Endowing Polyetheretherketone Implants with Osseointegration Properties: In Situ Construction of Patterned Nanorod Arrays

Multifunctional surface of the nano-morphic PEEK implant with enhanced angiogenic, osteogenic and antibacterial properties

Polyetheretherketone (PEEK) is a high-performance polymer suitable for use in biomedical coatings. The implants based on PEEK have been extensively studied in dental and orthopedic fields. However, their inherent inert surfaces and poor osteogenic properties limit their broader clinical applications. Thus, there is a pressing need to produce a multifunctional PEEK implant to address this issue. In response, we developed sulfonated PEEK (sPEEK)-Cobalt-parathyroid hormone (PTH) materials featuring multifunctional nanostructures. This involved loading cobalt (Co) ions and PTH (1-34) protein onto the PEEK implant to tackle this challenge. The findings revealed that the controlled release of Co2+ notably enhanced the vascular formation and the expression of angiogenic-related genes, and offered antimicrobial capabilities for sPEEK-Co-PTH materials. Additionally, the sPEEK-Co-PTH group exhibited improved cell compatibility and bone regeneration capacity in terms of cell activity, alkaline phosphatase (ALP) staining, matrix mineralization and osteogenic gene expression. It surpassed solely sulfonated and other functionalized sPEEK groups, demonstrating comparable efficacy even when compared to the titanium (Ti) group. Crucially, animal experiments also corroborated the significant enhancement of osteogenesis due to the dual loading of cobalt ions and PTH (1-34). This study demonstrated the potential of bioactive Co2+ and PTH (1-34) for bone replacement, optimizing the bone integration of PEEK implants in clinical applications.

Innovative Biomaterials for Bone Tumor Treatment and Regeneration: Tackling Postoperative Challenges and Charting the Path Forward

Surgical resection of bone tumors is the primary approach employed in the treatment of bone cancer. Simultaneously, perioperative interventions, particularly postoperative adjuvant anticancer strategies, play a crucial role in achieving satisfactory therapeutic outcomes. However, the occurrence of postoperative bone tumor recurrence, metastasis, extensive bone defects, and infection are significant risks that can result in unfavorable prognoses or even treatment failure. In recent years, there has been significant progress in the development of biomaterials, leading to the emergence of new treatment options for bone tumor therapy and bone regeneration. This progress report aims to comprehensively analyze the strategic development of unique therapeutic biomaterials with inherent healing properties and bioactive capabilities for bone tissue regeneration. These composite biomaterials, classified into metallic, inorganic non-metallic, and organic types, are thoroughly investigated for their responses to external stimuli such as light or magnetic fields, internal interventions including chemotherapy or catalytic therapy, and combination therapy, as well as their role in bone regeneration. Additionally, an overview of self-healing materials for osteogenesis is provided and their potential applications in combating osteosarcoma and promoting bone formation are explored. Furthermore, the safety concerns of integrated materials and current limitations are addressed, while also discussing the challenges and future prospects.

Polyetheretherketone development in bone tissue engineering and orthopedic surgery

Polyetheretherketone (PEEK) has been widely used in the medical field as an implant material, especially in bone tissue engineering and orthopedic surgery, in recent years. This material exhibits superior stability at high temperatures and is biosecured without harmful reactions. However, the chemical and biological inertness of PEEK still limits its applications. Recently, many approaches have been applied to improve its performance, including the modulation of physical morphology, chemical composition and antimicrobial agents, which advanced the osteointegration as well as antibacterial properties of PEEK materials. Based on the evolution of PEEK biomedical devices, many studies on the use of PEEK implants in spine surgery, joint surgery and trauma repair have been performed in the past few years, in most of which PEEK implants show better outcomes than traditional metal implants. This paper summarizes recent studies on the modification and application of biomedical PEEK materials, which provides further research directions for PEEK implants.

Polyetheretherketone implants with hierarchical porous structure for boosted osseointegration

BACKGROUND

Good osseointegration is the key to the long-term stability of bone implants. Thermoplastic polyetheretherketone (PEEK) has been widely used in orthopedics; however, its inherent biological inertia causes fibrous tissue to wrap its surface, which leads to poor osseointegration and thus greatly limits its clinical applications.

METHODS

Herein, we developed a facile yet effective surface modification strategy. A commonly used sulfonation coupled with "cold pressing" treatment in the presence of porogenic agent formed a three-dimensional hierarchical porous structure on PEEK surface. Subsequently, the effects of porous surface on the in vitro adhesion, proliferation and differentiation of rat bone marrow-derived mesenchymal stem cells (BMSCs) were evaluated. Finally, the osteoinduction and osseointegration of surface-porous PEEK implant were examined in the rat distal femoral defect model.

RESULTS

In vitro results showed that the surface modification did not significantly affect the mechanical performance and cytocompatibility of PEEK substance, and the porous structure on the modified PEEK substrate provided space for cellular ingrowth and enhanced osteogenic differentiation and mineralization of BMSCs. In vivo tests demonstrated that the surface-porous PEEK implant could effectively promote new bone formation and had higher bone-implant contact rate, thereby achieving good bone integration with the surrounding host bone. In addition, this modification technique was also successfully demonstrated on a medical PEEK interbody fusion cage.

CONCLUSION

The present study indicates that topological morphology plays a pivotal role in determining implant osseointegration and this facile and effective modification strategy developed by us is expected to achieve practical applications quickly.

Engineering Multifunctional Polyether Ether Ketone Implant: Mechanics-Adaptability, Biominerialization, Immunoregulation, Anti-Infection, Osteointegration, and Osteogenesis

Polyether ether ketone (PEEK) has become one of the most promising polymer implants in bone orthopedics, due to the biocompatibility, good processability, and radiation resistance. However, the poor mechanics-adaptability/osteointegration/osteogenesis/antiinfection limits the long-term in vivo applications of PEEK implants. Herein, a multifunctional PEEK implant (PEEK-PDA-BGNs) is constructed through in situ surface deposition of polydopamine-bioactive glass nanoparticles (PDA-BGNs). PEEK-PDA-BGNs exhibit good performance on osteointegration and osteogenesis in vitro and in vivo, due to their multifunctional properties including mechanics-adaptability, biominerialization, immunoregulation, anti-infection, and osteoinductive activity. PEEK-PDA-BGNs can show the bone tissue-adaptable mechanic surface and induce the rapid biomineralization (apatite formation) under a simulated body solution. Additionally, PEEK-PDA-BGNs can induce the M2 phenotype polarization of macrophages, reduce the expression of inflammatory factors, promote the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs), and improve the osseointegration and osteogenesis ability of the PEEK implant. PEEK-PDA-BGNs also show good photothermal antibacterial activity and can kill 99% of Escherichia coli (E. coli) and Methicillin-resistant Staphylococcus aureus (MRSA), suggesting their potential antiinfection ability. This work suggests that PDA-BGNs coating is probably a facile strategy to construct multifunctional (biomineralization, antibacterial, immunoregulation) implants for bone tissue replacement.

How Mechanical and Physicochemical Material Characteristics Influence Adipose-Derived Stem Cell Fate

Adipose-derived stem cells (ASCs) are a subpopulation of mesenchymal stem cells. Compared to bone marrow-derived stem cells, they can be harvested with minimal invasiveness. ASCs can be easily expanded and were shown to be able to differentiate into several clinically relevant cell types. Therefore, this cell type represents a promising component in various tissue engineering and medical approaches (e.g., cell therapy). In vivo cells are surrounded by the extracellular matrix (ECM) that provides a wide range of tissue-specific physical and chemical cues, such as stiffness, topography, and chemical composition. Cells can sense the characteristics of their ECM and respond to them in a specific cellular behavior (e.g., proliferation or differentiation). Thus, in vitro biomaterial properties represent an important tool to control ASCs behavior. In this review, we give an overview of the current research in the mechanosensing of ASCs and current studies investigating the impact of material stiffens, topography, and chemical modification on ASC behavior. Additionally, we outline the use of natural ECM as a biomaterial and its interaction with ASCs regarding cellular behavior.

Selective Polyetheretherketone Implants Combined with Graphene Cause Definitive Cell Adhesion and Osteogenic Differentiation

INTRODUCTION

Polyetheretherketone (PEEK) has good biosafety and chemical stability for bone repair. However, PEEK is biologically inert and cannot promote bone apposition. This study investigated whether graphene-modified PEEK (G-PEEK) could improve cell adhesion and osteogenic differentiation.

METHODS

G-PEEK was prepared by melted blending and was characterized. In vitro, the biocompatibility of G-PPEK and the ability to promote cell adhesion and osteogenic differentiation in rabbit bone marrow mesenchymal stem cells (rBMSCs) were examined using live and dead cell double staining, the cell counting kit-8 (CCK-8) assay, immunofluorescence and quantitative real-time PCR (qRT‒PCR). An in vivo rabbit extra-articular graft-to-bone healing model was established. At 4 and 12 weeks after surgery, CT analysis and histological evaluation were performed.

RESULTS

In vitro, G-PEEK significantly improved the adhesion and proliferation of rBMSCs, with good biocompatibility. In vivo, G-PEEK promoted new bone formation at the site of the bone defect.

CONCLUSION

G-PEEK showed excellent osteogenesis performance, which promises new applications in implant materials.

Bioheterojunction-Engineered Polyetheretherketone Implants With Diabetic Infectious Micromilieu Twin-Engine Powered Disinfection for Boosted Osteogenicity

Diabetic infectious micromilieu (DIM) leads to a critical failure rate of osseointegration by virtue of two main peculiarities: high levels of topical glucose and inevitable infection. To tackle the daunting issue, a bioheterojunction-engineered orthopedic polyetheretherketone (PEEK) implant consisting of copper sulfide/graphene oxide (CuS/GO) bioheterojunctions (bioHJs) and glucose oxidase (GOx) is conceived and developed for DIM enhanced disinfection and boosted osseointegration. Under hyperglycemic micromilieu, GOx can convert surrounding glucose into hydrogen peroxide (H₂ O₂ ). Then, upon infectious micromilieu, the bioHJs enable the catalyzation of H₂ O₂ to highly germicidal hydroxyl radical (·OH). As a result, the engineered implants massacre pathogenic bacteria through DIM twin-engine powered photo-chemodynamic therapy in vitro and in vivo. In addition, the engineered implants considerably facilitate cell viability and osteogenic activity of osteoblasts under a hyperglycemic microenvironment via synergistic induction of copper ions (Cu²⁺ ) and GO. In vivo studies using bone defect models of diabetic rats at 4 and 8 weeks further authenticate that bioHJ-engineering PEEK implants substantially elevate their osseointegration through biofilm elimination and vascularization, as well as macrophage reprogramming. Altogether, the present study puts forward a tactic that arms orthopedic implants with DIM twin-engine powered antibacterial and formidable osteogenic capacities for diabetic stalled osseointegration.

Modification of polyether ether ketone for the repairing of bone defects

Bone damage as a consequence of disease or trauma is a common global occurrence. For bone damage treatment - bone implant materials are necessary across three classifications of surgical intervention (i.e. fixation, repair, and replacement). Many types of bone implant materials have been developed to meet the requirements of bone repair. Among them, polyether ether ketone (PEEK) has been considered as one of the next generation of bone implant materials, owing to its advantages related to good biocompatibility, chemical stability, X-ray permeability, elastic modulus comparable to natural bone, as well as the ease of processing and modification. However, as PEEK is a naturally bioinert material, some modification is needed to improve its integration with adjacent bones after implantation. Therefore, it has become a very hot topic of biomaterials research and various strategies for the modification of PEEK including blending, 3D printing, coating, chemical modification and the introduction of bioactive and/or antibacterial substances have been proposed. In this systematic review, the recent advances in modification of PEEK and its application prospect as bone implants are summarized, and the remaining challenges are also discussed.