Kazuo Takakuda

Keio University, Tokyo, Tokyo-to, Japan

Are you Kazuo Takakuda?

Claim your profile

Publications (79)131.19 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Accordion nerve conduit of poly(lactide-co-glycolide-co-ε-caprolactone) with perforations was developed by excimer laser processing. We evaluated its in vivo function for nerve repairing and discussed the influence of pore size and density. It was found that perforations help inner nerve regeneration remarkably, which effect is unrelated to pore size or density, and is not parallel with revascularization increment. Inducing of permeability only to allow substance exchange but not vessel ingrowth could facilitate nerve regeneration too. Perforating micropores with the size of 100 μm and the density of 25/cm provides permeability and vessel ingrowth both, therefore promotes the axon extension the best, larger, and more pores do not advance axon regeneration more. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2013.
    Journal of Biomedical Materials Research Part B Applied Biomaterials 02/2014; · 2.31 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: This study introduces the application of method for electrically polarizing titanium implants coated with anatase TiO2 using micro-arc oxidation. It also describes the features of the electrically polarized titanium implants, on which surface charges are generated by the dipole moment of the TiO2, and describes how the surface charges affect the implants' in vivo bone-implant integration capability. A comprehensive assessment using biomechanical, histomorphological and radiographic analyses in a rabbit model was performed on polarized and non-polarized implants. The electrically polarized surfaces accelerated the establishment of implant biomechanical fixation, compared with the non-polarized surfaces. The percentage of the bone-implant contact ratio was higher using polarized implants than using non-polarized implants. In contrast, the bone volume around the implants was not affected by polarization. Thus, using the polarized implant, this study identified that controlled surface charges have a significant effect on the properties of titanium implants. The application of the electrical polarization process and the polarization-enhanced osteoinductivity, which resulted in greater bone-implant integration, was clearly demonstrated.
    Journal of Biomedical Materials Research Part A 10/2013; · 2.83 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: This article proposes less-invasive subperiosteal bone-bonding devices capable of realizing rapid osseointegration and the acquisition of fundamental knowledge required for their development. Three candidates were prepared: titanium rod specimens with a machined surface (Bare), hydroxyapatite (HAp) coating, and hydroxyapatite/collagen (HAp/Col) nanocomposite coating. To investigate bone formation around these rods, each specimen was placed under the periosteum of a male Sprague-Dawley rat calvarium. Four weeks after surgery, the samples were evaluated via histomorphometrical analyses and bonding strength tests. All the Bare specimens and more than half of the HAp specimens were encapsulated with fibrous tissue, whereas all the HAp/Col specimens were almost completely surrounded by new bone tissue without encapsulation. Histomorphometrical analyses showed that the HAp/Col group had the greatest bone contact ratio among all candidates (p < 0.05). Further, a bonding strength test indicated that the HAp/Col group exhibited the greatest bonding strength to bone (p < 0.05). Thus, HAp/Col-coated rods are considered as the best candidate materials for achieving rapid osseointegration onto a bone surface. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2013.
    Journal of Biomedical Materials Research Part B Applied Biomaterials 04/2013; · 2.31 Impact Factor
  • Seiji Asoda, Takayuki Arita, Kazuo Takakuda
    [Show abstract] [Hide abstract]
    ABSTRACT: Soft tissue attachment is a major concern for the improved design of dental and maxillofacial implants. This study evaluated the efficacy of mesh structures for soft tissue attachment in a rat percutaneous model. Four kinds of implant specimens were prepared - TI implants made of titanium cylinders, HA implants of hydroxyapatite-coated titanium, TI-Mesh implants with a titanium mesh covering a groove machined around a titanium cylinder, and similar HA-Mesh implants with a hydroxyapatite-coated mesh. These specimens were implanted percutaneously into the skin tissue of rats. The detachments of the implants were examined during the experimental period of 4 weeks. Survived implants were subjected to mechanical tests for the attachment strength and histological examinations. TI and HA implants demonstrated 0% of survival rates, while TI-Mesh and HA-Mesh showed significantly higher rates of 93.3% and 100% respectively. The attachment strengths were 159 ± 47 kPa in the TI-Mesh and 135 ± 16 kPa in the HA-Mesh. Histological observations revealed that collagen fibers originating from surrounding subcutaneous tissues were anchored to the mesh structures of the TI- and HA-Mesh implants. The results demonstrated the efficacy of the mesh structures for the attachment of soft connective tissues to implants. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2012.
    Journal of Biomedical Materials Research Part B Applied Biomaterials 12/2012; · 2.31 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The impact of continuous flow left ventricular assist device (LVAD) pumping on platelet aggregation was investigated in animal experiments utilizing six calves. A single-use MagLev centrifugal blood pump, MedTech MagLev, was used to bypass the calves' hearts from the left atrium to the descending aorta at a flow rate of 50 ml/kg/min. The LVAD's impact on blood coagulation activities was evaluated based on the platelet aggregability, which was measured with a turbidimetric assay method during the preoperative, operative, and postoperative periods. Heparin and warfarin were used for anticoagulation, while aspirin was used for the antiplatelet therapy. A decrease in platelet aggregation immediately after the pump started was observed in the cases of successful long-term pump operation, while the absence of such a decrease might have caused coagulation-related complications to terminate the experiments. Thus, the platelet aggregability was found to be significantly affected by the pump, and its initial trend may be related to the long-term outcome of the mechanical circulatory support.
    Journal of Artificial Organs 10/2012; · 1.41 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A novel hydroxyapatite (HAp)/poly(L-lactic acid) (PLLA) nanocomposite nonwoven fabric, which was coated and mixed with calcined HAp nanocrystals, and has submicron-sized dimples on its surface, was fabricated. First, HAp-mixed PLLA fabric was prepared by electrospinning a HAp nanocrystal dispersion in dichloromethane (DCM)-dissolved PLLA. It was found that most of the HAp nanocrystals were not exposed on the HAp-mixed PLLA fiber surface but covered with the PLLA matrix. A HAp-nanocrystal coating was applied onto the surface of the HAp-mixed PLLA fabric after corona discharge treatment followed by ethanol washing. The submicron-sized dimples were enlarged after the ethanol washing. After the HAp-nanocrystal coating, the HAp-mixed PLLA fabric surface was uniformly coated with the HAp nanocrystals. In vitro cell spread tests showed that the rat osteoblasts spread more on HAp-nanocrystal-coated fabrics than on non-HAp-coated fabrics. Upon covering calvarial defects, the in vivo hard tissue responses suggested earlier restoration of the defects with HAp-nanocrystal-coated fabrics than those with non-HAp-coated fabrics.
    Journal of Artificial Organs 07/2011; 14(4):331-41. · 1.41 Impact Factor
  • Source
    04/2011; , ISBN: 978-953-307-165-7
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The adaptive nature of bone formation under mechanical loading is well known; however, the molecular and cellular mechanisms in vivo of mechanical loading in bone formation are not fully understood. To investigate both mechanisms at the early response against mechanotransduction in vivo, we employed a noninvasive 3-point bone bending method for mouse tibiae. It is important to investigate periosteal woven bone formation to elucidate the adaptive nature against mechanical stress. We hypothesize that cell morphological alteration at the early stage of mechanical loading is essential for bone formation in vivo. We found the significant bone formation on the bone surface subjected to change of the stress toward compression by this method. The histological analysis revealed the proliferation of periosteal cells, and we successively observed the appearance of ALP-positive osteoblasts and increase of mature BMP-2, resulting in woven bone formation in the hypertrophic area. To investigate the mechanism underlying the response to mechanical loading at the molecular level, we established an in-situ immunofluorescence imaging method to visualize molecules in these periosteal cells, and with it examined their cytoskeletal actin and nuclei and the extracellular matrix proteins produced by them. The results demonstrated that the actin cytoskeleton of the periosteal cells was disorganized, and the shapes of their nuclei were drastically changed, under the mechanical loading. Moreover, the disorganized actin cytoskeleton was reorganized after release from the load. Further, inhibition of onset of the actin remodeling blocked the proliferation of the periosteal cells. These results suggest that the structural change in cell shape via disorganization and remodeling of the actin cytoskeleton played an important role in the mechanical loading-dependent proliferation of cells in the periosteum during bone formation.
    PLoS ONE 01/2011; 6(9):e24847. · 3.73 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Although the devices for large-caliber vessel (>2-mm diameter) anastomosis are available, there are no devices for performing anastomosis of small-caliber vessels. We designed a hooked device composed of a bioabsorbable polymer for sutureless anastomosis of small-caliber vessels. The efficacy of this device was evaluated by in vitro degradation and arterial-fixation strength tests as well as in vivo transplantation experiments with common carotid arteries of growing SD rats. A nonabsorbable device without hooks served as the control in the fixation strength and animal experiments. The tensile strength of the bioabsorbable device decreased to 27 and 9% of the initial value after 8- and 24-week incubation, respectively. The fixation strength was greater and the anastomotic time was shorter with this device than with the control. The transplantation experiments showed complete endothelial bridging in both devices at 2 weeks after surgery (n = 6). The control device created a considerable protrusion into the arterial lumen at 8 postoperative weeks, whereas the experimental device did not (n = 6). Arterial diameter measurements detected a significant difference between the inner diameters at the respective anastomotic sites (n = 6, P < 0.05) and demonstrated that the control device hindered the vessel growth while the experimental device did not. Therefore, the bioabsorbable hooked device was an effective tool for anastomosis of small-caliber arteries (ca. 1-mm diameter).
    Microsurgery 03/2010; 30(6):494-501. · 1.62 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Cement lines represent mineralized, extracellular matrix interfacial boundaries at which bone resorption by osteoclasts is followed by bone deposition by osteoblasts. To determine the contribution of cement lines to bone quality, the osteopetrotic c-Src mouse model-where cement lines accumulate and persist as a result of defective osteoclastic resorption-was used to investigate age-related changes in structural and mechanical properties of bone having long-lasting cement lines. Cement lines of osteopetrotic bones in c-Src knockout mice progressively mineralized with age up to the level that the entire matrix of cement lines was lost by EDTA decalcification. While it was anticipated that suppressed and abnormal remodeling, together with the accumulation of cement line interfaces, would lead to defective bone quality with advancing age of the mutant mice, unexpectedly, three-point bending tests of the long bones of 1-year-old c-Src-deficient mice indicated significantly elevated strength relative to age-matched wild-type bones despite the presence of numerous de novo microcracks. Among these microcracks in the c-Src bones, there was no sign of preferential propagation or arrest of microcracks along the cement lines in either fractured or nonfractured bones of old c-Src mice. These data indicate that cement lines are not the site of a potential internal failure of bone strength in aged c-Src osteopetrotic mice and that abundant and long-lasting cement lines in these osteopetrotic bones appear to have no negative impacts on the mechanical properties of this low-turnover bone despite their progressive hypermineralization (and thus potential brittleness) with age.
    Calcified Tissue International 02/2010; 86(2):172-83. · 2.50 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In this study, we investigated the use of perforated sheet platforms to improve the attachment of percutaneous devices to surrounding tissues. The model platform was created by a poly(methyl methacrylate) (PMMA) sheet with a matrix of 200-microm diameter perforations covering the groove (width, 3 mm; depth, 0.5 mm) prepared on the PMMA cylinder (diameter, 10 mm; length, 6 mm). Velour cuffs from peritoneal dialysis catheters were used as controls. Specimens were implanted percutaneously in rats, harvested with the surrounding tissues at 4 weeks after surgery, and subjected to mechanical tests and histological observations. The attachment strength of the experimental specimens to tissue was 138.4 +/- 123.6 kPa (n = 5, mean SD); although it was greater than the 67.23 +/- 45.78 kPa (n = 5) of the controls, no statistical significance was found. Histological observations of the experimental specimens revealed the collagen fibers originating from the surrounding tissues, passing through the perforations of the sheet, merging into the collagen fibers running behind the sheet, and thus anchoring the tissues to the device. In contrast, such anchoring of collagen fibers was not evident in the controls. These results suggest that the proposed perforated sheet structures are effective for soft tissue attachment.
    ASAIO journal (American Society for Artificial Internal Organs: 1992) 01/2010; 56(3):235-40. · 1.39 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The efficacy of hydroxyapatite (HAp) nanocoating on polyester vascular grafts was investigated in animal experiments. The HAp nanocrystals were covalently bonded separately between hydroxyl groups on a nanocrystal and alkoxysilyl groups in gamma-methacryloxypropyl triethoxysilane graft polymerized on a polyester substrate. Twelve HAp-coated polyester grafts and 10 control grafts of 20, 30, or 50 mm in length were implanted in canine common carotid arteries. Serious complications or occlusions were not observed in any of the dogs after implantation. A histologic evaluation was conducted by staining with hematoxylin and eosin (HE), the von Willebrand factor (vWf), and alpha-smooth muscle actin (alpha-SMA) around the inner lumen of the grafts. The number of inflammation cells and giant cells in the HAp-coated group was significantly lower than that in the group receiving noncoated grafts (p < 0.05).
    ASAIO journal (American Society for Artificial Internal Organs: 1992) 12/2009; 56(1):61-6. · 1.39 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The hydroxyapatite/collagen (HAp/Col) sponge with 95% (v/v) porosity was prepared by freeze-drying of a HAp/Col fiber suspension. MG63 cells were seeded onto the HAp/Col sponge and cultured under a pressure/perfusion condition with osteogenic supplements. A collagen (Col) sponge was used as a control. The cells with sponge were examined by a histology, total DNA content and gene expression. The cells showed good attachment and proliferation everywhere in the HAp/Col sponge, while the cells mainly proliferated at the peripheral part of the Col sponge. Thus, total DNA content in the HAp/Col sponges reached 1.8 times greater than that in the Col sponges at Day 21. Further, the cells and extracellular matrix only in the HAp/Col sponge were calcified, although the cells in both sponge evenly expressed osteogenic gene. These results suggest that the HAp/Col sponge could be useful as a scaffold for bone tissue engineering.
    Journal of Materials Science Materials in Medicine 11/2009; 21(4):1263-72. · 2.14 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Experimental anterior cruciate ligament (ACL) reconstruction was carried out in a rabbit model, in which a chitin-coated polyester graft was used as the scaffold, and a noncoated graft was used as a control graft. After 8 weeks implantation, a mechanical test of the knee and histometric measurement of the graft and surrounding tissues were carried out. A tensile test of the femur-graft-tibia specimen showed that the knee treated with the coated graft had a peak resistance force of 42.2 +/- 12.7 N, which was significantly greater than the 19.2 +/- 15.3 N of the knee treated with the control graft. The histometric measurement revealed that the area of bone tissue within the section of the coated graft in the femoral bone tunnel was 3.43 +/- 1.73 mm(2), which was significantly greater than the area of 0.29 +/- 0.37 mm(2) of the control graft. Similarly, the area of soft tissue within and around the midsubstance of the coated graft located in the articular cavity was significantly greater than that of the control graft. The chitin coating enhanced the formation of bone tissue in the femoral bone tunnel and soft tissue in the articular cavity, and increased the attachment strength of the graft to the bone. Thus, the efficacy of the chitin coating for the ACL reconstruction scaffolds was demonstrated.
    Artificial Organs 10/2009; 34(1):55-64. · 1.96 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Cell adhesion and tissue response to poly(l-lactic acid) (PLLA) fabric coated with nanosized hydroxyapatite (HAp) crystals were studied. The HAp nanocrystals were prepared by the wet chemical process followed by calcination at 800 degrees C with an anti-sintering agent to prevent calcination-induced sintering. After the PLLA fabric was hydrolyzed with an alkaline aqueous solution, the HAp nanocrystals were coated via ionic interaction between the calcium ions on the HAp and the carboxyl groups on the alkali-treated PLLA. The PLLA surface uniformly coated with the HAp nanocrystals was observed by scanning electron microscope. The ionic interaction between the HAp and the PLLA was estimated by FT-IR. Improved cell adhesion to the HAp nanocrystal-coated surface was demonstrated by in vitro testing using a mouse fibroblast cell line L929. Furthermore, reduced inflammatory response to the HAp nanocrystal-coated PLLA fabric (as compared with a non-treated one) was confirmed by a subcutaneous implantation test with rats. Thus the HAp nanocrystal-coated PLLA developed has possible efficacy as an implant material in the fields of general and orthopedic surgery, and as a cell scaffold in tissue engineering.
    Journal of Bioscience and Bioengineering 10/2009; 108(3):235-43. · 1.74 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Intervertebral disc degeneration induced by mechanical compression is an important issue in spinal disorder research. In this study, the biomechanical aspect of the rat tail model was investigated. An external loading device equipped with super-elastic TiNi springs was developed to apply a precise load to the rat tail. By using this device, rat tail discs were subjected to compressive stress of 0.5 or 1.0 MPa for 2 weeks. Discs in the sham group received an attachment of the device but no loading. After the experimental period, first the intact tail with peripheral tissues (PT) such as tendon and skin and then the retrieved disc without PT were subjected to a uniaxial tension-compression test; biomechanical characteristics such as range of motion (ROM), neutral zone (NZ), and hysteresis loss (HL) were evaluated. Furthermore, the load-bearing contribution of PT in the intact tail was estimated by comparing the load-displacement curves obtained by the mechanical tests performed with and without PT. The experimental findings revealed that the continuous compressive stress induced reduction in disc thickness. The intact tail demonstrated decreases in ROM and NZ as well as increases in HL. On the other hand, the retrieved disc demonstrated increases in ROM, NZ, and HL. Further, a significant increase in the load-bearing contribution of PT was indicated. These findings suggest that the load-bearing capacity of the disc was seriously deteriorated by the application of compressive stress of 0.5 or 1.0 MPa for 2 weeks.
    European Spine Journal 07/2009; 18(11):1595-603. · 2.13 Impact Factor
  • Source
    Materials Transactions - MATER TRANS. 01/2009; 50(6):1269-1272.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Increase of soft tissue attachment is a major concern for improving the design of novel dental implants. This study evaluated the use of mesh structures placed on the implant surface for the anchorage of fibrous tissues. Specimens were prepared by covering their surfaces with a nylon mesh. The following mesh spacings were used: 30, 46, 100, 200, and 500 microm. The specimens were retrieved along with the surrounding subcutaneous tissues at 4 weeks after their implantation into the dorsal subcutaneous tissues of rats. A tensile test was performed by using a material testing machine, and the load required to tear the tissue from the mesh was measured. Histological sections stained with hematoxylin-eosin or Azan were prepared and examined by performing light microscopy. The amount of fibrous tissue contributing to the mechanical attachment of the fibers to the mesh was qualitatively evaluated by performing image analysis. The attachment strength was the greatest in the 200-microm mesh-spacing group and considerably greater than that in the 30-microm mesh-spacing group. In addition, the effective width of the anchoring fibrous tissues was the greatest in the 200-microm mesh-spacing group. As compared with the other groups, the 200- and 500-microm mesh-spacing groups exhibited a considerably greater width of the anchoring fibrous tissues. The efficiency of mesh structures for the attachment of soft tissues to implants was demonstrated. A mesh spacing of approximately 200 microm was observed to be favorable for the anchorage of fibrous tissues.
    Clinical Oral Implants Research 12/2008; 19(11):1171-7. · 3.43 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Biological fixation or anchorage of fibrous materials to bone by bone ingrowth into the spaces between fibers is a major concern in developing novel medical implants, including artificial ligaments. Toward this end, we evaluated the efficacy of chitin/chitosan as a bone formation accelerator. Specimens of polyester nonwoven fabric coated with chitin/chitosan were implanted into holes drilled into the distal ends of rat femora. Uncoated fabric specimens were used as controls. At 1 or 2 weeks after implantation, the specimens were retrieved, and the fixation strength was measured by mechanical testing. Histological sections of 2-week implantation specimens were prepared, and the area of new bone tissue formed in the spaces between the fibers of the fabric was measured. The chitin/chitosan coating significantly increased the fixation strength and the area of bone tissue formed in the spaces between the fibers. The mean fixation strength of chitin/chitosan-coated fabric specimens was more than twice that of the controls at 2 weeks after implantation. These results demonstrated that the chitin/chitosan coating effectively induced bone formation in the spaces between the fibers and enhanced biological fixation of the fibrous materials to the bone.
    Journal of Biomedical Materials Research Part B Applied Biomaterials 09/2008; 88(1):264-70. · 2.31 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Acrylic bone cement is self-curing cement comprising of liquid and powder component of methyl methacrylate (MMA). It has been used extensively in orthopedics; however, adverse effects were associated with its use. Hence we investigated in this paper the possibility of new cement utilizing methacrylates with lower toxicity than MMA. LD50s of candidate monomers were determined with administration to the medullary cavity of the rat's femur. 2-Ethylhexyl methacrylate (EHMA) and trimethylolpropane trimethacrylate (TMP) demonstrated greater LD50 values of 187 mg/kg and 380 mg/kg, respectively, than MMA (108 mg/kg); they were selected as the liquid components of the new cement. The copolymer of EHMA and cyclohexyl methacrylate was then selected as the powder component. With this combination, we developed the new cement (EHMA cement).Temperature rise during polymerization of EHMA cement was 9 degrees C-13 degrees C, which was significantly lower than that of conventional cement. The compression strength of the polymerized EHMA cement was 57 MPa without TMP, and 67 MPa with TMP (15 wt%). Thus we concluded that new EHMA cement was slightly inferior in the compression strength than the conventional cement. However, it was characterized by the low toxicity of utilized monomers and the low temperature rise during polymerization.
    Journal of medical and dental sciences 07/2008; 55(2):189-96.

Publication Stats

1k Citations
131.19 Total Impact Points

Institutions

  • 2012
    • Keio University
      • Department of Dentistry and Oral Surgery
      Tokyo, Tokyo-to, Japan
  • 1996–2011
    • Tokyo Medical and Dental University
      • • Department of Biodesign
      • • Institute of Biomaterials and Bioengineering
      • • Faculty of Dentistry
      • • Department of Neurosurgery
      Edo, Tōkyō, Japan
  • 2009
    • Tokyo Denki University
      • Division of Mechanical System Engineering
      Tokyo, Tokyo-to, Japan
    • National Cerebral and Cardiovascular Center
      Ōsaka, Ōsaka, Japan
  • 2002–2005
    • National Institute for Materials Science
      Tsukuba, Ibaraki, Japan
  • 2000
    • University of Texas Health Science Center at San Antonio
      San Antonio, Texas, United States