3D printing of reduced glutathione grafted gelatine methacrylate hydrogel scaffold promotes diabetic bone regeneration by activating PI3K/Akt signaling pathway

Micromotion-Driven "Mechanical-Electrical-Pharmaceutical Coupling" Bone-Guiding Membrane Modulates Stress-Concentrating Inflammation Under Diabetic Fractures

The use of piezoelectric materials to convert micromechanical energy at the fracture site into electrical signals, thereby modulating stress-concentrated inflammation, has emerged as a promising treatment strategy for diabetic fractures. However, traditional bone-guiding membranes often face challenges in diabetic fracture repair due to their passive and imprecise drug release profiles. Herein, a piezoelectric polyvinylidene fluoride (PVDF) fibrous membrane is fabricated through electrospinning and oxidative polymerization to load metformin (Met) into a polypyrrole (PPy) coating (Met-PF@PPy), creating a "mechanical-electrical-pharmaceutical coupling" system. In a micromotion mechanical environment, Met-PF@PPy converts mechanical energy into electrical signals, activating the electrochemical reduction of PPy and triggering stress-responsive Met release. The generated electrical signals suppress inflammation through M1-to-M2 macrophage polarization and simultaneously enhance osteogenesis. Simultaneously, Met inhibits the NF-κB pathway to reduce pro-inflammatory cytokines while activating the AMPK pathway to promote osteogenesis and angiogenesis. In a diabetic mouse femoral fracture model, Met-PF@PPy significantly reduces inflammatory markers, enhances vascularization, and increases bone mineral density and bone volume fraction by over 30%. This "force-electric-drug coupling" strategy provides an innovative approach for active regulation in diabetic fracture repair and offers a versatile platform for advancing piezoelectric materials in regenerative medicine.

Antioxidant scaffolds for enhanced bone regeneration: recent advances and challenges

Bone regeneration is integral to maintaining bone function and integrity in the body, as well as treating bone diseases, such as osteoporosis and defects. However, oxidative stress often poses a significant obstacle during bone regeneration, leading to cell damage, inflammatory responses, and subsequent impediment of normal bone tissue formation. Therefore, to maintain bone regeneration, antioxidant therapy is essential. Bone scaffolds, serving as a temporary support for bone tissue, can provide an ideal microenvironment for cell proliferation and differentiation, effectively promoting bone tissue formation. In recent years, with in-depth research on antioxidants and their mechanisms of action, the development and application of antioxidant bone scaffolds have shown tremendous potential. These antioxidant bone scaffolds not only promote osteogenic differentiation and angiogenesis, but also effectively inhibit the inflammatory response and osteoclast formation, significantly improving the efficiency of bone regeneration. Notably, with the rapid development of nanotechnology, nanozymes with multi-enzyme-like activities have been successfully constructed and encapsulated within bone scaffolds, leading to the proposal of multifunctional antioxidant strategies. Therefore, this review summarizes recent research progress, categorically introducing types of bone scaffolds and antioxidants, elucidating therapeutic strategies of antioxidant bone scaffolds, and identifying current challenges, aiming to provide valuable guidance for subsequent research.

3D printed magnesium silicate/β-tricalcium phosphate scaffolds promote coupled osteogenesis and angiogenesis

Fabricating bone tissue engineering substitutes with functional activity remains a challenge for bone defect repair requiring coordinated coupling between osteogenesis and angiogenesis. In this research, we evaluated and analyzed magnesium silicate/β-Tricalcium phosphate (MS/β-TCP) scaffold on angiogenesis and bone regeneration in vitro and in vivo, and the mechanism of its action were described. Achieving magnesium and silicon ions sustained release, 3D printed MS/β-TCP scaffolds possessed appropriate mechanical properties and had excellent biocompatibility that was suitable for osteoblastic MC3T3-E1 cells and human umbilical vein endothelial cells (HUVECs) with proliferation, adhesion, and migration. Combined techniques of Transwell co-culture, we studied the effect of MS/β-TCP scaffold activated cell-level specific regulatory network, which promotes the osteogenic differentiation of MC3T3-E1 and the endothelial formation of HUVEC by significantly up-regulating the expression of related genes and proteins. In addition, RNA sequencing (RNA-seq) revealed MS/β-TCP scaffold plays a dual role in osteogenesis and angiogenesis by activating PI3K/Akt signal pathway, whereas the expression of genes and proteins associated with osteogenesis and angiogenesis was significantly downregulated the PI3K/Akt signaling pathway was inhibited. Additionally, in vivo studies showed that MS/β-TCP scaffolds increased the growth of vascular and promoted the bone regeneration at the bone defect sites in rats. In summary, 3D printed MS/β-TCP scaffolds with effectively osteogenic and angiogenic induction will be an ideal bone substitute applied in bone defect repair for clinical application in the future.

Gelatin Methacrylic Acid Hydrogel-Based Nerve Growth Factors Enhances Neural Stem Cell Growth and Differentiation to Promote Repair of Spinal Cord Injury

Background

The challenge in treating irreversible nerve tissue damage has resulted in suboptimal outcomes for spinal cord injuries (SCI), underscoring the critical need for innovative treatment strategies to offer hope to patients.

Methods

In this study, gelatin methacrylic acid hydrogel scaffolds loaded with nerve growth factors (GMNF) were prepared and used to verify the performance of SCI. The physicochemical and biological properties of the GMNF were tested. The effect of GMNF on activity of neuronal progenitor cells (NPCs) was investigated in vitro. Histological staining and motor ability was carried out to assess the ability of SCI repair in SCI animal models.

Results

Achieving nerve growth factors sustained release, GMNF had good biocompatibility and could effectively penetrate into the cells with good targeting permeability. GMNF could better enhance the activity of NPCs and promote their directional differentiation into mature neuronal cells in vitro, which could exert a good neural repair function. In vivo, SCI mice treated with GMNF recovered their motor abilities more effectively and showed better wound healing by macroscopic observation of the coronal surface of their SCI area. Meanwhile, the immunohistochemistry demonstrated that the GMNF scaffolds effectively promoted SCI repair by better promoting the colonization and proliferation of neural stem cells (NSCs) in the SCI region and targeted differentiation into mature neurons.

Conclusion

The application of GMNF composite scaffolds shows great potential in SCI treatment, which are anticipated to be a potential therapeutic bioactive material for clinical application in repairing SCI in the future.

Crosslinked hybrid polymer/ceramic composite coatings for the controlled release of clindamycin

A major risk associated with surgery, including bone tissue procedures, is surgical site infection. It is one of the most common as well as the most serious complications of modern surgery. A helpful countermeasure against infection is antibiotic therapy. In the present study, a methodology has been developed to obtain clindamycin-modified polymer-ceramic hybrid composite coatings for potential use in bone regenerative therapy. The coatings were prepared using a UV-light photocrosslinking method, and the drug was bound to a polymeric and/or ceramic phase. The sorption capacity of the materials in PBS was evaluated by determining the swelling ability and equilibrium swelling. The influence of the presence of ceramics on the amount of liquid bound was demonstrated. The results were correlated with the rate of drug release measured by high-performance liquid chromatography (HPLC). Coatings with higher sorption capacity released the drug more rapidly. Scanning electron microscopy (SEM) imaging was carried out comparing the surface area of the coatings before and after immersion in PBS, and the proportions of the various elements were also determined using the EDS technique. Changes in surface waviness were observed, and chlorine ions were also determined in the samples before incubation. This proves the presence of the drug in the material. The in vitro tests conducted indicated the release of the drug from the biomaterials. The antimicrobial efficacy of the coatings was tested against Staphylococcus aureus. The most promising material was tested for cytocompatibility (MTT reduction assay) against the mouse fibroblast cell line L929 as well as human osteoblast cells hFOB. It was demonstrated that the coating did not exhibit cytotoxicity. Overall, the results signaled the potential use of the developed polymer-ceramic hybrid coatings as drug carriers for the controlled delivery of clindamycin in bone applications. The studies conducted were the basis for directing samples for further in vivo experiments determining clinical efficacy.

Graphene Oxide/Black Phosphorus Functionalized Collagen Scaffolds with Enhanced Near-Infrared Controlled In Situ Biomineralization for Promoting Infectious Bone Defect Repair through PI3K/Akt Pathway

Infectious bone defects resulting from surgery, infection, or trauma are a prevalent clinical issue. Current treatments commonly used include systemic antibiotics and autografts or allografts. Nevertheless, therapies come with various disadvantages, including multidrug-resistant bacteria, complications arising from the donor site, and immune rejection, which makes artificial implants desirable. However, artificial implants can fail due to bacterial infections and inadequate bone fusion after implantation. Thus, the development of multifunctional bone substitutes that are biocompatible, antibacterial, osteoconductive, and osteoinductive would be of great clinical importance. This study designs and prepares 2D graphene oxide (GO) and black phosphorus (BP) reinforced porous collagen (Col) scaffolds as a viable strategy for treating infectious bone defects. The fabricated Col-GO@BP scaffold exhibited an efficient photothermal antibacterial effect under near-infrared (NIR) irradiation. A further benefit of the NIR-controlled degradation of BP was to promote biomineralization by phosphorus-driven and calcium-extracted phosphorus in situ. The abundant functional groups in GO could synergistically capture the ions and enhance the in situ biomineralization. The Col-GO@BP scaffold facilitated osteogenic differentiation of bone marrow-derived mesenchymal stem cells (BMSC) by leveraging its mild photothermal effect and biomineralization process, which upregulated heat shock proteins (HSPs) and activated PI3K/Akt pathways. Additionally, systematic in vivo experiments demonstrated that the Col-GO@BP scaffold obviously promotes infectious bone repair through admirable photothermal antibacterial performance and enhanced vascularization. As a result of this study, we provide new insights into the photothermal activity of GO@BP nanosheets, their degradation, and a new biological application for them.

Biomaterials Designed to Modulate Reactive Oxygen Species for Enhanced Bone Regeneration in Diabetic Conditions

Diabetes mellitus, characterized by enduring hyperglycemia, precipitates oxidative stress, engendering a spectrum of complications, notably increased bone vulnerability. The genesis of reactive oxygen species (ROS), a byproduct of oxygen metabolism, instigates oxidative detriment and impairs bone metabolism in diabetic conditions. This review delves into the mechanisms of ROS generation and its impact on bone homeostasis within the context of diabetes. Furthermore, the review summarizes the cutting-edge progress in the development of ROS-neutralizing biomaterials tailored for the amelioration of diabetic osteopathy. These biomaterials are engineered to modulate ROS dynamics, thereby mitigating inflammatory responses and facilitating bone repair. Additionally, the challenges and therapeutic prospects of ROS-targeted biomaterials in clinical application of diabetic bone disease treatment is addressed.

Application of Antioxidant Compounds in Bone Defect Repair

Bone defects caused by trauma, tumor resection, and infections are significant clinical challenges. Excessive reactive oxygen species (ROS) usually accumulate in the defect area, which may impair the function of cells involved in bone formation, posing a serious challenge for bone repair. Due to the potent ROS scavenging ability, as well as potential anti-inflammatory and immunomodulatory activities, antioxidants play an indispensable role in the maintenance and protection of bone health and have gained increasing attention in recent years. This narrative review aims to give an overview of the main research directions on the application of antioxidant compounds in bone defect repair over the past decade. In addition, the positive effects of various antioxidants and their biomaterial delivery systems in bone repair are summarized to provide new insights for exploring antioxidant-based strategies for bone defect repair.

The Edifice of Vasculature-On-Chips: A Focused Review on the Key Elements and Assembly of Angiogenesis Models

The conception of vascularized organ-on-a-chip models provides researchers with the ability to supply controlled biological and physical cues that simulate the in vivo dynamic microphysiological environment of native blood vessels. The intention of this niche research area is to improve our understanding of the role of the vasculature in health or disease progression in vitro by allowing researchers to monitor angiogenic responses and cell-cell or cell-matrix interactions in real time. This review offers a comprehensive overview of the essential elements, including cells, biomaterials, microenvironmental factors, microfluidic chip design, and standard validation procedures that currently govern angiogenesis-on-a-chip assemblies. In addition, we emphasize the importance of incorporating a microvasculature component into organ-on-chip devices in critical biomedical research areas, such as tissue engineering, drug discovery, and disease modeling. Ultimately, advances in this area of research could provide innovative solutions and a personalized approach to ongoing medical challenges.

Surface modification of additive manufactured Ti6Al4V scaffolds with gelatin/alginate- IGF-1 carrier: An effective approach for healing bone defects

The study investigates the potential of porous scaffolds with Gel/Alg-IGF-1 coatings as a viable candidate for orthopaedic implants. The scaffolds are composed of additively manufactured Ti6Al4V lattices, which were treated in an alkali solution to obtain the anatase and rutile phases. The treated surface exhibited hydrophilicity of <11.5°. A biopolymer carrier containing Insulin-like growth factor 1 was coated on the samples using immersion treatment. This study showed that the surface-modified porous Ti6Al4V scaffolds increased cell viability and proliferation, indicating potential for bone regeneration. The results demonstrate that surface modifications can enhance the osteoconduction and osteoinduction of Ti6Al4V implants, leading to improved bone regeneration and faster recovery. The porous Ti6Al4V scaffolds modified with surface coating of Gel/Alg-IGF-1 exhibited a noteworthy increase in cell viability (from 80.7 to 104.1%viability) and proliferation. These results suggest that the surface modified scaffolds have potential for use in treating bone defects.

Antioxidant Hydrogels: Antioxidant Mechanisms, Design Strategies, and Applications in the Treatment of Oxidative Stress-Related Diseases

Oxidative stress is a biochemical process that disrupts the redox balance due to an excess of oxidized substances within the cell. Oxidative stress is closely associated with a multitude of diseases and health issues, including cancer, diabetes, cardiovascular diseases, neurodegenerative disorders, inflammatory conditions, and aging. Therefore, the developing of antioxidant treatment strategies has emerged as a pivotal area of medical research. Hydrogels have garnered considerable attention due to their exceptional biocompatibility, adjustable physicochemical properties, and capabilities for drug delivery. Numerous antioxidant hydrogels have been developed and proven effective in alleviating oxidative stress. In the pursuit of more effective treatments for oxidative stress-related diseases, there is an urgent need for advanced strategies for the fabrication of multifunctional antioxidant hydrogels. Consequently, the authors' focus will be on hydrogels that possess exceptional reactive oxygen species and reactive nitrogen species scavenging capabilities, and their role in oxidative stress therapy will be evaluated. Herein, the antioxidant mechanisms and the design strategies of antioxidant hydrogels and their applications in oxidative stress-related diseases are discussed systematically in order to provide critical insights for further advancements in the field.

Fabrication and In Vivo Assessment of Oxidatively Responsive PolyHIPE Scaffolds for Use in Diabetic Orthopedic Applications

Achieving surgical success in orthopedic patients with metabolic disease remains a substantial challenge. Diabetic patients exhibit a unique tissue microenvironment consisting of high levels of reactive oxygen species (ROS), which promotes osteoclastic activity and leads to decreased bone healing. Alternative solutions, such as synthetic grafts, incorporating progenitor cells or growth factors, can be costly and have processing constraints. Previously, the potential for thiol-methacrylate networks to sequester ROS while possessing tunable mechanical properties and degradation rates has been demonstrated. In this study, the ability to fabricate thiol-methacrylate interconnected porous scaffolds using emulsion templating to create monoliths with an average porosity of 97.0% is reported. The average pore sizes of the scaffolds range from 27 to 656 µm. The scaffolds can sequester pathologic levels of ROS via hydrogen peroxide consumption and are not impacted by sterilization. Subcutaneous implantation shows no signs of acute toxicity. Finally, in a 6-week bilateral calvarial defect model in Zucker diabetic fatty rats, ROS scaffolds increase new bone volume by 66% over sham defects. Histologic analysis identifies woven bone infiltration throughout the scaffold and neovascularization. Overall, this study suggests that porous thiol-methacrylate scaffolds may improve healing for bone grafting applications where high levels of ROS hinder bone growth.

Raising the Bar: Progress in 3D-Printed Hybrid Bone Scaffolds for Clinical Applications: A Review

Damage to bones resulting from trauma and tumors poses a significant challenge to human health. Consequently, current research in bone damage healing centers on developing three-dimensional (3D) scaffolding materials that facilitate and enhance the regeneration of fractured bone tissues. In this context, the careful selection of materials and preparation processes is essential for creating demanding scaffolds for bone tissue engineering. This is done to optimize the regeneration of fractured bones. This study comprehensively analyses the latest scientific advancements and difficulties in developing scaffolds for bone tissue creation. Initially, we clarified the composition and process by which bone tissue repairs itself. The review summarizes the primary uses of materials, both inorganic and organic, in scaffolds for bone tissue engineering. In addition, we present a comprehensive study of the most recent advancements in the mainstream techniques used to prepare scaffolds for bone tissue engineering. We also examine the distinct advantages of each method in great detail. This article thoroughly examines potential paths and obstacles in bone tissue engineering scaffolds for clinical applications.

Current Biomedical Applications of 3D-Printed Hydrogels

Three-dimensional (3D) printing, also known as additive manufacturing, has revolutionized the production of physical 3D objects by transforming computer-aided design models into layered structures, eliminating the need for traditional molding or machining techniques. In recent years, hydrogels have emerged as an ideal 3D printing feedstock material for the fabrication of hydrated constructs that replicate the extracellular matrix found in endogenous tissues. Hydrogels have seen significant advancements since their first use as contact lenses in the biomedical field. These advancements have led to the development of complex 3D-printed structures that include a wide variety of organic and inorganic materials, cells, and bioactive substances. The most commonly used 3D printing techniques to fabricate hydrogel scaffolds are material extrusion, material jetting, and vat photopolymerization, but novel methods that can enhance the resolution and structural complexity of printed constructs have also emerged. The biomedical applications of hydrogels can be broadly classified into four categories-tissue engineering and regenerative medicine, 3D cell culture and disease modeling, drug screening and toxicity testing, and novel devices and drug delivery systems. Despite the recent advancements in their biomedical applications, a number of challenges still need to be addressed to maximize the use of hydrogels for 3D printing. These challenges include improving resolution and structural complexity, optimizing cell viability and function, improving cost efficiency and accessibility, and addressing ethical and regulatory concerns for clinical translation.

Current advances in anisotropic structures for enhanced osteogenesis

Bone defects are a challenge to healthcare systems, as the aging population experiences an increase in bone defects. Despite the development of biomaterials for bone fillers and scaffolds, there is still an unmet need for a bone-mimetic material. Cortical bone is highly anisotropic and displays a biological liquid crystalline (LC) arrangement, giving it exceptional mechanical properties and a distinctive microenvironment. However, the biofunctions, cell-tissue interactions, and molecular mechanisms of cortical bone anisotropic structure are not well understood. Incorporating anisotropic structures in bone-facilitated scaffolds has been recognised as essential for better outcomes. Various approaches have been used to create anisotropic micro/nanostructures, but biomimetic bone anisotropic structures are still in the early stages of development. Most scaffolds lack features at the nanoscale, and there is no comprehensive evaluation of molecular mechanisms or characterisation of calcium secretion. This manuscript provides a review of the latest development of anisotropic designs for osteogenesis and discusses current findings on cell-anisotropic structure interactions. It also emphasises the need for further research. Filling knowledge gaps will enable the fabrication of scaffolds for improved and more controllable bone regeneration.

Combined Molybdenum Gelatine Methacrylate Injectable Nano-Hydrogel Effective Against Diabetic Bone Regeneration

Introduction

Bone defects in diabetes mellitus (DM) remain a major challenge for clinical treatment. Fluctuating glucose levels in DM patients lead to excessive production of reactive oxygen species (ROS), which disrupt bone repair homeostasis. Bone filler materials have been widely used in the clinical treatment of DM-related bone defects, but overall they lack efficacy in improving the bone microenvironment and inducing osteogenesis. We utilized a gelatine methacrylate (GelMA) hydrogel with excellent biological properties in combination with molybdenum (Mo)-based polyoxometalate nanoclusters (POM) to scavenge ROS and promote osteoblast proliferation and osteogenic differentiation through the slow-release effect of POM, providing a feasible strategy for the application of biologically useful bone fillers in bone regeneration.

Methods

We synthesized an injectable hydrogel by gelatine methacrylate (GelMA) and POM. The antioxidant capacity and biological properties of the synthesized GelMA/POM hydrogel were tested.

Results

In vitro, studies showed that hydrogels can inhibit excessive reactive oxygen species (ROS) and reduce oxidative stress in cells through the beneficial effects of pH-sensitive POM. Osteogenic differentiation assays showed that GelMA/POM had good osteogenic properties with upregulated expression of osteogenic genes (BMP2, RUNX2, Osterix, ALP). Furthermore, RNA-sequencing revealed that activation of the PI3K/Akt signalling pathway in MC3T3-E1 cells with GelMA/POM may be a potential mechanism to promote osteogenesis. In an in vivo study, radiological and histological analyses showed enhanced bone regeneration in diabetic mice, after the application of GelMA/POM.

Conclusion

In summary, GelMA/POM hydrogels can enhance bone regeneration by directly scavenging ROS and activating the PI3K/Akt signalling pathway.

Progress in Pluronic F127 Derivatives for Application in Wound Healing and Repair

Pluronic F127 hydrogel biomaterial has garnered considerable attention in wound healing and repair due to its remarkable properties including temperature sensitivity, injectability, biodegradability, and maintain a moist wound environment. This comprehensive review provides an in-depth exploration of the recent advancements in Pluronic F127-derived hydrogels, such as F127-CHO, F127-NH2, and F127-DA, focusing on their applications in the treatment of various types of wounds, ranging from burns and acute wounds to infected wounds, diabetic wounds, cutaneous tumor wounds, and uterine scars. Furthermore, the review meticulously examines the intricate interaction mechanisms employed by these hydrogels within the wound microenvironment. By elucidating the underlying mechanisms, discussing the strengths and weaknesses of Pluronic F127, analyzing the current state of wound healing development, and expanding on the trend of targeting mitochondria and cells with F127 as a nanomaterial. The review enhances our understanding of the therapeutic effects of these hydrogels aims to foster the development of effective and safe wound-healing modalities. The valuable insights provided this review have the potential to inspire novel ideas for clinical treatment and facilitate the advancement of innovative wound management approaches.

Preparation of Heavy Metal Trapping Flocculant Polyacrylamide-Glutathione and Its Application for Cadmium Removal from Water

In this study, a heavy metal trapping gel with multiple ligand groups was prepared for the first time using response surface methodology. The gel was produced by condensing and grafting glutathione as a grafting monomer onto the main polyacrylamide chain, based on the Mannich reaction mechanism with formaldehyde. FTIR, SEM, TG-DSC, and zeta potentials were used to characterize the gel. The results demonstrated that the gel was morphologically folded and porous, with a net-like structure, which enhanced its net trapping and sweeping abilities, and that glutathione was used to provide sulfhydryl groups to boost the metal trapping ability of polyacrylamide. Coagulation experiments showed that the highest efficiency of the removal of Cd ions from water samples was achieved when the concentration of polyacrylamide-glutathione was 84.48 mgL^-1, the concentration of Cd was 10.0 mgL^-1, the initial turbidity was 10.40 NTU, and the initial pH was 9.0. Furthermore, the presence of two cations, Cu and Zn, had an inhibitory effect on the removal of Cd ions. In addition, analysis of the zeta potential revealed the flocculation of polyacrylamide-glutathione. The flocculation mechanism of glutathione is mainly chelation, adsorption bridging, and netting sweeping.