Synthetic biomaterials have been developed and used for bone grafting. Here, we developed a biodegradable sponge composite for bone tissue engineering by combining β-tricalcium phosphate (β-TCP) and collagen. In addition, we sought to determine the optimal β-TCP granules/ collagen ratio by evaluating and bone formation in vivo. Porous β-TCP granules were mixed with atelocollagen hydrochloride solution at various ratios — 0.02, 0.05, 0.1, and 0.2 g/ mL. The resultant mixtures were freeze-dried and subjected to dehydrothermal treatment in vacuo. The final composites obtained were designated β-TCP/ collagen sponge composites (β-TCP/ CS) . Through compression testing, it was found that the stress values for β-TCP/ CS (0.2 g/ mL) were higher than those of the other three composites over the whole strain range. Histological evaluation at four weeks after implantation revealed that the collagen sponge had degraded and newly formed bone was present on the surface of the β-TCP granules. At 12 weeks, the β-TCP granules were completely degraded and remodeling of the lamellar bone was observed.

A novel, injectable bone tissue engineering material was developed that consisted of β-tricalcium phosphate (β-TCP) beads as the solid phase and alginate as the gel phase. To prepare the instantaneously formed composite scaffold, an aqueous calcium chloride solution was dried on the surface of β-TCP beads and crosslinked with an alginic acid sodium solution, thereby forming stable β-TCP beads and alginate gel which were injectable via a syringe. This biodegradable composite was a three-dimensional (3D) material that could be used as an injectable scaffold for bone tissue engineering. In particular, the composite with 2.0 wt% alginate concentration exhibited a compressive strength of 69 kPa in dry conditions, which was significantly higher than that exhibited by 1.0 wt%. Furthermore, mesenchymal stem cells (MSC) were 3D-cultured within the composite and then investigated for osteogenic markers. MSC-loaded composite was subjected to scanning electron microscope (SEM) examination and implanted subcutaneously for in vivo experiment. Results showed that the scaffold provided support for osteogenic differentiation. In light of the encouraging results obtained, this novel injectable composite material may be useful for bone tissue engineering.

Japan's largest platform for academic e-journals: J-STAGE is a full text database for reviewed academic papers published by Japanese societies