by displaying multifunctional performance. First, we briefly introduce to the reader the effect of ES on promoting wound healing and why HA has become a vogue as a wound healing agent. Then, a selection of systems, chosen according to their multifunctional relevance, is presented. Special care has been taken to highlight those recently reported works (mainly from the last 3 years) with enhanced scalability and biomimicry. By doing that, we have turned a critical eye on the field considering what major challenges must be overcome for these systems to have real commercial, clinical, or other translational impact.

One-Pot Synthesis of Bioadhesive Double-Network Hydrogel Patch as Disposable Wound Dressing

Inventions of materials to achieve biocompatibility, bioadhesion, and easy manufacturing are the urgent demand for promoting wound healing in clinical treatment. Hyaluronic acid (HA) is probably the ideal candidate for current dressing materials due to its well-known biocompatibility. However, the unavoidable problem for HA dressings is their inherent low adhesiveness to wounds, which severely impairs their treatment efficacy, especially during body movement. Here, we report a one-pot facile fabrication of hybrid double-network polydopamine-HA (PDA-HA) hydrogel with significantly enhanced adhesiveness compared to the HA hydrogel. Besides the easy manufacturing and promoted effectiveness, the PDA-HA hydrogel could be vacuum-dried to form a patch, further benefitting from the convenience for storage and distribution. When applied on the wound, the PDA-HA patch quickly rehydrated by absorbing exudate and stuck tightly to the wound. The applied PDA-HA patches keep the wounds covered for more than 7 days against strenuous exercise. Thus, mouse full-thickness wounds treated with the PDA-HA patches exhibited increased healing rates, where epithelization was finished within 14 days. Moreover, the hydrogel dressing exhibited promoting effects on vascularization and cell proliferation/migration. Together with the easy manufacturing procedure, good adhesion/adaptation, and promotion of wound healing, the PDA-HA patch holds great potential for future clinical translation.

Secretory proteins in the orchestration of microbial virulence: The curious case of Staphylococcus aureus

Microbial virulence showcases an excellent model for adaptive changes that enable an organism to survive and proliferate in a hostile environment and exploit host resources to its own benefit. In Staphylococcus aureus, an opportunistic pathogen of the human host, known for the diversity of the disease conditions it inflicts and the rapid evolution of antibiotic resistance, virulence is a consequence of having a highly plastic genome that is amenable to quick reprogramming and the ability to express a diverse arsenal of virulence factors. Virulence factors that are secreted to the host milieu effectively manipulate the host conditions to favor bacterial survival and growth. They assist in colonization, nutrient acquisition, immune evasion, and systemic spread. The structural and functional characteristics of the secreted virulence proteins have been shaped to assist S. aureus in thriving and disseminating effectively within the host environment and exploiting the host resources to its best benefit. With the aim of highlighting the importance of secreted virulence proteins in bacterial virulence, the present chapter provides a comprehensive account of the role of the major secreted proteins of S. aureus in orchestrating its virulence in the human host.

Microwave-Treated Physically Cross-Linked Sodium Alginate and Sodium Carboxymethyl Cellulose Blend Polymer Film for Open Incision Wound Healing in Diabetic Animals-A Novel Perspective for Skin Tissue Regeneration Application

This study aimed at developing the microwave-treated, physically cross-linked polymer blend film, optimizing the microwave treatment time, and testing for physicochemical attributes and wound healing potential in diabetic animals. Microwave-treated and untreated films were prepared by the solution casting method and characterized for various attributes required by a wound healing platform. The optimized formulation was tested for skin regeneration potential in the diabetes-induced open-incision animal model. The results indicated that the optimized polymer film formulation (MB-3) has significantly enhanced physicochemical properties such as high moisture adsorption (154.6 ± 4.23%), decreased the water vapor transmission rate (WVTR) value of (53.0 ± 2.8 g/m²/h) and water vapor permeability (WVP) value (1.74 ± 0.08 g mm/h/m²), delayed erosion (18.69 ± 4.74%), high water uptake, smooth and homogenous surface morphology, higher tensile strength (56.84 ± 1.19 MPa), and increased glass transition temperature and enthalpy (through polymer hydrophilic functional groups depicting efficient cross-linking). The in vivo data on day 16 of post-wounding indicated that the wound healing occurred faster with significantly increased percent re-epithelialization and enhanced collagen deposition with optimized MB-3 film application compared with the untreated group. The study concluded that the microwave-treated polymer blend films have sufficiently enhanced physical properties, making them an effective candidate for ameliorating the diabetic wound healing process and hastening skin tissue regeneration.

Hyaluronic acid treatment versus standard of care in chronic wounds in a German setting: Cost-effectiveness analysis

Background and Aims

Chronic wounds are a major burden for worldwide health care systems. In the management of chronic wounds several strategies with innovative and active agents emerged in the past few years, such as hyaluronic acid containing wound dressings. Evidence comparing the cost-effectiveness of hyaluronan and standard of care dressings (hydrofiber with silver) is still missing. The aim of the study is thus, to assess the cost-effectiveness of hyaluronan versus standard of care dressings (hydrofiber with silver) in chronic wounds from a German statutory health insurance perspective.

Methods

A decision tree was modeled to quantify the cost and healing rate at 12 weeks for the hyaluronan and silver dressings strategies. Input parameters were collected literature-based, accounting for healing rates, dressing prices and prices for dressing changes and associated home care. Parameter uncertainty was accounted for by one-way and probabilistic sensitivity analysis.

Results

Hyaluronic acid showed a better healing rate (60.68%) and noticeable lower cost (749.80 Euro) compared to standard of care (silver containing) dressings (59.62%; 883.05 Euro), resulting in an Incremental Cost Effectiveness Ratio of -12,570.57. The hyaluronan approach is hence a dominant strategy in chronic wound management. Sensitivity analysis confirmed these results, giving a range of 60%- 70% of cost-effective scenarios.

Conclusions

Hyaluronic acid dressings showed to be a clinical more effective strategy at significantly lower cost in chronic wounds compared to standard of care (hydrofiber with silver).

A Nanozyme-Immobilized Hydrogel with Endogenous ROS-Scavenging and Oxygen Generation Abilities for Significantly Promoting Oxidative Diabetic Wound Healing

Non-healing wound is a common complication of diabetic patients associated with high morbidity and mortality. Engineered therapeutic hydrogels have enviable advantages in tissue regeneration, however, they are suboptimal for the healing of diabetic wounds characterized by reactive oxygen species (ROS) accumulation and chronic hypoxia. Here, a unique biological metabolism-inspired hydrogel, for ameliorating this hostile diabetic microenvironment, is presented. Consisting of natural polymers (hydrazide modified hyaluronic acid and aldehyde modified hyaluronic acid) and a metal-organic frameworks derived catalase-mimic nanozyme (ε-polylysine coated mesoporous manganese cobalt oxide), the engineered nanozyme-reinforced hydrogels can not only capture the endogenous elevated ROS in diabetic wounds, but also synergistically produce oxygen through the ROS-driven oxygen production ability. These fascinating properties of hydrogels protect skin cells (e.g., keratinocytes, fibroblasts, and vascular endothelial cells) from ROS and hypoxia-mediated death and proliferation inhibition. Diabetic wounds treated with the nanozyme-reinforced hydrogels highlight the potential of inducing the macrophages polarization from pro-inflammatory phenotype (M1) to anti-inflammatory subtype (M2). The hydrogel dressings demonstrate a prominently accelerated healing rate as shown by alleviating the excessive inflammatory, inducing efficiently proliferation, re-epithelialization, collagen deposition, and neovascularization. This work provides an effective strategy based on nanozyme-reinforced hydrogel as a ROS-driven oxygenerator for enhancing diabetic wound healing.

Development of Streptococcus equisimilis Group G Mutant Strains with Ability to Produce Low Polydisperse and Low-Molecular-Weight Hyaluronic Acid

Background

Background: Hyaluronic acid (HA), a natural polymer with wide applications in biomedicine and cosmetics, is mainly produced by Streptococcal fermentation at industrial scale. In the present study, chemical random mutagenesis was used for development of Streptococcus equisimilis group G mutant strains with high HA productivity.

Methods

Methods: The optimum of the pH of culture condition and cultivation time for HA production by wild strain group G were assessed. At first, two rounds of mutation at different concentrations of NTG was used for mutagenesis. Then, the nonhemolytic and hyaluronidase-negative mutants were screened on the blood and HA agar. HA productivity and molecular weight were determined by carbazole assay, agarose gel electrophoresis and specific staining. Moreover, stability of the high producer mutants was evaluated within 10 generations.

Results

Results: The results showed that the wild-type strain produced 1241 ± 2.1 µg/ml of HA at pH 5.5 and 4 hours of cultivation, while the screened mutants showed a 16.1-45.5% increase in HA production. Two mutant strains, named Gm2-120-21-3 (2470 ± 8.1 µg/ml) and Gm2-120-21-4 (2856 ± 4.2 µg/ml), indicated the highest titer and a consistent production. The molecular weight (Mw) of HA for the mutants was less than 160 kDa, considering as a low Mw HA.

Conclusion

Conclusion: The mutant strains producing a low polydisperse, as well as low Mw of HA with high titer might be regarded as potential industrial strains for HA production after further safety investigations.

M, Zarrintaj P, Formela K, Saeb MR, Bencherif SA. Clickable Polysaccharides for Biomedical Applications: A Comprehensive Review

Recent advances in materials science and engineering highlight the importance of designing sophisticated biomaterials with well-defined architectures and tunable properties for emerging biomedical applications. Click chemistry, a powerful method allowing specific and controllable bioorthogonal reactions, has revolutionized our ability to make complex molecular structures with a high level of specificity, selectivity, and yield under mild conditions. These features combined with minimal byproduct formation have enabled the design of a wide range of macromolecular architectures from quick and versatile click reactions. Furthermore, copper-free click chemistry has resulted in a change of paradigm, allowing researchers to perform highly selective chemical reactions in biological environments to further understand the structure and function of cells. In living systems, introducing clickable groups into biomolecules such as polysaccharides (PSA) has been explored as a general approach to conduct medicinal chemistry and potentially help solve healthcare needs. De novo biosynthetic pathways for chemical synthesis have also been exploited and optimized to perform PSA-based bioconjugation inside living cells without interfering with their native processes or functions. This strategy obviates the need for laborious and costly chemical reactions which normally require extensive and time-consuming purification steps. Using these approaches, various PSA-based macromolecules have been manufactured as building blocks for the design of novel biomaterials. Clickable PSA provides a powerful and versatile toolbox for biomaterials scientists and will increasingly play a crucial role in the biomedical field. Specifically, bioclick reactions with PSA have been leveraged for the design of advanced drug delivery systems and minimally invasive injectable hydrogels. In this review article, we have outlined the key aspects and breadth of PSA-derived bioclick reactions as a powerful and versatile toolbox to design advanced polymeric biomaterials for biomedical applications such as molecular imaging, drug delivery, and tissue engineering. Additionally, we have also discussed the past achievements, present developments, and recent trends of clickable PSA-based biomaterials such as 3D printing, as well as their challenges, clinical translatability, and future perspectives.

Complexed Polymer Film-Forming Spray: An Optimal Delivery System for Secretome of Mesenchymal Stem Cell as Diabetic Wound Dressing?

Diabetes-related wounds have physiological factors that make healing more complicated. High sugar levels can increase microbial infection risk while limiting nutrition and oxygen transfer to the wound area. The secretome of mesenchymal stem cells has been widely known for its efficacy in regenerative therapy. However, applying the secretome directly to the wound can reduce its effectiveness. In this review, we examined the literature on synthesizing the combinations of carboxymethyl chitosan, hyaluronic acid, and collagen tripeptides, as well as the possibility of physicochemical properties enhancement of the hydrogel matrix, which could potentially be used as an optimal delivery system of stem cell's secretome for diabetic wound healing.

Wet Electrospun Nanofibers-Fortified Gelatin/Alginate-Based Nanocomposite as a Single-Dose Biomimicking Skin Substitute

We report the development and evaluation of a series of well-designed single-dose extracellular matrix (ECM)-mimicking nanofibers (NFs)-reinforced hydrogel (HG)-based skin substitute for wound healing. The HG matrix of the proposed skin substitute is composed of gelatin (GE) and sodium alginate (SA), and incorporates hyaluronic acid (HA) as a key component of the natural ECM, as well as the antimicrobial Punica granatum extract (PE). This HG nanocomposite was cross-linked by the biocompatible N-(3-(dimethylamino)propyl)-N'-ethylcarbodiimide hydrochloride (EDC) cross-linker, and was reinforced with fragmented trans-ferulic acid (FA)-loaded cellulose acetate/polycaprolactone (PCL/CA) NFs. The NFs were obtained via wet electrospinning into a poly(vinyl alcohol) (PVA) coagulating solution to closely resemble the porous structure of the ECM fibers, which facilitates cell migration, attachment, and proliferation. The proposed design of the skin substitute allows adjustable mechanical characteristics and outstanding physical properties (swelling and biodegradability), as well as an excellent porous microstructure. The developed skin substitutes were characterized using Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), and electron microscopy. In addition, the biodegradability, biocompatibility, bioactivity, mechanical, and in vitro drug release characteristics were investigated. Moreover, an in vivo excisional full-thickness defect model was conducted to assess skin regeneration and healing effectiveness. The average diameters of the plain and FA-loaded NFs are 210 ± 12 nm and 452 ± 25 nm, respectively. The developed ECM-mimicking skin substitutes demonstrated good antibacterial activity, free-radical scavenging activity, cytocompatibility, porosity, water absorption ability, and good biodegradability. In vivo application of the ECM-mimicking skin substitutes revealed their excellent wound-healing activity and their suitability for single-dose treatment of deep wounds with reducing the wound diameter to 0.95 mm after 15 days of treatment. Moreover, the histological investigation of the wound area demonstrated that the applied skin substitutes have not only enhanced the wound healing progress, but also can participate in improving the quality of the regenerated skin in the treated area via facilitating collagen fibers regeneration and deposition.

A novel photosynthetic biologic topical gel for enhanced localized hyperoxygenation augments wound healing in peripheral artery disease

Peripheral artery disease and the associated ischemic wounds are substantial causes of global morbidity and mortality, affecting over 200 million people worldwide. Although advancements have been made in preventive, pharmacologic, and surgical strategies to treat this disease, ischemic wounds, a consequence of end-stage peripheral artery disease, remain a significant clinical and economic challenge. Synechococcus elongatus is a cyanobacterium that grows photoautotrophically and converts carbon dioxide and water into oxygen. We present a novel topical biologic gel containing S. elongatus that provides oxygen via photosynthesis to augment wound healing by rescuing ischemic tissues caused by peripheral artery disease. By using light rather than blood as a source of energy, our novel topical therapy significantly accelerated wound healing in two rodent ischemic wound models. This novel topical gel can be directly translated to clinical practice by using a localized, portable light source without interfering with patients' daily activities, demonstrating potential to generate a paradigm shift in treating ischemic wounds from peripheral artery disease. Its novelty, low production cost, and ease of clinical translatability can potentially impact the clinical care for millions of patients suffering from peripheral arterial disease.

Wound dressing adherence: a review

Wound dressing adherence is an important problem that is frequently encountered in wound care, and is associated with both clinical and economic burdens. However, only a few review articles have focused on this issue. The objective of this review was to present a comprehensive discussion of wound dressing adherence, including the mechanism of dressing adherence, adverse consequences (clinical burdens and economic burdens), factors affecting adherence (dressing-, patient- and wound-related factors, and factors related to the wound care procedure), tests to assess dressing adherence (in vitro assay, in vivo assay and clinical trials), and reduction of wound adherence (modification of dressing adherence and special care in particular patients). Accordingly, this review article emphasises an awareness of dressing adherence, and is intended to be an informative source for the development of new dressings and for wound management.

Rational design of hydrogels for immunomodulation

The immune system protects organisms against endogenous and exogenous harm and plays a key role in tissue development, repair, and regeneration. Traditional immunomodulatory biologics exhibit limitations including degradation by enzymes, short half-life, and lack of targeting ability. Encapsulating or binding these biologics within biomaterials is an effective way to address these problems. Hydrogels are promising immunomodulatory materials because of their prominent biocompatibility, tuneability, and versatility. However, to take advantage of these opportunities and optimize material performance, it is important to more specifically elucidate, and leverage on, how hydrogels affect and control the immune response. Here, we summarize how key physical and chemical properties of hydrogels affect the immune response. We first provide an overview of underlying steps of the host immune response upon exposure to biomaterials. Then, we discuss recent advances in immunomodulatory strategies where hydrogels play a key role through a) physical properties including dimensionality, stiffness, porosity, and topography; b) chemical properties including wettability, electric property, and molecular presentation; and c) the delivery of bioactive molecules via chemical or physical cues. Thus, this review aims to build a conceptual and practical toolkit for the design of immune-instructive hydrogels capable of modulating the host immune response.

Effect of Allogeneic Oral Mucosa Mesenchymal Stromal Cells on Equine Wound Repair

Objective

To assess the clinical value and safety of the application of allogeneic equine oral mucosa mesenchymal stromal cells (OM-MSCs) to wounds. Animals. 8 healthy adult horses without front limb skin lesions or musculoskeletal disease. Procedures. Stem cells were isolated from the oral mucosa of a donor horse. Horses were subjected to the creation of eight full-thickness cutaneous wounds, two on each distal forelimb (FL) and two on both sides of the thorax (TH). Each wound was subjected to one out of four treatments: no medication (T1), hyaluronic acid- (HA-) gel containing OM-MSC (T2), HA-gel containing OM-MSC secretome (T3), and HA-gel alone (T4). Gross macroscopic evaluation and laser digital photographic documentation were regularly performed to allow wound assessment including wound surface area. Full-thickness skin punch biopsy was performed at each site before wound induction (D0, normal skin) and after complete wound healing (D62, repaired skin).

Results

All wounds healed without adverse effect at D62. Distal limb wounds are slower to heal than body wounds. OM-MSC and its secretome have a positive impact on TH wound contraction. OM-MSC has a positive impact on the contraction and epithelialization of FL wounds. No significant difference between wound sites before and after treatment was noted at histological examination. Conclusion and Clinical Relevance. Using horse cells harvested from oral mucosa is a feasible technique to produce OM-MSC or its secretome. The gel produced by the combination of these biologic components with HA shows a positive impact when applied during the early stage of wound healing.

Screening of the Chemical Composition and Identification of Hyaluronic Acid in Food Supplements by Fractionation and Fourier-Transform Infrared Spectroscopy

Hyaluronic acid, together with collagen, vitamins or plant extracts, is a part of many cosmetic and food preparations. For example, this polysaccharide is used in formulation of many food supplements due to its protective effects on human health. In this work, the screening of the chemical composition of three chosen dietary supplements (powder, tablets and capsules) containing hyaluronic acid was carried out using Fourier-transform infrared spectroscopy. Because of the low amount of analyte in all these samples, it was isolated or concentrated prior to the analysis using a suitable sequential fractionation protocol. Individual isolation procedures were established for each sample based on their declared composition. Firstly, the major components such as collagen or vitamins were removed to obtain polysaccharide fractions by the enzymatic treatment and/or washing out with the appropriate solvents. In some cases, the water insoluble part was removed from the rest dissolved in water. Then, hyaluronic acid was precipitated with copper(II) cations and thus separated from the other polysaccharides. Finally, the analyte was identified in the enriched fractions by the characteristic vibrational bands. The amount of hyaluronic acid in the purified fractions was determined in three ways: gravimetrically, spectrophotometrically, and using isotachophoresis. The combination of the appropriate preparative and analytical steps led to the successful evaluation of chemical composition, finding and quantification of hyaluronic acid in all the studied samples.

Extracellular matrix-based combination scaffold for guided regeneration of large-area full-thickness rabbit burn wounds upon a single application

Regeneration of large acute and chronic wounds is a concern worldwide. The present study evaluates wound healing competence of a completely human-origin, extracellular matrix (ECM)-based skin substitute/graft. It comprises cell-less amniotic membrane (AM), clinical-grade fibrin (FIB), and hyaluronic acid (HA) termed as AMFIBHA. The use of large-area third-degree rabbit burn wounds evaluated the product efficiency. The AMFIBHA induces hemostasis and permits suture-less positioning on the wound bed. In wet wounds, the AMFIBHA degrades and release biologically active molecules and guide cell migration, proliferation, and regeneration. The study demonstrated the effectiveness of this wound care product in terms of epithelial-dermal regeneration with angiogenesis. The study assessed injury-associated inflammation and different wound healing markers after 28 days of experiment and compared with both positive and negative controls-treated wounds. The regeneration of mature epidermis and dermis with rete pegs and hair follicle-like structure was evident upon a single application. The active involvement of host cells resulted in supple tissue formation. The ECM organization of AMFIBHA-treated tissue resulted in re-gain of mechanical properties comparable to native skin after 56 days. These guided regenerative outcomes reveal a promising translational value of the novel AMFIBHA skin substitute as an off-the-shelf product for clinical use.

Efficacy of hyaluronic acid film on perianal wound healing in a rat model

Purpose

Postoperative pain and delayed wound healing are the main complications following anal surgery associated with poor quality of life. Hyaluronic acid (HA) supports tissue regeneration and rapid wound healing by promoting cell proliferation and migration. We investigated the effects of HA on perianal wound healing in a rat model.

Methods

Forty-eight 8-week-old Sprague-Dawley rats with perianal wounds created by biopsy punch were divided into 3 groups: simple dressing with gauze (control), dressing with topical HA film, and dressing with topical HA gel. HA agents were not reapplied postoperatively. Wound healing was evaluated by measuring the healed area, and histological analyses were randomly performed using hematoxylin and eosin and Masson trichrome staining.

Results

Fewer mean days were required for complete wound healing in the HA film and HA gel groups than in the control group (11.6 vs. 11.9 vs. 13.8 days, respectively; P = 0.010). The healed area in the HA film group on day 11 was larger than that in the HA gel and control groups (80.2% vs. 61.9% vs. 53.2%, respectively; P < 0.001). Histologically, the HA film group showed accelerated reepithelialization, a rapid transition to lymphocyte-predominant inflammation, and increased fibroblastic proliferation and collagen deposition compared to the other groups. There was no treatment-related toxicity in the HA application groups.

Conclusion

Topical application of HA film to perianal wounds improves the wound healing rate in a rat model. This finding suggests a potential benefit of HA film application in promoting wound healing after anal surgery in humans.

Hyaluronic Acid: A Key Ingredient in the Therapy of Inflammation

Hyaluronic acid (HA) is a natural polymer, produced endogenously by the human body, which has unique physicochemical and biological properties, exhibiting desirable biocompatibility and biodegradability. Therefore, it has been widely studied for possible applications in the area of inflammatory diseases. Although exogenous HA has been described as unable to restore or replace the properties and activities of endogenous HA, it can still provide satisfactory pain relief. This review aims to discuss the advances that have been achieved in the treatment of inflammatory diseases using hyaluronic acid as a key ingredient, essentially focusing on studies carried out between the years 2017 and 2021.

Polymer-Based Nanotherapeutics for Burn Wounds

Burn wounds are complex and intricate injuries that have become a common cause of trauma leading to significant mortality and morbidity every year. Dressings are applied to burn wounds with the aim of promoting wound healing, preventing burn infection and restoring skin function. The dressing protects the injury and contributes to recovery of dermal and epidermal tissues. Polymer-based nanotherapeutics are increasingly being exploited as burn wound dressings. Natural polymers such as cellulose, chitin, alginate, collagen, gelatin and synthetic polymers like poly (lactic-co-glycolic acid), polycaprolactone, polyethylene glycol, and polyvinyl alcohol are being obtained as nanofibers by nanotechnological approaches like electrospinning and have shown wound healing and re-epithelialization properties. Their biocompatibility, biodegradability, sound mechanical properties and unique structures provide optimal microenvironment for cell proliferation, differentiation, and migration contributing to burn wound healing. The polymeric nanofibers mimic collagen fibers present in extracellular matrix and their high porosity and surface area to volume ratio enable increased interaction and sustained release of therapeutics at the site of thermal injury. This review is an attempt to compile all recent advances in the use of polymer-based nanotherapeutics for burn wounds. The various natural and synthetic polymers used have been discussed comprehensively and approaches being employed have been reported. With immense research effort that is currently being invested in this field and development of proper characterization and regulatory framework, future progress in burn treatment is expected to occur. Moreover, appropriate preclinical and clinical research will provide evidence for the great potential that polymer-based nanotherapeutics hold in the management of burn wounds.

Modulation of hyaluronan signaling as a therapeutic target in human disease

The extracellular matrix is an active participant, modulator and mediator of the cell, tissue, organ and organismal response to injury. Recent research has highlighted the role of hyaluronan, an abundant glycosaminoglycan constituent of the extracellular matrix, in many fundamental biological processes underpinning homeostasis and disease development. From this basis, emerging studies have demonstrated the therapeutic potential of strategies which target hyaluronan synthesis, biology and signaling, with significant promise as therapeutics for a variety of inflammatory and immune diseases. This review summarizes the state of the art in this field and discusses challenges and opportunities in what could emerge as a new class of therapeutic agents, that we term "matrix biologics".

Hyaluronic acid-fibrin hydrogels show improved mechanical stability in dermo-epidermal skin substitutes

Human plasma-derived bilayered skin substitutes have been successfully used by our group in different skin tissue engineering applications. However, several issues associated with their poor mechanical properties were observed, and they often resulted in rapid contraction and degradation. In this sense, hydrogels composed of plasma-derived fibrin and thiolated-hyaluronic acid (HA-SH, 0.05-0.2% w/v) crosslinked with poly(ethylene glycol) diacrylate (PEGDA, 2:1, 6:1, 10:1 and 14:1 mol of thiol to moles of acrylate) were developed to reduce the shrinking rates and enhance the mechanical properties of the plasma-derived matrices. Plasma/HA-SH-PEGDA hydrogels showed a decrease in the contraction behaviour ranging from 5% to 25% and an increase in Young's modulus. Furthermore, the results showed that a minimal amount of the added HA-SH was able to escape the plasma/HA-SH-PEGDA hydrogels after incubation in PBS. The results showed that the increase in rigidity of the matrices as well as the absence of adhesion cellular moieties in the second network of HA-SH/PEGDA, resulted in a decrease in contraction in the presence of the encapsulated primary human fibroblasts (hFBs), which may have been related to an overall decrease in proliferation of hFBs found for all hydrogels after 7 days with respect to the plasma control. The metabolic activity of hFB returned to the control levels at 14 days except for the 2:1 PEGDA crosslinking ratio. The metabolic activity of primary human keratinocytes (hKCs) seeded on the hydrogels showed a decrease when high amounts of HA-SH and PEGDA crosslinker were incorporated. Organotypic skins formed in vitro after 21 days with plasma/HA-SH-PEGDA hydrogels with an HA content of 0.05% w/v and a 2:1 crosslinking ratio were up to three times thicker than the plasma controls, evidencing a reduction in contraction, while they also showed better and more homogeneous keratin 10 (K10) expression in the supra-basal layer of the epidermis. Furthermore, filaggrin expression showed the formation of an enhanced stratum corneum for the constructs containing HA. These promising results indicate the potential of using these biomimetic hydrogels as in vitro skin models for pharmaceutical products and cosmetics and future work will elucidate their potential functionality for clinical treatment.

Recent advances in PVA-polysaccharide based hydrogels and electrospun nanofibers in biomedical applications: A review

Among several types of carbohydrate polymers blend PVA hydrogel membranes used for biomedical applications in particular wound dressings; electrospun nanofibrous membranes have gained increased interest because of their extraordinary features e.g. huge surface area to volume ratio, high porosity, adequate permeability, excellent wound-exudates absorption capacity, architecture similarity with skin ECM and sustained release-profile over long time. In this study, modern perspectives of synthesized/developed electrospun nanofibrous hydrogel membranes based popular carbohydrate polymers blend PVA which recently have been employed for versatile biomedical applications particularly wound dressings, were discussed intensively and compared in detail with traditional fabricated membranes based films, as well. Clinically relevant and advantages of electrospun nanofibrous membranes were discussed in terms of their biocompatibility and easily fabrication and functionalization in different biomedical applications.

Advances in metabolic engineering of Corynebacterium glutamicum to produce high-value active ingredients for food, feed, human health, and well-being

The soil microbe Corynebacterium glutamicum is a leading workhorse in industrial biotechnology and has become famous for its power to synthetise amino acids and a range of bulk chemicals at high titre and yield. The product portfolio of the microbe is continuously expanding. Moreover, metabolically engineered strains of C. glutamicum produce more than 30 high value active ingredients, including signature molecules of raspberry, savoury, and orange flavours, sun blockers, anti-ageing sugars, and polymers for regenerative medicine. Herein, we highlight recent advances in engineering of the microbe into novel cell factories that overproduce these precious molecules from pioneering proofs-of-concept up to industrial productivity.

Efficacy of 0.2% hyaluronic acid in the healing of skin abrasions in rats

Acute injuries, such as surgical and traumatic, heal normally in an organized and rapid manner. Studies point to the healing activity of hyaluronic acid in all phases of healing. The aim was to evaluate the effectiveness of hyaluronic acid in skin abrasions on the dorsum of rats to compare to usual products on the market. Seventy-two Wistar rats were subjected to excoriation of approximately 2.0 cm2 on the back by dermabrasion. According to the treatment, 3 groups were established: saline, chlorhexidine digluconate and 0.2% hyaluronic acid for 14 days. Animals were photographed on the 2nd, 7th, 10th and 14th postinjury days, and the index of healing of the abrasions was calculated. Biochemically, myeloperoxidase measurements of skin biopsies in addition to histological studies to assess the crust and epidermal layers were performed. The group treated with hyaluronic acid showed better re-epithelialization from the other groups (p < 0.05) on the 7th and 10th days. For the thickness of the crust, the hyaluronic acid group presented thinner crust than other groups on the 10th and 14th days (p < 0.05), but in the epidermis, no difference was observed between the groups studied. All groups showed an increase in myeloperoxidase enzyme on the 2nd day, but a decreasing on the 7th day. On the 10th day, there was a difference in the hyaluronic acid group compared to the other groups (p < 0.05). The application of 0.2% hyaluronic acid significantly accelerated the re-epithelialization of skin abrasions compared to saline and chlorhexidine digluconate.

A New Dermal Substitute Containing Polyvinyl Alcohol with Silver Nanoparticles and Collagen with Hyaluronic Acid: In Vitro and In Vivo Approaches

The experimental use of poly (alcohol-vinyl) (PVA) as a skin curative is increasing widely. However, the use of this hydrogel is challenging due to its favorable properties for microbiota growth. The association with silver nanoparticles (AgNPs) as an antimicrobial agent turns the match for PVA as a dressing, as it focuses on creating a physical barrier to avoid wound dehydration. When associated with extracellular components, such as the collagen matrix, the device obtained can create the desired biological conditions to act as a skin substitute. This study aimed to analyze the anti-microbiological activity and the in vitro and in vivo responses of a bilaminar device of PVA containing AgNPs associated with a membrane of collagen-hyaluronic acid (col-HA). Additionally, mesenchymal stem cells were cultured in the device to evaluate in vitro responses and in vivo immunomodulatory and healing behavior. The device morphology revealed a porous pattern that favored water retention and in vitro cell adhesion. Controlled wounds in the dorsal back of rat skins revealed a striking skin remodeling with new epidermis fulfilling all previously injured areas after 14 and 28 days. No infections or significant inflammations were observed, despite increased angiogenesis, and no fibrosis-markers were identified as compared to controls. Although few antibacterial activities were obtained, the addition of AgNPs prevented fungal growth. All results demonstrated that the combination of the components used here as a dermal device, chosen according to previous miscellany studies of low/mid-cost biomaterials, can promote skin protection avoiding infections and dehydration, minimize the typical wound inflammatory responses, and favor the cellular healing responses, features that give rise to further clinical trials of the device here developed.

Polyblend Nanofibers to Regenerate Gingival Tissue: A Preliminary In Vitro Study

Aim: The regeneration of small periodontal defects has been considered an important divide and challenging issue for dental practitioners. The aim of this preliminary in vitro study was to analyze the effects of polycaprolactone (PCL) nanofibers enriched with hyaluronic acid and vitamin E vs. nude nanofibers on gingival fibroblasts activity, an innovative graft for periodontal soft tissue regeneration purposes.

Methods: Nanofibers were produced in PCL (NF) or PCL enriched with hyaluronic acid and vitamin E (NFE) by electrospinning technique. NF and NFE were stereologically and morphologically characterized by scanning electron microscope (SEM), and composition was analyzed by infrared spectroscopy. Human fibroblasts were obtained from one gingival tissue fragment (HGF) and then seeded on NF, NFE, and plastic (CT). Cell adhesion and morphology were evaluated using SEM at 24 h and cell viability after 24, 48, and 72 h by alamarBlue® assay. Gene expression for COL-I, LH2b, TIMP-1, PAX, and VNC was analyzed by real-time RT-PCR in samples run in triplicate and GAPDH was used as housekeeping gene. Slot blot analysis was performed and immunoreactive bands were revealed for MMP-1 and COL-I. YAP and p-YAP were analyzed by Western blot and membranes were reprobed by α-tubulin. Statistical analysis was performed.

Results: IR spectrum revealed the presence of PCL in NF and PCL and vitamin E and hyaluronic acid in NFE. At 24 h, HGF adhered on NF and NFE conserving fibroblast like morphology. At 72 h from seeding, statistically significant differences were found in proliferation of HGF cultured on NF compared to NFE. Expression of genes (LH2b, TIMP-1, and MMP-1) and proteins (COL-I) related to collagen turnover revealed a reduction of COL-1 secretion in cells cultured on NF and NFE compared to CT; however, NFE stimulated cross-linked collagen deposition. Mechanosensor genes (PAX, VNC, and YAP) were upregulated in HGF on NF while they were decreased in cells grown on NFE.

Conclusion: Preliminary data suggest that PCL-enriched nanofibers could represent a support to induce HGF proliferation, adhesion, collagen cross-linking, and to reduce collagen degradation, therefore favoring collagen deposition in gingival connective tissue.

Tattoo aftercare management with a dermo-cosmetic product: Improvement in discomfort sensation and skin repair quality

Background

A moisturizer application during the healing process after a tattoo session is a common practice to help wound healing and to reduce discomfort sensations. This practice was recently recommended by the standard European guidelines on tattoos, with the use of an adapted ointment to keep the site moist.

Aims

To assess the efficacy and the tolerability of a specific dermo‐cosmetic product (Cicabio Pommade, Laboratoire Bioderma, NAOS, France) in tattoo aftercare.

Patients/Methods

Thirty subjects included in this survey applied the product immediately after the tattoo session for 14 days. The objective symptoms (redness, edema, skin repair quality) were assessed by the tattooist and the subjects. The subjective symptoms, discomfort sensations (pain, itching, burning sensations, tingling), soothing, moisturizing, and undesirable effects were assessed by the tattooed individuals.

Results

After 14 days of application, redness was absent for 100% and 96% of subjects according to the tattoo artist and the subjects, respectively, and edema had completely disappeared for both assessors. Most of the subjects rated the skin quality repair and the aesthetic outcomes as very good to excellent. Soothing and moisturizing effects were observed as early as the first day. The effects were maintained over 14 days. Discomfort sensations were judged absent to slight in 96%–100% of cases after 7 days. They were assessed as absent to slight in all cases for pain, itching, and tingling, and in 96% for burning sensations after 14 days. The product was very well tolerated by 87% of the subjects.

Conclusions

Our survey demonstrates that this dermo‐cosmetic product is suitable for tattooed skin aftercare as it reduced skin discomfort as soon as the first day and led to a good skin quality repair while being well tolerated.