Reactive oxygen species-degradable polythioketal urethane foam dressings to promote porcine skin wound repair

Micropore structure engineering of injectable granular hydrogels via controlled liquid-liquid phase separation facilitates regenerative wound healing in mice and pigs

Biomaterials can play a crucial role in facilitating tissue regeneration, but their application is often limited by that they induce scarring rather than complete tissue restoration. Hydrogels with microporous architectures, engineered via 3D printing techniques or particle packing (granular hydrogels), have shown promise in providing a conducive microenvironment for cellular infiltration and favorable immune response. Nonetheless, there is a notably lacking in studies that demonstrate scarless regeneration solely through pore structure engineering. In this study, we demonstrate that optimizing micropore structure of injectable granular hydrogels via controlled liquid-liquid phase separation facilitates scarless wound healing. The building block particles are fabricated by precisely controlling the separation kinetics of two immiscible aqueous phases (gelling and porogenic) and timely arresting phase separation, to generate bicontinuous, hollow or closed porous structure. Employing a murine model, we reveal that the optimized pore structure significantly facilitates mature vascular network boosts pro-regenerative macrophage polarization (M2/M1) and CD4+/Foxp3+ regulatory T cells, culminating in scarless skin regeneration enriched with hair follicles. Moreover, our hydrogels outperform the clinical gold-standard collagen/proteoglycan scaffolds in a porcine model, showcasing superior cell infiltration, epidermal integration, and dermal regeneration. Micropore structure engineering of biomaterials presents a promising and biologics free pathway for tissue regeneration.

From saccharides to synthetics: exploring biomaterial scaffolds as cell transduction enhancers

Dry, transduction biomaterial scaffolds (Drydux) represent a novel platform for enhancing viral transduction, achieving drastic improvements in transduction efficiency (from ∼10% to >80%) while simplifying production of potent genetically engineered cells. This technology addresses a critical bottleneck in cell therapy manufacturing, where conventional methods require complex protocols and often yield suboptimal results. However, the underlying material science driving Drydux-enhanced transduction remains unclear. Here, we comprehensively assess biomaterial properties that influence viral transduction enhancement through systematic testing of polysaccharides, proteins, elastin-like polypeptides (ELPs), and synthetic polymers. Our findings reveal that surface porosity and liquid absorption are primary drivers of transduction enhancement, while polymer charge and flexibility play secondary roles. Negatively charged and flexible materials-particularly gelatin, hyaluronan, and alginate-demonstrated superior performance. Notably, despite promising material characteristics, synthetic polymers failed to enhance transduction, highlighting the unique advantages of specific biomaterial compositions. By elucidating these structure-function relationships, this work establishes design principles for optimizing biomaterial-enhanced transduction and expands the Drydux platform's potential for transforming cell therapy manufacturing, regenerative medicine, and beyond.

An Intelligent and Conductive Hydrogel with Multiresponsive and ROS Scavenging Properties for Infection Prevention and Anti-Inflammatory Treatment Assisted by Electrical Stimulation for Diabetic Wound

Diabetic wounds experience a hyperglycemic, hypoxic environment, combined with ongoing oxidative stress and inflammatory imbalances, significantly disrupts normal healing process. Advanced hydrogels have been considered one of the most exciting medical biomaterials for the potential in wounds healing. Herein, a novel conductive hydrogel (HEPP), designed to release nanozyme (PTPPG) in response to its microenvironment, was created to facilitate glucose (Glu) catabolism. Furthermore, the HEPP integrates photodynamic therapy (PDT), photothermal therapy (PTT), and self-cascading reactive oxygen species (ROS) to prevent bacterial infections while ensuring a continuous supply of oxygen (O2) to the wound. The HEPP not only adeptly controls high ROS levels, but also enhances the regulation of inflammation in the wound area via electrical stimulation (ES), thereby promoting healing that is supported by the immune response. Studies conducted in vitro, along with transcriptomic analyses, indicate that ES primarily mitigates inflammation by regulating Interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α). The effects of HEPP combined with ES are primarily connected to their impact on TNF signaling pathways. By reducing the formation of ROS and employing ES to effectively lessen inflammation, this approach offers an innovative method to manage complicated diabetic wounds, ulcers, and a range of inflammatory conditions linked to infections.

Phycocyanin-based multifunctional microspheres for treatment of infected radiation-induced skin injury

Radiation therapy is a primary modality for cancer treatment; however, it often leads to various degrees of skin injuries, ranging from mild rashes to severe ulcerations, for which no effective treatments are currently available. In this study, a multifunctional microsphere (PC@CuS-ALG) was synthesized by encapsulating phycocyanin-templated copper sulfide nanoparticles (PC@CuS) within alginate (ALG) using microfluidic technology. Phycocyanin, a natural protein derived from microalgae, shows abilities to scavenge reactive oxygen species, repair radiation-induced damage to skin cells, and ameliorate macrophage-related inflammatory responses. CuS contributes to photothermal conversion efficiency and exhibits antibacterial properties. The microspheres facilitate the sustained release of PC@CuS, retain moisture at the wound site, and provide a supportive environment for cell migration and growth. In a mouse model of infected radiation-induced skin injury, PC@CuS-ALG exhibited antibacterial and wound healing effects, resulting in accelerated epidermal tissue regeneration, increased thickness and maturation of dermal granulation tissue, and an ameliorated inflammatory response. This study presents a novel, effective, and safe approach for treating radiation-induced skin injuries complicated by bacterial infection.

A Self-healing, Antibacterial, Antioxidant, Injectable Hydrogel Containing Tannic Acid for Skin Wound Repair

Skin defects resulting from various causes are common issues in clinical practice. The predominant approach to skin wound repair involves the application of wound dressings to facilitate healing. However, the current treatment methods face significant limitations, including insufficient functional restoration and inadequate blood supply. In this study, an injectable, self-healing composite hydrogel for skin wound repair is developed using a dynamic Schiff base reaction and hydrogen bonding. The hydrogel incorporates oxidized sodium hyaluronate (OHA), carboxymethyl chitosan (CMCS), and tannic acid (TA). Results indicate that the bio-functional hydrogel demonstrates excellent injectability, self-healing capability, and antibacterial properties. Subcutaneous implantation experiments in rats confirm the in vivo biocompatibility and biodegradability of the hydrogel. Both in vitro and in vivo findings suggest that the bio-functional hydrogel can expedite full-thickness skin wound healing in SD rats by promoting skin regeneration, suppressing inflammatory responses, increasing collagen deposition, and facilitating blood vessel formation. This research introduces a novel approach to the development of bio-functional hydrogels for full-thickness skin wound healing and regeneration.

Local delivery of siRNA using lipid-based nanocarriers with ROS-scavenging ability for accelerated chronic wound healing in diabetes

Diabetic wound healing poses a significant clinical challenge with limited therapeutic efficacy due to uncontrolled reactive oxygen species (ROS), inflammatory responses, and extracellular matrix (ECM) degradation caused by abnormal macrophage activity in the wound microenvironment. To address these concerns, we propose a novel formulation that combines Tempo-conjugated lipid with the commercially cationic lipid DOTAP to expedite diabetic wound healing through targeted siRNA delivery (cLpT@siRNA) and restoration of the wound microenvironment. The developed cLpT@siRNA nanocomplexes effectively scavenge excessive ROS levels, facilitate polarization of proinflammatory M1 macrophages towards an anti-inflammatory M2 phenotype, and suppress MMP9 gene expression in macrophages. In the ICR mouse model of diabetic wounds, cLpT@siRNA nanocomplexes significantly accelerate wound healing, promoting neovascularization and collagen deposition. Overall, the cLpT@siRNA nanocomplexes based on antioxidant and cationic lipids provide a promising strategy for delivering siRNA in diabetic wound treatment and hold great potential for clinical translation.

Engineered in-situ-forming biomimetic hydrogel with self-regulated immunostimulatory capacity promotes postoperative tumor treatment

Post-resection tumors with microscopic foci and immunosuppressive microenvironments have high risk of recurrence and metastasis but respond poorly to various therapies. Herein, we propose a biomimetic hydrogel as a biocompatible, biodegradable and bioadhesive postoperative dressing that could be formed in situ by NaIO4-initiated thiourea-catechol crosslinking after syringe-injection into the resection cavity. The thiourea or catechol-bearing hyaluronic acid precursors are also separately engineered with phenylboronic acid and β-cyclodextrin (β-CD) groups, potentiating the reversible immobilization of (1S, 3R) RAS-selective lethal 3 (RSL3) and glycosylated granulocyte macrophage-colony stimulating factor (GM-CSF) without invasive chemical reactions. Meanwhile, the interconnected porous superstructure of the hydrogels allows the incorporation and self-regulated delivery of PD-L1 antibody (aPD-L1). RSL3-induced immunogenic ferroptosis and GM-CSF could cooperatively trigger robust adaptive tumor-specific immune responses, while aPD-L1 further alleviates the accumulated immunoresistance of tumor cells due to interferon γ-mediated PD-L1 upregulation, thus stimulating potent local and whole-body antitumor immunity to prevent postoperative tumor recurrence and metastasis. The biomimetic hydrogel may serve as a promising solution for the postoperative treatment of solid tumors.

An Investigation into the Structure of Wound-Healing Materials, Chemical Materials, Nature-Based Materials, and Wound Monitoring

With the recent development of advanced industries, in addition to simple abrasions, the demand for wound dressing is gradually increasing in fields such as diabetes care. Factors affecting wound healing include pH, temperature, genetic factors, stress, smoking, and obesity, and studies on these are also increasing. In addition, studies on hydrogels, electrospun nanofibers, foams, films, plant-based materials, chitosan, gelatin, 3D printing, and chemosensors for wound healing are also increasing. However, although there are many data related to wound healing, there are not many studies that have systematically divided them into structures, materials, and monitoring through a review of the literature. Therefore, based on various studies on wound healing, wound-healing materials were classified into structures (films, foams, gauzes, and electrospun nanofibers), chemical materials, nature-based materials, and monitoring sensors, and a literature review was conducted.

Oxidation-responsive, settable bone substitute composites for regenerating critically-sized bone defects

Critically-sized bone defects that cannot spontaneously heal on their own remain a significant problem in the clinic. Synthetic polymeric implants are promising therapies for improving bone healing as they are highly tunable and avoid the potential complications associated with autologous bone grafts. However, biostable implants such as poly(methyl methacrylate) (PMMA) suffer from numerous shortcomings including negligible biodegradability and limited osseointegration with bone. Hydrolytically-degradable polymeric implants such as poly(caprolactone) (PCL) or poly(lactic-co-glycolic acid) (PLGA) have shown promise facilitating bone growth before being resorbed, but matching the degradation rate of these polyesters with the rate of bone regeneration continues to be an engineering challenge. To address these limitations with current synthetic bone implant materials, cell-degradable polymer/hydroxyapatite composites were developed as in situ-curing bone substitutes. The polymeric component was formulated from a thioketal (TK) dithiol linker and a tri-functional epoxy to facilitate rapid crosslinking upon deployment. To enable biologically-responsive implant resorption, the TK unit is specifically cleaved by cell-produced reactive oxygen species (ROS). TK bone substitutes possessed tunable curing and mechanical properties, were selectively degraded in dose-dependent concentrations of ROS, were non-cytotoxic, and demonstrated significantly greater bone regeneration capacity than PMMA in a critically-sized rat skull defect model. These combined results highlight the therapeutic potential of cell-degradable bone void fillers compared against conventional polymeric bone implants.

Robust Controlled Degradation of Enzyme Loaded PCL-Based Fibrous Scaffolds Toward Scarless Skin Tissue Regeneration

Uncontrolled degradation of wound dressings may result in residues, causing several negative effects on wound healing, such as secondary damage, undesirable inflammation, and scar skin formation. Here, an available strategy associated with the synthesis of enzyme-loaded (Burkholderia cepacia lipase, BCL) polycaprolactone (PCL) nanofiber scaffolds, aligning with wound healing effects is reported. These scaffolds are fabricated via fiber microfluidic electrospinning degradation-control technique. The obtained scaffolds exhibit tunable degradation rates, achieving complete degradation within 12-72-h cycles. The acidic degradation products are further elucidated and reveal the potential degradation mechanism. The acidic degradation products create an optimal microenvironment during the hemostasis and inflammation stages of wound healing. Notably, in vivo experiments demonstrate the enzyme-loaded scaffolds effectively promote angiogenesis, reduce inflammatory responses, mitigate collagen deposition, and regulate fibroblast differentiation. This promotes rapid wound healing with a remarkable scarless rate of over 99% by day 21. New guidelines for scar-free healing dressings are proposed, which carry out faster degradation without microplastics (MPs) and toxic byproducts before scar formation. These principles might provide valuable insights and promise for developing more effective wound dressings.

An injectable and adaptable system for the sustained release of hydrogen sulfide for targeted diabetic wound therapy by improving the microenvironment of inflammation regulation and angiogenesis

The combined effects of persistent chronic inflammation, oxidative stress, microcirculation disorders, and dysregulated cellular energy metabolism often hinder the repair of diabetic skin wounds. Traditional treatment methods are typically insufficient in simultaneously addressing these complex factors, resulting in delayed wound healing and a high propensity for recurrence and chronic ulceration. This study developed an innovative strategy based on reactive oxygen species (ROS)-responsive nanoparticles loaded with an ultraviolet (UV)-light-responsive hydrogen sulfide (H2S) donor. This approach leverages the endogenous ROS present in diabetic wounds and external UV light as dual triggers to facilitate the controlled and stepwise release of H2S. The material design explicitly targets the critical challenges in diabetic wound repair, including the inhibition of chronic inflammation, oxidative stress reduction, microcirculation improvement, and support of cellular energy metabolism, thereby significantly accelerating wound healing. This adaptive release of signaling molecules effectively modulates the wound regeneration microenvironment, enhancing the repair process and offering a promising solution for diabetic skin wound management. STATEMENT OF SIGNIFICANCE: This study developed an innovative strategy based on reactive oxygen species (ROS)-responsive nanoparticles loaded with an ultraviolet (UV)-light-responsive hydrogen sulfide (H2S) donor. This approach leverages the endogenous ROS present in diabetic wounds and external UV light as dual triggers to facilitate the controlled and stepwise release of H2S. The material design explicitly targets the critical challenges in diabetic wound repair, including the inhibition of chronic inflammation, oxidative stress reduction, microcirculation improvement, and support of cellular energy metabolism, thereby significantly accelerating wound healing. This adaptive release of signaling molecules effectively modulates the wound regeneration microenvironment, enhancing the repair process and offering a promising solution for diabetic skin wound management.

Multifunctional Janus nanofibrous membrane with unidirectional water transport and pH-responsive color-changing for wound dressing

Chronic wounds often produce a significant volume of exudate, posing a substantial obstacle to healing. Consequently, there is a pressing demand for a versatile dressing capable of effectively managing exudate in chronic wounds. In this context, a Janus smart dressing is proposed, featuring unidirectional water transport and a pH-responsive color-changing for exudate management and wound monitoring. The dressing's mechanisms for unidirectional water transport and color changing are elucidated. The Janus dressing consists of a polyacrylonitrile (PAN)/sodium polyacrylate (SPA)/anthocyanin (An) hydrophilic layer with antioxidant and pH-sensitive functions and a poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) hydrophobic layer, enabling unidirectional exudate drainage without reverse osmosis. Studies indicate that the Janus dressing exhibits excellent air permeability, moisture permeability, mechanical properties, cytocompatibility, and antioxidant performance while promptly responding to color variations in solutions of varying pH levels. In vivo studies demonstrated the excellent wound healing ability of Janus PHBV-PAN/SPA/An membrane. Consequently, this study provides a promising solution to develop wound dressings that can effectively manage excessive wound exudate and dressing changes.

Anchoring of Probiotic-Membrane Vesicles in Hydrogels Facilitates Wound Vascularization

Inadequate vascularization significantly hampers wound recovery by limiting nutrient delivery. To address this challenge, we extracted membrane vesicles from Lactobacillus reuteri (LMVs) and identified their angiogenic potential via transcriptomic analysis. We further developed a composite hydrogel system (Gel-LMVs) by anchoring LMVs within carboxylated chitosan and cross-linking it with oxidized hyaluronic acid through a Schiff base reaction. The resulting Gel-LMVs exhibit good biocompatibility and retain the bioactivity of LMVs, which are released in a controlled manner to stimulate cell proliferation, migration, and angiogenesis in vitro by modulating gene expression in critical signaling pathways. Moreover, in an in vivo model, Gel-LMVs upregulate vascular endothelial growth factor (VEGF) and platelet endothelial cell adhesion molecule (CD31), leading to accelerated vascularization in early healing stages, while concurrently reducing inflammation and augmenting collagen deposition to enhance wound healing quality. This approach to functionalizing biomaterials with probiotic-MVs offers an advanced strategy for wound healing.

Reactive oxygen species-scavenging biomaterials for neural regenerative medicine

Reactive oxygen species (ROS) are natural by-products of oxygen metabolism. As signaling molecules, ROS can regulate various physiological processes in the body. However excessive ROS may be a major cause of inflammatory diseases. In the field of neurological diseases, ROS cause neuronal apoptosis and neurodegeneration, which severely impede neuroregeneration. Currently, ROS-scavenging biomaterials are considered as a promising therapeutic strategy for neurological injuries due to their ability to scavenge excessive ROS at defects and modulate the oxidative stress microenvironment. This review provides an overview of the generation and sources of ROS, briefly describes the dangers of generating excessive ROS in nervous system diseases, and highlights the importance of scavenging excessive ROS for neuroregeneration. We have classified ROS-scavenging biomaterials into three categories based on the different mechanisms of ROS clearance. The applications of ROS-responsive biomaterials for neurological diseases, such as spinal cord injury, brain injury, and peripheral nerve injury, are also discussed. Our review contributes to the development of ROS-scavenging biomaterials in the field of neural regeneration.

Composite Hyaluronic Acid Gas-Entrapping Materials to Promote Wound Healing

Tissue repair is often impaired in pathological states, highlighting the need for innovative wound-healing technologies. This study introduces composite hyaluronic acid gas-entrapping materials (GEMs) delivering carbon monoxide (CO) to promote wound healing in pigs. These composite materials facilitate burst release followed by sustained release of CO over 48 h. In a porcine full-thickness wound model, CO-GEMs significantly accelerated wound closure compared to the standard-of-care dressing (Tegaderm). Wound area closure with CO-GEMs was 68.6% vs 56.8% on day 14, 41.0% vs 25.1% on day 28, and 26.9% vs 11.8% on day 42, effectively reducing healing time by 14 days. Histological analysis revealed increased epithelialization and neovascularization with reduced inflammation. These findings demonstrate the potential of CO-GEMs as a topical therapeutic to enhance tissue repair in clinically relevant models, supporting further testing for wound-healing applications.

Bioactive sucralfate-based microneedles promote wound healing through reprogramming macrophages and protecting endogenous growth factors

Impaired wound healing due to insufficient cell proliferation and angiogenesis is a significant physical and psychological burden to patients worldwide. Therapeutic delivery of exogenous growth factors (GFs) at high doses for wound repair is non-ideal as GFs have poor stability in proteolytic wound environments. Here, we present a two-stage strategy using bioactive sucralfate-based microneedle (SUC-MN) for delivering interleukin-4 (IL-4) to accelerate wound healing. In the first stage, SUC-MN synergistically enhanced the effect of IL-4 through more potent reprogramming of pro-regenerative M2-like macrophages via the JAK-STAT pathway to increase endogenous GF production. In the second stage, sucralfate binds to GFs and sterically disfavors protease degradation to increase bioavailability of GFs. The IL-4/SUC-MN technology accelerated wound healing by 56.6 % and 46.5 % in diabetic mice wounds and porcine wounds compared to their respective untreated controls. Overall, our findings highlight the innovative use of molecular simulations to identify bioactive ingredients and their incorporation into microneedles for promoting wound healing through multiple synergistic mechanisms.

A microenvironment-modulating dressing with proliferative degradants for the healing of diabetic wounds

Diabetic wounds are usually entangled in a disorganized and self-perpetuating microenvironment and accompanied by a prolonged delay in tissue repair. Sustained and coordinated microenvironment regulation and tissue regeneration are key to the healing process of diabetic wounds, yet they continue to pose a formidable challenge. Here we report a rational double-layered dressing design based on chitosan and a degradable conjugated polymer polydiacetylene, poly(deca-4,6-diynedioic acid) (PDDA), that can meet this intricate requirement. With an alternating ene-yne backbone, PDDA degrades when reacting with various types of reactive oxygen species (ROS), and more importantly, generates proliferative succinic acid as a major degradant. Inheriting from PDDA, the developed PDDA-chitosan double layer dressing (PCD) can eliminate ROS in the microenvironment of diabetic wounds, alleviate inflammation, and downregulate gene expression of innate immune receptors. PCD degradation also triggers simultaneous release of succinic acid in a sustainable manner, enabling long-term promotion on tissue regeneration. We have validated the biocompatibility and excellent performance of PCD in expediting the wound healing on both diabetic mouse and porcine models, which underscores the significant translational potential of this microenvironment-modulating, growth-promoting wound dressing in diabetic wounds care.

Recent Advances in Degradable Biomedical Polymers for Prevention, Diagnosis and Treatment of Diseases

Biomedical polymers play a key role in preventing, diagnosing, and treating diseases, showcasing a wide range of applications. Their unique advantages, such as rich source, good biocompatibility, and excellent modifiability, make them ideal biomaterials for drug delivery, biomedical imaging, and tissue engineering. However, conventional biomedical polymers suffer from poor degradation in vivo, increasing the risks of bioaccumulation and potential toxicity. To address these issues, degradable biomedical polymers can serve as an alternative strategy in biomedicine. Degradable biomedical polymers can efficiently relieve bioaccumulation in vivo and effectively reduce patient burden in disease management. This review comprehensively introduces the classification and properties of biomedical polymers and the recent research progress of degradable biomedical polymers in various diseases. Through an in-depth analysis of their classification, properties, and applications, we aim to provide strong guidance for promoting basic research and clinical translation of degradable biomedical polymers.

High strength "breathable" glycosilicone/Aloe vera polysaccharide-based gel dressing for efficient wound repair

Medical wound dressings are effective in protecting wounds, maintaining moisture, creating an optimal healing environment and accelerating wound healing. However, their deficiencies in mechanical properties, adhesion and prevention of adhesion to the wound bed have been identified as limiting factors for their therapeutic efficacy in wound healing. To address these issues, we prepared glycosilicone gel dressings consisting of hydrophobic polysiloxanes and highly hydrophilic polysaccharides via ester exchange and silicone hydrogen addition reactions. Silicone gel dressings exhibit skin-like "respiratory" properties, with good permeability to O2 and CO2. Additionally, elongation and other important parameters are similar to those of the skin, which provides a foundation for the application of silicone gels in the field of wound dressings. The introduction of Aloe vera polysaccharide (AP) results in the glycosilicone gel exhibiting certain mechanical properties, including a tensile strength of 0.35 MPa and an adhesion force of 10 N/m. Furthermore, a mouse model of total skin defect demonstrated that the wound healing rate of the mice on the 12th day was 98 %, which effectively promotes wound healing. Consequently, the glycosilicone gel is anticipated to be an optimal wound dressing.

Light-activated nanoclusters with tunable ROS for wound infection treatment

Infected wounds pose a significant clinical challenge due to bacterial resistance, recurrent infections, and impaired healing. Reactive oxygen species (ROS)-based strategies have shown promise in eradicating bacterial infections. However, the excess ROS in the infection site after treatments may cause irreversible damage to healthy tissues. To address this issue, we developed bovine serum albumin-iridium oxide nanoclusters (BSA-IrOx NCs) which enable photo-regulated ROS generation and scavenging using near infrared (NIR) laser. Upon NIR laser irradiation, BSA-IrOx NCs exhibit enhanced photodynamic therapy, destroying biofilms and killing bacteria. When the NIR laser is off, the nanoclusters' antioxidant enzyme-like activities prevent inflammation and repair damaged tissue through ROS clearance. Transcriptomic and metabolomic analyses revealed that BSA-IrOx NCs inhibit bacterial nitric oxide synthase, blocking bacterial growth and biofilm formation. Furthermore, the nanoclusters repair impaired skin by strengthening cell junctions and reducing mitochondrial damage in a fibroblast model. In vivo studies using rat infected wound models confirmed the efficacy of BSA-IrOx NCs. This study presents a promising strategy for treating biofilm-induced infected wounds by regulating the ROS microenvironment, addressing the challenges associated with current ROS-based antibacterial approaches.

ECM-mimetic glucomannan hydrogel promotes pressure ulcer healing by scavenging ROS, promoting angiogenesis and regulating macrophages

Pressure ulcers (PUs) have emerged as a significant burden on both individuals and society. Effective treatment of PUs is a significant clinical challenge due to the compromised tissue microenvironment characterized by extracellular matrix (ECM) depletion, increased levels of reactive oxygen species (ROS), excessive inflammation and impaired angiogenesis. To this end, we have developed a glucomannan hydrogel (GM-Pgel) that mimics the skin's extracellular matrix to accelerate wound healing by regulating chronic inflammation in the PUs. This hydrogel not only faithfully replicates the components and nanofibrous architecture of ECM-like glycoproteins but also exhibits remarkable capabilities in enhancing neovascularization, scavenging ROS, and promoting macrophage polarization toward the M2 phenotype. In summary, this ECM-mimetic multifunctional hydrogel emerges as a promising dressing with diverse functionalities, capable of reshaping the compromised tissue environment without the need for additional drugs, exogenous cytokines, or cells. This presents a compelling and effective strategy for the repair and regeneration of chronic cutaneous 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.

Photo-crosslinking methacrylated-amylopectin/polyacrylamide hydrogels loading curcumin for applications as degradable, injectable, and antibacterial wound dressings

The preparation of biodegradable and antibacterial hydrogels has important clinical value. In this work, a novel strategy has been developed to prepare degradable hydrogel dressings without chemical crosslinking agent using methacrylate anhydride (MA)-modified amylopectin (APMA) and polyacrylamide (PAM). After introducing CC bonds, APMA/PAM hydrogels can be formed under light irradiation. This strategy improves the gelling ability of AP and degradation properties of the hydrogel by avoiding the addition of crosslinking agent. The degradation rate of APMA/PAM hydrogel is 74.04 ± 0.69 % within 12 weeks, while that of APMA/PAM hydrogel containing crosslinking agent is only 38.5 ± 0.1 %. The APMA/PAM hydrogel loading curcumin (Cur) (APMA/PAM-Cur) exhibits high antibacterial efficiency of 98.29 ± 0.41 % and 97.18 ± 0.81 % against S. aureus and E. coli, respectively, with light irradiation. Animal experiments show that the APMA/PAM-Cur hydrogel reduces the infiltration of inflammatory factors, increases the density of collagen, and makes the newly formed granulation tissue thicker and tighter. This study not only proves the promising potential of the APMA/PAM-Cur hydrogel as degradable and antibacterial wound dressing for clinical treatment, but also provides a new strategy for developing low-cost, degradable, and antibacterial wound dressings and reducing antibiotic abuse and environmental pollution caused by medical waste.

Bioresponsive Immunotherapeutic Materials

The human immune system is an interaction network of biological processes, and its dysfunction is closely associated with a wide array of diseases, such as cancer, infectious diseases, tissue damage, and autoimmune diseases. Manipulation of the immune response network in a desired and controlled fashion has been regarded as a promising strategy for maximizing immunotherapeutic efficacy and minimizing side effects. Integration of "smart" bioresponsive materials with immunoactive agents including small molecules, biomacromolecules, and cells can achieve on-demand release of agents at targeted sites to reduce overdose-related toxicity and alleviate off-target effects. This review highlights the design principles of bioresponsive immunotherapeutic materials and discusses the critical roles of controlled release of immunoactive agents from bioresponsive materials in recruiting, housing, and manipulating immune cells for evoking desired immune responses. Challenges and future directions from the perspective of clinical translation are also discussed.

Calcium‐dependent antimicrobials: Nature‐inspired materials and designs

Bacterial infection remains a major complication answering for the failures of various implantable medical devices. Tremendous extraordinary advances have been published in the design and synthesis of antimicrobial materials addressing this issue; however, the clinical translation has largely been blocked due to the challenge of balancing the efficacy and safety of these materials. Here, calcium's biochemical features, natural roles in pathogens and the immune systems, and advanced uses in infection medications are illuminated, showing calcium is a promising target for developing implantable devices with less infection tendency. The paper gives a historical overview of biomedical uses of calcium and summarizes calcium's merits in coordination, hydration, ionization, and stereochemistry for acting as a structural former or trigger in biological systems. It focuses on the involvement of calcium in pathogens' integrity, motility, and metabolism maintenance, outlining the potential antimicrobial targets for calcium. It addresses calcium's uses in the immune systems that the authors can learn from for antimicrobial synthesis. Additionally, the advances in calcium's uses in infection medications are highlighted to sketch the future directions for developing implantable antimicrobial materials. In conclusion, calcium is at the nexus of antimicrobial defense, and future works on taking advantage of calcium in antimicrobial developments are promising in clinical translation.

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.

Polysaccharide- and protein-based hydrogel dressings that enhance wound healing: A review

Hydrogels can possess desired biochemical and mechanical properties, excellent biocompatibility, satisfactory biodegradability, and biological capabilities that promote skin repair, making them ideal candidates for skin healing dressings. Polysaccharides, such as chitosan, hyaluronic acid and sodium alginate as well as proteins, including gelatin, collagen and fibroin proteins, are biological macromolecules celebrated for their biocompatibility and biodegradability, are at the forefront of innovative hydrogel dressing development. This work first summarizes the skin wound healing process and its influencing factors, and then systematically articulates the multifunctional roles of hydrogels based on biological macromolecules (polysaccharides and proteins) as dressing in addressing bacterial infection, hemorrhage and inflammation during wound healing. Furthermore, this review explores the potential of these hydrogels as vehicles for combination therapy, by incorporating growth factors or stem cells. Finally, the article offers insights into future directions of such hydrogels in wound repair field.

A Bilayer Polyurethane Patch with Sustained Growth Factor Release and Antibacteria for Re-epithelization of Large-Scale Oral Mucosal Defects

In the field of oral and maxillofacial surgery, extensive oral soft-tissue injuries occur repeatedly in clinical practice; however, effective restorative materials are lacking. In this study, a biodegradable waterborne polyurethane patch featuring a mucosa bionic bilayer structure is presented. This patch consists of a porous scaffold layer that faces the lesion, incorporating a polydopamine coating to achieve sustained release of epidermal growth factors (EGFs) for mucosal defect reconstruction. Additionally, there is a dense barrier layer toward the oral cavity loaded with silver nanoparticles, which prevents bacteria from entering the wound and simultaneously acts as a physical barrier. This patch can sustainably release EGF in vitro for 2 weeks, thereby facilitating the proliferation and migration of HaCaT and L929 cells, while effectively killing common oral cavity bacteria. In a rabbit buccal mucosal full-thickness defect model, the patch demonstrates better efficacy than the clinical benchmark, decellularized extracellular matrix (dECM). It effectively reduces wound inflammation and significantly upregulates gene expression associated with epithelialization by activating the EGF/epidermal growth factor receptor (EGFR) pathway. These mechanisms promote the proliferation, differentiation, and migration of epithelial/keratinocyte cells, ultimately expediting mucosal defect healing and wound closure.

Electrospun collagen/chitosan composite fibrous membranes for accelerating wound healing

The protein-polysaccharide nanofibers have attracted intensive attention in promoting wound healing, due to their components and nanoscale fibrous structure that mimics the native extracellular matrix (ECM). For the full-thickness wounds, in addition to promoting healing, hemostatic property and antibacterial activity are also of critical importance. However, currently, protein-polysaccharide-based nanofiber membranes exhibit poor mechanical properties, lack inherent hemostatic and antibacterial capabilities, as well as the ability to promote tissue repair. In this study, we developed composited membranes, which were composed of collagen (Col) and chitosan (Chs), through solvent alteration and post-processing, the membranes showed enhanced stability under physiological conditions, proper hydrophilic performance and improved mechanical property. Appropriated porosity and water vapor transmission rate, which benefit to wound healing, were detected among all the membranes except for Col membrane. Aimed at wound dressing, hemocompatibility, antibacterial activity and cell proliferation of the electrospun membranes were evaluated. The results indicated that the Col/Chs composited membranes exhibited superior blood clotting capacity, and the membranes with Chs exceeding 60% possessed sufficient antibacterial activity. Moreover, compared with Chs nanofibers, significant increase in cell grow was detected in Col/Chs (1:3) membrane. Taken together, the electrospun membrane with multiple properties favorable to wound healing, superior blood coagulation, sufficient antibacterial performance and promoting cell proliferation property make it favorable candidate for full-thickness skin wound healing.

Acetal-thiol Click-like Reaction: Facile and Efficient Synthesis of Dynamic Dithioacetals and Recyclable Polydithioacetals

Dithioacetals are heavily used in organic, material and medical chemistries, and exhibit huge potential to synthesize degradable or recyclable polymers. However, the current synthetic approaches of dithioacetals and polydithioacetals are overwhelmingly dependent on external catalysts and organic solvents. Herein, we disclose a catalyst- and solvent-free acetal-thiol click-like reaction for synthesizing dithioacetals and polydithioacetals. High conversion, higher than acid catalytic acetal-thiol reaction, can be achieved. High universality was confirmed by monitoring the reactions of linear and cyclic acetals (including renewable bio-sourced furan-acetal) with aliphatic and aromatic thiols, and the reaction mechanism of monomolecular nucleophilic substitution (SN1) and auto-protonation (activation) by thiol was clarified by combining experiments and density functional theory computation. Subsequently, we utilize this reaction to synthesize readily recyclable polydithioacetals. By simple heating and stirring, linear polydithioacetals withM ‾ ${\bar M}$ w of ~110 kDa were synthesized from acetal and dithiol, and depolymerization into macrocyclic dithioacetal and repolymerization into polydithioacetal can be achieved; through reactive extrusion, a semi-interpenetrating polymer dynamic network with excellent mechanical properties and continuous reprocessability was prepared from poly(vinyl butyral) and pentaerythritol tetrakis(3-mercaptopropionate). This green and high-efficient synthesis method for dithioacetals and polydithioacetals is beneficial to the sustainable development of chemistry.

Recent trends in 3D bioprinting technology for skeletal muscle regeneration

Skeletal muscle is a pro-regenerative tissue, that utilizes a tissue-resident stem cell system to effect repair upon injury. Despite the demonstrated efficiency of this system in restoring muscle mass after many acute injuries, in conditions of severe trauma such as those evident in volumetric muscle loss (VML) (>20 % by mass), this self-repair capability is unable to restore tissue architecture, requiring interventions which currently are largely surgical. As a possible alternative, the generation of artificial muscle using tissue engineering approaches may also be of importance in the treatment of VML and muscle diseases such as dystrophies. Three-dimensional (3D) bioprinting has been identified as a promising technique for regeneration of the complex architecture of skeletal muscle. This review discusses existing treatment strategies following muscle damage, recent progress in bioprinting techniques, the bioinks used for muscle regeneration, the immunogenicity of scaffold materials, and in vitro and in vivo maturation techniques for 3D bio-printed muscle constructs. The pros and cons of these bioink formulations are also highlighted. Finally, we present the current limitations and challenges in the field and critical factors to consider for bioprinting approaches to become more translationa and to produce clinically relevant engineered muscle. STATEMENT OF SIGNIFICANCE: This review discusses the physiopathology of muscle injuries and existing clinical treatment strategies for muscle damage, the types of bioprinting techniques that have been applied to bioprinting of muscle, and the bioinks commonly used for muscle regeneration. The pros and cons of these bioinks are highlighted. We present a discussion of existing gaps in the literature and critical factors to consider for the translation of bioprinting approaches and to produce clinically relevant engineered muscle. Finally, we provide insights into what we believe will be the next steps required before the realization of the application of tissue-engineered muscle in humans. We believe this manuscript is an insightful, timely, and instructive review that will guide future muscle bioprinting research from a fundamental construct creation approach, down a translational pathway to achieve the desired impact in the clinic.

Recent advances on thermosensitive hydrogels-mediated precision therapy

Precision therapy has become the preferred choice attributed to the optimal drug concentration in target sites, increased therapeutic efficacy, and reduced adverse effects. Over the past few years, sprayable or injectable thermosensitive hydrogels have exhibited high therapeutic potential. These can be applied as cell-growing scaffolds or drug-releasing reservoirs by simply mixing in a free-flowing sol phase at room temperature. Inspired by their unique properties, thermosensitive hydrogels have been widely applied as drug delivery and treatment platforms for precision medicine. In this review, the state-of-the-art developments in thermosensitive hydrogels for precision therapy are investigated, which covers from the thermo-gelling mechanisms and main components to biomedical applications, including wound healing, anti-tumor activity, osteogenesis, and periodontal, sinonasal and ophthalmic diseases. The most promising applications and trends of thermosensitive hydrogels for precision therapy are also discussed in light of their unique features.

Turning Polysaccharides into Injectable and Rapid Self-Healing Antibacterial Hydrogels for Antibacterial Treatment and Bacterial-Infected Wound Healing

Great efforts have been devoted to the development of novel and multifunctional wound dressing materials to meet the different needs of wound healing. Herein, we covalently grafted quaternary ammonium groups (QAGs) containing 12-carbon straight-chain alkanes to the dextran polymer skeleton. We then oxidized the resulting product into oxidized quaternized dextran (OQD). The obtained OQD polymer is rich in antibacterial QAGs and aldehyde groups. It can react with glycol chitosan (GC) via the Schiff-base reaction to form a multifunctional GC@OQD hydrogel with good self-healing behavior, hemostasis, injectability, inherent superior antibacterial activity, biocompatibility, and excellent promotion of healing of methicillin-resistant Staphylococcus aureus (MRSA)-infected wounds. The biosafe and nontoxic GC@OQD hydrogel with a three-dimensional porous network structure possesses an excellent swelling rate and water retention capacity. It can be used for hemostasis and treating irregular wounds. The designed GC@OQD hydrogel with inherent antibacterial activity possesses good antibacterial efficacy on both S. aureus (Gram-positive bacteria) and Escherichia coli (Gram-negative bacteria), as well as MRSA bacteria, with antibacterial activity greater than 99%. It can be used for the treatment of wounds infected by MRSA and significantly promotes the healing of wounds. Thus, the multifunctional antibacterial GC@OQD hydrogel has the potential to be applied in clinical practice as a wound dressing.

Degradable biomedical elastomers: paving the future of tissue repair and regenerative medicine

Degradable biomedical elastomers (DBE), characterized by controlled biodegradability, excellent biocompatibility, tailored elasticity, and favorable network design and processability, have become indispensable in tissue repair. This review critically examines the recent advances of biodegradable elastomers for tissue repair, focusing mainly on degradation mechanisms and evaluation, synthesis and crosslinking methods, microstructure design, processing techniques, and tissue repair applications. The review explores the material composition and cross-linking methods of elastomers used in tissue repair, addressing chemistry-related challenges and structural design considerations. In addition, this review focuses on the processing methods of two- and three-dimensional structures of elastomers, and systematically discusses the contribution of processing methods such as solvent casting, electrostatic spinning, and three-/four-dimensional printing of DBE. Furthermore, we describe recent advances in tissue repair using DBE, and include advances achieved in regenerating different tissues, including nerves, tendons, muscle, cardiac, and bone, highlighting their efficacy and versatility. The review concludes by discussing the current challenges in material selection, biodegradation, bioactivation, and manufacturing in tissue repair, and suggests future research directions. This concise yet comprehensive analysis aims to provide valuable insights and technical guidance for advances in DBE for tissue engineering.

A controlled light-induced gas-foaming porous hydrogel with adhesion property for infected wound healing

Porous hydrogels as scaffolds have great potential in tissue engineering. However, there are still challenges in preparing porous hydrogels with tunable pore size and controlled porosity. Here, we successfully established a photoinduced gas-foaming method of porous hydrogels with controlled macro-micro-nano multiscale. A diazirine (DZ)-modified gelatin (GelDZ) biomaterial was prepared by introducing photocrosslinked DZ group into gelatin. Upon exposure to 365 nm UV light, DZ could be converted to the active group carbene, which could randomly insert into OH, NH, or CH bonds to form covalent crosslinks. GelDZ generated N2 by photodegradation and formed gas-induced porous hydrogels by intermolecular crosslinking without initiator. The loose porous structure of the hydrogel can promote the infiltration of host cells and blood vessels, which was conducive to tissue repair. The interfacial crosslinking of photoactivated GelDZ with tissue proteins imparted adhesion properties to the hydrogel. GelDZ also possessed photoreduction ability, which can reduce silver ions from metal precursors to silver nanoparticles (Ag NPs) in situ, and showed great antibacterial activity due to the sustained release of Ag NPs. GelDZ-Ag NPs prepared by in situ photoreaction can effectively inhibit wound infection and promote skin wound healing, providing a new strategy for designing porous hydrogel in tissue engineering.

Self-assembly of PEG-PPS polymers and LL-37 peptide nanomicelles improves the oxidative microenvironment and promotes angiogenesis to facilitate chronic wound healing

Refractory diabetic wounds are associated with high incidence, mortality, and recurrence rates and are a devastating and rapidly growing clinical problem. However, treating these wounds is difficult owing to uncontrolled inflammatory microenvironments and defective angiogenesis in the affected areas, with no established effective treatment to the best of our knowledge. Herein, we optimized a dual functional therapeutic agent based on the assembly of LL-37 peptides and diblock copolymer poly(ethylene glycol)-poly(propylene sulfide) (PEG-PPS). The incorporation of PEG-PPS enabled responsive or controlled LL-37 peptide release in the presence of reactive oxygen species (ROS). LL-37@PEG-PPS nanomicelles not only scavenged excessive ROS to improve the microenvironment for angiogenesis but also released LL-37 peptides and protected them from degradation, thereby robustly increasing angiogenesis. Diabetic wounds treated with LL-37@PEG-PPS exhibited accelerated and high-quality wound healing in vivo. This study shows that LL-37@PEG-PPS can restore beneficial angiogenesis in the wound microenvironment by continuously providing angiogenesis-promoting signals. Thus, it may be a promising drug for improving chronic refractory wound healing.

Overcoming the Dilemma of In Vivo Stable Adhesion and Sustained Degradation by the Molecular Design of Polyurethane Adhesives for Bone Fracture Repair

Bone adhesive is a promising candidate to revolutionize the clinical treatment of bone repairs. However, several drawbacks have limited its further clinical application, such as unreliable wet adhesive performance leading to fixation failure and poor biodegradability inhibiting bone tissue growth. By incorporating catechol groups and disulfide bonds into polyurethane (PU) molecules, an injectable and porous PU adhesive is developed with both superior wet adhesion and biodegradability to facilitate the reduction and fixation of comminuted fractures and the subsequent regeneration of bone tissue. The bone adhesive can be cured within a reasonable time acceptable to a surgeon, and then the wet bone adhesive strength is near 1.30 MPa in 1 h. Finally, the wet adhesive strength to the cortical bone will achieve about 1.70 MPa, which is also five times more than nonresorbable poly(methyl methacrylate) bone cement. Besides, the cell culture experiments also indicate that the adhesives show excellent biocompatibility and osteogenic ability in vitro. Especially, it can degrade in vivo gradually and promote fracture healing in the rabbit iliac fracture model. These results demonstrate that this ingenious bone adhesive exhibits great potential in the treatment of comminuted fractures, providing fresh insights into the development of clinically applicable bone adhesives.

Neutrophil Function Conversion Driven by Immune Switchpoint Regulator against Diabetes-Related Biofilm Infections

Reinforced biofilm structures and dysfunctional neutrophils induced by excessive oxidative stress contribute to the refractoriness of diabetes-related biofilm infections (DRBIs). Herein, in contrast to traditional antibacterial therapies, an immune switchpoint-driven neutrophil immune function conversion strategy based on a deoxyribonuclease I loaded vanadium carbide MXene (DNase-I@V2 C) nanoregulator is proposed to treat DRBIs via biofilm lysis and redirecting neutrophil functions from NETosis to phagocytosis in diabetes. Owing to its intrinsic superoxide dismutase/catalase-like activities, DNase-I@V2 C effectively scavenges reactive oxygen species (ROS) in a high oxidative stress microenvironment to maintain the biological activity of DNase-I. By increasing the depth of biofilm penetration of DNase-I, DNase-I@V2 C thoroughly degrades extracellular DNA and neutrophil extracellular traps (NETs) in extracellular polymeric substances, thus breaking the physical barrier of biofilms. More importantly, as an immune switchpoint regulator, DNase-I@V2 C can skew neutrophil functions from NETosis toward phagocytosis by intercepting ROS-NE/MPO-PAD4 and activating ROS-PI3K-AKT-mTOR pathways in diabetic microenvironment, thereby eliminating biofilm infections. Biofilm lysis and synergistic neutrophil function conversion exert favorable therapeutic effects on biofilm infections in vitro and in vivo. This study serves as a proof-of-principle demonstration of effectively achieving DRBIs with high therapeutic efficacy by regulating immune switchpoint to reverse neutrophil functions.

Metal-Organic Frameworks and Their Composites for Chronic Wound Healing: From Bench to Bedside

Chronic wounds are characterized by delayed and dysregulated healing processes. As such, they have emerged as an increasingly significant threat. The associated morbidity and socioeconomic toll are clinically and financially challenging, necessitating novel approaches in the management of chronic wounds. Metal-organic frameworks (MOFs) are an innovative type of porous coordination polymers, with low toxicity and high eco-friendliness. Documented anti-bacterial effects and pro-angiogenic activity predestine these nanomaterials as promising systems for the treatment of chronic wounds. In this context, the therapeutic applicability and efficacy of MOFs remain to be elucidated. It is, therefore, reviewed the structural-functional properties of MOFs and their composite materials and discusses how their multifunctionality and customizability can be leveraged as a clinical therapy for chronic wounds.

Mechano-Activated Cell Therapy for Accelerated Diabetic Wound Healing

Chronic diabetic wounds are a significant global healthcare challenge. Current strategies, such as biomaterials, cell therapies, and medical devices, however, only target a few pathological features and have limited efficacy. A powerful platform technology combining magneto-responsive hydrogel, cells, and wireless magneto-induced dynamic mechanical stimulation (MDMS) is developed to accelerate diabetic wound healing. The hydrogel encapsulates U.S. Food and Drug Administration (FDA)-approved fibroblasts and keratinocytes to achieve ∼3-fold better wound closure in a diabetic mouse model. MDMS acts as a nongenetic mechano-rheostat to activate fibroblasts, resulting in ∼240% better proliferation, ∼220% more collagen deposition, and improved keratinocyte paracrine profiles via the Ras/MEK/ERK pathway to boost angiogenesis. The magneto-responsive property also enables on-demand insulin release for spatiotemporal glucose regulation through increasing network deformation and interstitial flow. By mining scRNAseq data, a mechanosensitive fibroblast subpopulation is identified that can be mechanically tuned for enhanced proliferation and collagen production, maximizing therapeutic impact. The "all-in-one" system addresses major pathological factors associated with diabetic wounds in a single platform, with potential applications for other challenging wound types.

An Immunomodulatory Hydrogel by Hyperthermia-Assisted Self-Cascade Glucose Depletion and ROS Scavenging for Diabetic Foot Ulcer Wound Therapeutics

Current therapeutic protocols for diabetic foot ulcers (DFUs), a severe and rapidly growing chronic complication in diabetic patients, remain nonspecific. Hyperglycemia-caused inflammation and excessive reactive oxygen species (ROS) are common obstacles encountered in DFU wound healing, often leading to impaired recovery. These two effects reinforce each other, forming an endless loop. However, adequate and inclusive methods are still lacking to target these two aspects and break the vicious cycle. This study proposes a novel approach for treating DFU wounds, utilizing an immunomodulatory hydrogel to achieve self-cascade glucose depletion and ROS scavenging to regulate the diabetic microenvironment. Specifically, AuPt@melanin-incorporated (GHM3) hydrogel dressing is developed to facilitate efficient hyperthermia-enhanced local glucose depletion and ROS scavenging. Mechanistically, in vitro/vivo experiments and RNA sequencing analysis demonstrate that GHM3 disrupts the ROS-inflammation cascade cycle and downregulates the ratio of M1/M2 macrophages, consequently improving the therapeutic outcomes for dorsal skin and DFU wounds in diabetic rats. In conclusion, this proposed approach offers a facile, safe, and highly efficient treatment modality for DFUs.

Treatment of superficial and deep partial width second degree burn's wound with allogeneic cord blood platelet gel

BACKGROUND

Burns are caused by a variety of mechanisms, including flames, hot liquids, metallurgy, chemicals, electric current, and ionizing and non-ionizing radiation. The most significant burn wound management involves complete repair and regeneration as soon as possible while minimizing infection, contraction, and scarring in the damaged tissue area. Some factors such as delivery of nutrients, growth factors, and oxygen are essential to promote and stimulate the wound healing progress in the burns area. When these factors are not provided, the burn wound undergoes a physiological crisis. The use of growth factors is a promising approach to overcoming this limitation. Umbilical cord blood platelet concentrates are a rich natural source of growth factors.

METHODS

This clinical trial used growth factors released from the lysis of umbilical cord blood platelet concentrates that have a key role in promoting re-epithelization and regeneration of damaged tissues by forming a fibrin network. This study evaluated the effectiveness of allogeneic cord blood platelet gel topical dressing in a group of patients diagnosed with superficial and deep partial thickness (second-degree) burn wounds. Clinical outcomes were compared between the intervention group and a control group of patients with superficial second-degree burn wounds who received the standard routine treatment including paraffin gauze wound dressing and silver sulfadiazine ointment.

RESULTS

The study's results showed that the increased rate of recovery and tissue granulation completely promoted to wound healing and burn wound closure, decreased the recovery time, and reduced inflammation and scars caused by burn injuries. However, the use of cord blood platelet gel topical dressing is not currently a routine treatment method in patients suffering from burn wounds. However, the study's results showed that allogenic cord blood platelet gel could be used to treat superficial and deep second-degree burns as a routine treatment. It was also shown that allogenic cord blood platelet gel topical dressing could be a candidate for autograft or after autograft skin transplantation surgery (in donor and recipient sites) instead of skin surgery in some patients.

CONCLUSION

Allogeneic topical wound dressing provides an effective treatment that offers a faster rate of epithelialization and healing of wounds and also decreases patients' scar and inflammation level as well as the length of recovery time. This, finally, leads to better burn wound management and the improved quality of burn wound treatment.

Harnessing exosomes as cutting-edge drug delivery systems for revolutionary osteoarthritis therapy

Exosomes, remarkable extracellular vesicles, have emerged as an advanced frontier in intercellular communication. This remarkable capacity positions them as promising contenders in drug delivery systems (DDSs) for osteoarthritis (OA) therapy, capitalizing on their inherent biocompatibility, stability, and minimal immunogenicity. In this comprehensive review, we summarize the emerging developments surrounding exosome-based DDSs for OA therapy. Focusing on exosome origins, we meticulously explore the diverse sources contributing to their production, including invaluable stem cells, immune cells, and an array of other cell types. In addition, we unravel the underlying mechanisms of action that govern these exosome-borne therapeutics, illuminating the intricate interplay between exosomes and recipient cells. In summary, this review highlights the present challenges that permeate exosome-based DDSs for OA therapy. Through an in-depth exploration of the intricacies within this emerging field, this review aims to shed light on the future direction of exosome-based DDSs in OA. It serves as a bridge for fostering collaboration and collective efforts in reshaping the treatment landscape of OA.

Incorporating the Antioxidant Fullerenol into Calcium Phosphate Bone Cements Increases Cellular Osteogenesis without Compromising Physical Cement Characteristics

Herein, fullerenol (Ful), a highly water-soluble derivative of C60 fullerene with demonstrated antioxidant activity, is incorporated into calcium phosphate cements (CPCs) to enhance their osteogenic ability. CPCs with added carboxymethyl cellulose/gelatin (CMC/Gel) are doped with biocompatible Ful particles at concentrations of 0.02, 0.04, and 0.1 wt v%-1 and evaluated for Ful-mediated mechanical performance, antioxidant activity, and in vitro cellular osteogenesis. CMC/gel cements with the highest Ful concentration decrease setting times due to increased hydrogen bonding from Ful's hydroxyl groups. In vitro studies of reactive oxygen species (ROS) scavenging with CMC/gel cements demonstrate potent antioxidant activity with Ful incorporation and cement scavenging capacity is highest for 0.02 and 0.04 wt v%-1 Ful. In vitro cytotoxicity studies reveal that 0.02 and 0.04 wt v%-1 Ful cements also protect cellular viability. Finally, increase of alkaline phosphatase (ALP) activity and expression of runt-related transcription factor 2 (Runx2) in MC3T3-E1 pre-osteoblast cells treated with low-dose Ful cements demonstrate Ful-mediated osteogenic differentiation. These results strongly indicate that the osteogenic abilities of Ful-loaded cements are correlated with their antioxidant activity levels. Overall, this study demonstrates exciting potential of Fullerenol as an antioxidant and proosteogenic additive for improving the performance of calcium phosphate cements in bone reconstruction procedures.

Hyaluronic acid-based dual network hydrogel with sustained release of platelet-rich plasma as a diabetic wound dressing

In recent years, the incidence of diabetic skin ulcers has increased. Because of its extremely high disability and fatality rate, it brings a huge burden to patients and society. Platelet-rich plasma (PRP) contains a large number of biologically active substances and is of great clinical value in the treatment of various wounds. However, its weak mechanical properties and the consequent abrupt release of active substances greatly limit its clinical application and therapeutic efficacy. Here, we chose hyaluronic acid (HA) and ε-polylysine (ε-PLL) to prepare a hydrogel with the ability to prevent wound infection and promote tissue regeneration. At the same time, using the macropore barrier effect of the lyophilized hydrogel scaffold, platelets in PRP are activated with calcium gluconate in the macropores of the scaffold carrier, and fibrinogen from PRP is converted in a fibrin-packed network forming a gel that interpenetrates the hydrogel scaffold carrier, thus creating a double network hydrogel with slow-release of growth factors from degranulated platelets. The hydrogel not only showed better performance in functional assays in vitro, but also showed more superior therapeutic effects in reducing inflammatory response, promoting collagen deposition, facilitating re-epithelialization and angiogenesis in the treatment of full skin defects in diabetic rats.

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

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

Design matters: A comparison of natural versus synthetic skin substitutes across benchtop and porcine wound healing metrics: An experimental study

Background and Aims

Skin substitutes, essential tools for helping close full thickness wounds with minimal scarring, are available in both collagen-based and synthetic polyurethane constructions. Here we explore fundamental differences between two frequently used skin substitutes and discuss how these differences may impact in vivo performance.

Methods

Polyurethane- and collagen-based matrices were characterized in vitro for pore size via scanning electron microscopy, hydrophobicity via liquid contact angle, conformability via bending angle, and biocompatibility via fibroblast and keratinocyte adhesion and proliferation. These matrices were then evaluated in a full-thickness excisional pig wound study followed by histological analysis. Statistical analysis was performed using t-tests or one-way analysis of variances with Tukey's multiple post hoc comparisons, where appropriate.

Results

Average pore diameter in the tested polyurethane matrix was over four times larger than that of the collagen matrix (589 ± 297 µm vs. 132 ± 91 µm). Through liquid contact angle measurement, the collagen matrix (not measurable) was found to be hydrophilic compared to the hydrophobic polyurethane matrix (>90°). The collagen matrix was significantly more conformable than the polyurethane matrix (9 ± 2° vs. 84 ± 5° bending angle, respectively). Fibroblast and keratinocyte adhesion and proliferation assays elucidated a significantly greater ability of both cell types to attach and proliferate on collagen versus polyurethane. While the porcine study showed minimal contraction of either matrix material, histological findings between the two treatments were markedly different. Collagen matrices were associated with early fibroblast infiltration and fibroplasia, whereas polyurethane matrices elicited a strong multinucleated giant cell response and produced a network of comparatively aligned collagen fibrils.

Conclusions

The more favorable in vitro properties of the collagen matrix led to less inflammation and better overall tissue response in vivo. Overall, our findings demonstrate how the choice of biomaterial and its design directly translate to differing in vivo mechanisms of action and overall tissue quality.

ROS scavenging and immunoregulative EGCG@Cerium complex loaded in antibacterial polyethylene glycol-chitosan hydrogel dressing for skin wound healing

The elevation of oxidative stress and inflammatory response after injury remains a substantial challenge that can deteriorate the wound microenvironment and compromise the success of wound healing. Herein, the assembly of naturally derived epigallocatechin-3-gallate (EGCG) and Cerium microscale complex (EGCG@Ce) was prepared as reactive oxygen species (ROS) scavenger, which was further loaded in antibacterial hydrogels as wound dressing. EGCG@Ce shows superior antioxidation capacity towards various ROS including free radical, O2- and H2O2 through superoxide dismutase-like or catalase-mimicking catalytic activity. Importantly, EGCG@Ce could provide mitochondrial protective effect against oxidative stress damages, reverse the polarization of M1 macrophages and reduce the secretion of pro-inflammatory cytokines. Furtherly, EGCG@Ce was loaded into the PEG-chitosan hydrogel with dynamic, porous, injectable and antibacterial properties as wound dressing, which accelerated the regeneration of both epidermal layer and dermis, resulting in improved healing process of full-thickness skin wounds in vivo. Mechanistically, EGCG@Ce re-shaped the detrimental tissue microenvironment and augmented the pro-reparative response through reducing ROS accumulation, alleviating inflammatory response, enhancing the M2 macrophage polarization and angiogenesis. Collectively, antioxidative and immunomodulatory metal-organic complex-loaded hydrogel is a promising multifunctional dressing for the repair and regeneration of cutaneous wounds without additional drugs, exogenous cytokines, or cells. STATEMENT OF SIGNIFICANCE: (1) We reported an effective antioxidant through self-assembly coordination of EGCG and Cerium for managing the inflammatory microenvironment at the wound site, which not only showed high catalytic capacity towards multiple ROS, but also could provide mitochondrial protective effect against oxidative stress damage, reverse the polarization of M1 macrophages and downregulate pro-inflammatory cytokines. EGCG@Ce was further loaded into porous and bactericidal PEG-chitosan (PEG-CS) hydrogel as a versatile wound dressing, which accelerated wound healing and angiogenesis. (2) The applicability of alleviating sustainable inflammation and regulating macrophage polarization through ROS scavenging is a promising strategy for tissue repair and regeneration without additional drugs, cytokines, or cells.