Journal of Hard Tissue Biology
Online ISSN : 1880-828X
Print ISSN : 1341-7649
ISSN-L : 1341-7649
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Original
  • Takuya Notomi, Chie Kise, Ryuichiro Kobayashi, Miki Otsuka, Yoshihiro ...
    2021 Volume 30 Issue 4 Pages 333-338
    Published: 2021
    Released: October 26, 2021
    JOURNAL FREE ACCESS

    Osteoclast differentiation is one of the key steps that regulate bone mass and involves RANKL-induced changes in the intracellular Ca2+ levels. Previously, we reported the function of a lysosomal Ca2+ channel, two-pore channel (TPC) subtype 2 (TPC2), using TPC2-knockout RAW264.7 cell line (RAW) during osteoclastogenesis. However, the effects of overexpressed TPC2 have not been examined because of the relatively low lipid-based efficiency transfection in RAW. In this study, TPC2 was transfected in RAW and RAW-derived mature osteoclast-like cells using an improved lipid-based transfection method. TPC2 was predominantly localized in the ruffled border-like structure of the osteoclasts. Moreover, overexpression of TPC2 promoted osteoclast differentiation. In addition, expression levels of TPC1 were measured, and TPC1-expressing vectors were transfected into RAW to investigate the role of TPC1 in osteoclastogenesis. Osteoclast differentiation was promoted in TPC1-transfected RAW. Notably, TPC2 expression was not influenced by TPC1 overexpression. Furthermore, TPC1 was knocked down by siRNA, resulting in reduced TRAP activity. TRAP is a biochemical indicator of osteoclastogenesis. Our findings suggest that TPC1 and TPC2 have independent essential roles in the differentiation of osteoclasts.

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  • Hiroshi Nakada, Takehiro Watanabe, Takahiro Takahashi, Hiroki Sato, Da ...
    2021 Volume 30 Issue 4 Pages 339-346
    Published: 2021
    Released: October 26, 2021
    JOURNAL FREE ACCESS

    This study focused on the post-implantation formation of new bone in the peri-implant region of synthetic bone mineral (SBM)-coated implants in rat femur models and aimed to elucidate the effects of SBM surface treatment on early bone formation and bone tissue quality. Twenty-four 8-week-old Wistar rats were randomly assigned to four experimental groups: two-week implantation with blasting-treated implant (6 rats; control group) or SBM-treated implant (6 rats; experimental group); and four-week implantation with blasting-treated implant (6 rats; control group) or SBM-treated implant (6 rats; experimental group). After implantation, the following data were collected and compared: pull-out strength, bone mineral density (BMD), BMD color images, and histological characteristics. Comparisons of the two- and four-week data indicated that the pull-out strengths and BMD of the SBM group were significantly higher than those of the control group. BMD color imaging and histological observations indicated that, in comparison with the control group, the new bone formed in the peri-implant region of the SBM group had greater width and higher BMD. Our results will aid the development of implant surface treatments that facilitate early bone formation. Further, the investigated SBM could be applied as a bone prosthetic filling material in regions with bone defects.

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  • Takuya Notomi, Ryuichiro Kobayashi, Miki Otsuka, Chie Kise, Yoshihiro ...
    2021 Volume 30 Issue 4 Pages 347-354
    Published: 2021
    Released: October 26, 2021
    JOURNAL FREE ACCESS

    Bone mass is regulated by bone remodeling, which involves bone formation by osteoblasts and bone resorption by osteoclasts. To prevent and treat bone loss, a basic understanding of the mechanism of bone formation is essential, including osteoblast differentiation, and its responses to mechanical stimuli that induce changes in membrane potential. During osteoblast differentiation, hyperpolarized membrane potential was observed. To understand osteoblast differentiation in response to membrane hyperpolarization, as well as the long-term effects of changes in membrane potential, we developed a light-controllable membrane potential system in MC3T3-E1 osteoblast-like cells by stably expressing the light-driven outward proton pump, archaerhodopsin-3. Archaerhodopsin-3 activation by yellow-green light hyperpolarizes the cell membrane Light-induced hyperpolarization accelerated osteoblast mineralization, as assessed by Alizarin Red staining, alkaline phosphatase activity, and expression levels of osteoblast differentiation markers. This promotion of osteoblast mineralization is related to voltage-gated Ca2+ channels. Our study revealed a novel role of membrane potential in non-excitable osteoblast-like cells.

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  • Junya Ono, Yasuo Okada, Yoriaki Kanri, Hiroto Sano, Hitoshi Hasegawa
    2021 Volume 30 Issue 4 Pages 355-362
    Published: 2021
    Released: October 26, 2021
    JOURNAL FREE ACCESS

    Clinically suspected oral lichen planus (OLP) includes histopathologically proven OLP, oral lichenoid lesion (OLL) or lichenoid stomatitis, and oral lichenoid dysplasia (OLD). Malignant transforming potential of OLD is a diagnostic issue. This study aimed to exclude OLD from OLP and OLL and examine the role of OLD in malignant transformation. Immunostaining for CK13, CK17, p53, Ki-67, Coxsackie‒adenovirus receptor (CAR) and E-Cadherin was conducted in 200 cases. CK13-positive rate was lower in OLD (33.3%) than in OLP and OLL. CK17-positive rate was slightly lower in OLP (89.2%) compared to OLL and OLD. Ki-67- positive rate from basal to spinous layer was higher in OLD (30.6%) than in OLP and OLL, and p53 showed similar trend (OLD: 19.4%). Rate of attenuated CAR staining intensity from basal layer to lower one-third of spinous layer was higher in OLD (77.8%) compared to OLP and OLL, similar to rate of attenuated E-Cadherin staining (OLD: 45.8%). In conclusion, a diagnosis of OLP or OLL is indicated when the lesion is CK13 positive and CK17 positive, with no attenuation of staining intensity for CAR and E-Cadherin from the basal layer to the lower onethird of the spinous layer. On the other hand, a diagnosis of OLD is indicated when the lesion is CK13 negative and CK 17 positive, with attenuation of staining intensity for CAR and E-Cadherin from the basal layer to the lower one-third of the spinous layer. In OLD, attenuated CAR expression may participate in malignant transformation by weakening cell junction in the epithelium and inducing epithelial mesenchymal transition.

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  • Wanlu Chen, Yong Zhou, Zhongxiong Ma, Yunde Xie
    2021 Volume 30 Issue 4 Pages 363-370
    Published: 2021
    Released: October 26, 2021
    JOURNAL FREE ACCESS

    To detect the expression of miR-590 in oral lichen planus (OLP) tissues and oral squamous cell carcinoma (OSCC) tissues, and to analyze the correlations with clinicopathological characteristics and prognosis of OSCC patients. The oral mucosa tissues were selected from 180 patients with OLP or OSCC. They were divided into OLP group (n=92) and OSCC group (n=88), and 40 healthy volunteers with normal oral mucosa tissues were set as control group. Human tongue squamous cell carcinoma cell line SCC9 and human oral keratinocyte HOK were used. The expressions of miR-590 in tissues and cells were detected using qPCR. SCC9 cells were transfected with small interfering (si)-miR-590 and si-NC plasmids. MTT assay, flow cytometry and Transwell assay were used to detect cell proliferation, apoptosis, migration and invasion abilities, respectively. The expression levels of apoptosis-, migration- and invasion-related proteins were examined using Western blotting. Control, OLP and OSCC groups displayed successively increased expression of miR-590, suggesting that the expression was related to the TNM stage and lymph node metastasis of OSCC patients (P<0.05). Following transfection with si-miR-590, the proliferation, migration and invasion abilities of SCC9 cells were weakened significantly, while the apoptosis rate rose (P<0.05). The expression levels of Bcl-2, N-cadherin and vimentin dropped significantly, whereas those of Bax and E-cadherin increased (P<0.05). MiR-590 is highly expressed in OSCC and SCC9 cells. Silencing miR-590 can suppress the proliferation, migration and invasion and promote the apoptosis of SCC9 cells.

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  • Ryusuke Nakatsuka, Yuka Sasaki, Mitsuko Masutani, Tadashige Nozaki
    2021 Volume 30 Issue 4 Pages 371-378
    Published: 2021
    Released: October 26, 2021
    JOURNAL FREE ACCESS

    Non-coding RNAs including microRNAs (miRNAs) derived from extracellular exosomes are considered as biomarkers for multiple intracellular communication pathways. Meanwhile, poly ADP-ribosylation (PARylation) catalyzed by poly (ADP-ribose) polymerase 1 (PARP1) is related to various intracellular processes. The comprehensive idea of cell-cell signaling phenomena mediated by PARP1-related exosomes remains unsolved, although individual molecules are considered to provoke disease pathogenesis and progression under aberrant regulation. In the present study, we knocked down the PARP1 gene in dental pulp stem cells (DPSCs) by gene targeting using the CRISPR-Cas9 system to determine the functions of exosomal miRNAs regulated by PARP1. The exosomes produced by PARP1-knockdown DPSCs were harvested and the miRNAs contained within these exosomes were comprehensively analyzed by next-generation sequencing. From the results, significantly altered miRNAs were picked up among the detected miRNAs. Gene ontology enrichment analyses were performed on these miRNAs to predict their cellular functions. Most of the up-regulated miRNAs after PARP1 knockdown were identified as cell proliferation-related functional non-coding RNAs, and were indicated to affect cellular processes regulating cellular senescence and differentiation. Therefore, the present findings suggest that PARP1 in DPSCs regulates cellular processes such as cell proliferation through intercellular communication mediated by exosomal miRNAs.

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  • Go Itakura, Kotaro Ito, Hirotaka Muraoka, Naohisa Hirahara, Hiroyuki O ...
    2021 Volume 30 Issue 4 Pages 379-382
    Published: 2021
    Released: October 26, 2021
    JOURNAL FREE ACCESS

    Maxillofacial trauma is a serious health problem because of the significant negative impact on an individual of the physical and psychological health. There are few studies reported that risk assessment of jawbone fracture by mandibular cortical bone width. The purpose of this study was to evaluate the mandibular cortical bone width using CT and to assess of the risk of jawbone fracture. This study included 381 patients (181 women and 200 men; 20-95 years of age, mean age 50.5 years) with suspected jawbone fractures due to falling who underwent CT at our hospital from April 2008 to March 2015. Mandibular cortical bone width was measured from distal to the mental foramen on both sides of the mandible using CT coronal images. All images were independently evaluated by two of oral radiologists. Each of the two groups were then compared about average of mandibular cortical bone width. Of the 381 patients, jawbone fractures were seen in 243 patients (63.8 %). The average mandibular cortical bone width in patients with jawbone fractures was 2.40±0.64 mm. In contrast, the average mandibular cortical bone width in patients without jawbone fracture was 2.76±0.61 mm (p < 0.01). The interobserver agreement for MCW was good (ICC=.795). The present study found that the MCW with fracture group was significant thinner than without fracture group. Our results suggested that the MCW on CT provide a risk assessment of jawbone fractures.

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Clinical Report
  • Shungo Ichiki, Hirotaka Muraoka, Naohisa Hirahara, Kotaro Ito, Hiroyuk ...
    2021 Volume 30 Issue 4 Pages 383-388
    Published: 2021
    Released: October 26, 2021
    JOURNAL FREE ACCESS

    Dental implants may help improve the general health and quality of life in older adults with tooth loss. Accurate assessment of the alveolar bone is key to implant treatment. Several studies have examined the value of jaw morphology diagnostic imaging; however, few studies have evaluated age-related changes in alveolar bone height and width using computed tomography (CT) scanning. The purpose of this study was to assess age-related changes in alveolar bone height and width using CT scans of patients undergoing dental implant treatment. We analyzed CT scans of 1960 sites in 655 cases (225 men, 430women; age rage, 20-85 years; mean age, 60.96 years) obtained from June 2016 to December 2018. The mean alveolar bone height and width were the outcomes of interest. The participants were dichotomized by age into groups of 20-64 and 65-85 years. Alveolar bone height and width were classified into six groups by site; the values were examined by age. Analyses were performed with the Mann-Whitney U test and Spearman correlation coefficients. Statistical significance was established at P<0.05. The height of the upper anterior (P<0.001), upper premolar (P<0.001), upper molar (P<0.01), lower anterior (P<0.01), lower premolar (P<0.05), and lower molar (P<0.01) sites, and the width of the upper anterior (P<0.01), upper premolar (P<0.01), and upper molar (P<0.01) sites in the alveolar bone were significantly associated with age. The present findings suggest that the decline in upper alveolar bone height and width and lower alveolar bone height is associated with aging in the present cohort. These findings suggest that older people may require implant treatment that is predicated on bone grafting.

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Clinical Note
  • Cui-min Zeng
    2021 Volume 30 Issue 4 Pages 389-394
    Published: 2021
    Released: October 26, 2021
    JOURNAL FREE ACCESS

    To evaluate the clinical effect of direct resin veneers and porcelain veneers in the esthetic restoration of anterior teeth affected by dental fluorosis, 64 patients suffering from dental fluorosis (328 teeth) between February 2015 and June 2016 were selected. Of these patients, 34 were given direct resin veneers (196 teeth) and 30 were given porcelain veneers (132 teeth). Clinical follow-up observation was carried out for 24 months on restoration integrity, marginal fit, gingival index, secondary caries, and patient satisfaction. After 24 months of restoration, it was found that there was no secondary caries in the direct resin veneer or porcelain veneer restoration, and the integrity of the restorations, marginal adhesiveness, and gingival condition examination scores were evaluated as excellent. The scores for patient satisfaction were 80.27 and 90.63, respectively, and the difference was statistically significant (p < 0.05). The results demonstrated that direct resin veneers and porcelain veneers can both achieve a positive clinical therapeutic effect in dental fluorosis esthetic restoration, but patient satisfaction after porcelain veneer restoration is higher.

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