ECM-mimetic immunomodulatory hydrogel for methicillin-resistant Staphylococcus aureus-infected chronic skin wound healing

Dermal fibroblast-derived extracellular matrix (ECM) synergizes with keratinocytes in promoting re-epithelization and scarless healing of skin wounds: Towards optimized skin tissue engineering

Skin serves as the first-order protective barrier against the environment and any significant disruptions in skin integrity must be promptly restored. Despite significant advances in therapeutic strategies, effective management of large chronic skin wounds remains a clinical challenge. Dermal fibroblasts are the primary cell type responsible for remodeling the extracellular matrix (ECM) in wound healing. Here, we investigated whether ECM derived from exogenous fibroblasts, in combination with keratinocytes, promoted scarless cutaneous wound healing. To overcome the limited lifespan of primary dermal fibroblasts, we established reversibly immortalized mouse dermal fibroblasts (imDFs), which were non-tumorigenic, expressed dermal fibroblast markers, and were responsive to TGF-β1 stimulation. The decellularized ECM prepared from both imDFs and primary dermal fibroblasts shared similar expression profiles of extracellular matrix proteins and promoted the proliferation of keratinocyte (iKera) cells. The imDFs-derived ECM solicited no local immune response. While the ECM and to a lesser extent imDFs enhanced skin wound healing with excessive fibrosis, a combination of imDFs-derived ECM and iKera cells effectively promoted the re-epithelization and scarless healing of full-thickness skin wounds. These findings strongly suggest that dermal fibroblast-derived ECM, not fibroblasts themselves, may synergize with keratinocytes in regulating scarless healing and re-epithelialization of skin wounds. Given its low immunogenic nature, imDFs-derived ECM should be a valuable resource of skin-specific biomaterial for wound healing and skin tissue engineering.

Injectable Arctium lappa polysaccharide-based composite hydrogel enhances diabetic wound healing

The slow healing of diabetic wounds remains a significant challenge. However, existing treatments often prove ineffective due to the complexity of diabetic wounds. The purpose of this study was to develop an injectable hydrogel loaded with natural polysaccharides to promote diabetic wound healing. Composite hydrogels containing different concentrations of Arctium lappa polysaccharides (ALP) were prepared. The differences in their microstructure, water content, degradation rate, rheological properties, biocompatibility, promotion of epidermal cell migration, and antibacterial properties were compared to determine the optimal ALP concentration. Additionally, a diabetic rat skin defect model was constructed to further validate the promoting effect of the ALP composite hydrogel. The results indicated that CMC/CBM/ALP hydrogels formed numerous dense and regular pores, and the addition of ALP improved the stability and water content of the gels. Among the various formulations, the composite hydrogel with 2 % ALP concentration exhibited superior biocompatibility, in vitro antibacterial properties, and effectively promoted the migration of HaCat epidermal cells. Compared to hydrogels without ALP, the ALP composite hydrogels accelerated the healing of skin wounds, promoted collagen deposition and vascularization, regulated M2 macrophage polarization, reduced inflammatory responses, and ultimately enhanced wound healing. Therefore, our study provided a feasible and effective polysaccharide-based hydrogel for treating diabetic wounds.

Injectable ADM temperature-sensitive hydrogel loaded with bFGF in diabetic rat wound healing study

Background: Diabetic wound is one of the most common diabetic chronic complications. Effective treatments of diabetic wound remain limited. Here, we explored the effects of basic fibroblast growth factor (bFGF)-acellular dermal matrix (ADM) hydrogel on the diabetic wound. Methods: The bFGF-ADM hydrogel was manufactured by mixing 180 µL ADM hydrogel and 20 µL bFGF aqueous solution (10 mg/mL). The morphology of ADM hydrogel and bFGF-ADM hydrogel was observed under scanning electron microscope. The release property of bFGF-ADM hydrogel was determined by ELISA. CCK-8 assay was utilized to estimate the cell viability of mouse skin fibroblasts. The diabetes mellitus (DM) model was established in rats. The four wounds on the back of each DM rat were treated with the ADM hydrogel, bFGF-ADM hydrogel, bFGF aqueous solution and no solution (control), respectively. The wound healing rate of each rat was estimated. The traumatized skin tissue of each rat was observed by H&E staining and Sirius red staining. Results: The bFGF-ADM hydrogel displayed an interconnected pore structure and bFGF was gradually released from the bFGF-ADM hydrogel over time. The bFGF-ADM hydrogel could enhance the cell viability of skin fibroblasts and promote the wound healing rate, the re-epithelialization of wound and increase the collagen fiber content of dermis. And the bFGF-ADM hydrogel exhibited better therapeutic effects of diabetic wound than either bFGF or ADM alone. Conclusions: Our study revealed that the bFGF-ADM hydrogel could promote diabetic wound healing.

An Off-the-Shelf Artificial Proregenerative Macrophage for Pressure Ulcer Treatment

Cell therapy is a promising approach in regenerative medicine. However, maintaining the survival and function of injected or implanted therapeutic cells remains a substantial challenge to success. In vivo modulatory strategy for cell therapeutics has been recently developed, but suffers from limited regenerative efficacy in injured tissue microenvironment with chronic inflammation. Here, an off-the-shelf artificial macrophage (artM) assembled by M2 macrophages-derived lysate proteins-loaded poly (lactic-co-glycolic acid) (PLGA) microspheres coated by macrophage cell membrane is developed. The synthetic artM fabricated in batches maintains its bioactivity with long-term cryostorage. Significantly, artM recapitulates the essential inflammation-regulatory and proregenerative characteristics of endogenous macrophages, including initiating M2 macrophage polarization, resolving excessive inflammation by releasing anti-inflammatory cytokines and growth factors, neutralizing endotoxins and proinflammatory cytokines, augmenting T-helper 2 (TH2) immune response, and coordinating cell migration and proliferation. In mouse model of deep tissue pressure injury (DTPI), the artM induces tissue regeneration by modulating the inflammatory microenvironment, promoting angiogenesis, reducing scar deposition, and accelerating the renewal of skin appendages. Depletion of macrophages in mice with skin ulcers highlights the immunomodulatory and proangiogenic functions of artM as effective as autogenous macrophages. Collectively, the engineered artM represents a cell-free, proreparative alternative to immune cell therapy in chronic wound management.

A dynamically phase-adaptive regulating hydrogel promotes ultrafast anti-fibrotic wound healing

Achieving rapid and scar-free wound repair is a key goal in the field of regenerative medicine. Herein, a dynamically Schiff base-crosslinked hydrogel (F/R gel) with phase-adaptive regulating functions is constructed to integratedly promote rapid re-epithelization with suppressed scars on chronic infected wounds. Specifically, the gel effectively eliminates multidrug-resistant bacterial biofilm at infection stage via antimicrobial activity of ε-polylysine firstly dissociated from hydrogel matrix in infectious microenvironment, and interrupts the severe oxidative stress-inflammation cycle at wound site by the released ceria nanozyme, thus stimulating a pro-regenerative environment to ensure tissue repair. Subsequently, fibroblast growth factor/c-Jun siRNA co-loaded microcapsules gradually disintegrate to release drugs, facilitating neoangiogenesis and cell proliferation but simultaneously blocking c-Jun overexpression for fibrotic scar suppression. Notably, the F/R gel facilitates normal-like skin regeneration with no perceptible scars formed on infected male mouse wound and female rabbit ear wound models. Our work offers a promising regenerative strategy emphasizing immunomodulatory and fibroblast subtype modulation for scarless wound repair.

Functional Wound Dressing Based on Natural Compounds from Traditional Chinese Medicines─Magnolol for Accelerating Wound Healing

Traditional petroleum-based foam dressings offer limitations due to poor biocompatibility, long preparation cycle, and serious environmental pollution. In addition, free small molecules of incomplete polymers and residual toxic cross-linkers pose a threat to the health of patients and hinder the rapid repair of wounds. Recently, natural compounds extracted from plants have gained a lot of interest in the field of wound repair due to their good biocompatibility, biodegradability, and therapeutic effects. In this study, we successfully prepared magnolol-based porous foams by a simple one-pot method using magnolol herbal exhibiting good mechanical properties, hydrophobicity, and biocompatibility, and meets the requirements of wound dressings. The Janus composite dressing was prepared using a magnolol-based porous foam as the inner layer, PVA nonwoven fabric as the middle layer, and polyacrylate as the outer layer. The three-layer structure of magnolol-based porous foam/PVA nonwoven fabric/polyacrylate (MPF/PVA/PAAS) has the capacity to realize unidirectional diversion and rapid water locking of liquid. In vivo experimental data showed that MPF/PVA/PAAS dressing significantly promoted collagen deposition and angiogenesis, and could shorten the wound healing cycle from 14 days to 10 days, significantly accelerating the wound healing process compared to traditional wound dressings. Hence, magnolol-based foam dressings show great application potential in the field of wound treatment.

Engineered Exosomes Loaded in Intrinsic Immunomodulatory Hydrogels with Promoting Angiogenesis for Programmed Therapy of Diabetic Wounds

Inducing rapid angiogenesis by delivering specific biological cues is critical for diabetic wound healing. Nevertheless, the angiogenesis is hindered by the inflammatory microenvironment, and the immune cells fail to orchestrate immune responses to wound healing. Herein, vascular endothelial growth factor (VEGF) plasmids-loaded macrophage exosomes (Exos) were fabricated and enfolded in injectable self-healing hydrogels for programmed therapy of diabetic wounds through sequentially intrinsically modulating the inflammatory microenvironment and promoting angiogenesis. The hydrogels, formed via dynamical Schiff base reactions using modified polysaccharides, intrinsically regulate the inflammatory microenvironment via broad-spectrum antioxidant activity and macrophage phenotype regulation, restoring tissue redox and immune homeostasis. Furthermore, the hydrogels can stabilize and release the engineered exosomes. By integration of generation and release of VEGF by plasmids-loaded macrophage Exos, VEGF secretion by M2 macrophages, and enhanced binding of VEGF to VEGF receptor 2 by high affinity of sulfated chitosan, the intrinsic immunomodulatory hydrogels effectively promote the angiogenesis and accelerate the diabetic wound healing process.

Photoresponsive Blood-Derived Protein Hydrogels Packed with Bioactive Carbon Dots Modulate Mitochondrial Homeostasis and Reprogram Metabolism for Chronic Wound Healing in Diabetes

Autologous platelet concentrates (APC) represent a class of personalized regenerative materials for vascularized tissue regeneration. However, shortcomings including poor controllability of gel formation, lack of reactive oxygen species (ROS) scavenging ability, and deficient anti-inflammatory capacity restrict the tissue healing outcomes of APC. This study proposes an APC-based synergistic platform (CurCDs@iPRF-MA) for the treatment of chronic wounds in diabetes. Such a platform is composed of injectable platelet-rich fibrin (iPRF), gelatin methacryloyl (GelMA), and a carbogenic nanodrug from curcumin (CurCDs) that is injectable before the light-induced gel formation process, greatly facilitating the clinical applications of APC. Significantly, CurCDs@iPRF-MA can modulate the mitochondrial homeostasis under inflammatory conditions, activate the oxidative phosphorylation (OXPHOS) program, and regulate the diabetic microenvironment through metabolic reprogramming to achieve macrophage phenotype regulation and ROS elimination, as well as promote vascularization by releasing autologous growth factors, dramatically improving the healing efficacy of the chronic wounds in diabetes. This study offers a practical and effective approach to developing spatiotemporally controllable and multifunctional APC-based hydrogels for highly effective tissue regeneration.

Peptide-based inflammation-responsive implant coating sequentially regulates bone regeneration to enhance interfacial osseointegration

Aseptic loosening is the primary cause of bone prosthesis failure, commonly attributed to inadequate osseointegration due to coatings misaligned with bone regeneration. Here, we modify the titanium surface with a mussel-inspired peptide to form a 3,4-dihydroxyphenylalanine (DOPA)-rich coating, then graft N3-K15-PVGLIG-K23 (P1) and N3-Y5-PVGLIG-K23 (P2), which are composed of anti-inflammatory (K23), angiogenic (K15), osteogenic (Y5), and inflammation-responsive (PVGLIG) sequences, onto the surface via click chemistry, forming the DOPA-P1@P2 coating. DOPA-P1@P2 promotes bone regeneration through sequential regulation. In the initial stage, the outermost K23 induces M2 macrophage polarization, establishing a pro-regenerative immune microenvironment. Subsequently, K15 and Y5, exposed by the release of K23, enhance angiogenesis and osteogenesis. In the final stage, DOPA-P1@P2 outperforms the TiO₂ control, showing a 161% increase in maximal push-out force, a 207% increase in bone volume fraction, and a 1409% increase in bone-to-implant contact. These findings show that DOPA-P1@P2 efficiently enhances interfacial osseointegration by sequentially regulating bone regeneration, providing viable insights into coating design.

Aldehyde-modified sodium alginate/gelatin-based bacteriophage-loaded multifunctional hydrogel for promoting the healing of multidrug-resistant bacterial-infected wounds

Multidrug-resistant bacterial infections in skin injuries are hard to repair. There is an urgent need to develop new antibacterials, antibiofilm formation, and immunomodulatory wound dressing. In this study, we produced a bacteriophage-loaded multifunctional hydrogel consisting of aldehyde-modified sodium alginate (ADA), gelatin (GEL), and carboxymethyl chitosan (CMCS) through a Schiff base reaction and borax complexation. These post-reactive ADA/GEL/CMCS/Phage (AGCP) hydrogels, particularly the AGCP3 hydrogel, boast a porous structure, high swelling rate, effective hemostasis, controlled degradation, good rheological properties, and strong antibacterial activity. Furthermore, the hydrogel developed in this study can sustainably release various bacteriophages targeting the bacteria responsible for major skin infections, thereby enhancing antibacterial activity and preventing bacterial biofilm formation. Besides, cytotoxicity and cell proliferation demonstrated that the hydrogel, comprising three polysaccharides, ADA, GEL, and CMCS, facilitates skin tissue regeneration by enhancing cellular proliferation and migration. The AGCP hydrogel enhanced healing and controlled inflammation in bacterial-infected wounds, as evidenced by wound closure, collagen deposition, and quantitative reverse transcription polymerase chain reaction results. In conclusion, the AGCP3 hydrogel exhibits strong antibacterial properties, excellent expands, biocompatibility, hemostatic properties, and a controlled release of bacteriophages, making it ideal for universal bacteriophage delivery systems and wound dressings for skin wounds infected with multidrug-resistant bacteria.

Research progress on MXenes in polysaccharide-based hemostasis and wound healing: A review

Traumatic events occur frequently in daily life, and hemostasis and infection prevention represent key challenges in trauma care. Polysaccharide-based materials (chitosan, cellulose, etc.) are widely used as hemostasis materials due to their excellent designability and biocompatibility. However, their insufficient antibacterial activity and limited hemostatic capabilities diminish their effectiveness in wound care. As emerging two-dimensional nanomaterials, MXene offers promising solutions to these limitations. With superior hydrophilicity, antibacterial properties and biocompatibility, MXene enhances the performance of polysaccharide-based hemostasis materials. This review summarizes the characteristics and synthesis methods of MXenes and outlines recent advances in MXene/polysaccharide composites for promoting wound healing by controlling bleeding and preventing infection. Additionally, we discuss the preparation methods, the mechanisms of action, and challenges in practical applications of MXene/polysaccharide composites, and propose future research directions. By integrating the advantages of MXenes and polysaccharides, we hope to provide a more effective solution for the research of polysaccharide-based hemostatic materials.

Hydrogel-Based Continuum Soft Robots

This paper comprehensively reviews the latest advances in hydrogel-based continuum soft robots. Hydrogels exhibit exceptional flexibility and adaptability compared to traditional robots reliant on rigid structures, making them ideal as biomimetic robotic skins and platforms for constructing highly accurate, real-time responsive sensory interfaces. The article systematically summarizes recent research developments across several key dimensions, including application domains, fabrication methods, actuator technologies, and sensing mechanisms. From an application perspective, developments span healthcare, manufacturing, and agriculture. Regarding fabrication techniques, the paper extensively explores crosslinking methods, additive manufacturing, microfluidics, and other related processes. Additionally, the article categorizes and thoroughly discusses various hydrogel-based actuators responsive to solute/solvent variations, pH, chemical reactions, temperature, light, magnetic fields, electric fields, hydraulic/electro-osmotic stimuli, and humidity. It also details the strategies for designing and implementing diverse sensors, including strain, pressure, humidity, conductive, magnetic, thermal, gas, optical, and multimodal sensors. Finally, the paper offers an in-depth discussion of the prospective applications of hydrogel-based continuum soft robots, particularly emphasizing their potential in medical and industrial fields. Concluding remarks include a forward-looking outlook highlighting future challenges and promising research directions.

A Narrative Review of Bioactive Hydrogel Microspheres: Ingredients, Modifications, Fabrications, Biological Functions, and Applications

Hydrogel microspheres are important in regenerative medicine and tissue engineering, acting as cargos of cells, drugs, growth factors, bio-inks for 3D printing, and medical devices. The antimicrobial and anti-inflammatory characteristics of hydrogel microspheres are good for treating injured tissues. However, the biological properties of hydrogel microspheres should be modified for optimal treatment of various body parts with different physiological and biochemical environments. In addition, specific preparation methods are required to produce customized hydrogel microspheres with different shapes and sizes for various clinical applications. Herein, the advances in hydrogel microspheres for biomedical applications are reviewed. Synthesis methods for hydrogel precursor solutions, manufacturing methods, and strategies for enhancing the biological functions of these hydrogel microspheres are described. The involvement of bioactive hydrogel microspheres in tissue repair is also discussed. This review anticipates fostering more insights into the design, production, and application of hydrogel microspheres in biomedicine.

Advancement of Nanomaterials- and Biomaterials-Based Technologies for Wound Healing and Tissue Regenerative Applications

Patients and healthcare systems face significant social and financial challenges due to the increasing number of individuals with chronic external and internal wounds that fail to heal. The complexity of the healing process remains a serious health concern, despite the effectiveness of conventional wound dressings in promoting healing. Recent advancements in materials science and fabrication techniques have led to the development of innovative dressings that enhance wound healing. To further expedite the healing process, novel approaches such as nanoparticles, 3D-printed wound dressings, and biomolecule-infused dressings have emerged, along with cell-based methods. Additionally, gene therapy technologies are being harnessed to generate stem cell derivatives that are more functional, selective, and responsive than their natural counterparts. This review highlights the significant potential of biomaterials, nanoparticles, 3D bioprinting, and gene- and cell-based therapies in wound healing. However, it also underscores the necessity for further research to address the existing challenges and integrate these strategies into standard clinical practice.

Cellulose nanofiber-reinforced antimicrobial and antioxidant multifunctional hydrogel with self-healing, adhesion for enhanced wound healing

Current conventional wound dressings used for wound healing are often characterized by restricted bioactivity and devoid of multifunctionality resulting in suboptimal treatment and prolonged healing. Despite recent advances, the simultaneous incorporation of excellent flexibility, good mechanical performance, self-healing, bioactivity, and adhesion properties into the dressings without complicating their efficacy while maintaining simple synthesis remains a grand challenge. Herein, we effectively synthesized hybrid hydrogels of cellulose nanofiber (CNF), polyvinyl alcohol (PVA), and curcumin-modified silver nanoparticles (cAg) through a one-step synthesis method based on hydrogen bonds, dynamic boronic ester bonds, and coordinate covalent bonds. A flexible high mechanical strength (tensile stress (231 kPa) and compressive stress (1.23 MPa), self-healing, adhesive, yet highly antioxidant and antimicrobial hydrogel (with improved activity against C. albicans, S. aureus, and E. coli) is successfully obtained. Concentric structure of the micropores endows the hydrogels, good biodegradability, and sustained drug release of silver and curcumin. More remarkably, the designed hydrogel dressings not only significantly enhance cell viability (over 98 %) and cell proliferation but also promote angiogenesis, re-epithelialization, and deposition of collagen, all of which signal wound closure and substantiate the therapeutic effect of CNF/PB/cAg hydrogels in chronic wounds. These findings open up new perspectives for the design of wound healing hydrogels and beyond.

Photothermally Responsive Hydrogel Releases Basic Fibroblast Growth Factor to Promote the Healing of Infected Wounds

The treatment of infected wounds is often complicated by bacterial infection and impaired scar healing. Antibiotics and growth factors are typically utilized to address these clinical challenges and expedite wound healing. However, the use of hydrogels containing these therapeutic agents is often restricted to complex cases and increases treatment costs considerably. In this study, we developed a quaternized-chitosan-based hybrid hydrogel dressing (SQFB) with intrinsic antibacterial properties to address these limitations. The hybrid hydrogel contained interpenetrating polymer networks of basic fibroblast growth factor and black phosphorus nanosheets, facilitating a photothermal response that triggers the release of basic fibroblast growth factor upon near-infrared irradiation. In vitro experiments demonstrated that SQFB exhibits superior antibacterial, hemostatic, enhanced cell proliferation, and angiogenesis functions. Importantly, the results showed that SQFB can promote the healing of infected wounds by accelerating all 4 stages of wound repair while preventing scarring formation. RNA sequencing analysis revealed that combined treatment with SQFB and near-infrared irradiation can effectively modulate genes primarily associated with epithelial regeneration pathways and metabolic processes. Collectively, our findings suggest that this hybrid hydrogel holds great promise for the effective management of infected wounds.

Versatile conductive hydrogel orchestrating neuro-immune microenvironment for rapid diabetic wound healing through peripheral nerve regeneration

Diabetic wound (DW), notorious for prolonged healing processes due to the unregulated immune response, neuropathy, and persistent infection, poses a significant challenge to clinical management. Current strategies for treating DW primarily focus on alleviating the inflammatory milieu or promoting angiogenesis, while limited attention has been given to modulating the neuro-immune microenvironment. Thus, we present an electrically conductive hydrogel dressing and identify its neurogenesis influence in a nerve injury animal model initially by encouraging the proliferation and migration of Schwann cells. Further, endowed with the synergizing effect of near-infrared responsive release of curcumin and nature-inspired artificial heterogeneous melanin nanoparticles, it can harmonize the immune microenvironment by restoring the macrophage phenotype and scavenging excessive reactive oxygen species. This in-situ formed hydrogel also exhibits mild photothermal therapy antibacterial efficacy. In the infected DW model, this hydrogel effectively supports nerve regeneration and mitigates the immune microenvironment, thereby expediting the healing progress. The versatile hydrogel exhibits significant therapeutic potential for application in DW healing through fine-tuning the neuro-immune microenvironment.

Double Enzyme Active Hydrogel Program Regulates the Microenvironment of Staphylococcus aureus-Infected Pressure Ulcers

The treatment of infected pressure ulcers (IUPs) requires addressing diverse microenvironments. A pressing challenge is to effectively enhance the regenerative microenvironment at different stages of the healing process, tailoring interventions as needed. Here, a dual enzyme mimetic and bacterial responsive self-activating antimicrobial hydrogel designed to enhance IPUs healing is introduced. This hydrogel incorporates pH-responsive dual enzyme-active nanoplatforms (HNTs-Fe-Ag) encapsulated within a methacrylate-modified silk fibroin (SFMA) and dopamine methacrylamide (DMA) matrix. This composite hydrogel exhibits adaptive microenvironment regulation capabilities. Under the low pH microenvironment of bacterial infection, it has excellent antimicrobial activity by self-activating the •OH generation in conjunction with photothermal effects. Under the neutral and alkaline microenvironment of chronic inflammation, it catalyzes the decomposition of hydrogen peroxide (H2O2) to produce oxygen (O2), thereby alleviating hypoxia and scavenging reactive oxygen species (ROS), which in turn remodulates the phenotype of macrophages. The composite hydrogel demonstrates on-demand therapeutic effects in the microenvironment of infected wounds, significantly enhancing the regenerative microenvironment of IUPs by promoting wound closure, inflammation regulation, and collagen deposition through self-activated antimicrobial action during infection and adaptive hypoxia relief during recovery. This approach offers a novel strategy for developing smart wound dressings.

Paeoniflorin Attenuates Limb Ischemia by Promoting Angiogenesis Through ERα/ROCK-2 Pathway

Background: Peripheral artery disease (PAD) is a high-risk vascular condition, and vascular remodeling has become a promising therapeutic approach. Paeoniflorin (PF) is the main bioactive compound in the roots of Paeonia lactiflora Pall, which is commonly used to treat a range of cardiovascular disorders. However, the mechanisms underlying the ameliorating effects of PF on PAD remain unclear. Therefore, the purpose of this study was to explore the therapeutic efficiency of PF on PAD and determine its mechanisms. Methods: The blood flow of mice was detected with a laser Doppler dot scanning imaging system. HE staining was used to observe the morphological changes of ischemic muscle. The changes in the serologic indexes were detected with an automatic biochemical assay, and the capillary density of ischemic gastrocnemius was detected with a Lectin immunofluorescence assay. The expression of angiogenesis-related proteins in ischemic gastrocnemius was detected with Western blotting, and the proportion of macrophages and neutrophils in total cells was detected with flow cytometry. Results: PF significantly increased blood flow, capillary density and protein expressions of vascular endothelial growth factor A (VEGFA), matrix metalloproteinase 2 (MMP2), matrix metalloproteinase 2 (MMP9), and estrogen receptor α (ERα) in mouse ischemic tissue in a PAD model. PF enhances the migration of endothelial cells and promotes the formation of tubular structures, involving the ERα/ROCK2 signaling pathway. Furthermore, PF was found to promote the phenotypic transformation of macrophages and alleviated grave inflammatory responses during vascular remodeling. Conclusions: We determined that PF as a potent compound in promoting angiogenesis and mitigating inflammatory responses during revascularization.

Polysaccharide-Based Self-Healing Hydrogel for pH-Induced Smart Release of Lauric Acid to Accelerate Wound Healing

It is highly desirable yet significantly challenging to fabricate an injectable, self-healing, controlled-release wound dressing that is responsive to the alkaline pH of the wounds. Herein, we propose a facile approach to prepare pH-responsive chitosan-oxidized carboxymethyl cellulose (CS-o-CMC) hydrogel constructs in which gelation was achieved via electrostatic and Schiff base formation. Importantly, the Schiff base was formed in acidic medium and the final pH of pregel solution was intrinsically raised to 7.0-7.4 due to the cross-linking by β-glycerol phosphate. The self-healing behavior of the hydrogel was an enthalpy-driven process and efficient in alkaline compared to acidic pH. The pH responsiveness offered a controlled release of lauric acid (LA) from CS-o-CMC/LA hydrogel and regulated the M2 polarization. Overall, reduction in inflammation led to rapid vascularization, reepithelialization, and significantly accelerated wound healing in rats. Our findings demonstrate a promising strategy for developing injectable, immunomodulatory wound dressings tailored to the challenging environment of wounds.

Intelligent sequential degradation hydrogels by releasing bimetal-phenolic for enhanced diabetic wound healing

Healing of diabetic wounds is significantly impeded by a complex environment comprising biofilm formation, excessive inflammation, and compromised angiogenic capacity, leading to a disordered physiological healing process. Restoration and maintenance of a normal and orderly healing process in diabetic wounds remain unmet therapeutic objectives. Herein, an innovative bimetal-phenolic network hydrogel system is designed with a concentric circular structure, enabling dual-drug delivery with differentiated release kinetics. The outer layer, Cu@TA (tannic acid)-loaded ε-PL (poly-l-lysine)-SilMA (methacrylated silk), is engineered for an initial release to scavenge reactive oxygen species and exert antibacterial and anti-inflammatory effects. The inner layer, Zn@TA-loaded ε-PL-SilMA, is designed for sustained release to promote cell migration, modulate the immune microenvironment, and induce angiogenesis. By incorporating a polyphenolic-metal network, the Cu@TA/Zn@TA/ε-PL-SilMA hydrogel can alter its degradation rate, enabling the sequential release of Cu@TA and Zn@TA. An in vivo diabetic rat wound model, transcriptomic sequencing, and histological staining analyses revealed that the Cu@TA/Zn@TA/ε-PL-SilMA hydrogel effectively activates the Wnt/β-catenin signaling pathway, synergistically promoting wound healing by accelerating angiogenesis, effectively reducing inflammation, and promoting collagen deposition. This innovative hydrogel, with sequential degradation and release properties, is broadly applicable, ensures orderly wound healing, and holds promise for accelerating diabetic wound repair.

Hydrogel-based therapies for diabetic foot ulcers: recent developments and clinical implications

The diabetic foot ulcer is among the most serious diabetes-associated complications, with a long disease course considerably increasing the pain and economic burden of patients, leading to amputation and even death. High blood sugar is characteristic of diabetic foot ulcers, with insufficient blood supply, oxidative stress disorder, and high-risk bacterial infection posing great challenges for disease treatment. Advances in hydrogel dressings have shown potential for the management of diabetic foot ulcers involving multisystem lesions. This study comprehensively reviews the pathogenesis of diabetic foot ulcers and advances in hydrogel dressings in treating diabetic foot ulcers, providing innovative perspectives for assessing the nursing care requirements and associated clinical applications.

Adhesive and antibacterial guar gum-based nanocomposite hydrogel for remodeling wound healing microenvironment

Hydrogels are promising wound dressings due to their extracellular matrix-like properties and tunable structure-function characteristics. Besides the physical isolation effect, hydrogel dressings are highly expected to possess tissue-adhesive performance and antibacterial capacity, which are beneficial for their clinical translations. Herein, a guar gum (GG)-based nanocomposite hydrogel was fabricated by mixing methacrylated GG (GGMA), acrylic acid, acrylated 3-aminophenylboronic acid, mangiferin (MF)-loaded cetyltrimethyl ammonium chloride (CTAC) micelles (MF@CTAC) and radical initiator. This hydrogel exhibited stable and tunable mechanical property as well as excellent biocompatibility. Borate crosslinking and physical interactions of the hydrogel produced a certain degree of self-healing ability, good tissue adhesive and hemostatic capacity. MF endowed the hydrogel with good antioxidant ability and excellent synergistic antibacterial ability with CATC. In vivo experiments indicated that the hydrogel significantly accelerated wound healing with a narrower wound edge, thicker granulation tissue, maturer epidermis and dermis tissue, higher collagen deposition level, milder inflammatory response, and enhanced angiogenesis. The hydrogel without adding antibiotics and other exogenous active ingredients showed great application potential as a versatile wound dressing material.

An effective drug-free hydrogel for accelerating the whole healing process of bacteria-infected wounds

Wound healing is a dynamic and complex process involving hemostasis, inflammation, fibroblast proliferation, and tissue remodeling. This process is highly susceptible to bacterial infection, which often leads to impaired and delayed wound repair. While antibiotic therapy remains the primary clinical approach for treating bacteria-infected wounds, its widespread use poses a significant risk of developing bacterial resistance. Here, a novel drug-free hydrogel was fabricated using polysaccharides and humic acid (HU) to facilitate the healing of bacteria-infected wounds. Specifically, hyaluronic acid (HA) was modified via oxidation with sodium periodate, introducing aldehyde groups along its main chains. Pectin (PT) was grafted with amino groups on its side chains through an amidation reaction with ethylenediamine. HU, a natural organic compound with hemostatic, antioxidant, antibacterial, anti-inflammatory, and photothermal properties, was reduced using sodium borohydride to generate an increased number of phenolic hydroxyl and catechol groups. The resulting hydrogel, called HA-PT/HUOH, was prepared by integrating these three chemically modified biomaterials through dynamic Schiff base cross-linking and hydrogen bonding. The HA-PT/HUOH hydrogel showed excellent injectability, strong bioadhesiveness, rapid self-healing capabilities, and potent photothermal performance. Both in vitro and in vivo studies demonstrated that HA-PT/HUOH significantly accelerated the healing of bacteria-infected wounds by modulating the entire wound-healing process. This included enhancing hemostasis, bacteriostasis, antioxidation, anti-inflammatory responses, fibroblast proliferation, and tissue remodeling. In summary, this multifunctional drug-free hydrogel presents a highly promising solution as a wound dressing for clinical application.

Super-hydrophilic and super-lubricating Zwitterionic hydrogel coatings coupled with polyurethane to reduce postoperative dura mater adhesions and infections

The dura trauma or large defects due to neurosurgical procedures can result in potential complications. Dural replacements have proven effective to reduce the risk of seizures, meningitis, cerebrospinal fluid leakage, cerebral herniation, and infection. Although various artificial dural patches have been developed, addressing iatrogenic infections and cerebral adhesions resulting from patches implantation remains a challenge. This study employed a network interpenetration modification strategy to introduce super-hydrophilic and super-lubricity zwitterionic hydrogel coatings on polyurethane Neuro-Patch® (NP®) dura mater patch. The successful modification with the hydrogel coating preserved the intrinsic properties of the NP®, such as their anti-leakage and tensile strength capabilities, while effectively reducing biofouling on the surface of the patches. Additionally, by constructing subdural implantation for each dura mater substitute in rabbits, we observed that artificial dura mater patches modified with the hydrogel coating effectively reduced the incidence of postoperative cerebral adhesions and infections. This suggests a promising application prospect of the hydrogel coating in dural repair. STATEMENT OF SIGNIFICANCE: The development of dural substitutes with anti-leakage, anti-adhesion and anti-infection functions is the key to the treatment of dural defects and cerebrospinal fluid leakage during trauma or neurosurgery. In this study, the amphoteric ionic hydrogel coating was firmly modified on the surface of polyurethane with a mild modification process to give the patch super-hydrophilic and super-lubricating properties. The adhesion of non-specific proteins and bacteria is effectively reduced. The rabbit dural defect repair model showed that the introduction of zwitterionic hydrogel coating effectively reduced the occurrence of postoperative infection, and no tissue adhesion was observed. Taken together, this study offers a promising way to enhance the performance of artificial dural patches, potentially benefiting patients undergoing neurosurgery.

Recent Advances in Asymmetric Wettability Dressings for Wound Exudate Management

The management of wound exudate is of vital importance for wound healing. Exudate accumulation around wound prolongs inflammation and hinders healing. Although traditional dressings can absorb wound exudate, they are unable to drain exudate in time, often resulting in a poor feature with wound healing. In recent years, the appearance of asymmetric wettability dressings has shown great potential in exudate management. Here, we summarize the latest progress of 3 kinds of asymmetric wettability wound dressings in exudate management, including Janus structure, sandwich structure, and gradient structure. The most common Janus structural dressing among asymmetric wettability dressings is highlighted from 2 aspects: single-layer modified Janus structure and double-layer Janus structure. The challenges faced by asymmetric wettability wound dressings are discussed, and the developing trends of smart wound dressings in this field are prospected.

3D Biofabrication of Microporous Hydrogels for Tissue Engineering

Microporous hydrogels have been utilized in an unprecedented manner in the last few decades, combining materials science, biology, and medicine. Their microporous structure makes them suitable for wide applications, especially as cell carriers in tissue engineering and regenerative medicine. Microporous hydrogel scaffolds provide spatial and platform support for cell growth and proliferation, which can promote cell growth, migration, and differentiation, influencing tissue repair and regeneration. This review gives an overview of recent developments in the fabrication techniques and applications of microporous hydrogels. The fabrication of microporous hydrogels can be classified into two distinct categories: fabrication of non-injectable microporous hydrogels including freeze-drying microporous method, two-phase sacrificial strategy, 3D biofabrication technology, etc., and fabrication of injectable microporous hydrogels mainly including microgel assembly. Then, the biomedical applications of microporous hydrogels in cell carriers for tissue engineering, including but not limited to bone regeneration, nerve regeneration, vascular regeneration, and muscle regeneration are emphasized. Additionally, the ongoing and foreseeable applications and current limitations of microporous hydrogels in biomedical engineering are illustrated. Through stimulating innovative ideas, the present review paves new avenues for expanding the application of microporous hydrogels in tissue engineering.

Melanin Hydrogel Inverse Opal Microneedle Patches for Wound Healing

Bacterial infected wounds bring an economic burden to the worldwide medical care field. A variety of bioactives-integrated hydrogel patches are developed in response to this challenge. Here, the melanin hydrogel inverse opal microneedle patches (MNs) with antioxidant and visual color sensing abilities for the management of bacterial infected wounds are proposed. The MNs are fabricated by applying melanin-loaded polyethylene glycol diacrylate (PEGDA) as the inverse opal hydrogel and using bacitracin-carried gelatin to fill those nanopores of hydrogel scaffold. Benefitting from the antioxidant capacity of melanin nanoparticles and the local antimicrobial ability of bacitracin, the resulting MNs possess the integrated functions of reactive oxygen species scavenging and antibacterial. Besides, the inverse opal structure endows the MNs with vivid structure color and detectable reflected wavelength, which can gradually shift with the release of the drug, thus allowing MNs to assess the drug delivery. Based on these characteristics, MNs perform excellent in in vitro drug delivery and monitoring, as well as the promotion of bacterial infected wound recovery in vivo, indicating the potential of MNs in the future wound management field.

Matrix Metalloproteinase-Responsive Controlled Release of Self-Assembly Nanoparticles Accelerates Heart Valve Regeneration In Situ by Orchestrating Immunomodulation

In situ tissue engineering heart valves (TEHVs) are the most promising way to overcome the defects of existing valve prostheses. Despite their promising prospects, the clinical translation of TEHVs remains a formidable challenge, mainly due to unpredictable host interactions post-implantation. An immunomodulatory idea based on hydrogel encapsulation of nanoparticle-coated heart valve scaffolds is introduced. Specifically, galactose-modified human serum albumin nanoparticles (miR-93@HSA NPs) to deliver microRNA-93 mimics are utilized, which target macrophages and induce their differentiation into the anti-inflammatory M2 subtype, fostering a conducive immune microenvironment. Matrix metalloproteinase (MMP)-responsive hydrogel is used to encapsulate the nanoparticles, enabling targeted and sustained release. Results show that the miR-93@HSA NPs exhibit excellent ability to induce macrophage polarization toward the M2 phenotype. A decellularized valve modified with hydrogel reveals MMP-response release of the miR-93@HSA NPs. In vitro, the immunomodulatory heart valve possesses good endocytocompatibility and effectively reprograms macrophages when cocultured with HUVECs or RAW264.7 macrophages. In vivo, this valve scaffold promises to mitigate early inflammatory damage and provide a pro-endothelialization niche for scaffolds' constructive remodeling. With the use of cell coculture systems and transcriptome sequencing, the mechanism of immune-modulating scaffold accelerating endothelialization is being elucidated. The immunomodulatory heart valve scaffold holds promising potential for clinical translation.

Peptide-Induced Hydrogelation with Ordered Metal-Organic Framework Nanoparticles Generating Reactive Oxygen Species for Integrated Wound Repair

Hydrogels, with their high water content and flexible nature, are a promising class of medical dressings for combating bacterial wound infections. However, their development has been hindered by low sterilization efficiency. Here, this issue is addressed by designing a peptide hydrogel that assembles ordered metal-organic framework (MOF) nanoparticles with photocatalytic bactericidal activity. Specifically, a short peptide, Nap-Gly-Phe-Phe-His (Nap-GFFH), is used to induce the assembly of zinc-imidazolate MOF (ZIF-8) into a hydrogel (NHZ gel). This innovative structure integrates three key features: 1) ZIF-8 nanoparticles are encapsulated within the hydrogel, overcoming their inherent brittleness, insolubility, and limited moldability; 2) the ordered ZIF-8 structure enhances charge transfer, enabling efficient generation of reactive oxygen species (ROS); and 3) ZIF-8 simultaneously improves the photocatalytic bactericidal efficiency and mechanical properties of the hydrogel. The NHZ gel demonstrates remarkable antibacterial performance, achieving >99.9% and 99.99% inactivation of Escherichia coli and Staphylococcus aureus, respectively, within 15 min of simulated solar radiation. Additionally, the NHZ gel exhibits excellent biocompatibility, water retention, and exudate absorption, highlighting its broad potential for wound healing.

Hydrogels and hydrogel-based drug delivery systems for promoting refractory wound healing: Applications and prospects

Refractory wounds represent a significant health concern that presents considerable challenges within clinical practice. The healing process of refractory wounds, which involves various cell types and biologically active molecules, is dynamically influenced by multiple factors, including diabetes, infections, and inflammation. Owing to their hydrophilicity, biocompatibility, and capacity for drug loading, hydrogels have emerged as promising and innovative biomaterials for enhancing wound healing. In recent decades, hydrogels with inherent therapeutic properties have been identified. Moreover, advanced hydrogel-based drug delivery systems have been developed to facilitate the sustained and controlled release of therapeutic agents at the site of refractory wounds. This review aims to summarize recent advancements and applications of hydrogels, including those with intrinsic therapeutic properties and hydrogel-based drug delivery systems, in the treatment of refractory wounds. Additionally, we discuss the limitations associated with hydrogel applications and propose future perspectives, which will lead to ongoing efforts to optimize hydrogels as ideal biomaterials for refractory wound healing.

Biologically inspired bioactive hydrogels for scarless corneal repair

Corneal injury-induced fibrosis occurs because of corneal epithelial basement membrane (EBM) injury and defective regeneration. Corneal fibrosis inhibition and transparency restoration depend on reestablished EBM, where the collagen network provides structural stability and heparan sulfate binds corneal epithelium-derived cytokines to regulate homeostasis. Inspired by this, bioactive hydrogels (Hep@Gel) composed of collagen-derived gelatins and highly anionic heparin were constructed for scarless corneal repair. Hep@Gel resembled the barrier function of the EBM regarding surface-confined binding, long-time sequestration, and progressive degradation of IL-1, TGF-β, and PDGF-BB, which robustly inhibited the apoptosis and myofibroblast transition of keratocytes. Animal models of rabbits and nonhuman primates confirmed that Hep@Gel effectively limited the influx of inflammatory and fibrotic cytokines from the epithelium into the stroma to down-regulate the wound healing cascade, contributing to better vision quality with 73% reduced fibrosis. Hep@Gel offers a solution for preventing corneal injury-induced scarring and substituting for lamellar keratoplasty to remove scarring.

Hyaluronan Scaffold Decorated with Bifunctional Peptide Promotes Wound Healing via Antibacterial and Anti-Inflammatory

The invasion of bacteria and inflammation impeded infected wounds heal. Here, a hyaluronan-based scaffold (HAG-g-C) was designed by cross-linking with gallic acid-modified gelatin to provide a protein microenvironment and decorated with cathelicidin-BF (CBF), a natural antimicrobial peptide, to remove bacterial infections and reverse the inflammatory environment. In vitro, HAG-g-C presented an antibacterial effect on Staphylococcus aureus and Escherichia coli. Meanwhile, it could drive the phenotypic switch of macrophage from M1 to M2 to accelerate tissue remodeling. In a mouse model of S. aureus-infected total skin defects, HAG-g-C inhibited the process of infection at the beginning of the wound and then regulated the M1 macrophage transformed to M2 phenotype on day 12. In addition, HAG-g-C induced collagen deposition, and reduced the expression of TNF-α, thereby significantly accelerating the reconstruction of infected wounds.

Immunomodulatory Hydrogel for Electrostatically Capturing Pro-inflammatory Factors and Chemically Scavenging Reactive Oxygen Species in Chronic Diabetic Wound Remodeling

Diabetic wound exhibits the complex characteristics involving continuous oxidative stress and excessive expression of pro-inflammatory cytokines to cause a long-term inflammatory microenvironment. The repair healing of chronic diabetic wounding is tremendously hindered due to persistent inflammatory reaction. To address the aforementioned issues, here, a dual-functional hydrogel is designed, consisting of N1-(4-boronobenzyl)-N3-(4-boronophenyl)-N1, N1, N3, N3-tetramethylpropane-1, 3-diaminium (TSPBA) modified polyvinyl alcohol (PVA) and methacrylamide carboxymethyl chitosan (CMCSMA) can not only electrostatically adsorb proinflammatory cytokines of IL1-β and TNF-α, but can also chemically scavenge the excessive reactive oxygen species (ROS) in situ. Both in vitro and in vivo evaluations verify that the negatively charged and ROS-responsive hydrogel (NCRH) can effectively modulate the chronic inflammatory microenvironment of diabetic wounds and significantly enhance wound remodeling. More importantly, the well-designed NCRH shows a superior skin recovery in comparison with the commercial competitor product of wound dressing. Consequently, the current work highlights the need for new strategies to expedite the healing process of diabetic wounds and offers a wound dressing material with immunomodulation.

LysSYL-Loaded pH-Switchable Self-Assembling Peptide Hydrogels Promote Methicillin-Resistant Staphylococcus Aureus Elimination and Wound Healing

Staphylococcus aureus (S. aureus), especially methicillin-resistant S. aureus (MRSA), causes wound infections, whose treatment remains a clinical challenge. Bacterium-infected wounds often create acidic niches with a pH 4.5-6.5. Endolysin LysSYL, which is derived from phage SYL, shows promise as an antistaphylococcal agent. However, endolysins generally exhibit instability and possess low bioavailability in acidic microenvironments. Here, an array of self-assembling peptides is designed, and peptide L5 is screened out based on its gel formation property and bioavailability. L5 exerted a pH-switchable antimicrobial effect (pH 5.5) and formed biocompatible hydrogels at neutral pH (pH 7.4). The LysSYL-loaded L5 can assemble L5@LysSYL hydrogels, increase thermal stability, and exhibit the slow-release effect of LysSYL. Effective elimination of S. aureus is achieved by L5@LysSYL through bacterial membrane disruption and cell separation inhibition. Moreover, L5@LysSYL hydrogels exhibit great potential in promoting wound healing in a mouse wound model infected by MRSA. Furthermore, L5@LysSYL hydrogels are safe and can decrease the cytokine levels and increase the number of key factors for vessel formation, which contribute to wound healing. Overall, the self-assembling L5@LysSYL can effectively clean MRSA and promote wound healing, which suggests its potential as a pH-sensitive wound dressing for the management of wound infections.

Licochalcone A loaded multifunctional chitosan hyaluronic acid hydrogel with antibacterial and inflammatory regulating effects to promote wound healing

The wound healing process is characterized by persistent infection and long-term inflammation. The licochalcone A (LicA) has the potential for skin wound healing and needs a good drug-loading platform to apply its antibacterial and anti-inflammatory effects. In this study, the LicA@chitosan (CS) -hyaluronic acid (HA) hydrogel with antibacterial and anti-inflammatory was developed for wound healing in mice. The SEM displayed that the hydrogel had an obvious porous structure and was very suitable to be used as a delivery carrier for LicA. The FTIR results suggested that the LicA can be effectively loaded in the CS-HA hydrogel. Variable strain scanning, frequency scanning and temperature scanning indicated that the LicA@CS-HA hydrogel can maintain the gel state. The LicA@CS-HA hydrogel had good biological safety, can inhibit the activity of Escherichia coli and Staphylococcus aureus, and can release LicA stably. The LicA@CS-HA hydrogel also has good adhesion and hemostatic properties. Finally, the LicA@CS-HA hydrogel significantly accelerated wound healing in mice skin injury model, and reduced inflammation and orderly collagen deposition were observed by HE and Masson staining. The immunohistochemistry indicated that the LicA@CS-HA hydrogel induced the positive expression of CD31, VEGF, and HIF-1α promoted neovascularization. The LicA@CS-HA hydrogel also down-regulated the expression of M1 macrophage markers CD86, IL-6, and TNF-α, and increased the expression of M2 macrophage markers CD206, IL-4, and IL-10 proteins. The molecular docking demonstrated that the target proteins had better binding activity to LicA. Collectively, the LicA@CS-HA hydrogel has broad application prospects in promoting wound healing.

Exploring the wound healing potential of dietary nitrate in diabetic rat model

Introduction

The wound healing in diabetes is hindered and prolonged due to long-term inflammation, oxidative stress damage, and angiogenesis disorders induced by high glucose status. The management of such difficult-to-treat wounds continues to pose a significant challenge in clinical treatment. Dietary nitrate, commonly found in greens such as beets and spinach, acts as a nutritional supplement and is metabolized in the body through the salivary nitrate-nitrite-NO pathway. This pathway plays a crucial role in various physiological functions, including enhancing blood flow and attenuating inflammation.

Methods

In this study, we established a diabetic rat wound model. Forty-eight rats were randomly divided into six groups (n = 8): the Con group, the Con + Nitrate group, the STZ group, the STZ + NaCl group, the STZ + rhEGF group, and the STZ + Nitrate group. Skin wound healing was assessed on the day of surgery and on postoperative days 3, 7, 10, and 14. Specimens were taken on days 7 and 14 post-surgery for relevant tests.

Results

We found that dietary nitrate could accelerate skin wound healing by promoting angiogenesis and increasing blood perfusion. Significantly, dietary nitrate also regulated glucose and lipid metabolism and exhibited anti-inflammatory and antioxidant properties.

Discussion

These findings provide a novel theoretical basis for managing wounds in diabetic individuals, indicating the broad potential of dietary nitrate in future clinical applications.

Rapidly in situ forming antibiotic-free injectable hydrogel wound dressing for eradicating drug-resistant bacterial infections in human skin organoids

The rising prevalence of global antibiotic resistance evokes the urgent requirement to explore the alternative antimicrobial candidates. It is of great significance to overcome these serious threats of multidrug-resistant bacterial infections and difficult-to-heal cutaneous wounds to human health. Herein, we proposed a rapidly in situ forming innovative antibiotic-free hydrogel dressing with excellent biocompatibility, easy injectability, strong tissue adhesion and superior antibacterial activity against drug-resistant bacteria. An octa-armed poly(ethylene glycol) amine (Octa-PEG-NH2) was quickly crosslinked with a green industrial microbicide tetrakis (hydroxymethyl) phosphonium chloride (THPC) to form an antibacterial hydrogel (OPTH) by simple mixing without any other initiators or crosslinkers. A significant broad-spectrum antibacterial efficacy was demonstrated against Gram-positive Staphylococcus aureus (S. aureus), Gram-negative Escherichia coli (E. coli) and methicillin-resistant Staphylococcus aureus (MRSA). Significantly, benefiting from its flexible injectability and reliable tissue adhesion, the excellent antibacterial performances were further evidenced by employing human-induced pluripotent stem cell (iPSC)-derived skin organoids in a 3D culture system and rat animal wound models in vivo with MRSA infection, thus allowing for reepithelization promotion and wound healing. Collectively, the findings not only propose a facile gelatinization strategy for readily accessible antibiotic-free hydrogel dressings for effective MRSA therapy but also hold great clinical translation potential in obliterating multi-pathogenic bacteria and accelerating wound healing.

Reactive oxygen species-responsive polydopamine-PtCuTe nanoparticle-loaded microneedle system for promoting the healing of infected skin wounds

Nanozymes, known for their high efficiency in scavenging reactive oxygen species (ROS), have received significant attention in promoting the healing of infected wounds. Herein, we reported a novel multifunctional PDA-PtCuTe nanozyme with excellent ROS scavenging, antibacterial, pro-angiogenic, anti-inflammatory, and immune regulatory properties. It was loaded onto microneedles (PTPP-MN) for treating infected wounds. In vitro experiments demonstrated its ability to scavenge ROS and exhibit antioxidant properties. Compared to PT-MN (11.03 ± 3.37 %) and PTP-MN (42.30 ± 2.60 %), the ROS scavenging rate of PTPP-MN reached 63.63 ± 4.42 %. The microneedle exhibits good biocompatibility, stimulating fibroblast migration, endothelial angiogenesis, and M2 macrophage polarization. Additionally, it effectively eliminates ROS and provides antioxidant effects while inhibiting the viability of S. aureus and E. coli. Animal experiments showed that the PTPP-MN group achieved near-complete re-epithelialization by the third day compared to other groups. Histological observations revealed that the PTPP-MN group exhibited enhanced granulation tissue formation, epithelial regeneration, and angiogenesis. After PTPP-MN treatment, the local immune response shifted from a pro-inflammatory state to a pro-regenerative state. Our results indicate that PTPP-MN holds great promise for infected wound healing with reduced scar formation.

Injectable hyaluronate-based hydrogel with a dynamic/covalent dual-crosslinked architecture for bone tissue engineering: Enhancing osteogenesis and immune regulation

In orthopedic practice, accommodating irregular defects caused by trauma or surgery with traditional preformed bone graft substitutes is often challenging. As a result, injectable hydrogels with seed cells have garnered significant interest in bone repair due to their adaptability and minimally invasive properties. However, they cannot simultaneously achieve injectability and mechanical properties, providing a biophysical and biochemical environment for cell support. In this study, a novel injectable hydrogel system (OA hydrogel) loaded with aspirin and bone mesenchymal stem cells (BMSCs) was developed to enhance osteogenesis and immune regulation in small irregular bone defects. OA hydrogels possessed self-healing and shear-thinning properties due to dynamic/covalent hydrazone bonds between aldehyde-modified hyaluronic acid methacrylate (ADH-HAMA) and oxidized hyaluronic acid (OHA). By photopolymerization of the enclosed HAMA, the OADC hydrogel was further reinforced, making it more suitable for cell proliferation. In vitro, composite hydrogels improved the osteogenic differentiation of BMSCs. Additionally, it promoted the M2 polarization of human monocytic leukemia (THP-1) cells. In vivo, the synergistic effect of acetylsalicylic acid (ASA) and BMSCs encapsulated within the OADC hydrogel promoted new bone formation in rat calvaria through increased recruitment and polarization of M2 macrophages. These findings underscore the significant promise of hydrogels for bone tissue engineering applications.

A Mg Battery-Integrated Bioelectronic Patch Provides Efficient Electrochemical Stimulations for Wound Healing

Bioelectronic patches hold promise for patient-comfort wound healing providing simplified clinical operation. Currently, they face paramount challenges in establishing long-term effective electronic interfaces with targeted cells and tissues due to the inconsistent energy output and high bio interface impedance. Here a new electrochemical stimulation technology is reported, using a simple wound patch, which integrates the efficient generation and delivery of stimulation. This is realized by employing a hydrogel bioelectronic interface as an active component in an integrated power source (i.e., Mg battery). The Mg battery enhances fibroblast functions (proliferation, migration, and growth factor secretion) and regulates macrophage phenotype (promoting regenerative polarization and down-regulating pro-inflammatory cytokines), by providing an electric field and the ability to control the cellular microenvironment through chemical release. This bioelectronic patch shows an effective and accelerated wound closure by guiding epithelial migration, mediating immune response, and promoting vasculogenesis. This new electrochemical-mediated therapy may provide a new avenue for user-friendly wound management as well as a platform for fundamental insights into cell stimulation.

Localized Surface Plasmon Resonance-Enhanced Photocatalytic Antibacterial of In Situ Sprayed 0D/2D Heterojunction Composite Hydrogel for Treating Diabetic Wound

Chronic diabetic wounds pose significant challenges due to uncontrolled bacterial infections, prolonged inflammation, and impaired angiogenesis. The rapid advancement of photo-responsive antibacterial therapy shows promise in addressing these complex issues, particularly utilizing 2D heterojunction materials, which offer unique properties. Herein, an in situ sprayed Bi/BiOCl 0D/2D heterojunction composite fibrin gel with the characteristics of rapid formation and effective near-infrared activation is designed for the treatment of non-healing diabetes-infected wounds. The sprayed composite gel can provide protective shielding for skin tissues and promote endothelial cell proliferation, vascularization, and angiogenesis. The Bi/BiOCl 0D/2D heterojunction, with its localized surface plasmon resonance (LSPR), can overcome the wide bandgap limitation of BiOCl, enhancing the generation of local heat and reactive oxygen species under near-infrared irradiation. This facilitates bacterial elimination and reduced inflammation, supporting the accelerated healing of diabetes-infected wounds. This study underscores the potential of LSPR-enhanced heterojunctions as advanced wound therapies for chronic diabetic wounds.

Advanced Hybrid Strategies of GelMA Composite Hydrogels in Bone Defect Repair

To date, severe bone defects remain a significant challenge to the quality of life. All clinically used bone grafts have their limitations. Bone tissue engineering offers the promise of novel bone graft substitutes. Various biomaterial scaffolds are fabricated by mimicking the natural bone structure, mechanical properties, and biological properties. Among them, gelatin methacryloyl (GelMA), as a modified natural biomaterial, possesses a controllable chemical network, high cellular stability and viability, good biocompatibility and degradability, and holds the prospect of a wide range of applications. However, because they are hindered by their mechanical properties, degradation rate, and lack of osteogenic activity, GelMA hydrogels need to be combined with other materials to improve the properties of the composites and endow them with the ability for osteogenesis, vascularization, and neurogenesis. In this paper, we systematically review and summarize the research progress of GelMA composite hydrogel scaffolds in the field of bone defect repair, and discuss ways to improve the properties, which will provide ideas for the design and application of bionic bone substitutes.

Caffeic acid-mediated photodynamic multifunctional hyaluronic acid-gallic acid hydrogels with instant and enduring bactericidal potency accelerate bacterial infected wound healing

The emergence of drug-resistant bacteria poses significant challenges in wound treatment. Antimicrobial photodynamic therapy has emerged as an effective approach to eliminating bacteria by inducing oxidative stress without causing drug resistance. Here, we developed a natural hyaluronic acid (HA)-gallic acid (GA) conjugation-based hydrogel combined with herbal photosensitizer-caffeic acid (CA), which exhibits self-healing ability, shape adaptability, biodegradability, and robust tissue adhesion. Under exposure to 400 nm light, caffeic acid acts as a photosensitizer, generating reactive oxygen species and oxidative damage to bacterial cell membranes. Furthermore, the presence of GA and CA displayed a continuous inhibitory effect on bacterial growth, along with antioxidant properties that promote wound healing even after the cessation of light exposure. The antibacterial mechanism of the HA-GA/CA hydrogel against MRSA, S. aureus, and E. coli was investigated through various assays measuring ATP levels, Zeta potential, hydroxyl radicals (·OH) generated by light irradiation, and biofilm clearance rate. Additionally, hydrogel's application in treating MRSA-infected wounds in mice under light irradiation demonstrated rapid wound-healing effects and biocompatibility. Overall, HA-GA/CA hydrogel provides a sustainable, antibiotic-free alternative for treating MRSA-infected wounds.

Photothermally enhanced antibacterial wound healing using albumin-loaded tanshinone IIA and IR780 nanoparticles

Chronic and infected wounds, particularly those caused by bacterial infections, present significant challenges in medical treatment. This study aimed to develop a novel nanoparticle formulation to enhance wound healing by combining antimicrobial and photothermal therapy using albumin as a carrier for Tanshinone IIA and the near-infrared photothermal agent IR780. The nanoparticles were synthesized to exploit the antimicrobial effects of Tanshinone IIA and the photothermal properties of IR780 when exposed to near-infrared laser irradiation. Characterization of the nanoparticles was performed using Transmission Electron Microscopy (TEM) and spectroscopic analysis to confirm their successful synthesis. In vitro antibacterial activity was evaluated using cultures of methicillin-resistant Staphylococcus aureus (MRSA), and in vivo efficacy was tested in a mouse model of MRSA-infected wounds. Wound healing progression was assessed over 16 days, with statistical analysis performed using two-way ANOVA followed by Tukey's post-hoc test. The nanoparticles demonstrated significant photothermal properties, enhancing bacterial eradication and promoting the controlled release of Tanshinone IIA. In vitro studies showed superior antibacterial activity, especially under photothermal activation, leading to a substantial reduction in bacterial viability in MRSA cultures. In vivo, nanoparticle treatment combined with near-infrared laser irradiation significantly improved wound closure rates compared to controls and treatments without photothermal activation. By the 16th day post-treatment, significant improvements in wound healing were observed, highlighting the potential of the combined photothermal and pharmacological approach. These findings suggest that albumin-loaded nanoparticles containing Tanshinone IIA and IR780, activated by near-infrared light, could offer an effective therapeutic strategy for managing chronic and infected wounds, promoting both infection control and tissue repair.

Designing injectable dermal matrix hydrogel combined with silver nanoparticles for methicillin-resistant Staphylococcus aureus infected wounds healing

Hydrogel-based delivery systems have now emerged as a pivotal platform for addressing chronic tissue defects, leveraging their innate capacity to suppress pathogenic infections and facilitate expedited tissue regeneration. In this work, an injectable hydrogel dressing, termed AgNPs-dermal matrix hydrogel (Ag@ADMH), has been designed to expedite the healing process of wounds afflicted with methicillin-resistant Staphylococcus aureus (MRSA), featuring sustained antibacterial efficacy. The synthesis of the hydrogel dressing entailed a self-assembly process of collagen fibers within an acellular dermal matrix to construct a three-dimensional scaffold, encapsulated with plant polyphenol-functionalized silver nanoparticles (AgNPs). The Ag@ADMH demonstrated exceptional biocompatibility, and enables a sustained release of AgNPs, ensuring prolonged antimicrobial activity. Moreover, the in vitro RT-qPCR analysis revealed that compared with ADMH, Ag@ADMH diminish the expression of iNOS while augmenting CD206 expression, thereby mitigating the inflammatory response and fostering wound healing. Especially, the Ag@ADMH facilitated a reduction in M1 macrophage polarization, as evidenced by a significant decrement in the M1 polarization trend and an enhanced M2/M1 ratio in dermal matrix hydrogels laden with AgNPs, corroborated by confocal microscopy and flow cytometry analyses of macrophage phenotypes. The in vivo assessments indicated that Ag@ADMH minimized fibrous capsule formation. In a full-thickness skin defect model of MRSA infection, the formulation significantly attenuated the inflammatory response by reducing MPO and CD68 expression levels, concurrently promoting collagen synthesis and CD34 expression, pivotal for vasculogenesis, thereby accelerating the resolution of MRSA-infected wounds. These attributes underscore the injectable extracellular matrix hydrogel as a formidable strategy for the remediation and regeneration of infected wounds.

Development of Biomaterials to Modulate the Function of Macrophages in Wound Healing

Wound healing is a complex and precisely regulated process that encompasses multiple stages, including inflammation, anti-inflammation, and tissue repair. It involves various cells and signaling molecules, with macrophages demonstrating a significant degree of plasticity and playing a crucial regulatory role at different stages. In recent years, the use of biomaterials, which include both natural and synthetic polymers or macromolecules, has proliferated for the purpose of enhancing wound healing. This review summarizes how these diverse biomaterials promote wound healing by modulating macrophage behavior and examines the broader implications of these modulations. Additionally, we discuss the limitations associated with the clinical application of immunomodulatory biomaterials and propose potential solutions. Finally, we look towards future developments in the design of immunomodulatory biomaterials intended to enhance wound healing.

Chitosan as a tool for tissue engineering and rehabilitation: Recent developments and future perspectives - A review

Chitosan has established itself as a multifunctional and auspicious biomaterial within the domain of tissue engineering, presenting a decade of uninterrupted advancements and novel implementations. This article provides a comprehensive overview of the most recent developments in chitosan-based tissue engineering, focusing on significant progress made in the last ten years. An exploration is conducted of the various techniques utilized in the modification of chitosan and the production of scaffolds, with an analysis of their effects on cellular reactions and tissue regeneration. The investigation focuses on the integration of chitosan with other biomaterials and the addition of bioactive agents to improve their functionalities. Upon careful analysis of the in vitro and in vivo research, it becomes evident that chitosan effectively stimulates cell adhesion, proliferation, and differentiation. Furthermore, we offer valuable perspectives on the dynamic realm of chitosan-based approaches tailored to distinct tissue categories, including nerve, bone, cartilage, and skin. The review concludes with a discussion of prospective developments, with particular attention given to possible directions for additional study, translational implementations, and the utilization of chitosan to tackle existing obstacles in the field of tissue engineering. This extensive examination provides a significant amalgamation of the advancements achieved over the previous decade and directs scholars towards uncharted territories in chitosan-based tissue engineering.

Lactobacillus rhamnosus GG and Bifidobacterium animalis subsp. lactis BB-12 promote infected wound healing via regulation of the wound microenvironment

Infected wounds can result in complex clinical complications and delayed healing, presenting a significant global public health challenge. This study explored the effects of topical application of two probiotics, Lactobacillus rhamnosus GG (LGG) and Bifidobacterium animalis subsp. lactis BB-12, on the microenvironment of infected wounds and their impact on wound healing. LGG and BB-12 were applied separately and topically on the Staphylococcus aureus (S. aureus)-infected skin wounds of the rat model on a daily basis. Both probiotics significantly accelerated wound healing, demonstrated by enhanced granulation tissue formation and increased collagen deposition, with BB-12 showing superior efficacy. LGG and BB-12 both effectively inhibited neutrophil infiltration and decreased the expression of pro-inflammatory cytokines tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). Notably, BB-12 markedly reduced IL-6 levels, while LGG significantly lowered TNF-α, transforming growth factor-β (TGF-β) and vascular endothelial growth factor (VEGF). Additionally, both probiotics promoted macrophage polarization towards the anti-inflammatory M2 phenotype. Microbiota analysis revealed that LGG and BB-12 significantly decreased the abundance of pathogenic bacteria (e.g. Staphylococcus and Proteus) and increased the proportion of beneficial bacteria (e.g. Corynebacterium). Particularly, BB-12 was more effective in reducing Staphylococcus abundance, whereas LGG excelled in promoting Corynebacterium growth. These findings suggest the ability of LGG and BB-12 to modulate the wound microenvironment, enhance wound healing and provide valuable insights for the management of infected wounds.

Injectable Oxygen-Carrying Microsphere Hydrogel for Dynamic Regulation of Redox Microenvironment of Wounds

The delayed healing of infected wounds can be attributed to the increased production of reactive oxygen species (ROS) and consequent damages to vascellum and tissue, resulting in a hypoxic wound environment that further exacerbates inflammation. Current clinical treatments including hyperbaric oxygen therapy and antibiotic treatment fail to provide sustained oxygenation and drug-free resistance to infection. To propose a dynamic oxygen regulation strategy, this study develops a composite hydrogel with ROS-scavenging system and oxygen-releasing microspheres in the wound dressing. The hydrogel itself reduces cellular damage by removing ROS derived from immune cells. Simultaneously, the sustained release of oxygen from microspheres improves cell survival and migration in hypoxic environments, promoting angiogenesis and collagen regeneration. The combination of ROS scavenging and oxygenation enables the wound dressing to achieve drug-free anti-infection through activating immune modulation, inhibiting the secretion of pro-inflammatory cytokines interleukin-6, and promoting tissue regeneration in both acute and infected wounds of rat skins. Thus, the composite hydrogel dressing proposed in this work shows great potential for dynamic redox regulation of infected wounds and accelerates wound healing without drugs.