Papers by Author: Akari Takeuchi

Abstract: Our previous study presented that sericin, a kind of silk protein, had high ability of apatite formation under a condition mimicking body environment when the sericin contains high content of β sheet structure. To confirm the effectiveness of β sheet structure on apatite nucleation, we attempted to synthesize of polypeptide containing β sheet structure and investigate apatite formation in 1.5SBF that has 1.5 times the inorganic ion concentrations of human blood plasma. Poly(FEFEFEFG) was synthesized as the polypeptide consisting mainly of β sheet structure. Formation of hydroxyapatite was observed on the film of the poly(FEFEFEFG) after soaking in 1.5SBF within 7 days. We could confirm that β sheet structure was effective even in the synthetic polypeptide.

Abstract: In order to overcome the disadvantage of commercialized PMMA bone cement, we have developed novel PMMA-based bone cement(7P3S) reinforced by 30 wt.% of bioactive CaO-SiO2 gel powders to induce the bioactivity as well as to increase mechanical property for the PMMA bone cement. The novel 7P3S bone cement hardened after mixing for about 7 minutes. For in vitro evaluation, apatite forming ability of it was investigated using SBF. When the novel 7P3S bone cement was soaked into SBF, it formed apatite on its surfaces within 1 week Furthermore; there is no decrease in its compressive strength within 9 weeks soaking in SBF. It is though that hardly decrease in compressive strength of 7P3S bone cement in SBF is due to the relative small amount of gel powder or its spherical shape and monosize. In vivo evaluation of the novel 7P3S bone cement was carried out using rabbit. After implantion into rabbit tibia for several periods, the interface between novel bone cement and natural bone was evaluated by CT images. According to the results, the novel bone cement directly contact to the natural bone without fibrous tissue after implantation for 4 weeks. This results indicates that the newly developed 7P3S bone cement can bond to the living bone and also be effectively used as bioactive bone cement without decrease in mechanical property.

Abstract: Porous a-tricalcium phosphate (a-TCP) ceramics are attractive as a novel bioresorbable material for bone repair, since they can be easily fabricated through conventional sintering of b-TCP at high temperature. However, the solubility of a-TCP is too high to keep its body until the bone defect is repaired completely. Coating of the a-TCP porous body with organic polymer is a way to reduce the degradation rate. In the present study, biodegradation of a-TCP porous body coated with silk sericin was evaluated in vivo. Bone repair at the defect made in rabbit tibia was nearly completed after 4 weeks. Higher density of cortical bone was estimated for a-TCP coated with sericin than for mere a-TCP. The a-TCP porous body coated with sericin is expected as a material that show less degradation than mere a-TCP, and may result in suitable bone repair.