In vivo bioresorbability and bone formation ability of sintered highly pure calcium carbonate granules.

Calcium carbonate-based bone substitutes derived from natural coral exoskeleton (aragonite) are resorbed and remodeled faster than calcium phosphate-based substitutes. However, coral species with structures appropriate for use as bone substitutes are very limited. Therefore, it is important to evaluate potential of artificial calcium carbonate ceramics as a bone substitute.

Binding of collagen gene products with titanium oxide.

Titanium is the only metal to which osteoblasts can adhere and on which they can grow and form bone tissue in vivo, resulting in a strong bond between the implant and living bone. This discovery provides the basis for the universal medical application of Ti. However, the biochemical mechanism of bond formation is still unknown.

Phosphorylated chitin increased bone formation when implanted into rat calvaria with the Ti-device.

Background: Previously we found that a group of phosphorylated proteins (SIBLINGs) in bone binds with the Ti-device, and increases the early bone formation around the Ti-implants remarkably. From these results, we explained the biochemical mechanism of a strong bond between living bone and Ti, which was discovered by Brånemark and colleagues. For the clinical application of our findings, we need a large amount of these proteins or their substitutes.

Enhanced bone formation in the vicinity of porous β-TCP scaffolds exhibiting slow release of collagen-derived tripeptides.

It has been experimentally proven that orally ingested collagen-derived tripeptides (Ctp) are quickly absorbed in the body and effectively promote the regeneration of connective tissues including bone and skin. Ctp are capable to activate osteoblasts and fibroblasts, which eventually promotes tissue regeneration. Based on these findings, a hypothesis was formulated in this study that direct delivery of Ctp to bone defect would also facilitate tissue regeneration as well as oral administration.

Enhancement of mechanical strength and in vivo cytocompatibility of porous β-tricalcium phosphate ceramics by gelatin coating.

Background: In an attempt to prepare scaffolds with porosity and compressive strength as high as possible, we prepared porous β-tricalcium phosphate (TCP) scaffolds and coated them with regenerative medicine-grade gelatin. The effects of the gelatin coating on the compressive strength and in vivo osteoblast compatibility were investigated.

Methods: Porous β-TCP scaffolds were prepared and coated with up to 3 mass% gelatin, and then subjected to thermal cross-linking.

Absorption and plasma kinetics of collagen tripeptide after peroral or intraperitoneal administration in rats.

Collagen tripeptide (CTP) is a collagen-derived compound containing a high concentration of tripeptides with a Gly-X-Y sequence. In this study, the concentrations and metabolites of CTP were monitored in rat plasma after its administration. We performed a quantitative analysis using high-performance liquid chromatography tandem mass spectrometry according to the isotopic dilution method with stable isotopes.

Bone enhancing effect of titanium-binding proteins isolated from bovine bone and implanted into rat calvaria with titanium scaffold.

Based on our previous finding that a chromatography with titanium beads selectively binds phosphoproteins, including caseins, phosvitin and dentin phosphoproteins, we investigated whether bone phosphoproteins also bind to titanium. Bovine bone matrix proteins were extracted with 2 M urea/PBS after demineralization. The 2 M urea extract was directly applied to the titanium chromatography column as reported.

Interaction between titanium and phosphoproteins revealed by chromatography column packed with titanium beads.

The biochemical mechanism behind the strong binding between titanium and living bone has not been fully elucidated, in spite of worldwide clinical application of this phenomenon. We hypothesized that one of the core mechanisms may reside in the interaction between certain proteins in the host tissues and the implanted titanium. To verify the interaction between titanium and proteins, we chose the technique of chromatography in that titanium spherical beads (45 μm) were packed into a column to obtain a bed volume of 16×50 mm, which was eluted with phosphate buffered saline (PBS) and a straight gradient system made by using PBS and 25 mM NaOH.