Hyaluronic acid/lysozyme self-assembled coacervate to promote cutaneous wound healing

Bioactive materials for in vivo sweat gland regeneration

Loss of sweat glands (SwGs) commonly associated with extensive skin defects is a leading cause of hyperthermia and heat stroke. In vivo tissue engineering possesses the potential to take use of the body natural ability to regenerate SwGs, making it more conducive to clinical translation. Despite recent advances in regenerative medicine, reconstructing SwG tissue with the same structure and function as native tissue remains challenging. Elucidating the SwG generation mechanism and developing biomaterials for in vivo tissue engineering is essential for understanding and developing in vivo SwG regenerative strategies. Here, we outline the cell biology associated with functional wound healing and the characteristics of bioactive materials. We critically summarize the recent progress in bioactive material-based cell modulation approaches for in vivo SwG regeneration, including the recruitment of endogenous cells to the skin lesion for SwG regeneration and in vivo cellular reprogramming for SwG regeneration. We discussed the re-establishment of microenvironment via bioactive material-mediated regulators. Besides, we offer promising perspectives for directing in situ SwG regeneration via bioactive material-based cell-free strategy, which is a simple and effective approach to regenerate SwG tissue with both fidelity of structure and function. Finally, we discuss the opportunities and challenges of in vivo SwG regeneration in detail. The molecular mechanisms and cell fate modulation of in vivo SwG regeneration will provide further insights into the regeneration of patient-specific SwGs and the development of potential intervention strategies for gland-derived diseases.

Exploring the therapeutic potential of recombinant human lysozyme: a review on wound management system with antibacterial

Lysozyme, a natural antibacterial enzyme protein, possesses the ability to dissolve the cell walls of Gram-positive bacteria, demonstrating broad-spectrum antibacterial activity. Despite its significant potential in treating wound infections and promoting wound healing, its widespread clinical application has yet to be realized. Current research is primarily focused on carrier-based delivery systems for lysozyme. In this review, we discuss four delivery systems that can be employed for lysozyme in wound healing treatment, specifically hydrogels, nanofilms, electrospun fibrous membranes, and modified-lysozyme composite systems. These systems not only enhance the stability of lysozyme but also enable its controlled and sustained release at wound sites, potentially overcoming some of the challenges associated with its direct application. Lastly, we delve into the perspectives and challenges related to the use of these delivery systems, hoping to spur further research and innovation in this promising field.

Accelerated Wound Healing with a Diminutive Scar through Cocrystal Engineered Curcumin

Pharmaceutical cocrystals ( Regulatory Classification of Pharmaceutical Co-Crystals Guidance for Industry; Food and Drug Administration, 2018) are crystalline solids produced through supramolecular chemistry to modulate the physicochemical properties of active pharmaceutical ingredients (APIs). Despite their extensive development in interdisciplinary sciences, this is a pioneering study on the efficacy of pharmaceutical cocrystals in wound healing and scar reducing. Curcumin-pyrogallol cocrystal (CUR-PYR) was accordingly cherry-picked since its superior physicochemical properties adequately compensate for limitative drawbacks of curcumin (CUR). CUR-PYR has been synthesized by a liquid-assisted grinding (LAG) method and characterized via FT-IR, DSC, and PXRD analyses. In vitro antibacterial study indicated that CUR-PYR cocrystal, CUR+PYR physical mixture (PM), and PYR are more effective against both Gram-negative (Pseudomonas aeruginosa and Escherichia coli) and Gram-positive (Staphylococcus aureus and Bacillus subtilis) bacteria in comparison with CUR. In vitro results also demonstrated that the viability of HDF and NIH-3T3 cells treated with CUR-PYR were improved more than those received CUR which is attributed to the effect of PYR in the form of cocrystal. The wound healing process has been monitored through a 15 day in vivo experiment on 75 male rats stratified into six groups: five groups treated by CUR-PYR+Vaseline (CUR-PYR.ung), CUR+PYR+Vaseline (CUR+PYR.ung), CUR+Vaseline (CUR.ung), PYR+Vaseline (PYR.ung), and Vaseline (VAS) ointments and a negative control group of 0.9% sodium chloride solution (NS). It was revealed that the wounds under CUR-PYR.ung treatment closed by day 12 postsurgery, while the wounds in other groups failed to reach the complete closure end point until the end of the experiment. Surprisingly, a diminutive scar (3.89 ± 0.97% of initial wound size) was observed in the CUR-PYR.ung treated wounds by day 15 after injury, followed by corresponding values for PYR.ung (12.08 ± 2.75%), CUR+PYR.ung (13.89 ± 5.02%), CUR.ung (16.24 ± 6.39%), VAS (18.97 ± 6.89%), and NS (20.33 ± 5.77%). Besides, investigating histopathological parameters including inflammation, granulation tissue, re-epithelialization, and collagen deposition signified outstandingly higher ability of CUR-PYR cocrystal in wound healing than either of its two constituents separately or their simple PM. It was concluded that desired solubility of the prepared cocrystal was essentially responsible for accelerating wound closure and promoting tissue regeneration which yielded minimal scarring. This prototype research suggests a promising application of pharmaceutical cocrystals for the purpose of wound healing.

Astragalus polysaccharides driven stretchable nanofibrous membrane wound dressing for joint wound healing

Joint wound dressings are currently significantly limited in their clinical applications due to their inferior mechanical properties and single therapeutic effect. Therefore, it is imperative to develop a versatile joint wound dressing that integrates adequate stretchability, desirable biocompatibility, and multiple biological effects into one system. We implemented the electrospinning technique in this study to fabricate a novel nanofibrous membrane (NFM) composed of gelatin (GEL) and astragalus polysaccharides (APS), termed GEL/APS NFM. The selection of GEL and APS confers excellent biocompatibility to GEL/APS NFM. Furthermore, the optimally proportioned GEL/APS NFM exhibits satisfactory stretchability and desirable wound healing efficiency. Furthermore, released APS can exert anti-inflammatory, procollagen deposition, and proangiogenic effects to accelerate epithelial tissue, enhancing joint wound healing. In summary, GEL/APS NFM offers a convenient and effective approach to promoting rapid joint wound healing, providing a novel approach to joint wound care.

Systematic study on lysozyme-hyaluronan complexes: Multi-spectroscopic characterization and molecular dynamics simulation

This study systematically investigated the complexation mechanism of lysozyme (LYS) and hyaluronan (HA) as well as their complex-formation process using multi-spectroscopy combined with molecular dynamics simulation. Overall, the results demonstrated that electrostatic interaction provides the primary self-assembly driving forces for LYS-HA complex formation. Circular dichroism spectroscopy revealed that the LYS-HA complexes formation primarily alters the α-helix and β-sheet structures of LYS. Fluorescence spectroscopy yielded an entropy of 0.12 kJ/mol·K and enthalpy of -44.46 kJ/mol for LYS-HA complexes. Molecular dynamics simulation indicated that the amino acid residues of ARG114 in LYS and 4ZB4 in HA contributed most significantly. HT-29 and HCT-116 cell experiments demonstrated that LYS-HA complexes possess excellent biocompatibility. Furthermore, LYS-HA complexes were found to be potentially useful the efficient encapsulation of several insoluble drugs and bioactives. These findings provide new insight into the binding mechanism between LYS and HA, and prove indispensable to promoting the potential application of LYS-HA complexes as bioactive compound delivery systems, emulsion stabilizers, or foaming agents in the food industry.

Functionalization of hyaluronic acid for development of self-healing hydrogels for biomedical applications: A review

Materials that are capable of undergoing self-repair following any physical damage or rupture due to external stimuli are identified as self-healing materials. Such materials are engineered by crosslinking the polymer backbone chains typically through reversible linkages. These reversible linkages include imines, metal-ligand coordination, polyelectrolyte interaction, disulfide, etc. These bonds are reversibly responsive to changes in various stimuli. Newer self-healing materials are now being developed in the field of biomedicine. Chitosan, cellulose, starch etc. are a few examples of polysaccharides that are generally used to synthesize such materials. Hyaluronic acid has been a very recent addition to the list of polysaccharides that are being investigated for construction of self-healing materials. It is non-toxic, non-immunogenic, has good gelation property and good injectability. Hyaluronic acid based self-healing materials are particularly employed for targeted drug delivery, protein and cell delivery, electronics, biosensors and many such biomedical applications. This review critically focuses on the functionalization of hyaluronic acid to fabricate self-healing hydrogels for biomedical applications. It also explores and sums up the mechanical data as well as self-healing efficiency of the hydrogels across wide range of interactions as discussed in the review below.

A wound-friendly antibacterial hyaluronic acid dressing with on-demand removability for infected wound healing

BACKGROUND

Antibacterial activity and on-demand removability are key characteristics governing the effectiveness of clinic wound dressing. However, the excellent tissue adhesion of new dressings is often overemphasized without a detailed discussion of dressing replacement. Besides, the inherent antibacterial ability of dressings is beneficial for promoting the healing of infected wound. Therefore, we rationally design an injectable antibacterial wound dressing with on-demand removability to accelerate infected wound healing.

METHOD

We design this wound dressing with a simple and feasible method based on the electrostatic self-assembly of hyaluronic acid and ε-polylysine. We investigated the efficacy of this dressing in terms of its microtopography, rheology, self-healing performance, adhesive ability, antimicrobial, hemostatic, on-demand removal properties, and wound healing promotion through various tests.

RESULTS

The prepared dressing possesses injectability, self-healing ability and antibacterial activity, showing NaCl-triggered on-demand dissolution due to the disruption of electrostatic interactions. When used as dressings for healing full-thickness wounds, it could effectively accelerate wound healing by killing bacteria, downregulating inflammation, promoting collagen deposition, enhancing keratinocyte migration and angiogenesis due to its excellent adhesion ability, favorable hemostatic property, and potent antibacterial performance.

CONCLUSION

All results indicate that this is a simple and practical dressing for clinical application. This strategy provides a novel idea for developing on-demand removal dressings with antibacterial and injectable properties.

Bilayer hydrogel dressing with lysozyme-enhanced photothermal therapy for biofilm eradication and accelerated chronic wound repair

Biofilms are closely associated with the tough healing and dysfunctional inflammation of chronic wounds. Photothermal therapy (PTT) emerged as a suitable alternative which could destroy the structure of biofilms with local physical heat. However, the efficacy of PTT is limited because the excessive hyperthermia could damage surrounding tissues. Besides, the difficult reserve and delivery of photothermal agents makes PTT hard to eradicate biofilms as expectation. Herein, we present a GelMA-EGF/Gelatin-MPDA-LZM bilayer hydrogel dressing to perform lysozyme-enhanced PTT for biofilms eradication and a further acceleration to the repair of chronic wounds. Gelatin was used as inner layer hydrogel to reserve lysozyme (LZM) loaded mesoporous polydopamine (MPDA) (MPDA-LZM) nanoparticles, which could rapidly liquefy while temperature rising so as to achieve a bulk release of nanoparticles. MPDA-LZM nanoparticles serve as photothermal agents with antibacterial capability, could deeply penetrate and destroy biofilms. In addition, the outer layer hydrogel consisted of gelatin methacryloyl (GelMA) and epidermal growth factor (EGF) promoted wound healing and tissue regeneration. It displayed remarkable efficacy on alleviating infection and accelerating wound healing in vivo. Overall, the innovative therapeutic strategy we came up with has significant effect on biofilms eradication and shows promising application in promoting the repair of clinical chronic wounds.

Coacervates: recent developments as nanostructure delivery platforms for therapeutic biomolecules

Coacervation is a liquid-liquid phase separation that can occur in solutions of macromolecules through self-assembly or electrostatic interactions. Recently, coacervates composed of biocompatible macromolecules have been actively investigated as nanostructure platforms to encapsulate and deliver biomolecules such as proteins, RNAs, and DNAs. One particular advantage of coacervates is that they are derived from aqueous solutions, unlike other nanoparticle delivery systems that often require organic solvents. In addition, coacervates achieve high loading while maintaining the viability of the cargo material. Here, we review recent developments in the applications of coacervates and their limitations in the delivery of therapeutic biomolecules. Important factors for coacervation include molecular structures of the polyelectrolytes, mixing ratio, the concentration of polyelectrolytes, and reaction conditions such as ionic strength, pH, and temperature. Various compositions of coacervates have been shown to deliver biomolecules in vitro and in vivo with encouraging activities. However, major hurdles remain for the systemic route of administration other than topical or local delivery. The scale-up of manufacturing methods suitable for preclinical and clinical evaluations remains to be addressed. We conclude with a few research directions to overcome current challenges, which may lead to successful translation into the clinic.

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.

Copper-Hydrazide Coordinated Multifunctional Hyaluronan Hydrogels for Infected Wound Healing

Bacterial infection and delayed healing are two major obstacles in cutaneous wound management, and developing multifunctional hydrogels with antibacterial and prohealing capabilities presents a promising strategy to dress wounds. However, the simple and facile fabrication of such hydrogel dressings remains challenging. Herein, we report the first observation on hydrazide-metal coordination crosslinking that is utilized to successfully construct a series of hyaluronan (HA)-metal hydrogels by mixing hydrazided HA and metal ion solutions. Considering the antibacterial, prohealing, and proangiogenic properties of HA and Cu(II), as a proof of principle, a HA-Cu hydrogel was systematically investigated as a wound dressing. Surprisingly, the hydrazide-Cu(II) coordination was dynamic in nature and imparted the HA-Cu hydrogel with physicochemical multifunctions, including spontaneous self-healing, shear-thinning injectability, reversible pH/redox/ion pair triple responsiveness, etc. Moreover, the HA-Cu hydrogel exhibited a robust broad-spectrum antibacterial activity and could significantly accelerate infectious wound healing. Impressively, glutathione-triggered hydroxyl radical generation further potentiated wound healing, providing a paradigm for on-demand antibacterial activity enhancement. Hence, the HA-Cu hydrogel is a clinically applicable "smart" dressing for multi-scenario wound healing. We envision that the simple and versatile coordination approach opens up a new avenue to develop multifunctional hydrogels and shows great potential in frontier fields, such as biomedicine, wearable devices, and soft robots.

A multifunctional 3D dressing unit based on the core-shell hydrogel microfiber for diabetic foot wound healing

The healing mechanism of diabetic foot wounds is very complicated, and it is difficult for a single-function medical dressing to achieve good therapeutic effects. We propose a simple coaxial biological 3D printing technology, which uses one-step 3D deposition to continuously produce multifunctional medical dressings on the basis of core-shell hydrogel fibers. These dressings have good biocompatibility, controlled drug-release performance, excellent water absorption and retention, and antibacterial and anti-inflammatory functions. In vivo experiments with type 2 diabetic rats were performed over a 14-day period to compare the performance of the multifunctional 3D dressing with a gauze control; the multifunctional 3D dressing reduced inflammation, effectively increased the post-healing thickness of granulation tissue, and promoted the formation of blood vessels, hair follicles, and highly oriented collagen fiber networks. Therefore, the proposed multifunctional dressing is expected to be suitable for clinical applications for healing diabetic foot wounds.

Ionic liquid functionalized injectable and conductive hyaluronic acid hydrogels for the efficient repair of diabetic wounds under electrical stimulation

The treatment and care of diabetic wounds remains a global challenge due to the the high rates of amputation, recurrence, and mortality. It has been proven that electrical stimulation has...

Hyaluronan as a Prominent Biomolecule with Numerous Applications in Medicine

Hyaluronan (HA) is a natural glycosaminoglycan present in many tissues of all vertebrates. HA has various biological functions, which are dependent on its molar mass. High-molar-mass HA has anti-angiogenic, immunosuppressive and anti-inflammatory properties, while low-molar-mass HA has opposite effects. HA has also antioxidative properties, however on the other hand it can be readily degraded by reactive oxygen species. For many years it has been used in treatment of osteoarthritis, cosmetics and in ophthalmology. In the last years there has been a growing interest of HA to also be applied in other fields of medicine such as skin wound healing, tissue engineering, dentistry and gene delivery. In this review we summarize information on modes of HA administration, properties and effects of HA in various fields of medicine including recent progress in the investigation of HA.

Injectable and pH-Sensitive Hyaluronic Acid-Based Hydrogels with On-Demand Release of Antimicrobial Peptides for Infected Wound Healing

Antibiotics' abuse in bacteria-infected wounds has threatened patients' lives and burdened medical systems. Hence, antibiotic-free hydrogel-based biomaterials, which exhibit biostability, on-demand release of antibacterial agents, and long-lasting antimicrobial activity, are highly desired for the treatment of chronic bacteria-infected wounds. Herein, we developed a hyaluronic acid (HA)-based composite hydrogel, with an antimicrobial peptide [AMP, KK(SLKL)₃KK] as a cross-linking agent through Schiff's base formation, which exhibited an acidity-triggered release of AMP (pathological environment in bacteria-infected wounds, pH ∼ 5.5-5.6). During the self-assembly process, AMP adopted an antiparallel β-sheet secondary structure due to the alternate arrangement of hydrophobic and hydrophilic residues of amino acids. Owing to Schiff's base formation between the primary amines derived from lysine residues and the aldehydes in oxidized HA, the AMP-HA composite hydrogel exhibited injectability, high biostability, and enhanced mechanical strength. Importantly, both AMP and the AMP-HA composite showed excellent broad-spectrum antibacterial activity in vitro and in vivo. Specifically, the AMP-HA composite hydrogel exhibited on-demand full thickness wound healing in an infected mice model. Therefore, this work provides an efficient strategy to fabricate antibiotic-free hydrogel-based biomaterials for the management of chronic bacteria-infected wounds.

Gelatin-biofermentative unsulfated glycosaminoglycans semi-interpenetrating hydrogels via microbial-transglutaminase crosslinking enhance osteogenic potential of dental pulp stem cells

Gelatin hydrogels by microbial-transglutaminase crosslinking are being increasingly exploited for tissue engineering, and proved high potential in bone regeneration. This study aimed to evaluate, for the first time, the combination of enzymatically crosslinked gelatin with hyaluronan and the newly developed biotechnological chondroitin in enhancing osteogenic potential. Gelatin enzymatic crosslinking was carried out in the presence of hyaluronan or of a hyaluronan–chondroitin mixture, obtaining semi-interpenetrating gels. The latter proved lower swelling extent and improved stiffness compared to the gelatin matrix alone, whilst maintaining high stability. The heteropolysaccharides were retained for 30 days in the hydrogels, thus influencing cell response over this period. To evaluate the effect of hydrogel composition on bone regeneration, materials were seeded with human dental pulp stem cells and osteogenic differentiation was assessed. The expression of osteocalcin (OC) and osteopontin (OPN), both at gene and protein level, was evaluated at 7, 15 and 30 days of culture. Scanning electron microscopy (SEM) and two-photon microscope observations were performed to assess bone-like extracellular matrix (ECM) deposition and to observe the cell penetration depth. In the presence of the heteropolysaccharides, OC and OPN expression was upregulated and a higher degree of calcified matrix formation was observed. Combination with hyaluronan and chondroitin improved both the biophysical properties and the biological response of enzymatically crosslinked gelatin, fastening bone deposition.

Effect of Complex Coacervation with Hyaluronic Acid on Protein Transition in a Subcutaneous Injection Site Model System

The occurrence of complex coacervation in an aqueous mixture of proteins (lysozyme, albumin, immunoglobulin G) and hyaluronic acid and its effect on protein transition in a model system was studied to elucidate factors determining the bioavailability of subcutaneously injected therapeutic proteins. Mixing of hyaluronic acid and the model proteins induced complex coacervation at solution pH close to or below the isoelectric point of the proteins. In vitro dialysis using membranes with large pore size tube represented a limitation in the protein transition of the coacervation mixture. Thermal analysis suggested there was retention of the protein conformation in the polymer complex.