Novel bioactive glass based injectable bone cement with improved osteoinductivity and its in vivo evaluation

Abstract

Recently, more and more attention has been paid to the development of a new generation of injectable bone cements that are bioactive, biodegradable and are able to have appropriate mechanical properties for treatment of vertebral compression fractures (VCFs). In this study, a novel PSC/CS composite cement with high content of PSC (a phytic acid-derived bioactive glass) was prepared and evaluated in both vitro and vivo. The PSC/CS cement showed excellent injectability, good resistance to disintegration, radiopacity and suitable mechanical properties. The in vitro test showed that the cement was bioactive, biocompatible and could maintain its shape sustainably, which made it possible to provide a long-term mechanical support for bone regeneration. Radiography, microcomputed tomography and histology of critical sized rabbit femoral condyle defects implanted with the cements proved the resorption and osteoinductivity of the cement. Compared with the PMMA and CSPC, there were more osteocyte and trabeculae at the Bone-Cement interface in the group PSC/CS cement. The volume of the residual bone cement suggested that PSC/CS had certain ability of degradation and the resorption rate was much lower than that of the CSPC cement. Together, the results indicated that the cement was a promising bone cement to treat the VCFs.

Figure 1

(a) The optical image of PSC/CS cement just injected and immersed in PBS for 24 h; (b) in vitro weight loss profiles of hardened CSC, CSPC and PSC/CS cements after immersion in SBF; the appearance of hardened (c) CSC and (d) PSC/CS cements after immersion in SBF for different time.

Figure 2

(a) FTIR spectra of the PSC/CS cement after immersion in SBF for 0, 1, 2, 3 and 8 weeks. (b) SEM images of PSC/CS cement after immersion in SBF for 8 weeks. (c) MTT assay for proliferation of MG63 cells after culturing for 48 h. (d) The MG63 cell morphologies on PSC/CS cement after culturing for 24 h.

Figure 3

Radiographic images of defect site of three groups.

Figure 4

Sagittal images (column I) and 3D reconstructed images (column II and III) by micro-CT imaging of the area surrounding the cement implants after 12 weeks. The green part represents newly formed bone, and the gray part represents residual cement.

Figure 5

Quantitative analysis of new bone formation and residual cement from micro-CT images. *Indicates significant differences between the groups connected with the line (P < 0.05).

Figure 6

Histology photomicrographs of H&E staining of bone defects for three groups after 12 weeks. Abbreviations and signs used: newly bone (NB), host bone (HB), the implanted material (IM), bone marrow (BM). Scale bar represents 500 μm (left row) and 100 μm (right row).