Angiogenesis and osteogenesis in tissue-engineered bone are the key factors in the clinical application of tissue-engineering technology to repair large bone defects. In vivo cells that are farther than 200 μm from capillaries cannot survive due to lack of nutrients and oxygen, and thus, the tissue-engineered bone is not suitable for repairing large bone defects. In this study, we constructed a novel artificial bone scaffold loaded with superparamagnetic plasmid gene microspheres. Magnetic micro-movement of the magnetic microspheres in the scaffold was generated by an oscillating magnetic field and a static magnetic field to promote the release of plasmid genes from microspheres for transfection of surrounding cells, resulting in protein expression of vascular endothelial growth factor, thus promoting angiogenesis and osteogenesis in the scaffold, internal vascularization of the artificial bone scaffold and repair of large bone defects.

This study aimed to improve the magnetofection of MG-63 osteoblasts by integrating the use of a novel uniform magnetic field with low molecular weight polyethylenimine modified superparamagnetic iron oxide nanoparticles (PEI-SPIO-NPs). The excellent characteristics of PEI-SPIO-NPs such as size, zeta potential, the pDNA binding and protective ability were determined to be suitable for gene delivery. The novel uniform magnetic field enabled polyethylenimine-modified superparamagnetic iron oxide nanoparticles/pDNA complexes (PEI-SPIO-NPs/pDNA complexes) to rapidly and uniformly distribute on the surface of MG-63 cells, averting local transfection and decreasing disruption of the membrane caused by the centralization of positively charged PEI-SPIO-NPs, thereby increasing the effective coverage of magnetic gene carriers during transfection, and improving magnetofection efficiency. This innovative uniform magnetic field can be used to determine the optimal amount between PEI-SPIO-NPs and pDNA, as well as screen for the optimal formulation design of magnetic gene carrier under the homogenous conditions. Most importantly, the novel uniform magnetic field facilitates the transfection of PEI-SPIO-NPs/pDNA into osteoblasts, thereby providing a novel approach for the targeted delivery of therapeutic genes to osteosarcoma tissues as well as a reference for the treatment of other tumors.

Background and purpose Open reduction and internal fixation through the posterior approach are standard methods for treating middle-inferior humerus fractures. Given the limited operative field and difficulty in locating the radial nerve, the minimally invasive percutaneous plate osteosynthesis (MIPPO) technique via the posterior approach to treat middle-inferior humerus fractures has rarely been reported. This study aims to evaluate the clinical effect of the preoperative study of the radial nerve position by B-ultrasound and its intraoperative protection combined with MIPPO in managing middle-inferior humerus fractures. Methods The data were studied retrospectively involving 64 participants who had surgery for middle-inferior humerus fractures from the start of 2017 to the end of 2020. Participants were divided into two groups, those treated with the MIPPO technique, including newly developed dual procedures and preoperative position and protection of radial nerve by B-ultrasound (group A), and those treated with open reduction and internal plating fixation (group B). Results All the cases were followed up for 12–34 months (an average of 25.6 ± 8.76 months), and there was no significant difference in the mean operative duration, surgical incision infection, range of motion (ROM) and MEPS (Mayo elbow performance score) for groups A and B. However, the occurrence of complications (radial nerve palsy, bone nonunion and flexible internal fixation or ruptures) in group B was significantly higher than the group A. A statistically significant difference was observed in the intraoperative blood loss, hospital stay and fracture nonunion time between the two groups. All the cases gained bone union within the MIPPO group. Conclusion MIPPO via the posterior dual approach associated with preoperative position and protection of radial nerve by B-ultrasound does not increase radial nerve injury, however, it exhibits obvious advantages in the bone union, which is worthy of clinical application.

To develop a vancomycin-loaded superparamagnetic chitosan nanoparticles (Vm-SPMCNs) system for the treatment of chronic pyogenic osteoarthrosis to avoid the critical side effects caused by the systemic administration of vancomycin, the preparation process of Vm-SPMCNs was optimized by the orthogonal array design method; the optimum parameters were 1.2 g of chitosan, 0.2 g of vancomycin, 0.3 g of magnetite (Fe3O4), 12 mL of glutaraldehyde and stirring at 400 rpm. The drug loading and encapsulation efficiencies of the optimum Vm-SPMCNs were 10.30 ± 0.42% and 79.02 ± 1.81%, respectively. The Fourier transform infrared spectra confirmed that vancomycin was successfully bound to the magnetic chitosan nanoparticles. The Vm-SPMCNs were superparamagnetic particles with a diameter of 207.2 nm. The results of in vitro release tests suggested that the Vm-SPMCNs could constantly release vancomycin to maintain the concentration above the minimum inhibitory concentration for ten days, and noninvasive external magnetic stimulation could modulate the release profile according to the actual therapeutic requirements.

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