Abstract
Numerous tissue-engineered constructs have been investigated as bone scaffolds in regenerative medicine. However, it remains challenging to non-invasively monitor the biodegradation and remodeling of bone grafts after implantation. Herein, silk fibroin/hydroxyapatite scaffolds incorporated with ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles were successfully synthesized, characterized, and implanted subcutaneously into the back of nude mice. The USPIO labeled scaffolds showed good three-dimensional porous structures and mechanical property, thermal stability for bone repair. After loaded with bone marrow-derived mesenchymal stem cells (BMSCs), the multifunctional scaffolds promoted cell adhesion and growth, and facilitated osteogenesis by showing increased levels of alkaline phosphatase activity and up-regulation of osteoblastic genes. Furthermore, in vivo quantitative magnetic resonance imaging (MRI) results provided valuable information on scaffolds degradation and bone formation simultaneously, which was further confirmed by computed tomography and histological examination. These findings demonstrated that the incorporation of USPIO into BMSCs-loaded multifunctional scaffold system could be feasible to noninvasively monitor bone regeneration by quantitative MRI. This tissue engineering strategy provides a promising tool for translational application of bone defect repair in clinical scenarios.
Highlights
Over the past decades, large progress has been made to develop new scaffolds and strategies in the field of bone tissue engineering
The HA spectrum showed the characteristic absorption bands in the region of 1100 cm−1, which corresponded to the O–H stretch, and at 603 cm−1, which corresponded to the PO4−3 stretch
The hybrid scaffolds possessed higher compressive modulus than pure silk fibroin (SF) scaffolds (0.61 ± 0.15MPa), and the compressive modulus of the scaffolds containing 0.75% ultrasmall superparamagnetic iron oxide (USPIO) were the best (1.18 ± 0.13MPa), following by the concentration of 0.25%(1.16 ± 0.10MPa). These results indicated that the incorporation of HA and USPIO nano-particles strengthened the mechanical property and thermal stability of scaffold to a certain extent, which are suitable for further studies
Summary
Large progress has been made to develop new scaffolds and strategies in the field of bone tissue engineering. Many different bone implant materials have been designed and evaluated in recent years (Bose et al, 2012; Walmsley et al, 2015; Roman et al, 2017; Roseti et al, 2017). Plenty of tissue engineering studies still utilize conventional tools, such as histological techniques. This requires tissue specimens by invasive methods, meaning that long-term follow-up assessment is extremely limited (Seung et al, 2015). Strategies for non-invasive imaging show great potential in the field of bone tissue engineering to facilitate longitudinal assessment of implants
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