A novel scaffold containing calcium polyphosphate and silk fibroin for bone tissue engineering

Objectives: Bioceramics have been extensively used for bone repairing and regeneration as an scaffold of bone tissue engineering. Despite bioceramics possess good biocompatibility and osteoconduction, they do not fulfill one of the key requirements for the complex bone engineering: osteointergration. Therefore, it is our goal to develop a new composite of bioceramics with osteointergration potential.
Methods: In this study, silk fibrion was applied to calcium polyphosphate through a simple crosslinking method. As a result, a novel bone repair scaffold based on the combination of silk fibroin (SF) and calcium polyphosphate (CPP) composite is developed. SF and CPP scaffolds with or without glutaraldehyde were blended together. The composite scaffolds were characterized by fourier transform infrared spectroscopy, XRD and SEM in order to reveal their composition, size distribution and surface morphology. Compressive strength and degradation tests were assessed to evaluate the mechanical and chemical stabilities of SF/CPP in vitro. The cell biocompatibility was measured with respect to the cytotoxicity of the extractions of scaffolds. The SF/CPP scaffolds yield a higher compressive strength and the degradation behavior after silk fibroin doped into CPP structure. In vivo bone implantation was performed to evaluate the biodegradability, osteoconductivity and osteointergration of the new scaffold, and the bone formation examined by using X-ray radiography.
Results: The results indicated that the obtained SF/CPP scaffolds exhibited a better cell biocompatibility and tissue biocompatibility than the conventional biomaterials such as CPP and hydroxyapatite (HA) scaffolds. The in vivo immunohistochemistry staining for VEGF also showed that SF/CPP had a potential to promote the formation of angiogenesis and the regeneration of bone.
Conclusions: Considering the suitable mechanical properties, good osteointergration and easy availability, SF/CPP could be a promising bone substitute/scaffold for tissue engineering.