Papers by Author: Atsuo Ito

Abstract: FGF-2-apatite and FGF-2-zinc-apatite composite layers were formed on commercially available anodically oxidized Ti external fixation rods using FGF-2-and ZnCl₂-containing supersaturated calcium phosphate solutions. The FGF-2-zinc-apatite composite layers precipitated on the Ti external fixation rods significantly enhanced proliferation of fibroblastic NIH3T3 and osteoblastic MC3T3-E1 cells in vitro.

Abstract: An apatite-pathogen-associated molecular patterns (PAMPs) adjuvant was prepared by coprecipitation of apatite and PAMPs using a supersaturated calcium phosphate solution supplemented with PAMPs. In this study, we used a hydrothermal extract of human tubercle bacillus (HTB) as PAMPs. The effects of coprecipitation conditions on immunogenic activity were studied. The adjuvants prepared using extract of at 10 and 20 μg/mL showed higher in vitro immunogenic activity than that at 2 μg/mL. The adjuvants prepared under stir at speed of 300 rpm showed better in vitro immunogenic activity than those under still. The adjuvants prepared using 10 μg/mL of extract of HTB under stir at speed of 300 rpm may be promising for cancer immune therapy.

Abstract: The purpose of this research is improvement of therapeutic treatment for periodontitis by using lipophilic and/or hydrophilic zinc materials. The sample suspension injections were prepared from zinc octanate, zinc stearate, zinc sulfate hepta-hydrate and tricalcium phosphate containing 6.17w/w% zinc. After administrating of all injections to around alveolar bone of zinc-deficient osteoporosis rats, plasma Zn concentration, bone mineral content and bone mechanical strength of jawbone and femur of Zn deficient rats were measured as therapeutic scores.

Abstract: Calcium phosphate (CaP) coating is an effective technique for surface functionalization of biomaterials. The objective of our research is to prepare calcium phosphate (CaP) coatings on a hydroxyapatite/collagen (HAp/Col) nanocomposite and subsequently provide it with gene delivery function through the immobilization of DNA in the coating. We have specifically selected the HAp/Col nanocomposite since it has the high potential as bone substitutes due to its similar composition, nanostructure, and biological properties to those of human bone. CaP coatings consisting of different sized particles were prepared on the HAp/Col nanocomposite membrane by immersing it in supersaturaterd CaP solutions (so-called RKM solutions) with the varied Ca and P concentration levels. We immobilized DNA in the CaP coatings together with lipid and fibronectin by supplementing DNA, lipid, and fibronectin to the RKM solutions (DLF-RKM solutions). Gene transfer capability of the resulting HAp/Col nanocomposite membrane was improved with decreasing concentration level of the DLF-RKM solution. It was confirmed that the present CaP coating technique was effective in providing the HAp/Col nanocomposite membrane with gene transfer capability and that the Ca and P concentration level of the DLF-RKM solution was a controlling factor affecting the gene transfer efficiency.

Abstract: Hydroxyapatite/collagen (HAp/Col) nanocomposites with bone-like self-organized nanostructure show excellent bioactivity in vivo. However, they show quite high absorbability for cationic ions and lower culture medium ionic concentrations which adversely affects bone cell proliferation and osteogenic differentiation in in vitro cell culture condition. To address this limitation, in this study we have supplemented Ca²⁺ and Mg²⁺ ions to the HAp/Col nanocomposite membrane sample prior to cell culture to improve it’s in vitro biological properties. The HAp/Col nanocomposite membrane samples were fabricated by the simultaneous titration method using Ca(OH)₂, type-I atelocollagen and H₃PO₄ as starting precursor materials. Prior to in vitro cell culture experiments, the HAp/Col samples were pretreated with Ca²⁺ and/or Mg²⁺ ions by immersing in 10 ml of 20 mM CaCl₂ solution, 20 mM MgCl₂ solution, or a solution containing 20 mM CaCl₂ and 20 mM MgCl₂ for 7 days. In vitro bone cell-material interactions on the pretreated and untreated HAp/Col samples were studied by culturing MC3T3-E1 cells up to 7 days. Enhanced bone cell proliferation was found on all the pretreated HAp/col samples as confirmed by the CCK-8 assay. Interestingly, the HAp/Col samples pretreated with both Ca²⁺ and Mg²⁺ ions showed the maximum viable bone cell density.

Abstract: A composite of co-polymer of lactic and glycolic acids (PLGA) loaded with gatifloxacine (GFLX), an antibiotics, and a β-tricalcium phosphate (βTCP) porous ceramic body was prepared by a solvent-free process in which no toxic solvent was used. The GFLX-loaded PLGA released GFLX for 8 weeks in Hanks’ balanced solution. The inhibitory zone diameter (26.25±0.95 mm) for GFLX-containing PLGA disk against S. milleri was significantly larger than 18 mm, and comparable to that (24.88±1.6 mm) for the KB paper disk containing 5 μg of GFLX/disk. This means that the GFLX-containing PLGA has the clinical efficacy. The molten PLGA containing GFLX was successfully loaded in the pores and on the surface of the porous βTCP ceramic at 120 °C at a reduced pressure of 0.02 MPa. The composite of GFLX-loaded porous βTCP ceramic would be promising for treating osteomyelitis.

Abstract: A composite layer of fibroblast growth factor-2 (FGF-2) and low-crystalline apatite was formed on an ethylene-vinyl alcohol copolymer specimen using two types of aqueous calcium phosphate solutions supplemented with 10 !g·mL-1 FGF-2; one is a CP solution that is prepared by dissolving chemical reagents into ultrapure water and the other is an RKB solution that can be prepared by mixing clinically approved infusion fluids. In both solutions, a sufficient amount of FGF-2 for new skin tissue formation (1 !g·cm-2) was immobilized on the specimen surface.

Abstract: Osteoclasts isolated from rabbits were cultured on zinc-containing tricalcium phosphate (ZnTCP) disks with zinc contents of 0.316 and 0.633 wt%, and on β-tricalcium phosphate (TCP) disks with nearly identical porosities, grain sizes and surface roughnesses. ZnTCPs directly suppressed the resorption activity of mature osteoclasts by enhancing apoptosis. We hypothesized that resorbing osteoclasts attached to ZnTCP locally accumulate zinc ions within the space defined by the clear zone during resorption, which in turn leads to apoptosis induction, even though the change in chemical composition of the culture medium is very small.

Abstract: A laminin–DNA–apatite composite layer was successfully formed on the surface of an ethylene–vinyl alcohol copolymer. The immobilized DNA was transferred to the cells adhering onto the laminin–DNA–apatite composite layer more efficiently than those adhering onto a lamininfree DNA–apatite composite layer. It is considered that laminin immobilized in the surface layer enhances cell adhesion and spreading, and DNA locally released from the layer is effectively transferred into the adhering cells, taking advantage of the large contact area. The present gene transferring system, which shows high efficiency and safety, would be useful in gene therapy and tissue engineering.