Papers by Author: Takahisa Anada

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Authors: Osamu Suzuki, Shinji Kamakura, Takahisa Anada
Abstract: The present study was designed to investigate the mechanism of in vivo conversion from synthetic octacalcium phosphate (OCP) into hydroxyapatite (HA) at ultrastructural level, where the implanted OCP is enhancing bone regeneration in mouse calvarial bone defect. OCP granules were implanted into the subperiosteal area of the calvaria of 7-week-old BALB/c mice for 3 weeks. Transmission electron microscopy of undecalcified frontal sections, obtained from the acrylic resin-embedded skull specimens showed that the bone crystals in newly formed bone directly bonded to the OCP particles implanted. The morphological characteristic of original plate-like OCP particles was remained unchanged even after the implantation, whereas a number of de novo nano-particles were also directly formed onto the plate-like OCP particles. Some of OCP particles were linked with other OCP particles through these nano-particles. The results suggest that the OCP-apatite conversion, involving the enhanced bone regeneration, advances via topotaxial conversion without changing the original OCP morphology, accompanied by solution-mediated de novo nano-apatite formation, in the vicinity of the implanted OCP particles.
Authors: Yoshitomo Honda, Shinji Kamakura, Kazuo Sasaki, Takahisa Anada, Taisuke Masuda, Osamu Suzuki
Authors: Shinji Kamakura, Kazuo Sasaki, Yoshitomo Honda, Taisuke Masuda, Takahisa Anada, Tadashi Kawai, Aritsune Matsui, Keiko Matsui, Seishi Echigo, Osamu Suzuki
Abstract: Our previous studies showed that synthetic octacalcium phosphate (OCP) enhances bone regeneration more than hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP). Also, a synthetic bone substitute constructed of synthetic octacalcium phosphate (OCP) and porcine atelocollagen sponge (OCP/Col) showed stable bone regeneration. The present study was designed to investigate the difference of bone regeneration by OCP/Col and other calcium phosphate-collagen composites. OCP/Col, β-TCP$-collagen% composite (β-TCP/Col), or HA$-collagen% composite (HA/Col) sponge was prepared from pepsin-digested atelocollagen isolated from the porcine dermis and OCP, β-TCP, or HA granules, respectively. A standardized critical-sized defect was made in the rat calvarium, and various calcium phosphate-collagen composites were implanted into the defect. The rats were fixed at four weeks after implantation and radiographic and histological examinations were performed by undecalcified cross sections of implants. Radiographic examination showed that uniform radiopaque masses were observed in the created defects treated with OCP/Col, whereas granulous and foggy radiopacity was observed in β-TCP/Col and HA/Col. Histological examination showed that newly formed bone was observed in the reticulum of OCP/Col and around the implanted OCP. The regenerated bone by β-TCP/Col or HA/Col seemed to be less than that by OCP/Col and would not to be nucleated by the granules of β-TCP or HA. The present study indicated that bone regeneration by OCP/Col was different from those of β-TCP/Col and HA/Col. Application of OCP/Col would be expected for clinical use in the future.
Authors: Takahisa Anada, Akihiro Araseki, Shou Matsukawa, Tomokazu Yamasaki, Shinji Kamakura, Osamu Suzuki
Abstract: Our previous studies suggested that synthetic octacalcium phosphate (OCP) enhances bone regeneration more than hydroxyapatite (HA). However, the molecular mechanisms to induce osteogenic phenotype in osteoblast by OCP have not been identified. OCP tended to convert into an apatite structure in vivo and in vitro, and its process was accompanied by calcium consumption from the surrounding solution and the release of phosphate ions into the solution at a physiological condition. The present study was designed to investigate whether the dissolution of ionic products of OCP affects on proliferation and differentiation of mouse bone marrow stromal ST-2 cells in vitro. The number of cells treated with OCP-conditioned medium was slightly decreased in comparison to that of control at day 7. On the other hand, the level of alkaline phosphatase activity increased in OCP-conditioned medium. These results demonstrated that OCP is capable of inducing osteoblastic cell differentiation in ST-2 cells.
Authors: Yusuke Orii, Hiroshi Masumoto, Takashi Goto, Yoshitomo Honda, Takahisa Anada, Keiichi Sasaki, Osamu Suzuki
Abstract: The surface oxide films were prepared by Electron Cyclotron Resonance (ECR) plasma oxidation on Ti substrates. Octacalcium phosphate (OCP) and dicalcium phosphate dihydrate (DCPD) peaks were formed after calcification by supersaturated calcium and phosphate solutions. Calcification ability was enhanced with increasing the oxidation time and the total pressure of ECR plasma treatment during oxidation. The results demonstrated that the calcium phosphate nucleation and the deposition can be controlled by various ECR plasma conditions.
Authors: Ryo Akatsuka, Ken Matsumura, Miyoko Noji, Chihiro Nishikawa, Kei Sato, Takayuki Hagiwara, Takahisa Anada, Osamu Suzuki, Tunemoto Kuriyagawa, Keiichi Sasaki
Abstract: This study aimed to create a thick hydroxyapatite (HAp) film on the surface of a human tooth by using a newly developed powder jet deposition (PJD) device for dental handpieces, and sought to examine the microstructural and mechanical properties of the resulting HAp film. The film was evaluated on three-dimensional view, surface roughness, Vickers hardness, and bonding strength before and after artificial aging through thermal cycling (555°C) for 500 cycles (30 sec for each cycle, 20 sec of dwell time).The HAp particles in the deposited film were densely packed, and the HAp films three-dimensional microstructure and its rough surface were maintained after thermal cycling. There was no significant difference in either the HAp films Vickers hardness or the bonding strength between the film and the enamel substrate before and after thermal cycling. The HAp films created in this study demonstrated excellent microstructural and mechanical properties even after the application of thermal stress. We demonstrated the possibility of using a new type of powder jet deposition (PJD) method we developed to form a new type of interface between the tooth and biomaterials. Consequently, we propose the use of this method in new dental treatments.
Authors: Shinji Kamakura, Takashi Kumagai, Yoshitomo Honda, Takahisa Anada, Keiichi Sasaki, Hidetoshi Shimauchi, Osamu Suzuki
Abstract: It has been shown that fluoride ions enhance OCP hydrolysis into Ca-deficient apatite and that fluoridation in hydroxyapatite (HA) affects osteoblast activity. The present study was designed to investigate whether fluoridated Ca-deficient apatite (F-HA) formed via OCP enhances bone regeneration. F-HA was obtained through hydrolysis of the OCP in a solution containing 2 ppm fluoride at 37 °C and pH 7.4. A standardized critical-sized defect was made in the rat calvarium, and granules of F-HA were implanted into the defect. Five rats from each group were fixed through four to twelve weeks after implantation. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) confirmed that F-HA corresponded well to apatite structure. In week four, new bone matrix was formed around F-HA. In week twelve of F-HA group, newly formed bone matrix was more abundant, whereas the implanted F-HA was unresorbed and still remained. A statistical analysis in week twelve showed that the newly formed bone in the defect with F-HA was higher than that with untreated group. The fact that new bone was directly formed on F-HA implant suggests F-HA formed via OCP could be used as a bone substitute material.
Authors: Osamu Suzuki, Takahisa Anada
Abstract: We have previously established a wet synthesis method of octacalcium phosphate (OCP) in a relatively large scale and found that OCP enhances bone formation more than synthetic hydroxyapatite (HA) if implanted onto bone surface and various bone defects. The present paper reviews, based on our studies, as to how OCP controls in vitro cellular activities of bone-related cells, such as bone marrow stromal cells, and how OCP enhances bone repair in critical sized bone defect experimentally created in animal models. OCP tends to progressively convert to HA in culture media and in rat calvaria defects. OCP is capable of enhancing in vitro osteoblast differentiation and osteoclast formation in the presence of osteoblasts. Recent our studies also indicated that OCP enhances odontoblast differentiation while suppresses chondrogenic differentiation. The physicochemical properties, such as chemical composition and adsorption affinity of serum proteins, vary depending on the advancement of conversion from OCP to HA, which suggests that the change on the surface property during the conversion of OCP may affect the cellular responses in vitro and tissue reaction in vivo. OCP could be used as a scaffold material that can control the activity of bone-related cells.
Authors: Takashi Kumagai, Takahisa Anada, Yoshitomo Honda, Masamichi Takami, Ryutaro Kamijyo, Hidetoshi Shimauchi, Osamu Suzuki
Abstract: The present study was designed to investigate whether bone morphogenetic protein-2 (BMP-2) adsorbed onto octacalcium phosphate (OCP) and hydroxyapatite (HA) surfaces influences osteoblastic cell differentiation. Osteoblastic cell line, UAMS32, were cultured on plastic plate that was coated of synthetic OCP and HA. BMP-2 was pre-adsorbed on these calcium phosphates at 4°C or room temperature for 24h. The cells more proliferated on the BMP-2 pre-adsorbed OCP and HA than that of the controls (OCP and HA coating without BMP-2). ALP activities were higher on HA than on OCP when BMP-2 were pre-adsorbed at 4°C than at room temperature. The results suggest that pre-adsorption of BMP-2 in different temperature affects osteoblastic cell differentiation, most probably through different adsorption state of BMP-2 on this calcium phosphate.
Authors: Yuko Suzuki, Naoyuki Nomura, Shuji Hanada, Shinji Kamakura, Takahisa Anada, Takeshi Fuji, Yoshitomo Honda, Taisuke Masuda, Keiichi Sasaki, Shoichi Kokubun, Osamu Suzuki
Abstract: The present study was designed to investigate whether porous titanium (Ti) having Young’s modulus similar to bone has osteoconductive characteristics in rat critical-sized calvarial bone defect. The effect of coating by octacalcium phosphate (OCP) was also examined. OCP is known as a precursor of initial mineral crystals of biological apatite in bones and teeth. Ti powder was prepared by plasma rotating electrode process in an Ar atmosphere. Then, porous Ti disks, 8 mm in diameter with 1 mm thick, were obtained using the particles ranging from 300 to 500 +m, by sintering at 1573 K without applied pressure. The disks had about 35 vol% in porosity and about 10 GPa in Young’s modulus which corresponds to that of human cortical bone. Newly formed bone was observed so as to fill the pore up at 12 weeks, confirming the ability to conduct the ingrowths of the bone tissue. Although in vitro study showed that proliferation of mouse bone marrow stromal ST-2 cells was inhibited on the dishes coated by OCP rather than the control dish, OCP coating on porous Ti seemed to stimulate the bone formation in vivo. Taken together, it seems likely that porous Ti having Young’s modulus similar to bone shows osteoconductive characteristics to conduct bone ingrowths. OCP could be a potential coating agent to assist bone regeneration on porous Ti.
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