Scarless Healing of Injured Vocal Folds Using an Injectable Hyaluronic Acid-Waterborne Polyurethane Hybrid Hydrogel to Tune Inflammation and Collagen Deposition

An injectable thermosensitive hyaluronic acid/pluronic F-127 hydrogel for deep penetration and combination therapy of frozen shoulder

Frozen shoulder (FS) is a common and progressive shoulder disorder that causes glenohumeral joint stiffness, characterized by inflammation and fibrosis. The treatment options are quite limited, and the therapeutic response is hindered by the fibrous membrane formed by excessive collagen and the rapid removal by synovial fluid. To address these challenges, we designed a hyaluronic acid/Pluronic F-127 (HP)-based injectable thermosensitive hydrogel as a drug carrier loaded with dexamethasone and collagenase (HPDC). We screened for an optimal HP hydrogel that can sustain drug release for approximately 10 days both in vitro and in vivo. In the meanwhile, we found that HP hydrogel could inhibit the proliferation and diminish the adhesion capacity of rat synovial cells induced by transforming growth factor-β1. Furthermore, using an established immobilization rat model of FS, intra-articular injection of HPDC significantly improved joint range of motion compared to medication alone. Relying on sustained drug release, the accumulated collagen fibers were degraded by collagenase to promote the deep delivery of dexamethasone. These findings showed a positive combined treatment effect of HPDC, providing a novel idea for the comprehensive treatment of FS.

A tough, antibacterial and antioxidant hydrogel dressing accelerates wound healing and suppresses hypertrophic scar formation in infected wounds

Wound management is an important issue that places enormous pressure on the physical and mental health of patients, especially in cases of infection, where the increased inflammatory response could lead to severe hypertrophic scars (HSs). In this study, a hydrogel dressing was developed by combining the high strength and toughness, swelling resistance, antibacterial and antioxidant capabilities. The hydrogel matrix was composed of a double network of polyvinyl alcohol (PVA) and agarose with excellent mechanical properties. Hyperbranched polylysine (HBPL), a highly effective antibacterial cationic polymer, and tannic acid (TA), a strong antioxidant molecule, were added to the hydrogel as functional components. Examination of antibacterial and antioxidant properties of the hydrogel confirmed the full play of the efficacy of HBPL and TA. In the in vivo studies of methicillin-resistant Staphylococcus aureus (MRSA) infection, the hydrogel had shown obvious promotion of wound healing, and more profoundly, significant suppression of scar formation. Due to the common raw materials and simple preparation methods, this hydrogel can be mass produced and used for accelerating wound healing while preventing HSs in infected wounds.

Recent advances in biopolymer-based hydrogels and their potential biomedical applications

Hydrogels are three-dimensional networks of polymer chains containing large amounts of water in their structure. Hydrogels have received significant attention in biomedical applications owing to their attractive physicochemical properties, including flexibility, softness, biodegradability, and biocompatibility. Different natural and synthetic polymers have been intensely explored in developing hydrogels for the desired applications. Biopolymers-based hydrogels have advantages over synthetic polymers regarding improved cellular activity and weak immune response. These properties can be further improved by grafting with other polymers or adding nanomaterials, and they structurally mimic the living tissue environments, which opens their broad applicability. The hydrogels can be physically or chemically cross-linked depending on the structure. The use of different biopolymers-based hydrogels in biomedical applications has been reviewed and discussed earlier. However, no report is still available to comprehensively introduce the synthesis, advantages, disadvantages, and biomedical applications of biopolymers-based hydrogels from the material point of view. Herein, we systematically overview different synthesis methods of hydrogels and provide a holistic approach to biopolymers-based hydrogels for biomedical applications, especially in bone regeneration, wound healing, drug delivery, bioimaging, and therapy. The current challenges and prospects of biopolymers-based hydrogels are highlighted rationally, giving an insight into the progress of these hydrogels and their practical applications.

Body temperature-induced adhesive hyaluronate/gelatin-based hybrid hydrogel dressing for promoting skin regeneration

Skin wound management faces significant clinical challenges, including continuous bacterial infection and inflammation. Therefore, developing removable hydrogel dressings with intrinsic multifunctional properties is highly desirable. In this study, a body temperature-induced adhesive and removable hydrogel was designed to treat skin defect wounds. The HA/Gel-R-Ag hybrid gel was prepared by incorporating a silver ion-crosslinked sulfhydryl hyaluronate/gelatin-based polymeric gel network into a supramolecular rhein gel network, thereby significantly enhancing its mechanical properties. Temperature-responsive gelatin chains give the hybrid gel reversible tissue adhesiveness and detachment, thus avoiding secondary injury to wounds when changing the hydrogels. The hybrid gel exhibited excellent bactericidal ability owing to the antibacterial capacity of the silver ions and rhein. Moreover, both HA and rhein endowed the hybrid gel with immunoregulatory effects by promoting macrophage polarization from pro-inflammatory M1 phenotype to anti-inflammatory M2 phenotype. In a full-thickness skin defect mouse mode, this porous, degradable, and biocompatible HA/Gel-R-Ag hybrid gel boosted skin regeneration by inhibiting inflammation and promoting collagen deposition and angiogenesis. It is thus a simple method for widening the application range of mechanically weak rhein gels and providing a promising wound dressing material with multiple intrinsic functions for treating skin wounds.

Phycocyanin/lysozyme nanocomplexes to stabilize Pickering emulsions for fucoxanthin encapsulation

Food-grade Pickering emulsions with plant proteins have attracted increasing interest in recent years. In this work, we report a type of phycocyanin (PC) electrostatic nanocomplex fabricated following a complexation between PC and lysozyme (Lys). The aim was to investigate toward investigating the performance of phycocyanin-Lysozyme (PC-Lys) nanocomplexes in stabilizing Pickering emulsions and protecting fucoxanthin (FX) from degradation. The properties of the PC-Lys nanocomplexes were characterized by 1H nuclear magnetic resonance (NMR) spectroscopy and three-phase contact angle. Using PC-Lys nanocomplexes as emulsifiers, Pickering emulsions were successfully prepared. Pickering emulsions stabilized by PC-Lys nanocomplexes generated a tight three-dimensional network structure, which increased the memory modulus and viscoelasticity of the emulsion. Furthermore, the produced Pickering emulsions considerably increased the chemical stability and bioavailability of FX. Overall, our study showed that PC-Lys nanocomplexes have the potential for use in Pickering emulsion construction with enhanced protective effects on loaded lipophilic ingredients.

Acylhydrazone-derived whole pectin-based hydrogel as an injectable drug delivery system

Injectable hydrogel-based drug delivery systems have attracted more and more attention due to their sustained-release performance, biocompatibility, and 3D network. The present study showed whole pectin-based hydrogel as an injectable drug delivery system, which was developed from oxidized pectin (OP) and diacylhydrazine adipate-functionalized pectin (Pec-ADH) via acylhydrazone linkage. The as-prepared hydrogels were characterized by 1H NMR, FT-IR, and SEM techniques. The equilibrium swelling ratio of obtained hydrogel (i.e., sample gel 5) was up to 4306.65 % in the distilled water, which was higher than that in PBS with different pH values. Increasing the pH of the swelling media, the swelling ratio of all hydrogels decreased significantly. The results that involved the swelling properties indicated the salt- and pH-responsiveness of the as-prepared hydrogels. The drug release study presented that 5-FU can be persistently released for more than 12 h without sudden release. Moreover, the whole pectin-based hydrogel presented high cytocompatibility toward L929 cell lines, and the drug delivery system showed a high inhibitory effect on MCF-7 cell lines. All these results manifested that the acylhydrazone-derived whole pectin-based hydrogel was an excellent candidate for injectable drug delivery systems.

A biodegradable injectable fluorescent polyurethane-oxidized dextran hydrogel for non-invasive monitoring

Hydrogels have been extensively used in the field of biomedical engineering. In order to achieve non-invasive and real-time visualization of the in vivo status of hydrogels, we designed a fluorescent polyurethane-oxidized dextran (PU-OD) hydrogel with good injectability and self-healing properties, which was cross-linked from a tetraphenyl ethylene (TPE)-containing fluorescent polyurethane emulsion with oxidized dextran by dynamic acylhydrazone bonds. The hydrogel can be used as a visual platform for drug delivery as well as monitoring its own degradation. The network structure of the hydrogel gave it drug-loading capability, and the acylhydrazone bond enabled its pH-responsive drug release. Meanwhile, the PU-OD hydrogel could undergo fluorescence resonance transfer with doxorubicin hydrochloride, showing its potential application in monitoring drug release. In addition, fluorometric and weighing methods were performed to monitor the degradation behavior of the hydrogels in vivo and in vitro, respectively, showing that the non-invasive fluorometric method can be consistent with the invasive weighing method. This work highlights that the introduction of aggregation-induced emission molecules into polyurethanes provides a visual platform that allows for non-invasive monitoring of the material without affecting its own function, which is convenient and less damaging to the body or animals. Consequently, it possesses excellent and promising potential in biomedical materials technologies.

Injectable, pore-forming, self-healing, and adhesive hyaluronan hydrogels for soft tissue engineering applications

Most existing injectable hydrogels are non-porous, thereby lacking a microporous structure to promote cell ingrowth. Also, most hydrogels do not effectively adhere to the host tissue. The present study describes an injectable double network hydrogel formed by combining two hyaluronic acid (HA) derivatives, namely dopamine grafted HA (DAHA) and methacrylated HA (HAMA). These constituents instantly form a physically crosslinked network through Fe3+-dopamine coordination, and confer fast gelation, pore formation, and self-healing properties to the hydrogel. Photocroslinked upon UV exposure, HAMA forms a chemically crosslinked network, thereby improving mechanical and degradation properties. The adhesive properties of this hydrogel are attributed to the presence of dopamine groups, inspired by mussel creatures. Proper modification of HA chains was confirmed by NMR spectroscopy. The physical, mechanical, rheological, and biological properties of the new hydrogels were quantified in wet laboratory conditions. The results revealed that the DAHA/HAMA hydrogel rapidly forms a self-healing microporous adhesive scaffold with a 26.9 µm pore size, 29.4 kPa compressive modulus, and 12.8 kPa adhesion strength in under 6 s. These findings suggest that the new hydrogel is a promising candidate for in situ repair of soft tissues, particularly mechanically dynamic ones such as the vocal folds, cartilage, and dermis.

In Vitro Effects of Waterborne Polyurethane 3D Scaffolds Containing Poly(lactic-co-glycolic acid)s of Different Lactic Acid/Glycolic Acid Ratios on the Inflammatory Response

The physical and chemical properties of tissue engineering scaffolds have considerable effects on the inflammatory response at the implant site in soft tissue repair. The development of inflammation-modulating polymer scaffolds for soft tissue repair is attracting increasing attention. In this study, in order to regulate the inflammatory response at the implant site, a series of waterborne polyurethane (WPU) scaffolds with different properties were synthesized using polyethylene glycol (PEG), polycaprolactone (PCL) and poly (lactic acid)–glycolic acid copolymers (PLGAs) with three lactic acid/glycolic acid (LA/GA) ratios as the soft segments. Then, scaffolds were obtained using freeze-drying. The WPU scaffolds exhibited a porous cellular structure, high porosity, proper mechanical properties for repairing nerve tissue and an adjustable degradation rate. In vitro cellular experiments showed that the degradation solution possessed high biocompatibility. The in vitro inflammatory response of C57BL/6 mouse brain microglia (immortalized) (BV2) cells demonstrated that the LA/GA ratio of the PLGA in WPU scaffolds can regulate the external inflammatory response by altering the secretion of IL-10 and TNF-α. Even the IL-10/TNF-α of PU5050 (3.64) reached 69 times that of the control group (0.053). The results of the PC12 culture on the scaffolds showed that the scaffolds had positive effects on the growth, proliferation and differentiation of nerve cells and could even promote the formation of synapses. Overall, these scaffolds, particularly the PU5050, indeed prevent BV2 cells from differentiating into a pro-inflammatory M1 phenotype, which makes them promising candidates for reducing the inflammatory response and repairing nerve tissue. Furthermore, PU5050 had the best effect on preventing the transformation of BV2 cells into the pro-inflammatory M1 phenotype.

Coating Methods of Carbon Nonwovens with Cross-Linked Hyaluronic Acid and Its Conjugates with BMP Fragments

The cross-linking of polysaccharides is a universal approach to affect their structure and physical properties. Both physical and chemical methods are used for this purpose. Although chemical cross-linking provides good thermal and mechanical stability for the final products, the compounds used as stabilizers can affect the integrity of the cross-linked substances or have toxic properties that limit the applicability of the final products. These risks might be mitigated by using physically cross-linked gels. In the present study, we attempted to obtain hybrid materials based on carbon nonwovens with a layer of cross-linked hyaluronan and peptides that are fragments of bone morphogenetic proteins (BMPs). A variety of cross-linking procedures and cross-linking agents (1,4-butanediamine, citric acid, and BDDE) were tested to find the most optimal method to coat the hydrophobic carbon nonwovens with a hydrophilic hyaluronic acid (HA) layer. Both the use of hyaluronic acid chemically modified with BMP fragments and a physical modification approach (layer-by-layer method) were proposed. The obtained hybrid materials were tested with the spectrometric (MALDI-TOF MS) and spectroscopic methods (IR and 1H-NMR). It was found that the chemical cross-linking of polysaccharides is an effective method for the deposition of a polar active substance on the surface of a hydrophobic carbon nonwoven fabric and that the final material is highly biocompatible.