An injectable and adaptable hydrogen sulfide delivery system for modulating neuroregenerative microenvironment

Vacancies-rich Z-scheme VdW heterojunction as H2S-sensitized synergistic therapeutic nanoplatform against refractory biofilm infections

Encapsulated in a self-produced negatively charged extracellular polymeric substance (EPS) matrix, the wound infected bacterial biofilms exhibit formidable resistance to conventional positively charged antibiotics and host's immune responses, which can undoubtedly lead to persistent infections and lethal complications. Nevertheless, developing efficacious strategies to root out stubborn biofilm and promote tissue regeneration still remains a challenge. To resolve this dilemma, a versatile vacancies-rich Z-scheme MoSSe Van der Waals heterojunction (MoSSe VdW HJ) is rationally fabricated as nanoplatform for hydrogen sulfide (H2S)-sensitized synergistic therapy of wound bacterial biofilm infection. The rich anion vacancies and Z-scheme heterostructure make the fabricated MoSSe VdW HJ can effectively augment H2S, localized hyperthermia, and reactive oxygen species production under the stimulation of biofilm microenvironments (BME) and irradiation of 808 nm near-infrared (NIR) light. Therefore, MoSSe VdW HJ is capable to integrate H2S gas, chemodynamic, photothermal, and photodynamic therapies to effectively destroy eDNA and polysaccharides in the EPS matrix, thereby breaching the biofilm barrier to eradicate bacteria and facilitate wound healing. The synergistic strategy exhibits superior anti-biofilm and wound repair effects both in vivo and in vitro, thus providing guideline for the development of BME and NIR light activated synergistic therapeutics to fight against refractory biofilm infections.

Monitoring the level of hydrogen sulfide in arthritis and its treatment with a novel near-infrared fluorescent probe

Hydrogen sulfide (H2S) is a physiological gaseous transmitter that plays a crucial role in maintaining the cellular redox state. Arthritis is usually accompanied by redness, swelling, pain, dysfunction and deformity of the joints, and in severe cases can lead to joint disability. Disorders of H2S level are associated with the pathological process of arthritis. In this paper, a near-infrared fluorescent probe (TX-H2S) was developed to detect the alterations in H2S levels of arthritis. TX-H2S has excellent response performance to H2S such as near-infrared emission (725 nm), large Stokes shift (125 nm) and high fluorescence enhancement (72-fold). Owing to low cytotoxicity, the probe can be employed to observe the alterations of exogenous and endogenous H2S level in HeLa and HepG2 cells. By making full use of near-infrared emission and good biocompatibility, the probe can be employed for exogenous H2S imaging in mice, and is able to track the fluctuation of H2S level during arthritis and its treatment. These make the probe have the potential to invent an efficient tool for the diagnosis of arthritic disease and its treatment.

Controlled Magnesium Ion Delivery via Mg-Sputtered Nerve Conduit for Enhancing Peripheral Nerve Regeneration

Autologous nerve grafting remains the gold standard for treating peripheral nerve injuries; however, it is constrained by limited donor nerve availability, the need for secondary surgeries, and sensory loss at the donor site. Biodegradable material-based nerve conduits have emerged as a promising alternative to address these limitations and enhance nerve regeneration. Among these materials, magnesium stands out due to its exceptional biocompatibility, biofunctionality, and neuroprotective properties. Despite its potential, magnesium's rapid corrosion rate and the need for controlled ion release necessitate advanced modifications, such as the development of Mg alloys. However, these approaches often face challenges, including viability concerns and material hardness, which can hinder nerve repair and damage surrounding tissues. In this study, a novel solution is introduced by sputtering magnesium onto a soft collagen sheet, achieving controlled magnesium ion release while preserving the material's nerve-like softness. This Mg-sputtered collagen sheet demonstrates excellent biocompatibility and significantly improves axon regeneration, muscle reinnervation, and functional recovery in a sciatic nerve defect model. These findings highlight the potential of an innovative Mg-based biodegradable nerve conduit, offering transformative applications across various medical fields.

Advancing Prosthetic Hand Capabilities Through Biomimicry and Neural Interfaces

Background and ObjectivesProsthetic hand development is undergoing a transformative phase, blending biomimicry and neural interface technologies to redefine functionality and sensory feedback. This article explores the symbiotic relationship between biomimetic design principles and neural interface technology (NIT) in advancing prosthetic hand capabilities.MethodsDrawing inspiration from biological systems, researchers aim to replicate the intricate movements and capabilities of the human hand through innovative prosthetic designs. Central to this endeavor is NIT, facilitating seamless communication between artificial devices and the human nervous system. Recent advances in fabrication methods have propelled brain-computer interfaces, enabling precise control of prosthetic hands by decoding neural activity.ResultsAnatomical complexities of the human hand underscore the importance of understanding biomechanics, neuroanatomy, and control mechanisms for crafting effective prosthetic solutions. Furthermore, achieving the goal of a fully functional cyborg hand necessitates a multidisciplinary approach and biomimetic design to replicate the body's inherent capabilities. By incorporating the expertise of clinicians, tissue engineers, bioengineers, electronic and data scientists, the next generation of the implantable devices is not only anatomically and biomechanically accurate but also offer intuitive control, sensory feedback, and proprioception, thereby pushing the boundaries of current prosthetic technology.ConclusionBy integrating machine learning algorithms, biomechatronic principles, and advanced surgical techniques, prosthetic hands can achieve real-time control while restoring tactile sensation and proprioception. This manuscript contributes novel approaches to prosthetic hand development, with potential implications for enhancing the functionality, durability, and safety of the prosthetic limb.

Hydrogel-Based Bioactive Synthetic Skin Stimulates Regenerative Gas Signaling and Eliminates Interfacial Pathogens to Promote Burn Wound Healing

Skin burn wounds (SBWs) are common clinical injuries due to excessive exposure to factors including heat, radiation, chemical agents, etc. However, the efficient healing of SBWs is still challenging due to persistent inflammation and high risk of local infection. To meet these challenges, we report a hydrogel-based bioactive synthetic skin (HBSS) from biocompatible components as dressing materials for burn wound treatment, which mediated localized H2S release to stimulate tissue regeneration while preventing bacterial infection and excessive inflammation. Here, the H2S donor (N-(benzoyl mercapto) benzamide) was first coassembled with thioketal (TK)-ligated dopamine dimer to form nanoscale assemblies (DDNs), which were then integrated into Schiff base-cross-linked hyaluronic acid-carboxymethyl chitosan hydrogels. The elevated acidity in burn wounds would trigger hydrogel degradation to release DDNs, which were further activated by ROS-induced cleavage of TK linkers to release H2S gas while attenuating local ROS stress in a self-immolative manner, thus promoting local angiogenesis and tissue regeneration through activating the AMPK and RAS-MAPK-AP1 prohealing pathways, while enabling M1-to-M2 macrophage reprogramming through activating the ERK1/2 and NRF2 signaling. Meanwhile, the chitosan components in the hydrogel network could inhibit bacterial colonization at the wound site to prevent local infection. These merits acted in a cooperative manner to enable accelerated and robust burn wound healing, offering an approach for burn wound treatment in the clinic.

MicroRNA-loaded antioxidant nanoplatforms for prevention and treatment of experimental acute and chronic uveitis

Uveitis, a frequently recurrent inflammatory condition of the uvea, poses a significant risk of visual impairment and blindness, primarily due to the excessive generation of reactive oxygen species (ROS) and the activation of signaling pathways that propagate inflammatory responses. Despite the widespread use of corticosteroid eye drops as a standard treatment, these therapies are hindered by limited efficacy, adverse side effects, and poor ocular bioavailability. To address these challenges, polyethyleneimine (PEI)-modified polydopamine (PDA) carrying microRNA-132-3p (miR-132), namely PEI/PDA@miR-132, was developed to simultaneously neutralize ROS and attenuate inflammation in experimental models of acute and chronic uveitis. Mechanistically, PEI/PDA@miR-132 demonstrated remarkable efficacy by suppressing ROS production, inhibiting the pro-inflammatory polarization of macrophages, and downregulating the IκBα/nuclear factor-kappa B (NF-κB) p65 signaling pathway. These effects culminated in the reduction of pro-inflammatory cytokines and mitigation of apoptosis. Therapeutically, PEI/PDA@miR-132 provided significant relief from hallmark symptoms of uveitis, including iris congestion, inflammatory exudation, and retinal folds, while exhibiting superior retinal safety compared to commercially available dexamethasone. Furthermore, it showcased excellent biocompatibility, positioning it as a promising therapeutic strategy for managing oxidative stress- and inflammation-driven diseases such as acute and chronic uveitis.

Reprogramming metabolic microenvironment for nerve regeneration via waterborne polylactic acid-polyurethane copolymer scaffolds

Cell metabolism, as the key driver of inflammation, revascularization and even subsequent tissue regeneration, is controlled by and also conversely influenced by signal transduction. Incorporation of cell metabolism into tissue engineering research holds immense potential for in-situ treatment repair and further understanding of the host-biomaterial cues in body response. In this study, an anti-inflammatory waterborne polyurethane scaffold incorporated with poly-l-lactic acid (PLLA) block was served to repair nerve injuries (LAx-WPU). Lactate was released through the degradation of LAx-WPU scaffolds, and the content increased with the addition of PLLA block over the degradation times. Thenceforth, the production of adenosine triphosphate (ATP) in primary neurons and neuronal axon growth were achieved by taking up lactate through monocarboxylate transporters (MCT2) for energy metabolism under glucose-free environment treated with LAx-WPU degradation solution. After LAx-WPU was implanted to repair brain nerve defects in rats, filamentous neurons elongation, rapid vascularization, and nerve tissue regeneration were realized up to 28 days with the positive expression of microtubule-associated protein (MAP2), β-tubulin (Tuj1), and platelet endothelial cell adhesion molecule (CD31) in the scaffolds. Results highlighted that the LAx-WPU scaffolds up-regulated not only the ATP-ADP-AMP purine metabolism compounds to mainly bridge neuroactive ligand-receptor interaction genes, cAMP pathway genes, and calcium pathway genes for neurocytes but also the ATP-GMP purine metabolism to angiogenesis in Gene Ontology (GO) analysis. Further analysis in reverse showed axonal regeneration is restrained by the inhibition of MCT2, proving LAx-WPU promoted nerve repair depended on lactate for energy. Therefore, LAx-WPU scaffolds construct an expected way to modulate the metabolic microenvironment for inducing nerve regeneration by intrinsic biomaterial metabolism cues without any bioactive factors.

From Autonomous Chemical Micro-/Nanomotors to Rationally Engineered Bio-Interfaces

Developing micro-/nanomotors that convert a chemical energy input into a local gradient field and motion is an appealing but challenging task that holds particular promise for the intersection of materials and nanoengineering. Over the past two decades, remarkable advancements have refined these out-of-equilibrium chemically powered micro-/nanomotors, enabling them to orchestrate in situ chemical transformations that dynamically change local environments. The ionic products, radicals, gases, and electric fields from these active materials reshape the microenvironment, paving the way for ecofriendly disease interventions. This review discusses the state-of-the-art reactions that propel these energy-consuming micro-/nanomotors and elucidates the emerging implications of their products on biological systems. Particular emphasis has been placed on their potential for neural modulation, reactive oxygen species (ROS) regulation, synergistic tumor therapy, antibacterial strategies, and tissue regeneration. Collectively, these sketches provide a landscape of therapeutic modalities, heralding a new era of biomedicine. By harnessing the in situ product field of this active matter, we envision a paradigm shift toward active therapies that transcend conventional approaches, promising breakthroughs in disease diagnosis, treatment, and prevention.

Gasotransmitter-Nanodonor for Spatial Regulation of Anxiety-Like Behavior and Bone Metastasis

Anxiety is highly prevalent among cancer patients, significantly impacting their prognosis. Current cancer therapies typically lack anxiolytic properties and may even exacerbate anxiety. Here, a gasotransmitter-nanodonors (GND) system is presented that exerts dual anxiolytic and anti-tumor effects via a "tumor-brain axis" strategy. The GND, synthesized by co-embedding Fe2⁺ and S2⁻ ions along with glucose oxidase (GOx) within bovine serum albumin (BSA) nanoparticles (FSG@AB), enables the controlled release of the gasotransmitter hydrogen sulfide (H₂S) in the acidic tumor microenvironment. H₂S and GOx synergistically deplete tumor energy sources, resulting in robust anti-tumor effects. Meanwhile, H₂S generated at the tumor site is transported through the bloodstream to the anterior cingulate cortex (ACC) in the brain, where it modulates neuronal activity. Specifically, in the ACC, H₂S upregulates glutamate transporter 1 (GLT-1), which reduces extracellular glutamate levels and attenuates the hyperactivity of glutamatergic neurons, thereby alleviating anxiety-like behavior. This study proposes a GND system that targets both oncological and psychiatric dimensions of cancer through the "tumor-brain axis" strategy, resulting in improved therapeutic outcomes.

An immunoregulation PLGA/Chitosan aligned nanofibers with polydopamine coupling basic fibroblast growth factor and ROS scavenging for peripheral nerve regeneration

The repair and functional recovery of long-segment peripheral nerve injuries are crucial in clinical settings. Nerve conduits are seen as promising alternatives to autologous nerve grafts, but their effectiveness is limited by the controlled delivery of bioactive factors and meeting various functional requirements during different stages of repair. This research developed multifunctional nerve conduits using electrospinning and polydopamine (PDA) coating techniques to integrate bioactive substances. Chitosan-composite PLGA electrospun nerve conduits demonstrated exceptional mechanical properties and biocompatibility. Nanofibers with specific topological structures effectively promoted oriented cell growth. The PDA coating provided ROS scavenging and immune modulation functions. The bFGF growth factor attached to the PDA coating facilitated sustained release, enhancing Schwann cell functionality and stimulating neurite outgrowth. In a rat sciatic nerve defect model with a 10 mm gap, PLGA/CS-PDA-bFGF nerve conduits showed a positive impact on nerve regeneration and functional recovery. Consequently, nerve conduits with multiple functions modified with PDA-coated bioactive molecules are poised to be excellent materials for mending peripheral nerve injuries.

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.

Photo-Responsive H2S Composite System Regulates the Nerve Regeneration Microenvironment Through Multiple Pathways

After injury, the imbalance of the regeneration microenvironment caused by inflammation, oxidative stress, insufficient neurovascularization, and inadequate energy supply affects nerve regeneration. Drug-delivery nerve conduits play a role in repairing the regenerative microenvironment. However, traditional drugs often fail to cross the blood-nerve barrier and lack multifunctionality, limiting the effectiveness of conduit therapy. Therefore, it is necessary to construct a multifunctional conduit that regulate the regeneration microenvironment timely and effectively. Herein, a photo-responsive hydrogen sulfide (H2S) composite nerve conduit, artificially controlled H2S release, is developed. A new structure of zinc-citric acid organic metal framework (Zn-CA MOFs) is utilized to improve its drug loading rate, achieving the joint regulation of the nerve regeneration microenvironment by H2S and Zn2+. In addition, RGD modification of polyester amide (P(CL-MMD-MAC)-RGD)) combined with aligned structure is used to improve the performance of the conduit. Relevant results demonstrate that H2S and Zn2+ can regulate inflammatory response and oxidative stress and promote mitochondrial function recovery and angiogenesis. Furthermore, the aligned structure can promote cell adhesion and guide cell directed migration. Overall, this study provides a method of combining gas neurotransmitters with ions to improve the nerve regeneration microenvironment, accelerate nerve regeneration, and restore motor function.

In situ valence-transited arsenic nanosheets for multi-modal therapy of colorectal cancer

Late-stage and advanced colorectal cancer (CRC) often prove to be resistant to current treatment regimens, due to the evolving tumor microenvironment. Chemotherapy-dominated multi-modal therapeutic strategies based on the specific CRC microenvironment open a new horizon for eradicating colorectal tumors. Here, in situ valence-transited arsenic nanosheets are developed as a multi-modal therapeutic platform by responding to the H2S-enriched CRC microenvironment. Carrier-free pegylated nanosheets of pentavalent arsenic (AsV), aminooxyacetic acid (AOAA), and copper ion (Cu2+) are innovatively self-assembled via coordination with high loading content and good stability. AsV in pegylated arsenic nanosheets (CAA-PEG NSs) is rapidly released and reduced to trivalent arsenic (AsIII) to exert its chemotherapy in the local tumor. Furthermore, the immunosuppressive microenvironment is thoroughly remodeled via H2S depletion of AsV to AsIII conversion and impairment of H2S production by AOAA. Additionally, the in situ produced ultrasmall CuS nanoparticles exhibit photothermal activity against CRC under the guidance of photoacoustic imaging. This multi-modal therapeutic strategy, dominated by chemotherapy, completely inhibits CRC progression and prevents its relapse.

ROS-triggered biomimetic hydrogel soft scaffold for ischemic stroke repair

Millions of individuals worldwide suffer from ischemic stroke (IS). The focal hypo-perfused brain brings about hostile pathological environment, which further restricts endogenous neurogenesis post-stroke. In this work, we report an ROS-triggered hyaluronic acid (HA) and platelet lysates (pls) composite biomimetic hydrogel soft scaffold (pls gel) encapsulating matrix metalloproteinase (MMPs)-responsive triglycerol monostearate nanoparticles loaded with docosahexaenoic acid (TGMS@DHA, TD). Pls gel was chosen to be the hydrogel matrix to mimic brain extracellular matrix (ECM) to provide physical support for cell infiltration and accelerate angiogenesis as a growth factors (GFs) box. The borate ester bonded hydrogel could respond to reactive oxygen species and relieve oxidative stress. The loaded TD nanoparticles could be enzymatically cleaved by overexpressed MMPs in cerebral infarcted site, which could improve the adverse effects triggered by overexpressed MMPs. DHA with rich unsaturated bonds was proven that not only inhibit neuroinflammatory and oxidative stress, but also take part in promote neurogenesis. In brief, the ROS-triggered hydrogel scaffold pls gel@TD created an optimized microenvironment to manipulate the survival and differentiation of neural stem cells and promote endogenous regenerative repair processes. The in vitro results exhibited the biomimetic soft scaffold eliminated oxygen-glucose deprivation-derived free radical, saved mitochondrial dysfunction, reduced neuronal apoptosis, and promoted neovascularization. In the mice focal IS model, the biomimetic hydrogel scaffold regulated pathological environment in the ischemic site and induced migration and differentiation of endogenous neural stem cells, consequently relieved neuron ischemia injury. During the long-term observation, the hydrogel improved mice neurobehavioral functions. In conclusion, the hydrogel soft scaffold pls gel@TD was demonstrated to have promising therapeutic effects on remodeling pathological environment by transforming the hostile state into a pro-regenerative one in the infarct site, consequently promoting endogenous regenerative repair processes.

Hyaluronic Acid-Based Therapy for Alleviating Early Lipid Peroxidation in Peripheral Nerve Compression Injury Repair

BACKGROUND

Peripheral nerve injuries compromise sensory and motor functions, severely affecting patients' quality of life. Early lipid peroxidation drives oxidative stress, disrupting the regenerative microenvironment. Hyaluronic acid (HA), an essential extracellular matrix component, shows promise in mitigating oxidative damage and fostering repair.

METHODS

In a rat sciatic nerve crush model, HA hydrogel was applied to enhance retention at the injury site. Transcriptomic analysis at 24 hours postinjury identified key pathways. In vitro assays examined HA's protective effects on Schwann cells against lipid peroxidation and oxidative stress. In vivo, HA hydrogel was administered immediately (0 hour) postcrush, followed by 4-methylumbelliferone-induced inhibition of endogenous HA synthesis and exogenous HA supplementation to clarify HA's role.

RESULTS

HA treatment reduced early lipid peroxidation, upregulated glutathione metabolism, and stimulated extracellular matrix receptor interactions, notably elevating CD44 expression. In vitro, HA lowered oxidative stress and maintained Schwann cell viability. In vivo, early HA intervention mitigated muscle atrophy, preserved myelin sheaths, and improved Sciatic Functional Index scores compared to delayed or untreated controls. Inhibiting endogenous HA synthesis impaired recovery, which was partially reversed by exogenous HA.

CONCLUSIONS

Early HA intervention modulates lipid peroxidation and oxidative stress via the HA/CD44 axis, establishing a supportive microenvironment for peripheral nerve regeneration and functional recovery. These findings underscore the potential of HA-based strategies to curb early lipid peroxidation, thereby expediting nerve repair and accelerating regeneration.

Hydrogels for Peripheral Nerve Repair: Emerging Materials and Therapeutic Applications

Peripheral nerve injuries pose a significant clinical challenge due to the complex biological processes involved in nerve repair and their limited regenerative capacity. Despite advances in surgical techniques, conventional treatments, such as nerve autografts, are faced with limitations like donor site morbidity and inconsistent functional outcomes. As such, there is a growing interest in new, novel, and innovative strategies to enhance nerve regeneration. Tissue engineering/regenerative medicine and its use of biomaterials is an emerging example of an innovative strategy. Within the realm of tissue engineering, functionalized hydrogels have gained considerable attention due to their ability to mimic the extracellular matrix, support cell growth and differentiation, and even deliver bioactive molecules that can promote nerve repair. These hydrogels can be engineered to incorporate growth factors, bioactive peptides, and stem cells, creating a conducive microenvironment for cellular growth and axonal regeneration. Recent advancements in materials as well as cell biology have led to the development of sophisticated hydrogel systems, that not only provide structural support, but also actively modulate inflammation, promote cell recruitment, and stimulate neurogenesis. This review explores the potential of functionalized hydrogels for peripheral nerve repair, highlighting their composition, biofunctionalization, and mechanisms of action. A comprehensive analysis of preclinical studies provides insights into the efficacy of these hydrogels in promoting axonal growth, neuronal survival, nerve regeneration, and, ultimately, functional recovery. Thus, this review aims to illuminate the promise of functionalized hydrogels as a transformative tool in the field of peripheral nerve regeneration, bridging the gap between biological complexity and clinical feasibility.

Probiotic biofilm modified scaffolds for facilitating osteomyelitis treatment through sustained release of bacteriophage and regulated macrophage polarization

Osteomyelitis has gradually become a catastrophic complication in orthopedic surgery due to the formation of bacterial biofilms on the implant surface and surrounding tissue. The therapeutic challenges of antibiotic resistance and poor postoperative osseointegration provide inspiration for the development of bioactive implants. We have strategically designed bioceramic scaffolds modified with Lactobacillus reuteri (LR) and bacteriophages (phages) to achieve both antibacterial and osteogenic effects. Leveraging the tendency of bacteria to adhere to the surface of implants, bioceramics have been modified with LR biofilm to promote bone repair. The LR biofilm, sterilized by pasteurization, prevents sepsis caused by live bacteria and is biocompatible with phages. Phages, being natural enemies of bacteria, not only effectively kill bacteria and inhibit biofilm formation but also readily adsorb onto the surface of bioceramics. Hence, this scaffold, loaded with a phage cocktail, lysates specific bacterial populations, namely Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). More importantly, the inactivated LR biofilm stimulates macrophages RAW264.7 to polarize towards an anti-inflammatory M2 phenotype, creating an immune microenvironment favorable for inducing osteogenic differentiation of rat mesenchymal stem cells in vitro. In a rat model of infectious cranial defects, the scaffold not only effectively eliminated S. aureus and alleviated associated inflammation but also mediated macrophage-mediated immunoregulation, thus resulting in effective osteogenesis. Collectively, these multifunctional modified scaffolds offer an integrated approach to both bacterium elimination and bone repair, presenting a new strategy for bioactive implants in the clinical management of osteomyelitis.

Hydrogel-Based Innovations in Carpal Tunnel Syndrome: Bridging Pathophysiological Complexities and Translational Therapeutic Gaps

Carpal Tunnel Syndrome (CTS) is a prevalent neuropathic disorder caused by chronic compression of the median nerve, leading to sensory and motor impairments. Conventional treatments, such as corticosteroid injections, wrist splinting, and surgical decompression, often fail to provide adequate outcomes for chronic or recurrent cases, emphasizing the need for innovative therapies. Hydrogels, highly biocompatible three-dimensional biomaterials with customizable properties, hold significant potential for CTS management. Their ability to mimic the extracellular matrix facilitates localized drug delivery, anti-adhesion barrier formation, and tissue regeneration. Advances in hydrogel engineering have introduced stimuli-responsive systems tailored to the biomechanical environment of the carpal tunnel, enabling sustained therapeutic release and improved tissue integration. Despite these promising developments, hydrogel applications for CTS remain underexplored. Key challenges include the absence of CTS-specific preclinical models and the need for rigorous clinical validation. Addressing these gaps could unlock the full potential of hydrogel-based interventions, which offer minimally invasive, customizable solutions that could improve long-term outcomes and reduce recurrence rates. This review highlights hydrogels as a transformative approach to CTS therapy, advocating for continued research to address translational barriers. These innovations have the potential to redefine the treatment landscape, significantly enhancing patient care and quality of life.

Mesoporous Prussian blue nanoparticle neuroconduit for the biological therapy targeting oxidative stress reduction, inflammation inhibition, and nerve regeneration

The applications of nanomaterials in regenerative medicine encompass a broad spectrum. The functional nanomaterials, such as Prussian blue and its derivative nanoparticles, exhibit potent anti-inflammatory and antioxidant properties. By combining it with the corresponding scaffold carrier, the fusion of nanomaterials and biotherapy can be achieved, thereby providing a potential avenue for clinical treatment. The present study demonstrates the fabrication of a Mesoporous Prussian blue nanoparticles (MPBN) functionalized Inverse Opal Film (IOF) neuroconduit for peripheral nerve repair through reverse replication and freeze-drying techniques. The binding of MPBN to the neuroconduit can effectively decreasing reactive oxygen species and inflammatory factors in the vicinity of the residual nerve, thereby providing protective effects on the damaged nerve. Furthermore, comprehensive behavioral, electrophysiological, and pathological analyses unequivocally substantiate the efficacy of MPBN in increasing nerve structure regeneration and ameliorating denervation-induced myopathy. Moreover, MPBN enhances the antioxidant capacity of Schwann cells by activating the AMPK/SIRT1/PGC-1 pathway. The findings suggest that MPBN, a biocompatible nanoparticle, can safeguard damaged nerves by optimizing the microenvironment surrounding nerve cells and augmenting the antioxidant capacity of nerve cells, thereby facilitating nerve regeneration and repair. This also establishes a theoretical foundation for exploring the integration and clinical translation between nanomaterials and biotherapy.

Engineering spatially-confined conduits to tune nerve self-organization and allodynic responses via YAP-mediated mechanotransduction

Chronic allodynia stemming from peripheral stump neuromas can persist for extended periods, significantly compromising patients' quality of life. Conventional managements for nerve stumps have demonstrated limited effectiveness in ensuring their orderly termination. In this study, we present a spatially confined conduit strategy, designed to enhance the self-organization of regenerating nerves after truncation. This innovative approach elegantly enables the autonomous slowing of axonal outgrowth in response to the gradually constricting space, concurrently suppressing neuroinflammation through YAP-mediated mechanotransduction activation. Meanwhile, the decelerating axons exhibit excellent alignment and remyelination, thereby helping to prevent failure modes in nerve self-organization, such as axonal twisting in congested regions and overgrowth beyond the conduit's capacity. Additionally, proteins associated with mechanical allodynia, including TRPA1 and CGRP, exhibit a gradual reduction in expression as spatial constraints tighten, a trend inversely validated by the administration of the YAP-targeted inhibitor Verteporfin. This spatially confined conduit strategy significantly alleviates allodynia, thus preventing autotomy behavior and reducing pain-induced gait alterations.

Mechanism and Application of Biomaterials Targeting Reactive Oxygen Species and Macrophages in Inflammation

Inflammation, an adaptive reaction to harmful stimuli, is a necessary immune system response and can be either acute or chronic. Since acute inflammation tends to eliminate harmful stimuli and restore equilibrium, it is generally advantageous to the organism. Chronic inflammation, however, is caused by either increased inflammatory signaling or decreased pro-anti-inflammatory signaling. According to current studies, inflammation is thought to be a major factor in a number of chronic diseases, including diabetes, cancer, arthritis, inflammatory bowel disease, and obesity. Consequently, reducing inflammation is essential for both preventing and delaying diseases. The application of biomaterials in the treatment of inflammatory illnesses has grown in recent years. A variety of biomaterials can be implanted either by themselves or in conjunction with other bioactive ingredients and therapeutic agents. The mechanisms of action and therapeutic applications of well-known anti-inflammatory biomaterials are the main topics of this article.

Dynamic Hyaluronic Acid Hydrogels for Comprehensively Regulating Inflammation, Angiogenesis, and Metabolism to Effectively Proheal Diabetic Wounds

Despite the great progress of various multifunctional wound dressings, it is challenging to simultaneously achieve complete healing and functional remodeling for diabetic foot ulcers and refractory chronic wounds. Aiming to comprehensively regulate chronic inflammation, angiogenesis, and metabolism processes, herein, a novel kind of dynamic hyaluronic acid (HA) hydrogel was designed by combining boronate and coordination chemistry. Besides having injectability, self-healing, and detachment properties, dynamic HA hydrogels presented diabetic wound-responsive degradation and controllable H2S release. They could efficiently polarize M1-to-M2 polarization and regulate inflammatory cytokine secretion and multiple inflammation-related mRNA expressions through cooperative actions of reactive oxygen species elimination + H2S release + Zn2+ regulation, thus driving chronic inflammation into the proliferation and remodeling stages. Moreover, the screened lead hydrogel HTZS could regulate angiogenesis-related signaling pathways and metabolism processes to promote neovascularization and mature vessel formation, re-epithelization, high-level collagen-I deposition, and dense hair follicle regeneration, achieving complete healing and functional remodeling in diabetic wounds. Importantly, this work opens a new avenue to design dynamic biopolymer hydrogels for high-performance wound dressing and decipher the key role of multiple orchestrated regulations of inflammation-angiogenesis-metabolism on complete healing and functional remodeling in chronic and diabetic wounds.

Hydrogen sulfide mitigates mitochondrial dysfunction and cellular senescence in diabetic patients: Potential therapeutic applications

Diabetes induces a pro-aging state characterized by an increased abundance of senescent cells in various tissues, heightened chronic inflammation, reduced substance and energy metabolism, and a significant increase in intracellular reactive oxygen species (ROS) levels. This condition leads to mitochondrial dysfunction, including elevated oxidative stress, the accumulation of mitochondrial DNA (mtDNA) damage, mitophagy defects, dysregulation of mitochondrial dynamics, and abnormal energy metabolism. These dysfunctions result in intracellular calcium ion (Ca2+) homeostasis disorders, telomere shortening, immune cell damage, and exacerbated inflammation, accelerating the aging of diabetic cells or tissues. Hydrogen sulfide (H2S), a novel gaseous signaling molecule, plays a crucial role in maintaining mitochondrial function and mitigating the aging process in diabetic cells. This article systematically explores the specific mechanisms by which H2S regulates diabetes-induced mitochondrial dysfunction to delay cellular senescence, offering a promising new strategy for improving diabetes and its complications.

Hydrosulphide-methaemoglobin-albumin cluster: a hydrogen sulphide donor

Methaemoglobin (metHb) possesses inherent characteristics that facilitate reversible binding to hydrogen sulphide. Exogenous hydrogen sulphide supplementation imparts beneficial bioactive effects, including antioxidant and anti-inflammatory; hence, we hypothesized that the metHb-hydrogen sulphide complex could act as a hydrogen sulphide donor for medication. In this study, we prepared a hydrosulphide-metHb-albumin (H2S-metHb-albumin) cluster and examined its applicability as a hydrogen sulphide donor in the mice model of hepatic ischemia-reperfusion injury. Structural analysis revealed that the H2S-metHb-albumin cluster exhibited a nanostructure wherein one metHb was wrapped by an average of three albumins, and hydrogen sulphide was bound to the haem. Additionally, the H2S-metHb-albumin cluster exhibited low-pH responsiveness, leading to sustained release of hydrogen sulphide. Owing to these structural and pharmaceutical characteristics, the severity of hepatic ischemia-reperfusion injury was alleviated via antioxidant and anti-inflammatory effects of the H2S-metHb-albumin cluster treatment. The protective effects were more potent in the H2S-metHb-albumin cluster compared to that in a conventional hydrogen sulphide donor (sodium hydrogen sulphide). No abnormal signs of toxic and biological responses were observed after the H2S-metHb-albumin cluster administration, confirming high biological compatibility. These results successfully establish the proof of concept that the H2S-metHb-albumin cluster is a promising hydrogen sulphide donor. To the best of our knowledge, this is the first report demonstrating the remarkable potential of metHb as a biomaterial for hydrogen sulphide donors.

Porphyrin-based-MOF nanocomposite hydrogels for synergistic sonodynamic and gas therapy against tumor

The glioma is one of the most aggressive tumors in humans, which is difficult to eradicate clinically. Therefore, we devised a porphyrin-based metal-organic frameworks (MOFs) crosslinking hyaluronic acid (HA) hydrogel nanocomposite through double-network (Cu-MOF-S-S-HA-Gel, CSSH-Gel), which is tumor responsive for enhanced gas therapy and sonodynamic therapy (SDT). Firstly, the hydrogels show extraordinary injectability and biocompatibility, which enables intratumor administration to circumvent the danger associated with surgery. The Cu-MOF-Cys and HA-Cys are interconnected through ether and disulfide bonds to establish a dual-network gel structure. The overexpressed glutathione (GSH) in tumor microenvironment (TME) reacts with disulfide bonds to release of the nanosensitizer (Cu-MOF). Subsequently, Cu-MOF generates reactive oxygen species (ROS) upon ultrasound irradiation for SDT, and releases L-cysteine(L-Cys) catalyzed by 3-mercapto pyruvate sulfotransferase (3-MST) to generate H2S for gas therapy. The CSSH-Gel obtained excellent synergistic anti-tumor effects (82.34 % inhibition ratio in vivo), which holds tremendous promise for the advancement of minimally invasive glioma therapies.

Blood-Brain Barrier-Penetrating Metal-Organic Framework Antioxidant Nanozymes for Targeted Ischemic Stroke Therapy

Overproduction of reactive oxygen species (ROS) during reperfusion in ischemic stroke (IS) severely impedes neuronal survival and results in high rates of morbidity and disability. The effective blood-brain barrier (BBB) penetration and brain delivery of antioxidative agents remain the biggest challenge in treating ischemic reperfusion-induced cerebrovascular and neural injury. In this study, a metal-organic framework (MOF) nanozyme (MIL-101-NH2(Fe/Cu)) with ROS scavenging activities to encapsulate neuroprotective agent rapamycin is fabricated and decorating the exterior with BBB-targeting protein ligands (transferrin), thereby realizing enhanced drug retention and controlled release within ischemic lesions for the synergistic treatment of IS. Through the receptor-mediated transcellular pathway, the transferrin-coated MOF nanoparticles achieved efficient transport across the BBB and targeted accumulation at the cerebral ischemic injury site of mice with middle cerebral artery occlusion/reperfusion (MCAO/R), wherein the nanocarrier exhibited catalytic activities of ROS decomposition into O2 and H2O2-responsive rapamycin release. By its BBB-targeting, antioxidative, anti-inflammatory, and antiapoptotic properties, the MOF nanosystem addressed multiple pathological factors of IS and realized remarkable neuroprotective effects, leading to the substantial reduction of cerebral infarction volume and accelerated recovery of nerve functions in the MCAO/R mouse model. This MOF-based nanomedicine provides valuable design principles for effective IS therapy with multi-mechanism synergies.

Hybrid construction of tissue-engineered nerve graft using skin derived precursors induced neurons and Schwann cells to enhance peripheral neuroregeneration

Peripheral nerve injury is a major challenge in clinical treatment due to the limited intrinsic capacity for nerve regeneration. Tissue engineering approaches offer promising solutions by providing biomimetic scaffolds and cell sources to promote nerve regeneration. In the present work, we investigated the potential role of skin-derived progenitors (SKPs), which are induced into neurons and Schwann cells (SCs), and their extracellular matrix in tissue-engineered nerve grafts (TENGs) to enhance peripheral neuroregeneration. SKPs were induced to differentiate into neurons and SCs in vitro and incorporated into nerve grafts composed of a biocompatible scaffold including chitosan neural conduit and silk fibroin filaments. In vivo experiments using a rat model of peripheral nerve injury showed that TENGs significantly enhanced nerve regeneration compared to the scaffold control group, catching up with the autograft group. Histological analysis showed improved axonal regrowth, myelination and functional recovery in animals treated with these TENGs. In addition, immunohistochemical staining confirmed the presence of induced neurons and SCs within the regenerated nerve tissue. Our results suggest that SKP-induced neurons and SCs in tissue-engineered nerve grafts have great potential for promoting peripheral nerve regeneration and represent a promising approach for clinical translation in the treatment of peripheral nerve injury. Further optimization and characterization of these engineered constructs is warranted to improve their clinical applicability and efficacy.

PLCL/SF/NGF nerve conduit loaded with RGD-TA-PPY hydrogel promotes regeneration of sciatic nerve defects in rats through PI3K/AKT signalling pathways

Peripheral nerve defect are common clinical problem caused by trauma or other diseases, often leading to the loss of sensory and motor function in patients. Autologous nerve transplantation has been the gold standard for repairing peripheral nerve defects, but its clinical application is limited due to insufficient donor tissue. In recent years, the application of tissue engineering methods to synthesize nerve conduits for treating peripheral nerve defect has become a current research focus. This study introduces a novel approach for treating peripheral nerve defects using a tissue-engineered PLCL/SF/NGF@TA-PPy-RGD conduit. The conduit was fabricated by combining electrospun PLCL/SF with an NGF-loaded conductive TA-PPy-RGD gel. The gel, synthesized from RGD-modified tannic acid (TA) and polypyrrole (PPy), provides growth anchor points for nerve cells. In vitro results showed that this hybrid conduit could enhance PC12 cell proliferation, migration, and reduce apoptosis under oxidative stress. Furthermore, the conduit activated the PI3K/AKT signalling pathway in PC12 cells. In a rat model of sciatic nerve defect, the PLCL/SF/NGF@TA-PPy-RGD conduit significantly improved motor function, gastrocnemius muscle function, and myelin sheath axon thickness, comparable to autologous nerve transplantation. It also promoted angiogenesis around the nerve defect. This study suggests that PLCL/SF/NGF@TA-PPy-RGD conduits provide a conducive environment for nerve regeneration, offering a new strategy for peripheral nerve defect treatment, this study provided theoretical basis and new strategies for the research and treatment of peripheral nerve defect.

Pleiotropic effects of nitric oxide sustained-release system for peripheral nerve repair

The regenerative microenvironment after peripheral nerve injury is imbalanced and difficult to rebalance, which is mainly affected by inflammation, oxidative stress, and inadequate blood supply. The difficulty in remodeling the nerve regeneration microenvironment is the main reason for slow nerve regeneration. Traditional drug treatments have certain limitations, such as difficulty in penetrating the blood-nerve barrier and lack of pleiotropic effects. Therefore, there is an urgent need to build multifunctional nerve grafts that can effectively regulate the regenerative microenvironment and promote nerve regeneration. Nitric oxide (NO), a highly effective gas transmitter with diatomic radicals, is an important regulator of axonal growth and migration, synaptic plasticity, proliferation of neural precursor cells, and neuronal survival. Moreover, NO provides potential anti-inflammation, anti-oxidation, and blood vessel promotion applications. However, excess NO may cause cell death and neuroinflammatory cell damage. The prerequisite for NO treatment of peripheral nerve injury is that it is gradually released over time. In this study, we constructed an injectable NO slow-release system with two main components, including macromolecular NO donor nanoparticles (mPEG-P(MSNO-EG) nanoparticles, NO-NPs) and a carrier for the nanoparticles, mPEG-PA-PP injectable temperature-sensitive hydrogel. Due to the multiple physiological regulation of NO and better physiological barrier penetration, the conduit effectively regulates the inflammatory response and oxidative stress of damaged peripheral nerves, promotes nerve vascularization, and nerve regeneration and docking, accelerating the nerve regeneration process. STATEMENT OF SIGNIFICANCE: The slow regeneration speed of peripheral nerves is mainly due to the destruction of the regeneration microenvironment. Neural conduits with drug delivery capabilities have the potential to improve the microenvironment of nerve regeneration. However, traditional drugs are hindered by the blood nerve barrier and cannot effectively target the injured area. NO, an endogenous gas signaling molecule, can freely cross the blood nerve barrier and act on target cells. However, excessive NO can lead to cell apoptosis. In this study, a NO sustained-release system was constructed to regulate the microenvironment of nerve regeneration through various pathways and promote nerve regeneration.

Hydrogen Sulfide can Scavenge Free Radicals to Improve Spinal Cord Injury by Inhibiting the p38MAPK/mTOR/NF-κB Signaling Pathway

Spinal cord injury (SCI) causes irreversible cell loss and neurological dysfunctions. Presently, there is no an effective clinical treatment for SCI. It can be the only intervention measure by relieving the symptoms of patients such as pain and fever. Free radical-induced damage is one of the validated mechanisms in the complex secondary injury following primary SCI. Hydrogen sulfide (H2S) as an antioxidant can effectively scavenge free radicals, protect neurons, and improve SCI by inhibiting the p38MAPK/mTOR/NF-κB signaling pathway. In this report, we analyze the pathological mechanism of SCI, the role of free radical-mediated the p38MAPK/mTOR/NF-κB signaling pathway in SCI, and the role of H2S in scavenging free radicals and improving SCI.

An Adaptable Drug Delivery System Facilitates Peripheral Nerve Repair by Remodeling the Microenvironment

The multifaceted process of nerve regeneration following damage remains a significant clinical issue, due to the lack of a favorable regenerative microenvironment and insufficient endogenous biochemical signaling. However, the current nerve grafts have limitations in functionality, as they require a greater capacity to effectively regulate the intricate microenvironment associated with nerve regeneration. In this regard, we proposed the construction of a functional artificial scaffold based on a "two-pronged" approach. The whole system was developed by encapsulating Tazarotene within nanomicelles formed through self-assembly of reactive oxygen species (ROS)-responsive amphiphilic triblock copolymer, all of which were further loaded into a thermosensitive injectable hydrogel. Notably, the hydrogel exhibits obvious temperature sensitivity at a concentration of 6 wt %, and the nanoparticles possess concentration-dependent H2O2-response capability with a controlled release profile in 48 h. The combined strategy promoted the repair of injured peripheral nerves, attributed to the dual role of the materials, which mainly involved providing structural support, modulating the immune microenvironment, and enhancing angiogenesis. Overall, this study opens up intriguing prospects in tissue engineering.