Abstract
Nowadays, artificial bone materials have been widely applied in the filling of non-weight bearing bone defects, but scarcely ever in weight-bearing bone defects. This study aims to develop an artificial bone with excellent mechanical properties and good osteogenic capability. Firstly, the collagen-thermosensitive hydrogel-calcium phosphate (CTC) composites were prepared as follows: dissolving thermosensitive hydrogel at 4 °C, then mixing with type I collagen as well as tricalcium phosphate (CaP) powder, and moulding the composites at 37 °C. Next, the CTC composites were subjected to evaluate for their chemical composition, micro morphology, pore size, Shore durometer, porosity and water absorption ability. Following this, the CTC composites were implanted into the muscle of mice while the 70% hydroxyapatite/30% β-tricalcium phosphate (HA/TCP) biomaterials were set as the control group; 8 weeks later, the osteoinductive abilities of biomaterials were detected by histological staining. Finally, the CTC and HA/TCP biomaterials were used to fill the large segments of tibia defects in mice. The bone repairing and load-bearing abilities of materials were evaluated by histological staining, X-ray and micro-CT at week 8. Both the CTC and HA/TCP biomaterials could induce ectopic bone formation in mice; however, the CTC composites tended to produce larger areas of bone and bone marrow tissues than HA/TCP. Simultaneously, bone-repairing experiments showed that HA/TCP biomaterials were easily crushed or pushed out by new bone growth as the material has a poor hardness. In comparison, the CTC composites could be replaced gradually by newly formed bone and repair larger segments of bone defects. The CTC composites trialled in this study have better mechanical properties, osteoinductivity and weight-bearing capacity than HA/TCP. The CTC composites provide an experimental foundation for the synthesis of artificial bone and a new option for orthopedic patients.
Highlights
Nowadays, artificial bone materials have been widely applied in the filling of non-weight bearing bone defects, but scarcely ever in weight-bearing bone defects
The conventional hydroxyapatite/β-tricalcium phosphate (HA/TCP) biomaterials contained 70 wt% HA and 30 wt% β-TCP were prepared as follows: the ceramic powders were prepared by wet method using Ca(NO3)2·4H2O and (NH4)2HPO4 as raw materials, 10% H 2O2 as foaming agent was mixed with powders to form slurry, which was heated for foaming at 70–80 °C
The SEM photos showed that collagen and hydrogel were mixed with collagen as well as tricalcium phosphate (CaP) in collagenthermosensitive hydrogel-calcium phosphate (CTC) bio-composites, especially in the photo of higher proportions (10,000×), which presented the materials wrapped by hydrogel and formed many tiny pores (< 5 μm)
Summary
Artificial bone materials have been widely applied in the filling of non-weight bearing bone defects, but scarcely ever in weight-bearing bone defects. The bone repairing and load-bearing abilities of materials were evaluated by histological staining, X-ray and micro-CT at week 8 Both the CTC and HA/TCP biomaterials could induce ectopic bone formation in mice; the CTC composites tended to produce larger areas of bone and bone marrow tissues than HA/TCP. This study takes advantage of thermosensitive hydrogel, type I collagen, and CaP powders as the raw materials to synthesize the CTC composites. CaP material was an excellent artificial bone: we speculated that the hardness and elasticity of the bio-composites would be improved with the help of thermosensitive hydrogel and collagen I. The CTC composites would be implanted in muscle to induce ectopic bone formation and filled in large segments of tibia defects in mice. The overall idea of the experiment is shown in the Fig. 1
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