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Biomedical subjects

Tsuyoshi Takato

Publications and source records attributed to Tsuyoshi Takato.

At least 19 recordsLinked to original sources

Tailor-made tricalcium phosphate bone implant directly fabricated by a three-dimensional ink-jet printer.

Rapid prototyping (RP) is a molding technique that builds a three-dimensional (3D) model from computer-aided design (CAD) data. We fabricated new tailor-made bone implants (TIs) from alpha-tricalcium phosphate powder using an RP ink-jet printer based on computed tomography (CT) data, and evaluated their safety and efficacy. CT data of the skulls of seven beagle dogs were obtained and converted to CAD data, and bone defects were virtually made in the skull bilaterally. TIs were designed to fit the defects and were fabricated using the 3D ink-jet printer with six horizontal cylindrical holes running through the implants, designed for possible facilitation of vascular invasion and bone regeneration. As a control, hydroxyapatite implants (HIs) were cut manually from porous hydroxyapatite blocks. Then, craniectomy was performed to create real skull defects, and TIs and HIs were implanted. After implantation, CT was performed regularly, and the animals were euthanized at 24 weeks. No major side effects were observed. CT analysis showed narrowing of the cylindrical holes; bony bridging between the implants and the temporal bone was observed only for TIs. Histological analysis revealed substantial new bone formation inside the cylindrical holes in the TIs, while mainly connective tissues invaded the porous structures in HIs. Bone marrow was observed only in TIs. Osteoclasts were seen to resorb regenerated bone from inside the cylindrical holes and to invade and probably resorb the TIs. These data suggest that TIs are a safe and effective bone substitute, possessing osteoconductivity comparable with that of HIs.

Animals↗

UV absorption in human oral mucosal epithelial sheets for ocular surface reconstruction.

BACKGROUND: Ocular surface reconstruction with autologous oral mucosal epithelium has attracted attention as a novel treatment strategy that avoids allograft rejection. OBJECTIVES: To evaluate the absorption of ultraviolet (UV) A or B irradiation by human oral mucosal epithelium cultured on human amniotic membrane. METHODS: Human oral mucosal and limbal epithelial cells were co-cultured on amniotic membrane with inactivated 3T3 fibroblasts. The cell sheets were also subjected to UV-A (365 nm) or UV-B (302 nm) irradiation at energy levels ranging from 50 to 800 microW/cm2, and the UV absorption rate was measured with a UV irradiation meter. RESULTS: Cultured oral mucosal epithelium had a structure with 3-5 layers of cells, consistent with the histological features of cultured corneal limbal epithelium after 4 weeks. The decrease in UV-A absorption of cultivated oral mucosal epithelium ranged from 25 to 36% of that for cultured corneal epithelium. The increase in UV-B absorption by cultured oral mucosal epithelium between 200 and 800 microW/cm2 was approximately 145% of that for cultured corneal limbal epithelium. CONCLUSION: Our data demonstrated that cultured oral mucosal epithelium has low UV-A and high UV-B absorption capacity as compared with those of cultured corneal epithelium, suggesting that oral mucosal epithelium can compensate for UV absorption of corneal epithelium.

3T3 Cells↗

Highly efficient ex vivo expansion of human hematopoietic stem cells using Delta1-Fc chimeric protein.

Ex vivo expansion of hematopoietic stem cells (HSCs) has been explored in the fields of stem cell biology, gene therapy, and clinical transplantation. Here, we demonstrate efficient ex vivo expansion of HSCs measured by long-term severe combined immunodeficient (SCID) repopulating cells (SRCs) from human cord blood CD133-sorted cells using a soluble form of Delta1. After a 3-week culture on immobilized Delta1 supplemented with stem cell factor, thrombopoietin, Flt-3 ligand, interleukin (IL)-3, and IL-6/soluble IL-6 receptor chimeric protein (FP6) in a serum- and stromal cell-free condition, we achieved approximately sixfold expansion of SRCs when evaluated by limiting dilution/transplantation assays. The maintenance of full multipotency and self-renewal capacity during culture was confirmed by transplantation to nonobese diabetic/SCID/gammac(null) mice, which showed myeloid, B, T, and natural killer cells as well as CD133(+)CD34(+) cells, and hematopoietic reconstitution in the secondary recipients. Interestingly, the CD133-sorted cells contained approximately 4.5 times more SRCs than the CD34-sorted cells. The present study provides a promising method to expand HSCs and encourages future trials on clinical transplantation.

AC133 Antigen↗

Marked and independent prognostic significance of the CpG island methylator phenotype in neuroblastomas.

The CpG island methylator phenotype (CIMP) was closely associated with poor overall survival (OS) in Japanese neuroblastoma (NBL) cases in our previous study. Here, in German NBL cases, CIMP(+) cases (n=95) showed markedly poorer OS (hazard ratio (HR)=9.5; P<0.0001) and disease-free survival (DFS) (HR=5.4; P<0.0001) than CIMP(-) cases (n=50). All the 23 cases with N-myc amplification had CIMP. Among the remaining cases without N-myc amplification, CIMP(+) cases (n=27) had a poorer OS (HR=4.5; P=0.02) and DFS (HR=5.2; P<0.0001) than CIMP(-) cases (n=95). In multivariate analysis, CIMP and N-myc amplification had an influence on OS and DFS independent of age and disease stage. CIMP had a stronger influence on DFS than N-myc amplification while N-myc had a stronger influence on OS.

Adolescent↗

Cartilage tissue engineering using human auricular chondrocytes embedded in different hydrogel materials.

To seek a suitable scaffold for cartilage tissue engineering, we compared various hydrogel materials originating from animals, plants, or synthetic peptides. Human auricular chondrocytes were embedded in atelopeptide collagen, alginate, or PuraMatrix, all of which are or will soon be clinically available. The chondrocytes in the atelopeptide collagen proliferated well, while the others showed no proliferation. A high-cell density culture within each hydrogel enhanced the expression of collagen type II mRNA, when compared with that without hydrogel. By stimulation with insulin and BMP-2, collagen type II and glycosaminoglycan were significantly accumulated within all hydrogels. Chondrocytes in the atelopeptide collagen showed high expression of beta1 integrin, seemingly promoting cell-matrix signaling. The N-cadherin expression was inhibited in the alginate, implying that decrease in cell-to-cell contacts may maintain chondrocyte activity. The matrix synthesis in PuraMatrix was less than that in others, while its Young's modulus was the lowest, suggesting a weakness in gelling ability and storage of cells and matrices. Considering biological effects and clinical availability, atelopeptide collagen may be accessible for clinical use. However, because synthetic peptides can control the risk of disease transmission and immunoreactivities, some improvement in gelling ability would provide a more useful hydrogel for ideal cartilage regeneration.

Atrial Appendage↗

Inflammatory responses involving tumor necrosis factor receptor-associated factor 6 contribute to in-stent lesion formation in a stent implantation model of rabbit carotid artery.

OBJECTIVE: Inflammatory responses are considered to represent a unique property after stent implantation, and we previously demonstrated that inflammatory signaling involving tumor necrosis factor receptor-associated factor 6 (TRAF6) contributes to neointimal formation in a balloon injury model of rabbit carotid artery. The purpose of this study was to examine the role of TRAF6 in in-stent lesion formation after stent implantation in the rabbit carotid artery. METHODS: Rabbit carotid arteries were injured with a 2F Fogarty catheter, and 28 days later, the same arteries were implanted with a 3-mm-diameter Palmaz-Schatz stent. A dominant negative (DN) form of TRAF6 (pME-FLAG-T6deltaRZ5) was then transferred using a plasmid-based electroporation method. Its effects were evaluated compared with the findings in arteries treated with control plasmid (pME-FLAG). RESULTS: Immunostaining with anti-FLAG tag antibody showed that an expression plasmid vector containing the DN-TRAF6 sequence was successfully transferred to the arterial intima and media. Morphometric analyses revealed that the increase of intimal area in in-stent lesions was significantly inhibited by DN-TRAF6 14 days after stent implantation (DN-TRAF6 group, 3.01 +/- 0.25 x 10(5) microm2 vs control group, 4.25 +/- 0.23 x 10(5) microm2, P < .01), and the cell density was increased compared with that in the control group. In the DN-TRAF6 plasmid-treated vessels, cell replication was prevented in both the intima and media, and fewer leukocytes adhered to the luminal surface. Moreover, DN-TRAF6 suppressed macrophage infiltration, activation of proteases, and proteoglycan accumulation in the in-stent intima. CONCLUSIONS: These findings suggest that TRAF6 plays an important role in cell replication, inflammatory cell infiltration, protease activity, and extracellular matrix accumulation that contributes to in-stent lesion development.

Animals↗

Isolation of human corneal endothelial cell precursors and construction of cell sheets by precursors.

PURPOSE: To review recently published experimental data on human corneal endothelium (CE) precursors. METHODS: A sphere-forming assay was used for the isolation of human CE precursors from human donor corneas and cultured human CE. CE morphology derived from precursors was compared with that from cultured human CE. RESULTS: Human CE from donor corneas formed primary and secondary sphere colonies and expressed neural and mesenchymal proteins. The progeny of these colonies had a human-CE-like hexagonal shape and showed transport activity, suggesting that the isolated spheres were indeed precursors of human CE. Similar precursors were isolated from cultured human CE, which provided further evidence that the sphere-forming assay facilitates the mass production of human CE precursors. Cultured human CE obtained in this manner had a regular hexagonal morphology in contrast to passaged, cultured human CE. CONCLUSION: The sphere-forming assay may become a powerful tool for the regeneration of human CE by precursor injection and the construction of cultured CE sheets.

Adult Stem Cells↗

Segmental alveolar distraction for the correction of unilateral open-bite caused by multiple ankylosed teeth: a case report.

Ankylosed teeth fail to erupt to meet their counterparts in the opposite jaw. In cases where ankylosis occurs in multiple teeth, the occlusion shows an open bite. This article describes a case of unilateral open bite caused by multiple ankylosed teeth, where treatment involved segmental alveolar bone distraction. A 25-year-old female patient presented with a left-sided unilateral open bite. On the left-hand side, only the lower incisors were not ankylosed. On the right, the maxillary first molar was ankylosed. All these ankylosed teeth were positioned below the occlusal plane. Her mother and brother also had multiple ankylosed teeth, and a familial cause was considered. Orthodontic tooth movement was considered impossible and segmental osteotomy on the left maxillary alveolar bone and downward bone distraction were performed as an alternative. A distractor consisting of orthodontic bands, wires and screws was devised and worn in the left mandibular dentition. Multi-bracket orthodontic appliances were also used for distraction. The amount of vertical movement was 7 mm at the premolar region. Five months after distraction, the multibracket appliance was removed, and fixed and removable retainers were placed. Eight months after distraction, prosthodontic restorations on the occlusal surfaces of the ankylosed teeth were made to obtain the final occlusion. The unilateral open bite was successfully treated and a good occlusion was obtained. The occlusion has shown good long-term stability for more than 3 years.

Adult↗

Assessment of dental arch relationships in Japanese patients with unilateral cleft lip and palate.

OBJECTIVE: Evaluation of the dental arch relationships of Japanese patients with unilateral cleft lip and palate (UCLP) from the orthodontic clinic of the University of Tokyo Hospital (UTH) compared with patients treated by the Oslo Cleft Team, Norway. DESIGN: Retrospective study and comparison with previous reports. MATERIALS: Dental models of 24 patients with UCLP in UTH taken before orthodontic treatment and before alveolar bone grafting were included. Surgeons in many hospitals performed primary surgeries. These models were matched for age and gender with 24 models from a consecutive series of patients treated by the Oslo Cleft Team as part of the Eurocran Good Practice Archive. A total of 48 models were evaluated. MAIN OUTCOME MEASURE: Dental arch relationship was rated with the Goslon Yardstick. The strength of agreement of rating was assessed with weighted kappa statistics. RESULTS: Intra- and interexaminer agreements evaluated by weighted kappa statistics were high, indicating good reproducibility. Almost 60% of the patients in UTH were classified into poor or very poor categories, and the mean Goslon score was 3.50. These results show a contrast to those in Oslo and were the poorest in comparison with previous reports. CONCLUSION: Dental arch relationships in patients with UCLP in UTH were poor. This seemed to be attributable to surgical procedures, but a factor of racial difference in the craniofacial morphology was also considered. Further intercenter research is required to clarify this point.

Alveoloplasty↗

Suppression of adjuvant-induced arthritic bone destruction by cyclooxygenase-2 selective agents with and without inhibitory potency against carbonic anhydrase II.

UNLABELLED: In vitro assays revealed that COX-2 inhibitors with CA II inhibitory potency suppressed both differentiation and activity of osteoclasts, whereas that without the potency reduced only osteoclast differentiation. However, all COX-2 inhibitors similarly suppressed bone destruction in adjuvant-induced arthritic rats, indicating that suppression of osteoclast differentiation is more effective than that of osteoclast activity for the treatment. INTRODUCTION: Cyclooxygenase (COX)-2 and carbonic anhydrase II (CA II) are known to play important roles in the differentiation of osteoclasts and the activity of mature osteoclasts, respectively. Because several COX-2 selective agents were recently found to possess an inhibitory potency against CA II, this study compared the bone sparing effects of COX-2 selective agents with and without the CA II inhibitory potency. MATERIALS AND METHODS: Osteoclast differentiation was determined by the mouse co-culture system of osteoblasts and bone marrow cells, and mature osteoclast activity was measured by the pit area on a dentine slice resorbed by osteoclasts generated and isolated from bone marrow cells. In vivo effects on arthritic bone destruction were determined by radiological and histological analyses of hind-paws of adjuvant-induced arthritic (AIA) rats. RESULTS: CA II was expressed predominantly in mature osteoclasts, but not in the precursors. CA II activity was inhibited by sulfonamide-type COX-2 selective agents celecoxib and JTE-522 similarly to a CA II inhibitor acetazolamide, but not by a methylsulfone-type COX-2 inhibitor rofecoxib. In vitro assays clearly revealed that celecoxib and JTE-522 suppressed both differentiation and activity of osteoclasts, whereas rofecoxib and acetazolamide suppressed only osteoclast differentiation and activation, respectively. However, bone destruction in AIA rats was potently and similarly suppressed by all COX-2 selective agents whether with or without CA II inhibitory potency, although only moderately by acetazolamide. CONCLUSIONS: Suppression of osteoclast differentiation by COX-2 inhibition is more effective than suppression of mature osteoclast activity by CA II inhibition for the treatment of arthritic bone destruction.

Adjuvants, Immunologic↗

The canonical Wnt signaling pathway promotes chondrocyte differentiation in a Sox9-dependent manner.

To better understand the role of the canonical Wnt signaling pathway in cartilage development, we adenovirally expressed a constitutively active (ca) or a dominant negative (dn) form of lymphoid enhancer factor-1 (LEF-1), the main nuclear effector of the pathway, in undifferentiated mesenchymal cells, chondrogenic cells, and primary chondrocytes, and examined the expression of markers for chondrogenic differentiation and hypertrophy. caLEF-1 and LiCl, an activator of the canonical pathway, promoted both chondrogenic differentiation and hypertrophy, whereas dnLEF-1 and the gene silencing of beta-catenin suppressed LiCl-promoted effects. To investigate whether these effects were dependent on Sox9, a master regulator of cartilage development, we stimulated Sox9-deficient ES cells with the pathway. caLEF-1 and LiCl promoted both chondrogenic differentiation and hypertrophy in wild-type, but not in Sox9-deficient, cells. The response of Sox9-deficient cells was restored by the adenoviral expression of Sox9. Thus, the canonical Wnt signaling pathway promotes chondrocyte differentiation in a Sox9-dependent manner.

Animals↗

CpG island methylator phenotype is a strong determinant of poor prognosis in neuroblastomas.

Neuroblastoma, one of the most common pediatric solid tumors, is characterized by two extreme disease courses, spontaneous regression and life-threatening progression. Here, we conducted a genome-wide search for differences in DNA methylation that distinguish between neuroblastomas of the two types. Three CpG islands (CGI) and two groups of CGIs were found to be methylated specifically in neuroblastomas with a poor prognosis. By quantitative analysis of 140 independent cases, methylation of all the five CGI (groups) was shown to be closely associated with each other, conforming to the CpG island methylator phenotype (CIMP) concept. The presence of CIMP was sensitively detected by methylation of the PCDHB CGIs and associated with significantly poor survival (hazard ratio, 22.1; 95% confidence interval, 5.3-93.4; P < 0.0001). Almost all cases with N-myc amplification (37 of 38 cases) exhibited CIMP. Even in 102 cases without N-myc amplification, the presence of CIMP (30 cases) strongly predicted poor survival (hazard ratio, 12.4; 95% confidence interval, 2.6-58.9; P = 0.002). Methylation of PCDHB CGIs, located in their gene bodies, did not suppress gene expression or induce histone modifications. However, CIMP was significantly associated with methylation of promoter CGIs of the RASSF1A and BLU tumor suppressor genes. The results showed that neuroblastomas with CIMP have a poor prognosis and suggested induction of silencing of important genes as an underlying mechanism.

Cell Line, Tumor↗

Molecular and pharmacological characteristics of transient voltage-dependent K+ currents in cultured human pulmonary arterial smooth muscle cells.

The A-type voltage-dependent K(+) current (I(A)) has been identified in several types of smooth muscle cells including the pulmonary artery (PA), but little is known about the pharmacological and molecular characteristics of I(A) in human pulmonary arterial smooth muscle cells (hPASMCs). We investigated I(A) expressed in cultured PASMCs isolated from the human main pulmonary artery, using patch-clamp techniques, reverse transcriptase-polymerase chain reaction (RT-PCR), quantitative real-time RT-PCR and immunocytochemical studies. With high EGTA and ATP in the pipette, the outward currents were dominated by a transient K(+) current (I(A)), followed by a relatively small sustained outward current (I(K)). I(A) was inhibited by 4-aminopyridine (4-AP) concentration-dependently, and could be separated pharmacologically into two components by tetraethylammonium (TEA) sensitivity. A component was sensitive to TEA, and the second component was insensitive to TEA. I(A) was inhibited by blood depressing substrate (BDS)-II, a specific blocker of K(V)3.4 subunit, and phrixotoxin-II, a specific blocker of K(V)4.2 and 4.3. Flecainide inhibited I(A) concentration-dependently, but it inhibited it preferentially in the presence of TEA (TEA-insensitive I(A)). Systematic screening of expression of K(V) genes using RT-PCR showed the definite presence of transcripts of the I(A)-encoding genes for K(V)3.4, K(V)4.1, K(V)4.2 and K(V)4.3 as well as the I(K)-encoding genes for K(V)1.1, K(V)1.5 and K(V)2.1. The real-time RT-PCR analysis showed that the relative abundance of the encoding genes of I(A) alpha-subunit and K(V) channel-interacting proteins (KChIPs) was K(V)4.2 > K(V)3.4 > K(V)4.3 (long) > K(V)4.1, and KChIP3 >> KChIP2, respectively. The presence of K(V)3.4, K(V)4.2 and K(V)4.3 proteins was also demonstrated by immunocytochemical studies, and confirmed by immunohistochemical staining using intact human PA sections. These results suggest that I(A) in cultured hPASMCs consists of two kinetically and pharmacologically distinct components, probably K(V)3.4 and K(V)4 channels.

Calcium-Binding Proteins↗

Total reconstruction of the upper lip after resection of a malignant melanoma.

The upper lip was totally reconstructed with a radial forearm sensory flap and vermilionplasty using medical tattooing after resection of a malignant melanoma. Three courses of chemotherapy (dacarbazine, nimustine, and vincristine) were given postoperatively. The reconstructed lip had good contour, colour, and sensory recovery.

Aged↗

Reconstruction necessitated by severe hypoplasia or a columella defect.

In reconstruction necessitated by severe hypoplasia or a columella defect, the surgeon must consider various factors in each case, such as the characteristic columellar shape, color match, texture, patient age, original disease, and surrounding scars. In these cases, reconstruction of both the cartilaginous strut and the overlying skin is necessary and important to obtain good results. The authors report three cases of reconstruction of the columella with satisfactory results. Case 1 involved a 6-year-old girl with complete bilateral cleft lip and severe hypoplasia of the premaxilla and prolabium. Columellar reconstruction was performed with small triangular flaps at the columella base, together with a rib chondral graft for cartilaginous support. Case 2 involved a 12-year-old girl with a complete bilateral cleft lip and cleft palate. Columellar reconstruction was performed with small triangular flaps at the columella base, together with bilateral conchal cartilage grafts. Case 3 involved a 17-year-old boy with a right complete cleft lip and columellar defect caused by previous infection after secondary cheiloplasty. Columellar reconstruction was performed using a left nasal vestibular flap and septal cartilage grafting, together with a bilateral conchal cartilage graft beneath the flap. The authors consider the unilateral nasal vestibular flap to be very useful in carefully selected unilateral cleft cases.

Adolescent↗

Synergistic effects of FGF-2 with insulin or IGF-I on the proliferation of human auricular chondrocytes.

Chondrocyte preparation with the safety and efficiency is the first step in cartilage regenerative medicine. To prepare a chondrocyte proliferation medium that does not contain fetal bovine serum (FBS) and that provides more than a 1000-fold increase in cell numbers within approximately 1 month, we attempted to use the medium containing 5% human serum (HS), but it exerted no more than twofold increase in 2 weeks. To compensate for the limited proliferation ability in HS, we investigated the combinational effects of 12 factors [i.e., fibroblast growth factor (FGF)-2, insulin-like growth factor (IGF)-I, insulin, bone morphogenetic protein-2, parathyroid hormone, growth hormone, dexamethasone, 1alpha25-dihydroxy vitamin D3, L-3,3',5'-triodothyronine, interleukine-1 receptor antagonist, 17beta-estradiol, and testosterone] on the proliferation of human auricular chondrocytes by analysis of variance in fractional factorial design. As a result, FGF-2, dexamethasone, insulin, and IGF-I possessed promotional effects on proliferation, while the combination of FGF-2 with insulin or IGF-I synergistically enhanced the proliferation. Actually, the chondrocytes increased 7.5-fold in number in 2 weeks in a medium containing 5% HS with 10 ng/ml FGF-2, while the cell number synergistically gained a 10-12-fold increase with 5 microg/ml insulin or 100 ng/ml IGF-I in the same period. The proliferation effects were more enhanced at a concentration of 100 ng/ml for FGF-2, and especially for the combination of 100 ng/ml FGF-2 and 5 microg/ml insulin (approximately 16-fold within 2 weeks). In the long-term culture with repeated passaging, this combination provided more than 10,000-fold within 8 weeks (i.e., passage 4). Thus, we concluded that such a combination of FGF-2 with insulin or IGF-I may be useful for promotion of auricular chondrocyte proliferation in a clinical application for cartilage regeneration.

Adolescent↗

Gelatin hydrogel microspheres enable pinpoint delivery of basic fibroblast growth factor for the development of functional collateral vessels.

BACKGROUND: Various growth factors promote collateral vessel development and are regarded as promising for the treatment of vascular occlusive diseases. However, an efficacious delivery system for them has yet to be established. We devised a strategy to augment functional collateral vessels by using acidic gelatin hydrogel microspheres (AGHMs) incorporating basic fibroblast growth factor (bFGF). The aim of the present study was to investigate the hypothesis that by intra-arterial (IA) administration of bFGF-impregnated AGHMs, bFGF could be delivered from AGHMs trapped in distal small-diameter vessels and thereby induce functional collateral vessels with an assured blood supply through the process of arteriogenesis. METHODS AND RESULTS: Various sizes of AGHMs (3 mg) incorporating 125I-labeled bFGF were injected into the left internal iliac artery of a rabbit model of hindlimb ischemia. Less than 50% of radioactivity accumulated in the ischemic hindlimb after injection of AGHMs that were 10 mum in diameter, whereas approximately 80% of radioactivity was counted in the ischemic limb after administration of 29- or 59-microm-diameter AGHMs. Calf blood pressure ratio and the ratio of regional blood flow of the bilateral hindlimbs immediately before and after IA administration of 29-microm-diameter AGHMs showed no significant change. Then we evaluated the function of the developed collateral vessels 28 days after IA administration of bFGF-impregnated, 29-microm-diameter AGHMs. IA administration of bFGF-impregnated AGHMs induced marked collateral vessel improvement compared with IA administration of phosphate buffered saline-treated AGHMs and intramuscular administration of bFGF-impregnated AGHMs. CONCLUSIONS: IA administration of bFGF-impregnated, 29-microm-diameter AGHMs strongly induced functional collateral vessels without worsening ischemia, indicating the possible therapeutic usefulness of this approach.

Animals↗