Abstract
The optimal conditions for the preparation of superparamagnetic chitosan plasmid (pReceiver‐M29‐VEGF165/DH5a) gelatin microspheres (SPCPGMs) were determined. Then, the performance of the SPCPGMs during neovascularization was evaluated in vivo. The SPCPGMs were prepared through a cross‐linking curing method and then filled into the hollow scaffold of an artificial bone. Neovascularization at the bone defect position was histologically examined in samples collected 2, 4, 6, and 8 weeks after the operation. The cellular magnetofection rate of superparamagnetic chitosan nanoparticles/plasmid (pReceiver‐M29‐VEGF165/DH5a) complexes reached 1–3% under static magnetic field (SMF). Meanwhile, the optimal conditions for SPCPGM fabrication were 20% Fe3O4 (w/v), 4 mg of plasmid, 5.3 mg of glutaraldehyde, and 500 rpm of emulsification rotate speed. Under oscillating magnetic fields (OMFs), 4–6 μg of plasmids was released daily for 21 days. Under the combined application of SMF and OMF, evident neovascularization occurred at the bone defect position 6 weeks after the operation. This result is expected to provide a new type of angiogenesis strategy for the research of bone tissue engineering.
Highlights
Large segmental bone defect is one of the major problems that require urgent clinical solution (Verrier, Alini, Alsberg, et al, 2016; Yassine, Mokhtar, Houari, Karim, & Mohamed, 2017)
SPCPGM or chitosan plasmid (pReceiverM29-VEGF165/DH5a) gelatin microspheres (CPGMs) were filled into the porous bone implants (Figure 4b) and plasmid release status was observed under a thermostatic water bath and oscillating magnetic fields (OMFs)
The specific mechanism remains to be clarified, and whether the magnetic transfection of cells was completed because OMF facilitated the interchange of oxygen, protein, and other nutritive substances inside and outside the scaffold and surrounding cells still needs to be verified through a follow-up experiment
Summary
Large segmental bone defect is one of the major problems that require urgent clinical solution (Verrier, Alini, Alsberg, et al, 2016; Yassine, Mokhtar, Houari, Karim, & Mohamed, 2017). Multiple artificial bone vascularization methods have been adopted, the application of prevascularized engineered bone tissues and a graft combined with cocultured endothelial cells, osteoblasts, and stem cells (Almubarak et al, 2016; Fan, Zeng, Wang, Zhu, & Pei, 2014; Myeroff & Archdeacon, 2011; Zhang et al, 2016). The use of a magnetic carrier drug microsphere and bioactive artificial bone under magnetic fields in vitro (OMF and/or SMF) for vascularization has not been reported before Basing on those above theories, we constructed superparamagnetic chitosan plasmid (pReceiver-M29-VEGF165/DH5a) gelatin microspheres (SPCPGMs) and obtained their optimal formula through a cross-linking curing method. This application is expected to provide a new type of angiogenesis strategy for bone tissue engineering
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