Addressing bone defects is a complex medical challenge that involves dealing with various skeletal conditions, including fractures, osteoporosis (OP), bone tumours, and bone infection defects. Despite the availability of multiple conventional treatments for these skeletal conditions, numerous limitations and unresolved issues persist. As a solution, advancements in biomedical materials have recently resulted in novel therapeutic concepts. As an emerging biomaterial for bone defect treatment, graphene oxide (GO) in particular has gained substantial attention from researchers due to its potential applications and prospects. In other words, GO scaffolds have demonstrated remarkable potential for bone defect treatment. Furthermore, GO-loaded biomaterials can promote osteoblast adhesion, proliferation, and differentiation while stimulating bone matrix deposition and formation. Given their favourable biocompatibility and osteoinductive capabilities, these materials offer a novel therapeutic avenue for bone tissue regeneration and repair. This comprehensive review systematically outlines GO scaffolds’ diverse roles and potential applications in bone defect treatment.

Cite this article: Bone Joint Res 2024;13(12):725–740.

Introduction

Ink engineering can advance 3D-printability for better therapeutics, with optimized proprieties. Herein, we describe a methodology for yielding 3D-printable nanocomposite inks (NC) using low-viscous matrices, via the interaction between the organic and inorganic phases by chemical coupling.

Introduction

Intervertebral disc degeneration (IVDD) associated with low back pain is a major contributor to global disability. Current treatments are poorly efficient in the long-term resulting in medical complications. Therefore, minimally invasive injectable therapies are required to repopulate damaged tissues and aid regeneration. Among injectable biomaterials, self-assembling peptide hydrogels (SAPHs) represent potential candidates as 3D cell carriers. Moreover, the advent of graphene-related materials has opened the route for the fabrication of graphene-containing hydrogel nanocomposites to direct cellular fate. Here, we incorporated graphene oxide (GO) within a SAPH to develop a biocompatible and injectable hydrogel to be used as cell carrier to treat IVDD.

The enhancement of current bone cement properties is a challenging issue that has been the focus of much research. Developing bone composites with high level of cytocompatibility, mechanical and antibacterial properties is a challenging task. We overcome this challenge by designing a nanocomposite that contain two-dimensional (2D) nanosheets. To develop our novel bone cement nanocomposite, 2D nanosheets were synthesized, mixed in different ratios, and then added to the PMMA matrix. The results reveal that the incorporation of 2D nanosheets into the PMMA matrix leads to increase in the antibacterial properties of the bone cement composite against E. coli bacteria. In addition, the 2D nanosheets improve the compression strength of the bone cement nanocomposite significantly. We also show that nanosheets increased the bioactivity of the bone cements. Finally, MTT assay results indicate that PMMA as a control sample has the lowest cytocompatibility, however, our novel nanocomposites have the highest amount of cytocompatibility. Thus, the current study suggests that 2D nanosheets are potential filler components for the next generation of PMMA bone cement nanocomposites. The findings of this work reveal that the excellent performance of the proposed bone composite can result in a paradigm shift in design of state-of-the art bone cement composites.

The use of mesenchymal stem cells (MSCs) for cartilage and bone tissue engineering needs to be supported by scaffolds that may release stimuli for modulate cell activity.

The objective of this study was to asses if MSC undergo differentiation when cultured upon a membrane of nanofibers of poly-L-lactic acid loaded with hydroxyapatite nanoparticles (PLLA/HAp).

The PLLA/HAp nanocomposite was prepared by electrospinning. Membranes microstructure was evaluated by SEM. MSCs were seeded on PLLA/HAp membranes by standard static seeding and cultured either in basal medium or Chondrogenic Differentiation Medium. Cell attachment and engraftment was assessed 3 days after seeding and MSC differentiation was evaluated by immunostaining for CD29, SOX-9 and Aggrecan under a confocal microscope after 14 days.

PLLA/HAp membrane obtained was composed by fibers (average diameter of 7μm) with nano-dispersed hydroxyapatite aggregates (average diameter of 0.3μm). 3 days after seeding, MSCs were well adhered on the PLLA/HAp fibers with a spindled shape. After 14 days of culture all MSCs were positive for SOX-9 in both basal and chondrogenic media groups. Aggrecan was present around the cells. MSCs were either CD29 positive or negative.

We demonstrated that PLLA/HAp nanocomposites are able to induce differentiation of MSCs in chondrocyte-like cells. Since HAp has osteoinductive properties, the chondrogenic phenotype acquired by the MSCs may be either stable or an intermediate stage toward enchondral ossification. The presence of CD29 and SOX-9 double positive cells indicate intermediate differentiation phases.

This nanocomposite could be a susceptible scaffold for bone or cartilage tissue engineering using undifferentiated MSCs.

Aims: to investigate the mechanical properties of a new nanocomposite bone cement radiopacified with Barium Sulfate (BaSu) nanoparticles added at different concentrations, compared to a control cement with the classical BaSu microparticles. Methods: the starting material was Endurance (J& J/ DePuy, USA) bone cement without BaSu; the radi-opacifier particles have been mixed into the cement powder in several different concentrations of 5, 10, 20, 30, 40% of the weight respectively. Two groups were studied: controls, with classical medical grade BaSu particles (average size 1000 nm) and nanocomposites, with nanoparticles (av. size 100 nm). In accordance with the ASTM, an Instron 4201 machine tested a minimum of 6 specimens for each concentration. Tensile tests were performed at cross-head speeds of 1mm/sec, while compression tests were performed at 25,4 mm/sec. Results were statistically analysed. Results: nanocomposites had higher compressive Yield strength in all groups except 30 and 40% and lower compressive Modulus in all but 5% group (no significant difference). Nanocomposites had higher tensile values in 5%, 10%, and 40% concentrations for Strain-to-failure, yield stress, and Work-of-Fracture, and no significant differences in the other concentrations. Tensile modulus had not statistically significant variations. Higher BaSu concentrations give increases in tensile modulus and decreases in the other tensile properties for both the groups. The nanocomposite outperformed the control in the 5, 10, and 20% groups, while the 30 and 40% groups had no significant differences; all the results were above ASTM requirements. Conclusions: bone cement has several uses, like joint replacement, filling defects in tumour or revision surgery, and more recently vertebroplasty. These applications require different properties and would have benefits from the possibility to change viscosity, radiopacity, time of polymerisation, mechanical features. Previous studies have demonstrated the improved performances of the new nanocomposite cement at the clinical used concentration of 10%. This study investigated the possibility to augment the concentration of BaSu and therefore the radiopacity and their relative effect on the mechanical properties; the results demonstrated the good compliance of the nanoparticles cement in this field. This would be useful in particular for specific applications such vertebroplasty. Further studies are needed to investigate and determine the ideal fatigue, handling and mixing properties, viscosity and radiopacity