Cu-Sr Bilayer Bioactive Glass Nanoparticles/Polydopamine Functionalized Polyetheretherketone Enhances Osteogenic Activity and Prevents Implant-Associated Infections through Spatiotemporal Immunomodulation

Vancomycin-encapsulated hydrogel loaded microarc-oxidized 3D-printed porous Ti6Al4V implant for infected bone defects: Reconstruction, anti-infection, and osseointegration

Infected bone defect is a formidable clinical challenge. Conventional approaches to prevention and treatment for infected bone defects are unsatisfactory. The key elements of the treatment are bone defect reconstruction, anti-infection, and osteogenesis. Conventional treatment methods remain unsatisfactory owing to the absence of composite integrating materials with anti-infective, and osteogenic activities as well as proper mechanical strength at the same time. In this study, we fabricated a vancomycin-encapsulated hydrogel with bacteria-responsive release properties combined with a shaved porous (submicron-micron) three-dimensional-printed Ti6Al4V implant. The implant surface, modified with submicron-sized pores through microarc oxidation (MAO), showed enhanced osteogenic activity and integrated well with the hydrogel drug release system, enabling sustained vancomycin release. In vitro experiments underscored the commendable antibacterial ability, biosafety, and osteoinductive potential. Effective antibacterial and osteogenic abilities of the implant were further demonstrated in vivo in infected rabbit bone defects. These results showed that the vancomycin-encapsulated hydrogel-loaded microarc-oxidized 3D-printed porous Ti6Al4V can repair the infected bone defects with satisfactory anti-infection and osseointegration effects.

MBG/BSA Bone Grafts Immunomodulate Bone Regeneration by Releasing Bioactive Ions in Inflammatory Bone Defects

Since the diseases that cause bone defects are mostly inflammatory diseases, the current bone grafts are unable to effectively regulate osteoimmune activity, leading to the impaired osteogenesis and unfavorable bone regeneration. In this study, inspired by bone composition, biomimetic mesoporous bioactive glass nanoparticle (MBG)/bovine serum albumin (BSA) bone grafts are designed for inflammatory bone defects. Systematically, MBG/BSA bone grafts are evaluated for characterization, bioactivity, anti-inflammatory, antioxidant activity, and osteogenic activity. MBG/BSA bone grafts are proved to be biocompatible and can release bioactive ions including calcium and silicon in a sustained manner. Furthermore, MBG/BSA reprograms the macrophage phenotype toward anti-inflammation that is beneficial for bone regeneration. The antioxidative activity is also validated under inflammation and the mechanism may be via the interleukin-4 (IL-4)/Signal transducer and activator of transcription 6 (STAT6) pathway. The osteogenic differentiation and mineralization are also facilitated due to the improved immunoregulation of MBG/BSA. Overall, this work suggests that the MBG/BSA bone grafts with improved immunomodulatory properties are an ideal material for inflammatory bone regeneration application.

Copper metabolism in osteoarthritis and its relation to oxidative stress and ferroptosis in chondrocytes

Ferroptosis, an iron-ion-dependent process of lipid peroxidation, damages the plasma membrane, leading to non-programmed cell death. Osteoarthritis (OA), a prevalent chronic degenerative joint disease among middle-aged and older adults, is characterized by chondrocyte damage or loss. Emerging evidence indicates that chondrocyte ferroptosis plays a role in OA development. However, most research has concentrated on ferroptosis regulation involving typical iron ions, potentially neglecting the significance of elevated copper ions in both serum and joint fluid of patients with OA. This review aims to fill this gap by systematically examining the interplay between copper metabolism, oxidative stress, ferroptosis, and copper-associated cell death in OA. It will provide a comprehensive overview of copper ions' role in regulating ferroptosis and their dual role in OA. This approach seeks to offer new insights for further research, prevention, and treatment of OA.

Engineering Ga-doped mesoporous bioactive glass-integrated PEEK implants for immunomodulatory and enhanced osseointegration effects

With the increasing aging population, the demand for orthopedic implants is also growing. Polyether ether ketone (PEEK) is considered a promising material for orthopedic implants due to its excellent biocompatibility. However, the lack of bioactivity and excessive immune response post-implantation often impair bone integration. Therefore, it is urgent to bio-functionalize PEEK-based implants to promote bone integration. This study employs a simple, economical, and feasible method to coat Ga-ion doped bioactive glass nanoparticles (Ga-MBGs) onto sulfonated PEEK surfaces, constructing a multifunctional PEEK-based orthopedic implant. The resulting bio-functionalized PEEK implants promote macrophage M2 phenotype polarization, thus fostering an anti-inflammatory immune microenvironment. Moreover, the direct osteogenic effect of Ga ions and the immuno-osteogenic effect through promoting macrophage M2 polarization enhance osteogenic differentiation potential in vitro and bone integration in vivo. A sequence of in vivo and in vitro experiments substantiates the essential and intricate function of this innovative orthopedic implants. in regulating normal bone immunity and metabolism. Overall, the application of Ga-MBGs provides a simple, economical, and effective method for developing multifunctional orthopedic implants. This surface bio-functionalized PEEK implant, capable of modulating immunity and bone metabolism, holds significant clinical application potential as an orthopedic implant.

Polydopamine-Based Biomaterials in Orthopedic Therapeutics: Properties, Applications, and Future Perspectives

Polydopamine is a versatile and modifiable polymer, known for its excellent biocompatibility and adhesiveness. It can also be engineered into a variety of nanoparticles and biomaterials for drug delivery, functional modification, making it an excellent choice to enhance the prevention and treatment of orthopedic diseases. Currently, the application of polydopamine biomaterials in orthopedic disease prevention and treatment is in its early stages, despite some initial achievements. This article aims to review these applications to encourage further development of polydopamine for orthopedic therapeutic needs. We detail the properties of polydopamine and its biomaterial types, highlighting its superior performance in functional modification on nanoparticles and materials. Additionally, we also explore the challenges and future prospects in developing optimal polydopamine biomaterials for clinical use in orthopedic disease prevention and treatment.

3D printing technology and its combination with nanotechnology in bone tissue engineering

With the graying of the world's population, the morbidity of age-related chronic degenerative bone diseases, such as osteoporosis and osteoarthritis, is increasing yearly, leading to an increased risk of bone defects, while current treatment methods face many problems, such as shortage of grafts and an incomplete repair. Therefore, bone tissue engineering offers an alternative solution for regenerating and repairing bone tissues by constructing bioactive scaffolds with porous structures that provide mechanical support to damaged bone tissue while promoting angiogenesis and cell adhesion, proliferation, and activity. 3D printing technology has become the primary scaffold manufacturing method due to its ability to precisely control the internal pore structure and complex spatial shape of bone scaffolds. In contrast, the fast development of nanotechnology has provided more possibilities for the internal structure and biological function of scaffolds. This review focuses on the application of 3D printing technology in bone tissue engineering and nanotechnology in the field of bone tissue regeneration and repair, and explores the prospects for the integration of the two technologies.

Macrophages in the process of osseointegration around the implant and their regulatory strategies

PURPOSE/AIM OF THE STUDY

To summarize and discuss macrophage properties and their roles and mechanisms in the process of osseointegration in a comprehensive manner, and to provide theoretical support and research direction for future implant surface modification efforts.

MATERIALS AND METHODS

Based on relevant high-quality articles, this article reviews the role of macrophages in various stages of osseointegration and methods of implant modification.

RESULTS AND CONCLUSIONS

Macrophages not only promote osseointegration through immunomodulation, but also secrete a variety of cytokines, which play a key role in the angiogenic and osteogenic phases of osseointegration. There is no "good" or "bad" difference between the M1 and M2 phenotypes of macrophages, but their timely presence and sequential switching play a crucial role in implant osseointegration. In the implant surface modification strategy, the induction of sequential activation of the M1 and M2 phenotypes of macrophages is a brighter prospect for implant surface modification than inducing the polarization of macrophages to the M1 or M2 phenotypes individually, which is a promising pathway to enhance the effect of osseointegration and increase the success rate of implant surgery.

2D silicene nanosheets-loaded coating for combating implant-associated infection

Implant-associated infection (IAI) is an unsolved problem in orthopaedics. Current therapies, including antibiotics and surgical debridement, can lead severe clinical and financial burdens on patients. Therefore, there is an urgent need to reinforce the inherent antibacterial properties of implants. Recently, two-dimensional (2D) silicene nanosheets (SNs) have gained increasing attention in biomedical fields owing to their considerable biocompatibility, biodegradability and strong photothermal-conversion performance. Herein, a dual-functional photosensitive coating on a Ti substrate (denoted as TPSNs) was rationally fabricated for bacterial inhibition and osteogenesis promotion. For the first time, SNs were loaded onto the surface of implants. Hyperthermia generated by the SNs and polydopamine (PDA) coating under 808 nm laser irradiation achieved the in vitro anti-bacterial efficiency of 90.7 ± 2.4 % for S. aureus and 88.0 ± 5.8 % for E. coli, respectively. In addition, TPSNs exhibited promising biocompatibility for the promotion of BMSC (bone marrow mesenchymal stem cells) proliferation and spreading. The presence of silicon (Si) in TPSNs contributed to the improved osteogenic differentiation of BMSCs, elevating the expressions of RUNX2 and OCN. In animal experiments, the combination of TPSNs with photothermal therapy (PTT) achieved an anti-bacterial efficiency of 89.2 % ± 1.6 % against S. aureus. Furthermore, TPSNs significantly improved bone-implant osseointegration in vivo. Overall, the development of a dual-functional TPSNs coating provides a new strategy for combating IAI.

PRP coating on different modified surfaces promoting the osteointegration of polyetheretherketone implant

Introduction: Polyetheretherketone (PEEK) material implants have been applied more and more clinically recently. In order to increase the osteogenic activity of PEEK material, the microstructure change of the material surface and the construction of functional microcoatings have become a hot research topic. This study investigated the ability of PEEK surfaces modified by different methods to carry Platelet-rich plasma (PRP) and the osteogenic ability of different PEEK microstructures after carrying PRP in vivo/in vitro. Methods: In this study, PEEK surfaces were modified by sulfuric acid, gaseous sulfur trioxide and sandpaper. Next, PRP from SD rats was prepared and incubated on PEEK material with different surface microstructures. Lactate dehydrogenase test, scanning electron microscope and Elisa assay was used to evaluate adhesion efficiency of PRP. Then in vitro tests such as CCK-8, ALP staining, ARS staining and RT-qPCR et al were used to further evaluate osteogenesis ability of the PRP coating on PEEK surface. Finally, The tibia defects of SD rats were established, and the new bone was evaluated by Micro-CT, HE staining, and immunofluorescence staining. Results: The sandpaper-polished PEEK with the strongest PRP carrying capacity showed the best osteogenesis. Our study found that the modified PEEK surface with PRP coating has excellent osteogenic ability and provided the basis for the interface selection of PRP for the further application of PEEK materials. Discussion: Among the three PEEK modified surfaces, due to the most PRP carrying and the strongest osteogenic ability in vitro/vivo, the frosted surface was considered to be the most suitable surface for the preparation of PRP coating.