Effects of jaw movement in bimaxillary orthognathic surgery on the upper airway: Computational fluid dynamics analysis.

Maxillomandibular repositioning in orthognathic surgeries has both morphologic and functional effects. These surgeries are thought to change the pharyngeal space and cause obstructive sleep apnoea syndrome, however. The primary purpose of this study is to evaluate the effects of jaw movement in bimaxillary orthognathic surgery on airway function and to identify the morphometric factors that can predict postoperative airway function. The subjects were 11 males and 12 females who had undergone orthognathic surgeries of the maxilla and mandible. The results of cephalometric analysis, cross-sectional area of the pharynx (CSA), pharyngeal volume and computational fluid dynamics (CFD) were compared. The CSA of the nasal (CSA1), total volume and total nasal volume decreased after surgery with statistical significance. Velocity at the oropharyngeal space (V2) increased after surgery with statistical significance. V2, CSA of the oropharyngeal space (CSA2) and PV were correlated with the horizontal posterior movement of point B, point Menton and overjet. V2 and CSA2 were correlated with SNB before and after surgery in all 46 analyses. Changes in pharyngeal airflow were more affected by pressure drop in the pharyngeal space (ΔPp) than by pressure drop in the nasal space (ΔPn). The relationship between the actual amount of change in the cephalometric reference point and the airway function is evident. CFD may thus be very useful as morphological analysis in preoperative treatment decision making.

Three-dimensional Analysis of Factors Related to the Effective Alveolar Molding in Presurgical Infant Orthopedics: Findings From a Pilot Study.

OBJECTIVE: Presurgical infant orthopedics (PIO) reduces the severity of the original cleft and burden on patients and their parents, provides better esthetics and function, and enables surgeons to achieve better surgical repair. To reduce the alveolar cleft width and to predict treatment difficulty using PIO, various measures were examined in pretreatment cast models. DESIGN: Retrospective case-control pilot study. PATIENTS: The patients were 22 infants with non-syndromic unilateral cleft lip and palate (UCLP), and cast models of these infants were used. METHODS: After PIO using passive plates, infants with UCLP were divided into two groups: contact group (12 cases with close proximity of the greater and lesser segments) and non-contact group (10 cases without proximity of segments). The two groups were compared, and variables related to the proximity between alveolar clefts were examined. RESULTS: There was no significant difference in age at PIO initiation between the two groups. However, the treatment duration was significantly longer in the non-contact group than in the contact group. Among the 13 variables, the initial lateral deviation of the nasal septum was significantly larger in the contact group than in the non-contact group. A significant positive correlation was observed between the initial lateral deviation of the nasal septum and reduction of the alveolar cleft width by PIO. CONCLUSION: Initial lateral deviation of the nasal septum is a predictive factor for the proximity between alveolar segments in infants with UCLP at the PIO.

Orthodontic treatment of a skeletal Class III malocclusion with severe root resorption of the maxillary anterior teeth. Autotransplantation using a 3-dimensional printed replica of the donor tooth.

This case report describes the successful orthodontic treatment of a 12-year-old girl with skeletal Class III malocclusion and severe root resorption of the maxillary anterior teeth. Ectopic eruption and mesial inclination of the bilateral maxillary canines caused severe root resorption of the right central and lateral incisors and the left lateral incisor. These 3 teeth were extracted, and traction was applied to the maxillary right and left canines toward the extracted right central incisor and left lateral incisor, respectively. In the mandibular arch, the bilateral first premolars were extracted, and the crowding was corrected. The extracted mandibular right first premolar was transplanted after extraction of the maxillary right lateral incisor. To prepare for the tooth transplantation, a cone-beam computed tomography image was used to fabricate a 3-dimensional printed replica of the donor tooth. The crown shape of the maxillary anterior teeth was corrected, and the patient achieved functional occlusion with pleasing esthetics. Root resorption was negligible in the transplanted tooth. This study demonstrates the satisfactory treatment outcome and an effective 3-dimensional simulation for tooth transplantation.

Orthodontic treatment-induced temporal alteration of jaw-opening reflex excitability.

The impairment of orofacial motor function during orthodontic treatment needs to be addressed, because most orthodontic patients experience pain and motor excitability would be affected by pain. In the present study, the temporal alteration of the jaw-opening reflex excitability was investigated to determine if orthodontic treatment affects orofacial motor function. The excitability of jaw-opening reflex evoked by electrical stimulation on the gingiva and recorded bilaterally in the anterior digastric muscles was evaluated at 1 (D1), 3 (D3), and 7 days (D7) after orthodontic force application to the teeth of right side; morphological features (e.g., osteoclast genesis and tooth movement) were also evaluated. To clarify the underlying mechanism of orthodontic treatment-induced alteration of orofacial motor excitability, analgesics were administrated for 1 day. At D1 and D3, orthodontic treatment significantly decreased the threshold for inducing the jaw-opening reflex but significantly increased the threshold at D7. Other parameters of the jaw-opening reflex were also evaluated (e.g., latency, duration and area under the curve of anterior digastric muscles activity), and only the latency of the D1 group was significantly different from that of the other groups. Temporal alteration of the jaw-opening reflex excitability was significantly correlated with changes in morphological features. Aspirin (300 mg·kg-1·day-1) significantly increased the threshold for inducing the jaw-opening reflex, whereas a lower dose (75-150 mg·kg-1·day-1) of aspirin or acetaminophen (300 mg·kg-1·day-1) failed to alter the jaw-opening reflex excitability. These results suggest that an increase of the jaw-opening reflex excitability can be induced acutely by orthodontic treatment, possibly through the cyclooxygenase activation.NEW & NOTEWORTHY It is well known that motor function is affected by pain, but the effect of orthodontic treatment-related pain on the trigeminal motor excitability has not been fully understood. We found that, during orthodontic treatment, trigeminal motor excitability is acutely increased and then decreased in a week. Because alteration of trigeminal motor function can be evaluated quantitatively by jaw-opening reflex excitability, the present animal model may be useful to search for alternative approaches to attenuate orthodontic pain.

[Growth of maxillo-facial region and related anomalies.]

Since maxillo-facial region is quite complex, growth and developmental defect cause various anomalies. It is known that 70% of whole genetic disorders have any symptom or abnormal condition in maxilla-facial region. Cleft lip and/or palate is the most popular congenital anomaly and is seen in 0.2% of general population. Cases with Treacher Collins syndrome and Robin sequence are with respiratory problem due to the small mandible or mandibular retrusion. Achondroplasia is a genetic disease with short-limbed dwarfism due to abnormal proliferation or differentiation of chondrocytes. Interestingly, in this disease, growth of condylar cartilage is not impaired and causes mandibular prognathism. In this review, various diseases caused by the abnormality in growth and development of maxilla-facial region are discussed.

Establishment of a novel model of chondrogenesis using murine embryonic stem cells carrying fibrodysplasia ossificans progressiva-associated mutant ALK2.

Fibrodysplasia ossificans progressiva (FOP) is a genetic disorder characterized by heterotopic endochondral ossification in soft tissue. A mutation in the bone morphogenetic protein (BMP) receptor ALK2, R206H, has been identified in patients with typical FOP. In the present study, we established murine embryonic stem (ES) cells that express wild-type human ALK2 or typical mutant human ALK2 [ALK2(R206H)] under the control of the Tet-Off system. Although wild-type ALK2 and mutant ALK2(R206H) were expressed in response to a withdrawal of doxycycline (Dox), BMP signaling was activated only in the mutant ALK2(R206H)-expressing cells without the addition of exogenous BMPs. The Dox-dependent induction of BMP signaling was blocked by a specific kinase inhibitor of the BMP receptor. The mutant ALK2(R206H)-carrying cells showed Dox-regulated chondrogenesis in vitro, which occurred in co-operation with transforming growth factor-ß1 (TGF-ß1). Overall, our ES cells are useful for studying the molecular mechanisms of heterotopic ossification in FOP in vitro and for developing novel inhibitors of chondrogenesis induced by mutant ALK2(R206H) associated with FOP.

Reduced menthol sensitivity in a prodromal Parkinson's disease model induced by intranasal rotenone treatment.

Parkinson's disease (PD) is a neurodegenerative disorder characterized by motor symptoms, and it is associated with several prodromal non-motor symptoms, including an impaired sense of smell, taste and touch. We previously reported that bitter taste impairments occur independently of olfactory impairments in an early-stage PD animal model using short-term intranasal rotenone-treated mice. Cool temperatures also affect bitter taste perception, but it remains unclear whether or not bitter taste impairments result from an altered sensitivity for intraoral cool stimuli. We examined disturbances in the intraoral menthol sensitivity, such as coolness at low concentrations of menthol, using a brief-access test. Once a day, one solution from the 7-concentration series of (-)-menthol (0-2.3 mM) or the bitter taste quinine-HCl (0.3 mM) was randomly presented 20 times for 10 s to water-deprived mice before and 1 week after rotenone treatment. The total number of licks within 20 times was significantly decreased with the presentation of 2.3 mM menthol and quinine-HCl, compared to distilled water in untreated mice, but not in rotenone-treated mice. The correlation between the licks for quinine-HCl and that for menthol was increased after rotenone treatment. In contrast, the 2-bottle choice test for 48 h clarified that menthol sensitivity was increased after rotenone treatment. Furthermore, a thermal place preference test revealed that seeking behavior toward a cold-floored room was increased in the rotenone-treated mice despite the unchanged plantar cutaneous cold sensitivity. These results suggest that taste impairments in this model mice are at least partly due to intraoral somatosensory impairments, accompanied by peripheral/central malfunction.

Serum calcium-decreasing factor, caldecrin, inhibits receptor activator of NF-κB ligand (RANKL)-mediated Ca2+ signaling and actin ring formation in mature osteoclasts via suppression of Src signaling pathway.

Osteoclasts are essential for bone dynamics and calcium homeostasis. Recently, we reported that serum calcium-decreasing factor, caldecrin, which is a secretory-type serine protease isolated from the pancreas, inhibits osteoclast differentiation by suppression of NFATc1 activity regardless of its own protease activity (Hasegawa, H., Kido, S., Tomomura, M., Fujimoto, K., Ohi, M., Kiyomura, M., Kanegae, H., Inaba, A., Sakagami, H., and Tomomura, A. (2010) Serum calcium-decreasing factor, caldecrin, inhibits osteoclast differentiation by suppression of NFATc1 activity. J. Biol. Chem. 285, 25448-25457). Here, we investigated the effects of caldecrin on the function of mature osteoclasts by treatment with receptor activator of NF-κB ligand (RANKL). Caldecrin inhibited the RANKL-stimulated bone resorptive activity of mature osteoclasts. Furthermore, caldecrin inhibited RANKL-mediated sealing actin ring formation, which is associated with RANKL-evoked Ca(2+) entry through transient receptor potential vanilloid channel 4. The inhibitors of phospholipase Cγ, Syk, and c-Src suppressed RANKL-evoked Ca(2+) entry and actin ring formation of mature osteoclasts. Interestingly, caldecrin significantly inhibited RANKL-stimulated phosphorylation of c-Src, Syk, phospholipase Cγ1 and Cγ2, SLP-76, and Pyk2 but not that of ERK, JNK, or Akt. Caldecrin inhibited RANKL-stimulated c-Src kinase activity and c-Src·Syk association. These results suggest that caldecrin inhibits RANKL-stimulated calcium signaling activation and cytoskeletal organization by suppression of the c-Src·Syk pathway, which may in turn reduce the bone resorptive activity of mature osteoclasts. Thus, caldecrin is capable of acting as a negative regulator of osteoclastogenesis and osteoclast function of bone resorption.

Low-density lipoprotein receptor deficiency causes impaired osteoclastogenesis and increased bone mass in mice because of defect in osteoclastic cell-cell fusion.

Osteoporosis is associated with both atherosclerosis and vascular calcification attributed to hyperlipidemia. However, the cellular and molecular mechanisms explaining the parallel progression of these diseases remain unclear. Here, we used low-density lipoprotein receptor knockout (LDLR(-/-)) mice to elucidate the role of LDLR in regulating the differentiation of osteoclasts, which are responsible for bone resorption. Culturing wild-type osteoclast precursors in medium containing LDL-depleted serum decreased receptor activator of NF-κB ligand (RANKL)-induced osteoclast formation, and this defect was additively rescued by simultaneous treatment with native and oxidized LDLs. Osteoclast precursors constitutively expressed LDLR in a RANKL-independent manner. Osteoclast formation from LDLR(-/-) osteoclast precursors was delayed, and the multinucleated cells formed in culture were smaller and contained fewer nuclei than wild-type cells, implying impaired cell-cell fusion. Despite these findings, RANK signaling, including the activation of Erk and Akt, was normal in LDLR(-/-) preosteoclasts, and RANKL-induced expression of NFATc1 (a master regulator of osteoclastogenesis), cathepsin K, and tartrate-resistant acid phosphatase was equivalent in LDLR-null and wild-type cells. In contrast, the amounts of the osteoclast fusion-related proteins v-ATPase V(0) subunit d2 and dendritic cell-specific transmembrane protein in LDLR(-/-) plasma membranes were reduced when compared with the wild type, suggesting a correlation with impaired cell-cell fusion, which occurs on the plasma membrane. LDLR(-/-) mice consistently exhibited increased bone mass in vivo. This change was accompanied by decreases in bone resorption parameters, with no changes in bone formation parameters. These findings provide a novel mechanism for osteoclast differentiation and improve the understanding of the correlation between osteoclast formation and lipids.

Effect of angiotensin II receptor blocker on experimental periodontitis in a mouse model of Marfan syndrome.

Marfan syndrome is an autosomal dominant disease characterized by aneurysm and dilatation of the aortic root, tall stature, and ectopia lentis. These manifestations reflect excessive signaling of transforming growth factor beta (TGF-ß). Moreover, cases are frequently associated with severe periodontitis, which is a chronic inflammation of the gingiva, periodontal ligament, and alveolar bone. Recently, angiotensin II receptor blockers (ARBs) were discovered to be an effective drug class that can prevent aortic aneurysm and dilation in Marfan syndrome by inhibiting TGF-ß signaling. To investigate the effect of ARB on the progression of periodontitis, the application of a potent ARB, telmisartan, was examined in a mouse model of Marfan syndrome (MgΔ). Six-week-old male heterozygous MgΔ and wild-type mice were challenged with Porphyromonas gingivalis, which causes chronic periodontitis, with and without telmisartan application. After infection, alveolar bone resorption was measured by micro-computed tomography (µCT), and inflammatory cytokine levels were examined. Infection of Porphyromonas gingivalis induced alveolar bone resorption in both MgΔ and wild-type mice. The amount of resorption was significantly larger in the former than the latter. Immunoarray and enzyme-linked immunosorbent assay (ELISA) analyses demonstrated that interleukin-17 (IL-17) and tumor necrosis factor alpha (TNF-α) levels were significantly higher in infected MgΔ mice than infected wild-type mice. Telmisartan treatment significantly suppressed the alveolar bone resorption of infected MgΔ mice. Telmisartan also significantly decreased levels of TGF-ß, IL-17, and TNF-α in infected MgΔ mice to levels seen in infected wild-type mice. This study suggests that ARB can prevent the severe periodontitis frequently seen in Marfan syndrome.

Dental and maxillofacial characteristics of six Japanese individuals with ectrodactyly-ectodermal dysplasia-clefting syndrome.

Objective : Ectrodactyly-ectodermal dysplasia-clefting syndrome is a congenital anomaly characterized by ectodermal dysplasia, ectrodactyly, cleft lip and palate, and lacrimal duct anomalies. Because this syndrome is frequently accompanied by a congenital lack of teeth, narrow palate, and malocclusion, comprehensive orthodontic intervention is required. Design : To highlight the specific dental and maxillofacial characteristics of ectrodactyly-ectodermal dysplasia-clefting syndrome, six Japanese individuals diagnosed with the syndrome are described here. Patients : The subjects consisted of two boys and four girls (age range, 6.0 to 13.9 years) diagnosed with ectrodactyly-ectodermal dysplasia-clefting syndrome by medical and dental specialists. Their conditions included ectodermal dysplasia (hypodontia, microdontia, enamel hypoplasia, and abnormalities in hair and nails), cleft lip and/or palate, and ectrodactyly. Cephalograms, panoramic x-rays, and dental casts were taken; systemic complications were recorded at the first visit to our dental hospital. Results : All individuals had severe oligodontia with 9 to 18 missing teeth. The missing teeth were mainly maxillary and mandibular incisors and second bicuspids, arranged in a symmetrical manner. Cephalometric analysis showed retruded and short maxilla due to cleft lip and/or palate. It is interesting that all individuals showed a characteristically shaped mandibular symphysis with a retruded point B. It is likely that this unusual symphyseal morphology is due to the lack of mandibular incisors. Conclusions : This study demonstrates the presence of severe oligodontia in the incisal and premolar regions and describes a characteristic maxillary and mandibular structure in Japanese individuals with ectrodactyly-ectodermal dysplasia-clefting syndrome.

ADAMTSL6ß protein rescues fibrillin-1 microfibril disorder in a Marfan syndrome mouse model through the promotion of fibrillin-1 assembly.

Marfan syndrome (MFS) is a systemic disorder of the connective tissues caused by insufficient fibrillin-1 microfibril formation and can cause cardiac complications, emphysema, ocular lens dislocation, and severe periodontal disease. ADAMTSL6ß (A disintegrin-like metalloprotease domain with thrombospondin type I motifs-like 6ß) is a microfibril-associated extracellular matrix protein expressed in various connective tissues that has been implicated in fibrillin-1 microfibril assembly. We here report that ADAMTSL6ß plays an essential role in the development and regeneration of connective tissues. ADAMTSL6ß expression rescues microfibril disorder after periodontal ligament injury in an MFS mouse model through the promotion of fibrillin-1 microfibril assembly. In addition, improved fibrillin-1 assembly in MFS mice following the administration of ADAMTSL6ß attenuates the overactivation of TGF-ß signals associated with the increased release of active TGF-ß from disrupted fibrillin-1 microfibrils within periodontal ligaments. Our current data thus demonstrate the essential contribution of ADAMTSL6ß to fibrillin-1 microfibril formation. These findings also suggest a new therapeutic strategy for the treatment of MFS through ADAMTSL6ß-mediated fibrillin-1 microfibril assembly.

Apert syndrome mutant FGFR2 and its soluble form reciprocally alter osteogenesis of primary calvarial osteoblasts.

Apert syndrome is characterized by craniosynostosis and syndactyly, and is predominantly caused by mutation of either S252W or P253W in the fibroblast growth factor receptor (FGFR) 2 gene. In this study, we characterized the effects of one of the mutations (S252W) using primary calvarial osteoblasts derived from transgenic mice, Ap-Tg and sAp-Tg, that expressed an Apert-type mutant FGFR2 (FGFR2IIIc-S252W; FGFR2IIIc-Ap), and the soluble form (extracellular domain only) of the mutant FGFR2 (sFGFR2IIIc-Ap), respectively. Compared to WT-derived osteoblasts, osteoblasts from Ap-Tg mouse showed a higher proliferative activity and enhanced differentiation, while those from sAp-Tg mouse exhibited reduced potential for proliferation and osteogenic differentiation. When transplanted with ß-tricalcium phosphate (ß-TCP) granules into immunodeficient mice, Ap-Tg-derived osteoblasts showed a higher bone forming capacity, whereas sAp-Tg-derived osteoblasts were completely deficient for this phenotype. Phosphorylation of extracellular signal-regulated kinase (ERK), MEK, PLCγ, and p38 was increased in Ap-Tg-derived osteoblasts, whereas phosphorylation of these signaling molecules was reduced in sAp-Tg-derived osteoblasts. Interestingly, when these experiments were carried out using osteoblasts from the mice generated by crossing Ap-Tg and sAp-Tg (Ap/sAp-Tg), which co-expressed FGFR2IIIc-Ap and sFGFR2IIIc-Ap, the results were comparable to those obtained from WT-derived osteoblasts. Taken together, these results indicate that osteoblasts expressing FGFR2IIIc-Ap proliferate and differentiate via highly activated MEK, ERK, and p38 pathways, while these pathways are suppressed in osteoblasts expressing sFGFR2IIIc-Ap. Our findings also suggest that altered FGFR2IIIc signaling in osteoblasts is mostly responsible for the phenotypes seen in Apert syndrome, therefore these osteoblast cell lines are useful tools for investigating the pathogenesis of Apert syndrome.

Orthognathic treatment for a patient with facial asymmetry associated with unilateral scissors-bite and a collapsed mandibular arch.

Subapical mandibular surgeries have been used to correct vertical malocclusion and interdental problems associated with mandibular deformity. Subapical surgery to the anterior part of the mandible is applicable in many patients with anterior open bite and deepbite. Surgery of the posterior part of the mandible is needed less frequently than surgery of the anterior part. This case report describes the surgical-orthodontic treatment of a 21-year-old woman who underwent posterior subapical mandibular surgery. Her chief complaint was facial asymmetry, and she had a collapsed mandibular arch with a scissors-bite of the right premolars and molars. After subapical osteotomy, surgically assisted correction of the collapsed right mandibular arch was performed with a lingual arch appliance. Comprehensive orthodontic treatment was initiated in both arches after this correction. Le Fort I osteotomy and sagittal split ramus osteotomy were used to correct the facial asymmetry. Her facial appearance and temporomandibular problems were markedly improved, and she achieved a functional and stable occlusion after these treatments. This case report demonstrates the efficiency of posterior subapical mandibular surgery for a patient with a collapsed mandibular arch and a scissors-bite.

[Tooth and bone research using genetically modified mice].

Teeth and bone are both hard tissues and composed of hydroxyapatite. Tooth development initiates with the invasination of oral epithelium, followed by aggregation of supporting ectomesenchymal cells. From mouse study, numbers of molecules have been discovered to relate tooth development. These discoveries have helped to clarify the responsible genes of human genetic disorders with abnormal tooth number and structure. During tooth development, teeth erupt into the outer environment, oral cavity. From this point, teeth are completely different from bone which is always covered by soft tissues. Tooth eruption is composed of two different processes, that is, eruption pathway formation and vertical tooth movement. In this review, mutant mice with abnormal tooth development and eruption are introduced, and molecular mechanism required for this process is discussed.

Role of reduced enamel epithelium in root resorption.

BACKGROUND: The precise mechanism of root resorption in human primary teeth is unclear. However, research has suggested that the enamel organ and dental follicle of the successive (permanent) teeth are important for this process. This review focuses on the mechanism of root resorption. HIGHLIGHT: Impaction of the maxillary permanent canines is occasionally seen. Computer tomography studies have shown that these canines cause root resorption in 12.5% of the neighboring central and lateral incisors. In such cases, enlargement of the radiolucent areas around the canine crowns is frequently seen. These radiolucent areas include dental follicles and reduced enamel epithelium, which are composed of degraded ameloblasts and cells of the papillary layer. Root resorbing factors, expressed from the reduced enamel epithelium, are likely to induce the odontoclastic root resorption. Physiological root resorption of the primary teeth is generally milder than this pathological root resorption, but involvement of the reduced enamel epithelium of the permanent tooth can be also proposed. CONCLUSION: This review highlights the role of the reduced enamel epithelium in root resorption under both pathological and physiological conditions.

Systemic and maxillofacial characteristics of patients with Beckwith-Wiedemann syndrome not treated with glossectomy.

INTRODUCTION: Beckwith-Wiedemann syndrome (BWS) is a genetic disorder characterized by exomphalos, macroglossia and gigantism. Previous studies reported a wide variation in the skeletal and occlusal characteristics in individuals affected by BWS. However, these studies were performed by analyzing both individuals who had and those had not received a glossectomy, which has a high impact on the jaw growth and occlusion. To highlight the intrinsic characteristics of BWS, 7 Japanese affected individuals without glossectomy were analyzed in this study. METHODS: Seven individuals who had been diagnosed with BWS by medical specialists and had not undergone glossectomy were analyzed. Cephalograms and dental casts were taken and systemic complications were recorded at the first visit. RESULTS: Individuals uniformly showed a higher birth height and weight, macroglossia, large anterior cranial base, and mandibular body. They exhibited a wide dental arch and an anterior open bite due to the undererupted and proclined anterior teeth. A wide variation was seen in the gonial angle, but the facial height was large overall. CONCLUSIONS: As intrinsic characteristics of BWS, individuals exhibited macroglossia resulting in an anterior open bite and a wide dental arch. A long facial height and an enlarged anterior cranial base and mandibular body were also noted.

Localization of heat shock protein 27 (hsp27) in the rat gingiva and its changes with tooth eruption.

Heat shock protein 27 kDa (Hsp27) functions as a molecular chaperon to prevent apoptosis as well as to contribute to the regulation of cell proliferation and differentiation during development. In the present study, the localization of Hsp27 in the oral epithelium of rats and its expression change during formation of the gingiva with the tooth eruption were examined immunohistochemically to elucidate the roles of Hsp27 in the oral mucosa.In adult rats, Hsp27-immunoreactivity was localized in the prickle and granular layers but absent in the basal and horny layers of the oral epithelium. On the other hand, in the outer and sulcular epithelia of the free gingival, Hsp27-immunoreactivity was detected in the whole layers, while it was not found in the proliferation zone of the junctional epithelium immunoreactive for Ki67. In immature rats on 10th postnatal day, Hsp27-immunoreactivity was intense in the prickle and granular layers of the oral epithelium, but was not detected in its basal layer. In rats at the eruptive phase on 15th postnatal day, Hsp27-immunoreactivity was detected in sites of the basal layer adjacent to where the dental cusps penetrated through the oral epithelium. Although the immunoreactivity for Ki67 was found in the basal layer of the oral epithelium, it was not localized in the Hsp27-immunopositive sites of tooth-penetration in the basal layer. Just after the tooth-eruption on 20th postnatal day, Hsp27-immunoreactivity was not found in the stratified squamous epithelium at the dentogingival junction, whereas it was intense in a single layer of cuboidal epithelial cells attached to the tooth neck. Ki67-positive cells were scattered in the stratified squamous epithelium at the dentogingival junction, whereas no positive cells were found in the portion of a single layer of cuboidal epithelial cells.These findings suggest that the outer and sulcular epithelia of the free gingiva have a relatively slower rate of proliferation than other gingival and oral epithelia, and that Hsp27 might inhibit the proliferation of the basal cells. Such specific phenomenon in the free gingiva occurred immediately after the dental cusps were exposed to the oral cavity.

Regeneration in Experimental Alveolar Bone Defect Using Human Umbilical Cord Mesenchymal Stem Cells.

Cleft lip and palate is a congenital disorder including cleft lip, and/or cleft palate, and/or alveolar cleft, with high incidence.The alveolar cleft causes morphological and functional abnormalities. To obtain bone bridge formation and continuous structure between alveolar clefts, surgical interventions are performed from infancy to childhood. However, desirable bone bridge formation is not obtained in many cases. Regenerative medicine using mesenchymal stem cells (MSCs) is expected to be a useful strategy to obtain sufficient bone bridge formation between alveolar clefts. In this study, we examined the effect of human umbilical cord-derived MSCs by transplantation into a rat experimental alveolar cleft model. Human umbilical cords were digested enzymatically and the isolated cells were collected (UC-EZ cells). Next, CD146-positive cells were enriched from UC-EZ cells by magnetic-activated cell sorting (UC-MACS cells). UC-EZ and UC-MACS cells showed MSC gene/protein expression, in vitro. Both cells had multipotency and could differentiate to osteogenic, chondrogenic, and adipogenic lineages under the differentiation-inducing media. However, UC-EZ cells lacked Sox2 expression and showed the lower ratio of MSCs than UC-MACS cells. Thus, UC-MACS cells were transplanted with hydroxyapatite and collagen (HA + Col) into alveolar cleft model to evaluate bone formation in vivo. The results of micro computed tomography and histological staining showed that UC-MACS cells with HA + Col induced more abundant bone formation between the experimental alveolar clefts than HA + Col implantation only. Cells immunopositive for osteopontin were accumulated along the bone surface and some of them were embedded in the bone. Cells immunopositive for human-specific mitochondria were aligned along the newly formed bone surface and in the new bone, suggesting that UC-MACS cells contributed to the bone bridge formation between alveolar clefts. These findings indicate that human umbilical cords are reliable bioresource and UC-MACS cells are useful for the alveolar cleft regeneration.