Sclerostin in periodontal ligament: Homeostatic regulator in biophysical force-induced tooth movement.

AIM: To study the role of sclerostin in periodontal ligament (PDL) as a homeostatic regulator in biophysical-force-induced tooth movement (BFTM). MATERIALS AND METHODS: BFTM was performed in rats, followed by microarray, immunofluorescence, in situ hybridization, and real-time polymerase chain reaction for the detection and identification of the molecules. The periodontal space was analysed via micro-computed tomography. Effects on osteoclastogenesis and bone resorption were evaluated in the bone-marrow-derived cells in mice. In vitro human PDL cells were subjected to biophysical forces. RESULTS: In the absence of BFTM, sclerostin was hardly detected in the periodontium except in the PDL and alveolar bone in the furcation region and apex of the molar roots. However, sclerostin was up-regulated in the PDL in vivo by adaptable force, which induced typical transfiguration without changes in periodontal space as well as in vitro PDL cells under compression and tension. In contrast, the sclerostin level was unaffected by heavy force, which caused severe degeneration of the PDL and narrowed periodontal space. Sclerostin inhibited osteoclastogenesis and bone resorption, which corroborates the accelerated tooth movement by the heavy force. CONCLUSIONS: Sclerostin in PDL may be a key homeostatic molecule in the periodontium and a biological target for the therapeutic modulation of BFTM.

Expression of amelogenin and effects of cyclosporin A in developing hair follicles in rats.

Amelogenin, an enamel matrix protein has been considered to be exclusively expressed by ameloblasts during odontogenesis. However, burgeoning evidence indicates that amelogenin is also expressed in non-mineralizing tissues. Under the hypothesis that amelogenin may be a functional molecule in developing hair follicles which share developmental features with odontogenesis, this study for the first time elucidated the presence and functional changes of amelogenin and its receptors during rat hair follicle development. Amelogenin was specifically localized in the outer epithelial root sheath of hair follicles. Its expression appeared in the deeper portion of hair follicles, i.e. the bulbar and suprabulbar regions rather than the superficial region. Lamp-1, an amelogenin receptor, was localized in either follicular cells or outer epithelial sheath cells, reflecting functional changes during development. The expression of amelogenin splicing variants increased in a time-dependent manner during postnatal development of hair follicles. Amelogenin expression was increased by treatment with cyclosporin A, which is an inducer of anagen in the hair follicle, whereas the level of Lamp-1 and -2 was decreased by cyclosporin A treatment. These results suggest that amelogenin may be a functional molecule involved in the development of the hair follicle rather than an inert hair shaft matrix protein.

Acute physical stress induces the alteration of the serotonin 1A receptor density in the hippocampus.

Stress affects the serotonergic system, which is associated with depression. Previous research has showed that chronic stress causes the deactivation of the limbic system. However, the influence of the acute physical stress on the serotonergic system in vivo was primarily unclear. The purpose of this research is to elucidate the effects of the acute physical stress in vivo using PET. For quantification of the 5-HT1A receptors in the brain, we measured [(18)F]Mefway uptake in the two experiment groups (control and despair rats). The despair group was subjected to the external stressful situation (i.e., forced swimming) and total duration time of immobility, refers to the despair severity, and was analyzed. In the intercomparison experiment, the resulting PET images of [(18)F]Mefway in the despair rat displayed a significant reduction of radioactivity in the hippocampus (HP) compared with the control. The nondisplaceable binding potential (BPND ) refers to the ratio of the concentration of radioligand in the receptor-rich region (i.e., HP) to the concentration of that in the receptor-free region (i.e., cerebellum). The hippocampal uptake and the BPND in the despair group were respectively about 25 and 18% lower than those of the control group. The ratio of specific binding to nonspecific binding in the despair group was 18% lower than that of the control. In the intracomparison experiments, the BPND and immobility in the despair group showed a strong negative correlation. Taken together, the data illustrates that an acute physical stress induces the change in the serotonergic system that correlates with the behavioral despair.

Regulatory role of N-myc downregulated genes in amelogenesis in rats.

Cytodifferentiation of odontogenic cells, a late stage event in odontogenesis is based on gene regulation. However, studies on the identification of the involved genes are scarce. The present study aimed to search for molecules for the cytodifferentiation of ameloblastic cells in rats. Differential display-PCR revealed a differentially expressed gene between cap/early bell stage and hard tissue formation stage in molars. This gene was identified as N-myc Downregulated Gene 1 (Ndrg1), which is the first report in tooth development. Real time PCR and western blotting confirmed that the mRNA level of Ndrg1 was higher during enamel formation than the cap stage. Ndrg1 expression was upregulated in the early bell, crown, and root stages in a time-dependent manner. These patterns of expression were similar in Ndrg2, but Ndrg3 and Ndrg4 levels did not change during the developmental stages. Immunofluorescence revealed that strong immunoreactivity against Ndrg1 were detected in differentiated ameloblasts only, not inner enamel epithelium, odontoblasts and ameloblastic cells in defected enamel regions. Alkaline phosphatase and alizarin red s stains along with real time PCR, revealed that Ndrg1 and Ndrg2 were involved in cytodifferentiation and enamel matrix mineralization by selectively regulating amelogenin and ameloblastin genes in SF2 ameloblastic cells. These results suggest that Ndrg may play a crucial functional role in the cytodifferentiation of ameloblasts for amelogenesis.

Synaptic vesicle protein 2b is expressed temporospatially in (pre)odontoblasts in developing molars.

The formation of dentin and enamel is initiated by the differentiation of odontogenic precursor cells into odontoblasts and ameloblasts, respectively. This study was performed to identify new molecules involved in the differentiation of odontogenic cells. The genes expressed differentially between the root stage (after the differentiation of odontogenic cells and dental hard-tissue formation) and the cap stage (before the differentiation of odontogenic cells and dental hard-tissue formation) were searched using differential display PCR. For the first time, synaptic vesicle protein (SV) 2b, an important transmembrane transporter of Ca(2+) -stimulated vesicle exocytosis, was identified as a differentially expressed molecule. Real-time PCR and western blotting revealed an increase in the transcriptional and translational levels of SV2b during or after the differentiation of odontogenic cells. Immunofluorescence revealed this molecule to be localized in not only fully differentiated odontoblasts but also in pre-odontoblasts before dentin matrix secretion. The expression pattern of the SV2a isoform was similar to that of the SV2b isoform, whereas the SV2c isoform showed a contrasting pattern of expression. After treatment with alendronate, an inhibitor of protein isoprenylation for the transport of secretory vesicles, the expression of SV2a and SV2b decreased, whereas that of SV2c increased. These results suggest that the SV2 isoforms are functional molecules of (pre)odontoblasts which may be involved in vesicle transport.

Relaxin is up-regulated in the rat ovary by orthodontic tooth movement.

Relaxin (Rln) is an ovarian hormone that stimulates osteoclastic and osteoblastic activities and connective tissue turnover. To investigate the expression of Rln during orthodontic tooth movement, rats were implanted with orthodontic appliances that connected a spring from the upper incisors to the first molar with a 70 cN force. Rats in each group were killed 6, 48, and 144 h after activating the appliance, and the levels of Rln1 and Rln3 expression in the ovary were determined by real-time RT-PCR, northern blots, western blots, and immunofluorescence analyses. The amount of tooth movement induced by the orthodontic force increased in a time-dependent manner. The levels of Rln1 mRNA increased by 12-, 41-, and 263-fold at 6, 48, and 144 h, respectively, after orthodontic tooth movement. The time-dependent increase in the concentration of Rln 1 protein in the ovary was also confirmed by western blotting. Rln 1 was localized in the granulosa cells of the ovarian follicles, and the immunoreactivity against Rln 1 was increased by the movement. In contrast, the concentration of Rln 3 was below the level of detection. The results of this study suggest that local changes in periodontal tissues induced by orthodontic tooth movement may affect Rln1 expression in the ovary. However, further studies are needed to decipher the mechanisms involved and the possible contribution of the increased level of expression of Rln 1 to the tooth movement.

Regulatory role of insulin-like growth factor-binding proteins in odontogenic mineralization in rats.

Much information is currently available for molecules in early odontogenesis, but there is limited knowledge regarding terminal cytodifferentiation of ameloblasts and odontoblasts for the determination of normal crown morphology. The present differential display PCR (DD-PCR) revealed that insulin-like growth factor-binding protein 5 (IGFBP5) was differentially expressed in molar tooth germs between the cap (before crown mineralization) and root formation (after crown mineralization) stages. Real-time PCR confirmed that the expression levels of IGFBP1-4 were not significantly changed but those of IGFBP5-7 were upregulated in a time-dependent manner. Immunoreactivities for IGFBP5-7 were hardly seen in molar germs at the cap/early bell stage and protective-stage ameloblasts at the root formation stage. However, the reactivity was strong in odontoblasts and maturation-stage ameloblasts, which are morphologically and functionally characterized by wide intercellular space and active enamel matrix mineralization. The localization of each IGFBP was temporospatial. IGFBP5 was localized in the nuclei of fully differentiated odontoblasts and ameloblasts, while IGFBP6 was localized in the apical cytoplasm of ameloblasts and odontoblasts with dentinal tubules, and IGFBP7 was mainly found in the whole cytoplasm of odontoblasts and the intercellular space of ameloblasts. IGFBP silencing using specific siRNAs upregulated representative genes for dentinogenesis and amelogenesis, such as DMP1 and amelogenin, respectively, and augmented the differentiation media-induced mineralization, which was confirmed by alizarin red s and alkaline phosphatase staining. These results suggest that IGFBP5-7 may play independent and redundant regulatory roles in late-stage odontogenesis by modulating the functional differentiation of ameloblasts and odontoblasts.

Dual role of phosphatidylserine and its receptors in osteoclastogenesis.

Fusion and apoptosis share a breakdown of the membrane phospholipids asymmetry, modes of which are largely unknown in osteoclastogenesis. Here, we investigated the externalization of phosphatidylserine (PS) and its receptors, and their biological functions in osteoclastogenesis. Strong immunoreactivities in vivo for the PS receptors TIM4, BAI1, and STAB2 were observed in the TRAP-positive multinucleated cells in the alveolar bone that was being remodeled around the developing dental follicles in rats. These receptors were significantly upregulated during M-CSF/RANKL-induced in vitro osteoclastogenesis using mouse bone marrow-derived cells. PS externalization in preosteoclasts was increased by the M-CSF/RANKL treatment. Multinucleation of preosteoclasts was markedly inhibited by antibodies against PS and its receptors. Among the investigated lipid transporter proteins, floppases (Abcb4, Abcc5, and Abcg1) were upregulated, whereas flippases (Atp11c and Atp8a1) downregulated during osteoclastogenesis. Preosteoclast fusion was markedly blocked by the ATPase inhibitor Na3VO4 and siRNAs against Abcc5 and Abcg1, revealing the importance of these lipid transporters in PS externalization. Further, the levels of Cd47 and Cd31, don't-eat-me signal inducers, were increased or sustained in the early phase of osteoclastogenesis, whereas those of AnnexinI and Mfg-e8, eat-me signals inducers, were increased in the late apoptotic phase. In addition, Z-VAD-FMK, a pan caspase inhibitor, had no effect on preosteoclast fusion in the early phase of osteoclastogenesis, whereas Abs against PS, TIM4, and BAI1 decreased osteoclast apoptosis during the late phase. These results suggest that PS externalization is essential for the whole process of osteoclastogenesis and share PS receptors and transporters in the early stage fusion and late stage apoptosis. Therefore, modulation of PS and its receptors could be a useful strategy to develop anti-bone resorptive agents.

Inhibitory effect of C-X-C motif chemokine ligand 14 on the osteogenic differentiation of human periodontal ligament cells through transforming growth factor-beta1.

OBJECTIVE: This study aimed to determine the expression of chemokine (C-X-C motif) ligand 14 (CXCL14) in pulpal and periodontal cells in vivo and in vitro, and investigate function of CXCL14 and its underlying mechanism in the proliferation and osteogenic differentiation of human periodontal ligament (hPDL) cells. METHODS: To determine the expression level of CXCL14 in adult rat oral tissues and in hPDL cells after application of biophysical forces, RT-PCR, western blot, and histological analyses were performed. The role of CXCL14 in proliferation and osteogenic differentiation of PDL cells was evaluated by measuring dehydrogenase activity and Alizarin red S staining. RESULTS: Strong immunoreactivity against CXCL14 was observed in the PDL tissues and pulpal cells of rat molar, and attenuated apparently by orthodontic biophysical forces. As seen in rat molar, highly expressed CXCL14 was observed in human dental pulp and hPDL cells, and attenuated obviously by biophysical tensile force. CXCL14 expression in hPDL cells was increased in incubation time-dependent manner. Proliferation of hPDL cells was inhibited dramatically by small interfering (si) RNA against CXCL14. Furthermore, dexamethasone-induced osteogenic mineralization was inhibited by recombinant human (rh) CXCL14, and augmented by CXCL14 siRNA. rhCXCL14 increased transforming growth factor-beta1 (TGF- ß1) in hPDL cells. Inhibition of the cell proliferation and osteogenic differentiation of hPDL cells by CXCL14 siRNA and rhCXCL14 were restored by rhTGF-ß1 and SB431542, respectively. CONCLUSION: These results suggest that CXCL14 may play roles as a growth factor and a negative regulator of osteogenic differentiation by increasing TGF-ß1 expression in hPDL cells.

Synergistic alveolar bone resorption by diabetic advanced glycation end products and mechanical forces.

BACKGROUND: The association between diabetes mellitus (DM) and bone diseases is acknowledged. However, the mechanistic pathways leading to the alveolar bone (AB) destruction remain unclear. This study aims to elucidate the mechanical forces (MF)-induced AB destruction in DM and its underlying mechanism. METHODS: In vivo periodontal tissue responses to MF were evaluated in rats with diabetes. In vitro human periodontal ligament (PDL) cells were either treated with advanced glycation end products (AGEs) alone or with AGEs and MF. RESULTS: In vivo, the transcription of VEGF-A, colony stimulating factor-1 (CSF-1), and Ager was upregulated in diabetes, whereas changes in DDOST and Glo1 mRNAs were negligible. DM induced VEGF-A protein in the vascular cells of the PDL and subsequent angiogenesis, but DM itself did not induce osteoclastogenesis. MF-induced AB resorption was augmented in DM, and such augmentation was morphologically substantiated by the occasional undermining resorption as well as the frontal resorption of the AB by osteoclasts. The mRNA levels of CSF-1 and vascular endothelial growth factor (VEGF) during MF application were highly elevated in diabetes, compared with those of the normal counterparts. In vitro, AGEs treatment elevated Glut-1 and CSF-1 mRNA levels via the p38 and JNK pathways, whereas OGT and VEGF levels remained unchanged. Compressive MF especially caused upregulation of VEGF, CSF-1, and Glut-1 levels, and such upregulation was further enhanced by AGEs treatment. CONCLUSIONS: Overloaded MF and AGEs metabolites may synergistically aggravate AB destruction by upregulating CSF-1 and VEGF. Therefore, regulating the compressive overloading of teeth, as well as the levels of diabetic AGEs, may prove to be an effective therapeutic modality for managing DM-induced AB destruction.

Myelin basic protein is temporospatially expressed in developing rat molars.

Tooth development occurs through a complex and intricate set of gene-expression cascades. Although its early events have been examined extensively, there are fewer reports on the late events, such as dental hard-tissue formation. This study searched for genes involved in the late stages of tooth development. Differential display-polymerase chain reaction revealed myelin basic protein (MBP) mRNA to be expressed differentially in the second molar root stage germs compared with the third molar cap/early bell stage germs. The MBP expressed during hard tissue formation was confirmed to be a 21.5 kDa molecule by Western blotting. Immunoreactivity of MBP in the third molar (cap/early bell stage) germs was barely detectable in the dental papilla and inner enamel epithelia, whereas strong reactivity was noted in the differentiating and differentiated ameloblasts and odontoblasts in a temporospatial pattern. However, after complete formation of the full-thickness enamel, no reactivity was observed in the maturation-stage and protection stage ameloblasts. Myelin basic protein immunoreactive nerve fibers were also observed near the developing molar germs. This is the first report showing the presence of MBP in dental hard tissue cells, and its functional implications should be studied further.

P-Glycoprotein, not BCRP, Limits the Brain Uptake of [(18)F]Mefway in Rodent Brain.

PURPOSE: The aim of this study was to determine whether the brain uptake of [(18)F]Mefway is influenced by the action of P-glycoprotein (P-gp) and breast cancer resistance protein (Bcrp) in rodents. PROCEDURES: [(18)F]Mefway was applied to rats pharmacologically inhibited with tariquidar (TQD) and to genetically disrupted mice. RESULTS: Pretreatment of TQD results in 160% higher hippocampal uptake compared with control rats. In genetically disrupted mice, a maximal brain uptake value of 3.2 SUV in the triple knockout mice (tKO, Mdr1a/b((-/-))Bcrp1((-/-))) was comparable to that of the double knockout mice (dKO, Mdr1a/b((-/-))) and 2-fold those of the wild-type and Bcrp1((-/-)) knockout mice. The differences of binding values were statistically insignificant between control and experimental groups. The brain-to-plasma ratios for tKO mice were also two to five times higher than those for other groups. CONCLUSIONS: [(18)F]Mefway is modulated by P-gp, and not by Bcrp in rodents.

Platelet-activating factor induces matrix metalloproteinase-9 expression through Ca(2+)- or PI3K-dependent signaling pathway in a human vascular endothelial cell line.

Platelet-activating factor (PAF) augments angiogenesis by promoting the synthesis of a variety of angiogenic factors, via the nuclear factor (NF)-kappaB activation. Recently, we reported that PAF upregulates MMP-9 expression in a NF-kappaB-dependent manner. In this study, we investigated the signaling pathway involved in PAF-induced MMP-9 expression in ECV304 cells. Our current data indicate that the Ca(2+)- or phosphatidylinositol 3-kinase (PI3K)-dependent signaling pathway is necessary for PAF-induced MMP-9 expression. Furthermore, PAF-induced NF-kappaB activation was blocked by selective inhibitors of Ca(2+), PI3K, or extracellular signal-regulated kinase (ERK). Our results suggest that PAF-induced MMP-9 expression, in a NF-kappaB-dependent manner, is regulated by Ca(2+), PI3K and ERK signaling pathways.

[(18)F]FPEB and [(18)F]FDEGPECO comparative study of mGlu5 quantification in rodent brain.

The aim of this study is to compare [(18)F]FPEB and [(18)F]FDEGPECO for the quantification of mGlu5 receptors in rodent brains. After preparation of radioligands, dynamic PET data was acquired for 90min. Estimated non-displaceable binding potential (BPND) values were calculated from the non-invasive Logan's graphical analysis method. Although both radioligands showed similar radiochemical amenability, [(18)F]FPEB PET showed higher brain uptake and superior binding potential values than those of [(18)F]FDEGPECO PET (peak brain uptakes in the hippocampus and the striatum: 7.2-8.7 vs. 5.0-6.2, BPND: 7.3-9.6 vs. 0.3-0.4 for [(18)F]FPEB and [(18)F]FDEGPECO, respectively). In addition, the target-to-reference ratios for [(18)F]FPEB is >4 fold than those of [(18)F]FDEGPECO. From this evidence, we conclude that [(18)F]FPEB is a superior radioligand for mGlu5 imaging in preclinical studies.

18F-Mefway PET imaging of serotonin 1A receptors in humans: a comparison with 18F-FCWAY.

INTRODUCTION: The purpose of this research is to evaluate the prospects for the use of 4-(trans-18F-fluoranylmethyl)-N-[2-[4-(2-methoxyphenyl)piperazin-1-yl]ethyl]-N-pyridin-2-ylcyclohexane-1-carboxamide (18F-Mefway) in comparison to 18F-trans-4-fluoro-N-2-[4-(2-methoxyphenyl)piperazin-1-yl]ethyl]-N-(2-pyridyl)cyclohexanecarboxamide (18F-FCWAY) for the quantification of 5-HT1A receptors in human subjects. METHOD: Five healthy male controls were included for two positron emission tomography (PET) studies: 18F-FCWAY PET after the pretreatment with 500 mg of disulfiram and two months later, 18F-Mefway PET without disulfiram. Regional time-activity curves (TACs) were extracted from nine cortical and subcortical regions in dynamic PET images. Using cerebellar cortex without vermis as reference tissue, in vivo kinetics for both radioligands were compared based on the distribution volume ratio (DVR) calculated by non-invasive Logan graphical analysis and area under the curve ratio of the TACs (AUC ratio). RESULT: Although the pattern of regional uptakes in the 18F-Mefway PET was similar to that of the 18F-FCWAY PET (highest in the hippocampus and lowest in the cerebellar cortex), the amount of regional uptake in 18F-Mefway PET was almost half of that in 18F-FCWAY PET. The skull uptake in 18F-Mefway PET was only 25% of that in 18F-FCWAY PET with disulfiram pretreatment. The regional DVR values and AUC ratio values for 18F-Mefway were 17-40% lower than those of 18F-FCWAY. In contrast to a small overestimation of DVR values by AUC ratio values (< 10%) in 18F-FCWAY PET, the overestimation bias of AUC ratio values was much higher (up to 21%) in 18F-Mefway PET. CONCLUSION: As 18F-Mefway showed lower DVR values and greater overestimation bias of AUC ratio values, 18F-Mefway may appear less favorable than 18F-FCWAY. However, in contrast to 18F-FCWAY, the resistance to in vivo defluorination of 18F-Mefway obviates the need for the use of a defluorination inhibitor. Thus, 18F-Mefway may be a good candidate PET radioligand for 5-HT1A receptor imaging in human.

Relaxin augments BMP-2-induced osteoblast differentiation and bone formation.

Relaxin (Rln), a polypeptide hormone of the insulin superfamily, is an ovarian peptide hormone that is involved in a diverse range of physiological and pathological reactions. In this study, we investigated the effect of Rln on bone morphogenetic protein 2 (BMP-2)-induced osteoblast differentiation and bone formation. Expression of Rln receptors was examined in the primary mouse bone marrow stem cells (BMSCs) and mouse embryonic fibroblast cell line C3H/10T1/2 cells by RT-PCR and Western blot during BMP-2-induced osteoblast differentiation. The effect of Rln on osteoblast differentiation and mineralization was evaluated by measuring the alkaline phosphatase activity, osteocalcin production, and Alizarin red S staining. For the in vivo evaluation, BMP-2 and/or Rln were administered with type I collagen into the back of mice, and after 3 weeks, bone formation was analyzed by micro-computed tomography (µCT). Western blot was performed to determine the effect of Rln on osteoblast differentiation-related signaling pathway. Expression of Rxfp 1 in BMSCs and C3H/10T1/2 cells was significantly increased by BMP-2. In vitro, Rln augmented BMP-2-induced alkaline phosphatase expression, osteocalcin production, and matrix mineralization in BMSCs and C3H/10T1/2 cells. In addition, in vivo administration of Rln enhanced BMP-2-induced bone formation in a dose-dependent manner. Interestingly, Rln synergistically increased and sustained BMP-2-induced Smad, p38, and transforming growth factor-ß activated kinase (TAK) 1 phosphorylation. BMP-2-induced Runx 2 expression and activity were also significantly augmented by Rln. These results show that Rln enhanced synergistically BMP-2-induced osteoblast differentiation and bone formation through its receptor, Rxfp 1, by augmenting and sustaining BMP-2-induced Smad and p38 phosphorylation, which upregulate Runx 2 expression and activity. These results suggest that Rln might be useful for therapeutic application in destructive bone diseases.

Dopaminergic neuron destruction reduces hippocampal serotonin 1A receptor uptake of trans-[(18)F]Mefway.

The purpose of the present study is to investigate the relationship between dopaminergic neuron destruction and 5-HT system changes in a hemiparkinsonian rat model. We performed PET imaging studies with trans-[(18)F]Mefway in a hemiparkinsonian model of unilateral 6-hydroxydopamine (6-OHDA) rats. Region-of-interests (ROIs) were drawn in the hippocampus (HP) and cerebellum (CB). HP uptake, the ratios of specific binding to non-specific binding in the HP, and non-displaceable binding potential (BPND) in the HP were compared between 6-OHDA and control rats. As a result, unilateral 6-OHDA-lesioned rats exhibited significant bilateral reduction of HP uptake and trans-[(18)F]Mefway BPND compared to the intact control group. Therefore, the results demonstrate that destruction of the dopaminergic system causes the reduction of the serotonergic system.

Focal adhesion linker proteins expression of fibroblast related to adhesion in response to different transmucosal abutment surfaces.

PURPOSE: To evaluate adherence of human gingival fibroblasts (HGFs) to transmucosal abutment of dental implant with different surface conditions with time and to investigate the roles of focal adhesion linker proteins (FALPs) involved in HGFs adhesion to abutment surfaces. MATERIALS AND METHODS: Morphologies of cultured HGFs on titanium and ceramic discs with different surface were observed by scanning electron microscopy. Biocompatibility and focal adhesion were evaluated by ultrasonic wave application and cell viability assay. FALPs expression levels were assessed by RT-PCR and western blot. RESULTS: There seemed to be little difference in biocompatibility and adhesion strength of HGFs depending on the surface conditions and materials. In all experimental groups, the number of cells remaining on the disc surface after ultrasonic wave application increased more than 2 times at 3 days after seeding compared to 1-day cultured cells and this continued until 7 days of culture. FALPs expression levels, especially of vinculin and paxillin, also increased in 5-day cultured cells compared to 1-day cultured fibroblasts on the disc surface. CONCLUSION: These results might suggest that the strength of adhesion of fibroblasts to transmucosal abutment surfaces increases with time and it seemed to be related to expressions of FALPs.

Differential expression of cyclophilin A and EMMPRIN in developing molars of rats.

A complex and intricate cascade of gene expression is essential for late stage tooth development. This study was performed to detect molecules involved in dental hard tissue formation and tooth eruption by comparing gene expression in cap stage molar germs (before eruptive movement and dental hard tissue formation) with that in root formation stage molar germs (after eruptive movement and dental hard tissue formation). DD-PCR revealed that cyclophilin A (Cyp-A), a potent chemoattractant for monocytes as well as a ligand for extracellular matrix metalloproteinase inducer (EMMPRIN) was expressed differentially in the two stages molar germs. The levels of Cyp-A and EMMPRIN mRNA were significantly higher at the root formation stage than at the cap and crown stages of the molar germs. Immunofluorescence showed that Cyp-A and EMMPRIN were expressed strongly in the follicular cells overlaying the occlusal region of the molar germs at the root formation stage. In contrast, their immunoreactivity was weak in the follicular tissues and was not region-specific in molar germs at the cap stage. In addition, the MCP-1 and CSF-1 mRNA levels increased in parallel to that of Cyp-A mRNA and the increased number of osteoclasts at the occlusal region. Immunoreactivity against Cyp-A and EMMPRIN was also observed in the fully differentiated ameloblasts and odontoblasts. This study suggests that Cyp-A and EMMPRIN play roles in the maturation of dental hard tissue and the formation of an eruption pathway.