Histological and Immunohistochemical Studies to Determine the Mechanism of Cleft Palate Induction after Palatal Fusion in Mice Exposed to TCDD.

Rupture of the basement membrane in fused palate tissue can cause the palate to separate after fusion in mice, leading to the development of cleft palate. Here, we further elucidate the mechanism of palatal separation after palatal fusion in 8-10-week-old ICR female mice. On day 12 of gestation, 40 µg/kg of 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD), sufficient to cause cleft palate in 100% of mice, was dissolved in 0.4 mL of olive oil containing toluene and administered as a single dose via a gastric tube. Fetal palatine frontal sections were observed by H&E staining, and epithelial cell adhesion factors, apoptosis, and cell proliferation were observed from the anterior to posterior palate. TUNEL-positive cells and Ki67-positive cells were observed around the posterior palatal dissection area of the TCDD-treated group. Moreover, in fetal mice exposed to TCDD, some fetuses exhibited cleft palate dehiscence during fusion. The results suggest that palatal dehiscence may be caused by abnormal cell proliferation in epithelial tissues, decreased intercellular adhesion, and inhibition of mesenchymal cell proliferation. By elucidating the mechanism of cleavage after palatal fusion, this research can contribute to establishing methods for the prevention of cleft palate development.

Intraperitoneal injection of PDTC on the NF-kB signaling pathway and osteogenesis indexes of young adult rats with anterior palatal suture expansion model.

In recent years, many studies have found that mechanical tension can activiate NF-kB signal pathway and NF-kB plays an important role in the process of osteogenesis. However, it is still unclear whether this process exists in the anterior palatal suture expansion. In this paper, we mainly studied the effect of intraperitoneal injection of PDTC on the NF-kB signaling pathway and osteogenesis index of the anterior palatal suture expansion model in young adult rats. The expansion model is grouped and established: 45 male 8-week-old Sprague-Dawley rats were randomly divided into three groups, an expansion only (EO) group, an expansion plus PDTC (PE) group, and a control group. The results revealed that PDTC inhibited the activity of NF-kB signaling pathway and promote one morphogenetic protein 2 (BMP-2), steocalatin (OCN) expression. Compared with the control group, the optical density (OD) value of BMP in the EO group and PE group rats increased significantly from the first day to the seventh day, and the difference was statistically significant (P<0.05). After 6.0Gy irradiation, PDTC administration group could slightly increase the total SOD level in the liver and serum of rats, and reduce the MDA level in the liver and serum, especially the effect of 60mg/kg and 90mg/kg was the most obvious.

Correlation between TGF-ß2/3 promoter DNA methylation and Smad signaling during palatal fusion induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin.

2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is a persistent organic pollutant that is strongly associated with a number of human diseases and birth defects, including cleft palate. Transforming growth factor (TGF) plays a significant role during mammalian palatogenesis. However, the epigenetic mechanism of transforming growth factors in the process of TCDD-induced cleft palate is unclear. The purpose of this research was to investigate the relationship and potential mechanism between TGF-ß2/3 promoter DNA methylation and Smad signaling during TCDD-induced cleft palate. Pregnant C57BL/6N mice were exposed to 64 µg/kg TCDD on gestational day 10 (GD10) to establish the cleft palate model and palatal tissues of embryos were collected on GD13, GD14, and GD15 for subsequent experiments. TGF-ß2/3 mRNA expression, TGF-ß2/3 promoter methylation, and Smad signaling molecules expression were assessed in the palate of the two groups. The results showed that the incidence of cleft palate was 94.7% in the TCDD-treated group whereas no cleft palate was found in the control group. TCDD-treated group altered specific CpG sites of TGF-ß2/3 promoter methylation. Compared to the control group, the proliferation of mouse embryonic palate mesenchymal stromal cells (MEPM), the expressions of TGF-ß2/3, p-Smad2, and Smad4 were all reduced, while the expression of Smad7 was significantly increased in the atAR group. Smad signaling was downregulated by TCDD. Therefore, we suggest that TGF-ß2/3 promoter methylation and Smad signaling may be involved in TCDD-induced cleft palate formation in fetal mice.

Anti-epileptic drug topiramate upregulates TGFß1 and SOX9 expression in primary embryonic palatal mesenchyme cells: Implications for teratogenicity.

Topiramate is an anti-epileptic drug that is commonly prescribed not just to prevent seizures but also migraine headaches, with over 8 million prescriptions dispensed annually. Topiramate use during pregnancy has been linked to significantly increased risk of babies born with orofacial clefts (OFCs). However, the exact molecular mechanism of topiramate teratogenicity is unknown. In this study, we first used an unbiased antibody array analysis to test the effect of topiramate on human embryonic palatal mesenchyme (HEPM) cells. This analysis identified 40 differentially expressed proteins, showing strong connectivity to known genes associated with orofacial clefts. However, among known OFC genes, only TGFß1 was significantly upregulated in the antibody array analysis. Next, we validated that topiramate could increase expression of TGFß1 and of downstream target phospho-SMAD2 in primary mouse embryonic palatal mesenchyme (MEPM) cells. Furthermore, we showed that topiramate treatment of primary MEPM cells increased expression of SOX9. SOX9 overexpression in chondrocytes is known to cause cleft palate in mouse. We propose that topiramate mediates upregulation of TGFß1 signaling through activation of γ-aminobutyric acid (GABA) receptors in the palate. TGFß1 and SOX9 play critical roles in orofacial morphogenesis, and their abnormal overexpression provides a plausible etiologic molecular mechanism for the teratogenic effects of topiramate.

LncRNA Meg3-mediated regulation of the Smad pathway in atRA-induced cleft palate.

Palatal mesenchymal cell proliferation is essential to the process of palatogenesis, and the proliferation of mouse embryonic palate mesenchymal (MEPM) cells is impacted by both all-trans retinoic acid (atRA) and the TGF-ß/Smad signaling pathway. The long non-coding RNA (lncRNA) MEG3 has been shown to activate TGF-ß/Smad signaling and to thereby regulate cell proliferation, differentiation, and related processes. Herein, we found that atRA treatment (100 mg/kg) promoted Meg3 upregulation in MEPM cells, and that such upregulation was linked to the suppression of MEPM cell proliferation in the context of secondary palate fusion on gestational day (GD) 13 and 14. Moreover, the demethylation of specific CpG sites within the lncRNA Meg3 promoter was detected in atRA-treated MEPM cells, likely explaining the observed upregulation of this lncRNA. Smad signaling was also suppressed by atRA treatment in these cells, and RNA immunoprecipitation analyses revealed that Smad2 can directly interact with Meg3 in MEPM cells following atRA treatment. Therefore, we propose a model wherein Meg3 is involved in the suppression of MEPM cell proliferation, functioning at least in part via interacting with the Smad2 protein and thereby suppressing Smad signaling in the context of atRA-induced cleft palate.

Comparison of the biological behaviors of palatal mesenchymal and epithelial cells induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin in vitro.

2,3,7,8-Tetrachlorodibenzo- p-dioxin (TCDD) effectively induces cleft palate at increased doses, but its mechanism of involvement is unclear, and arguments have examined palatal shelf contact and/or fusion failure. The role of different types of cells constituting palatal skulls remains elusive regarding TCDD dosage. No reports have simultaneously compared the biological behaviors of TCDD- induced mesenchymal and epithelial cells in vitro. This study employed primary epithelial and mesenchymal cells as models in vitro to explore proliferation, migration, apoptosis and epithelial-to-mesenchymal transition with two different doses of TCDD (10 nmol/L, 100 nmol/L), contrasted with a control group without TCDD. Interestingly, we found the EMT process of primary palatal epithelial cells occurred automatically in vitro without helping bilateral palatal contact. The results showed that, with the low dose of TCDD, transformation of epithelial cells to mesenchymal cells was inhibited, and mesenchymal cell proliferation and migration were promoted. At high doses, mesenchymal cells decreased, preventing palate development, uprising and contact, while the EMT of epithelial cells decreased. Regardless of dose of TCDD, no impact on migration and apoptosis of epithelial cells was noted, but there was increased apoptosis of mesenchymal cell in a dose-dependent manner.

RNA-seq analysis of palatal transcriptome changes in all-trans retinoic acid-induced cleft palate of mice.

Cleft palate is a common congenital maxillofacial malformation in newborns. All-trans retinoic acid (atRA) is an ideal exogenous stimulus to construct a mouse cleft palate model. However, the precise pathogenic mechanism remains to be elucidated. In our study, to explore the toxicity of atRA on palatal shelves during different stages of palate development, a total of 100 mg/kg atRA was administered to C57BL/6 mice at embryonic day 10.5 (E10.5). Mouse embryonic palatal shelves at E13.5, E14.5, E15.5, and E16.5 were collected for RNA extraction and histological treatment. Changes in gene expression were tested through RNA-seq. Selected differentially expressed genes (DEGs) related to metabolic pathways, such as Ptgds, Ttr, Cyp2g1, Ugt2a1 and Mgst3, were validated and analyzed by Quantitative real-time PCR (qRT-PCR). In addition, Gene Oncology analysis showed that transcriptional changes of genes from extracellular matrix (ECM) components, such as Spp1, and crystallin family might play important role in palatal shelves elevation (E13.5-E14.5). Therefore, the protein expression level of Ttr and Spp1 from E13.5 to E16.5 were tested by immunohistochemistry (IHC). Besides, the mRNA level of Spp1, were down-regulated at E16.5 and the protein were down-regulated at E15.5 and E16.5 in all-trans retinoic acid group, suggesting that atRA may involve in palatal bone formation by regulating Spp1. Overall, gene transcriptional profiles were obviously different at each time point of palate development. Thus, this study summarized some pathways and genes that may be related to palatogenesis and cleft palate through RNA-seq, to provide a direction for subsequent studies on the mechanism and targeted therapy of cleft palate.

Evaluation of the Effect of Topical Hypericum perforatum Oil on Excisional Palatal Wound Healing in Rabbits.

Aim: The aim of this study was to evaluate the effect of Hypericum perforatum (HP) oil on wound-healing process in rabbit palatal mucosa. Materials and Methods: Thirty-six New Zealand albino rabbits were randomly allocated to following groups; (1) HP oil (test, n = 18) and (2) olive oil (control, n = 18). Palatinal excisional wounds were created and the oils were topically applied (0.1 ml, 30 s, twice a day). Gingival biopsies were excised, and analyzed for re-epithelialization (RE) and granulation tissue maturation (GTM) on days 3, 7, and 14 after surgery. Levels of vascular endothelial growth factor (VEGF) and fibroblast growth factor 2 (FGF-2) were assessed using the immunohistochemical method. Apoptotic cells (ACs) were evaluated using TUNEL staining. Enzyme-linked immunosorbent assay was used to assess tissue catalase (CAT) and malondialdehyde (MDA) levels. Results: RE and GTM were completed earlier in the HP oil group than in the control group. The number of positively stained cells/vessels was higher in olive oil than in the test group on day 3 for FGF-2 and on days 3 and 7 for VEGF (p < 0.05). In contrast, on day 14, a higher number of vessels was observed in the HP oil group than in the control group. HP oil treatment reduced the number of ACs compared to olive oil (p < 0.05), but the difference during the healing period did not reach significance. Tissue CAT and MDA levels between groups were not different, and also the results were the same when the levels were analyzed by the evaluated time periods (p > 0.05). Conclusions: The results of this study demonstrated that topical HP oil treatment did not provide an additional benefit to its base, olive oil, in the early phase of secondary wound healing.

TCDD inhibited the osteogenic differentiation of human fetal palatal mesenchymal cells through AhR and BMP-2/TGF-ß/Smad signaling.

Exposure to environmental toxicant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) causes cleft palate at high rates, but little is known about the underlying biological mechanisms. In the present study, we cultured osteoblasts from human fetal palate mesenchymal cells (hFPMCs) to explore the effects of TCDD on osteogenic differentiation. The results showed that TCDD significantly decreased cell proliferation, alkaline phosphatase (ALP) activity and calcium deposition. RNA analyses and protein detection demonstrated that TCDD downregulated a wide array of pro-osteogenic biomarkers. Further investigation of the underlying molecular mechanisms revealed that exposure to TCDD activated aryl hydrocarbon receptor (AhR) signaling and inhibited BMP-2/TGF-ß1/Smad pathway molecules. The inactivation of AhR signaling using CRISPR/Cas9-mediated AhR deletion or by genetic siRNA knockdown significantly blocked the effects induced by TCDD, suggesting a critical role of AhR activation in the TCDD-mediated inhibition of hFPMC osteogenic differentiation. The cotreatment with TGF-ß1 or BMP-2 and TCDD significantly relieved the activation of AhR and rescued the impairment of osteogenesis caused by TCDD. Taken together, our findings indicated that TCDD inhibited the osteogenic differentiation of hFPMCs via crosstalk between AhR and BMP-2/TGF-ß1/Smad signaling pathway.

MiR-106a-5p modulates apoptosis and metabonomics changes by TGF-ß/Smad signaling pathway in cleft palate.

BACKGROUND: The molecular mechanisms of abnormal palatogenesis were investigated in this study. A key regulator, miR-106a-5p, and its target pathway were analyzed. OBJECTIVES: This research is trying to clarify the underlying mechanism of the modulation of miRNA transcription during the formation of cleft palate by 7T and 9.4T NMR metabolomic platforms. METHOD: Differentially expressed miRNAs and mRNAs were analyzed by microarray analysis and verified by qRT-PCR. The protein expression in TGFß signaling pathways were analyzed by Western Blotting. The relationship between miR-106a-5p and TGFß were analyzed by luciferase reporter assay. Cell apoptosis were analyzed by flow cytometer. And finally, the metabonomics were analyzed by NMR and multivariate data analysis models (MVDA). RESULTS: The expression of miR-106a-5p increased in cleft palatal tissue and negatively correlated with the protein level of Tgfbr2. The luciferase assay further proved that the tgfbr2 was a direct target of miR-106a-5p. In another aspect, miR-106a-5p increased apoptosis level in palatal mesenchymal cells, possibly because its inhibition of TGFß signaling pathway. Moreover, low cholesterol and choline levels with high citric acid and lipid levels were observed by 7T and 9.4T NMR metabonomic analysis, which inferred the disorder of cell membrane synthesis in cleft palate formation. Furthermore, transformation from choline to phosphatidylcholine regulated by miR-106a-5p was also disrupted, resulting in phosphatidic choline synthesis disorder and reduced cell membrane synthesis. CONCLUSIONS: The regulatory mechanism of cleft palate was studied at transcriptional and metabolomics levels, which may provide important information in understanding the primary cause of this abnormality.

Children with Fetal Alcohol Syndrome (FAS): 3D-Analysis of Palatal Depth and 3D-Metric Facial Length.

Background: Drinking alcohol during pregnancy can result in severe developmental disorders in the child. Symptoms of the fetal alcohol spectrum disorder (FASD) comprise growth deficiencies, abnormal facial phenotype and damage or dysfunction of the central nervous system. Numerous diagnostic methods for facial phenotyping in FASD exist, but diagnoses are still difficult. Our aim was to find additional and objective methods for the verification of FAS(D). Methods: Three-dimensional dental models of 60 children (30 FAS and 30 controls) were used to metrically determine maximum palatal depths at the median palatine raphe. Three-dimensional facial scans were taken, and vertical distances of the face were measured at five defined facial landmarks (FP1-FP5) for each child. Results: Mean palatal height, total facial length (FP1-FP5) as well as FP4-FP5 did not significantly differ between the FAS group and the control group. Comparing vertical facial subdivisions, however, resulted in significant differences for distances FP1 to FP2 (p = 0.042, FAS > controls), FP2 to FP3 (p < 0.001, FAS < controls), FP3 to FP4 (p < 0.001, FAS > controls) and FP3 to FP5 (p = 0.007, FAS > controls). Conclusions: Metric vertical measurements of the face can be used as additional objective criteria for FAS diagnoses. However, no significant differences were reported for palatal depth evaluation in the specific age range tested in the present study.

Capacidad de Disolución del Hipoclorito de Sodio con o sin Activación / Dissolution Capacity of Sodium Hypochlorite with or without Activation

Introducción: Una de las propiedades del hipoclorito de sodio (NaOCl) es la disolución de tejido pulpar remanente después de la instrumentación. Los sistemas de activación del irrigante pretenden mejorar esta propiedad. Este trabajo tiene como objetivo determinar la capacidad de disolución de tejido de NaOCl con y sin activación sónica o ultrasónica en diferentes concentraciones. Metodología: 300 muestras de tejido conectivo de paladar de cerdo de 4,5 * 2 mm obtenidos 1 día antes del estudio, congelado a-15°C en 100% de humedad, fueron pesados en una balanza analítica y sometidos a la acción de NaOCl 1%, 3% y 5% con y sin activación durante 45 minutos, cambiando la solución cada 10 minutos. Se secaron en papel filtro y se pesaron nuevamente. Los datos se analizaron mediante tests Kolmogorov-Smirnov; Kruskal-Wallis y Mann-Whitney. Resultados y Discusión: NaOCl 1% tiene menor capacidad de disolución que mejora levemente al activarlo. NaOCl 3% tiene mejor capacidad de disolución que NaOCl 1%, pero la activación no la mejora significativamente. NaOCl 5% tiene mayor capacidad de disolución, que aumenta con la activación, sin significancia entre activación sónica y ultrasónica, lo que se debería a que la mucosa palatina porcina requiere más tiempo para su disolución completa, y a que el volumen de tejido utilizado es mayor que una pulpa dental. Conclusiones: Bajo las condiciones de este estudio, sólo NaOCl 5% mostró mayor capacidad de disolución con la activación. NaOCl 1% y 3% no mejoraron significativamente con la activación

Introduction: One of the properties of sodium hypochlorite (NaOCl) is dissolution of pulp tissue remaining after instrumentation. Irrigant activation systems aim to improve this property. The objective of this work is to determine tissue dissolution capacity of NaOCl with and without sonic or ultrasonic activation in different concentrations. Methodology: 300 pork palate connective tissue samples of 4.5 * 2 mm obtained 1 day before the study, frozen at-15 ° C in 100% humidity, weighed on an analytical balance and subjected to the action of NaOCl 1%, 3% and 5% with and without activation for 45 minutes, changing the solution every 10 minutes. They were dried on filter paper and weighed again. The data were analyzed by Kolmogorov-Smirnov tests; Kruskal-Wallis and Mann-Whitney. Results and Discussion: NaOCl 1% has a lower dissolution capacity that improves slightly when activated. NaOCl 3% has better dissolution capacity than NaOCl 1%, but the activation does not significantly improve it. NaOCl 5% has greater dissolution capacity, which increases with activation, without significance between sonic and ultrasonic activation, which is due to the fact that the porcine palatine mucosa requires more time for its complete dissolution, since the volume of tissue used is greater than a dental Pulp. Conclusions: Under the conditions of this study, only NaOCl 5% showed greater dissolution capacity with activation. NaOCl 1% and 3% did not improve significantly with activation

Evaluating the Effects of a Topical Preparation with Dexpanthenol, Silbiol, Undecylenic Acid, and Lidocaine on Palatal Mucosa Wound Healing in a Rat Model

Background: Postoperative complications occur after periodontal plastic surgeries, but an ideal treatment to overcome them has not been found yet. Aims: To evaluate the effects of topically applied Oral-norm gel on the healing of excisional wounds. Study Design: Animal experiment. Methods: Excisional wounds with a diameter of 3 mm were made in the center of the palatal mucosa of 63 Sprague Dawley rats. Seven animals were sacrificed at time 0. The remaining rats were divided into two groups: a test group in which the topical Oral-norm gel was applied three times a day and a control group in which nothing was applied. Seven animals in each group were sacrificed at 3, 7, 14, and 21 days. Mean wound surface area was measured photographically, while wound healing and width were evaluated microscopically. Results: The mean wound surface area decreased significantly after 3 days in both groups (p<0.001). Between days 3 and 7, the mean wound surface area decreased from 6.62 (2.85) to 0.83 (1.62) mm2 in the control group and 5.07 (0.88) to 1.42 (1.67) mm2 in the test group. The wound width decreased significantly on day 7 in both groups (p<0.001), with no further changes by day 14. Both groups had a significant increase in inflammation and vascularization on day 3 (p<0.001), with a reduction thereafter. No significant differences in macroscopic and microscopic measurements were observed between the groups at any time point (p>0.05). Conclusion: The Oral-norm gel has no positive healing effects in the palatal mucosa of rats.

Efficacy of rhBMP-2 in Cleft Lip and Palate Defects: Systematic Review and Meta-analysis.

The aim of this study was to analyze the efficacy of using rhBMP-2 (recombinant human morphogenetic protein-2) in the treatment of patients with cleft lip and palate defects (CLPD). Seven databases were screened: PubMed (Medline), Lilacs, Ibecs, Web of Science, BBO, Scopus, and The Cochrane Library. Clinical trials that evaluated the use of bioactive treatment with rhBMP-2 in the treatment of patients with CLPD were included. Statistical analyses were performed by comparing the standardized mean difference of bone formation volume and bone filling percentage (p = 0.05). Ten studies compared the use of rhBMP-2 and iliac crest bone graft (ICBG). The global analysis for bone formation volume and bone filling percentage showed that bioactive materials were similar to ICBG with a standardized mean difference of respectively 0.07 (95% CI - 0.41 to 0.56) and 0.24 (95% CI - 0.32 to 0.80). The available literature suggested that use of rhBMP-2 presented similar bone formation results to those of ICBG in secondary alveolar bone grafting for patients with CLPD.

A Three-Dimensional Organoid Culture Model to Assess the Influence of Chemicals on Morphogenetic Fusion.

Embryologic development involves cell differentiation and organization events that are unique to each tissue and organ and are susceptible to developmental toxicants. Animal models are the gold standard for identifying putative teratogens, but the limited throughput of developmental toxicological studies in animals coupled with the limited concordance between animal and human teratogenicity motivates a different approach. In vitro organoid models can mimic the three-dimensional (3D) morphogenesis of developing tissues and can thus be useful tools for studying developmental toxicology. Common themes during development like the involvement of epithelial-mesenchymal transition and tissue fusion present an opportunity to develop in vitro organoid models that capture key morphogenesis events that occur in the embryo. We previously described organoids composed of human stem and progenitor cells that recapitulated the cellular features of palate fusion, and here we further characterized the model by examining pharmacological inhibitors targeting known palatogenesis and epithelial morphogenesis pathways as well as 12 cleft palate teratogens identified from rodent models. Organoid survival was dependent on signaling through EGF, IGF, HGF, and FGF pathways, and organoid fusion was disrupted by inhibition of BMP signaling. We observed concordance between the effects of EGF, FGF, and BMP inhibitors on organoid fusion and epithelial cell migration in vitro, suggesting that organoid fusion is dependent on epithelial morphogenesis. Three of the 12 putative cleft palate teratogens studied here (theophylline, triamcinolone, and valproic acid) significantly disrupted in vitro organoid fusion, while tributyltin chloride and all-trans retinoic acid were cytotoxic to fusing organoids. The study herein demonstrates the utility of the in vitro fusion assay for identifying chemicals that disrupt human organoid morphogenesis in a scalable format amenable to toxicology screening.

Effect of Topical Erythropoietin (EPO) on palatal wound healing subsequent to Free Gingival Grafting (FGG).

Free gingival grafting, the most predictable technique to increase the keratinized gingiva, leaves an open wound on the palate and the resulting discomfort during the healing phase is a significant concern. This study was intended to evaluate the effect of topical erythropoietin on healing of the donor site. Twelve patients lacking an attached gingiva at two sites in the mandible were included. In the test group, 1 mL of gel containing erythropoietin at a concentration of 4,000 IU mL-1 was applied to the donor site, whereas the control group was treated with 2 mL of the gel alone. On the second day after surgery, the same procedure was repeated. H2O2 was used to evaluate the amount of epithelialization. Clinical healing was compared using photographs and direct examination. The EPO group showed significantly better keratinization only on day 21. Comparison of clinical healing based on direct examination revealed significantly better healing in the test group on day 28. Furthermore, inflammation in the test group was lower than in the control group on the same day. Topical application of EPO improves palatal wound healing during the third and fourth weeks after free gingival graft procedures.

Cell Polarity and PAR Complex Likely to Be Involved in Dexamethasone-Induced Cleft Palate.

Accumulating studies demonstrated that PAR complex contributed to the establishment and maintenance of cell polarity which was fundamental to many aspects of cell and developmental biology. The purpose of this study was to investigate whether dexamethasone (DEX) could downregulate the PAR complex and disrupt cell polarity in palatal epithelium during palatal fusion in mice. The C57BL/6J mice were selected for the experiment. Pregnant mice in control group and DEX-treated group were injected intraperitoneally with 0.9% sodium chloride 0.1 mL, which contained DEX 6 mg/kg respectively, every day from E10 to E12. The palatal epithelia morphology was observed with hematoxylin and eosin and scanning electron microscopy. Immunofluorescence staining, western blot, and real-time polymerase chain reaction were performed to detect the expression of PAR3/PAR6/aPKC. After being treated with DEX, the palatal shelves showed delayed development and became shorter and smaller. During the process of palatogenesis, PAR3 and PAR6 expressed in the palatal epithelium, and aPKC expressed in both the epithelium and the mesenchyme. Dexamethasone could downregulate the expression levels of PAR3/PAR6/aPKC in both protein and gene level. In conclusions, DEX affected the PAR complex of mouse embryonic palate, and could perturb the PAR complex and the cell polarity of medial edge epithelium cells, and caused the failure of palatal fusion.

Effect of Topical Erythropoietin (EPO) on palatal wound healing subsequent to Free Gingival Grafting (FGG)

Abstract Free gingival grafting, the most predictable technique to increase the keratinized gingiva, leaves an open wound on the palate and the resulting discomfort during the healing phase is a significant concern. This study was intended to evaluate the effect of topical erythropoietin on healing of the donor site. Twelve patients lacking an attached gingiva at two sites in the mandible were included. In the test group, 1 mL of gel containing erythropoietin at a concentration of 4,000 IU mL-1 was applied to the donor site, whereas the control group was treated with 2 mL of the gel alone. On the second day after surgery, the same procedure was repeated. H2O2 was used to evaluate the amount of epithelialization. Clinical healing was compared using photographs and direct examination. The EPO group showed significantly better keratinization only on day 21. Comparison of clinical healing based on direct examination revealed significantly better healing in the test group on day 28. Furthermore, inflammation in the test group was lower than in the control group on the same day. Topical application of EPO improves palatal wound healing during the third and fourth weeks after free gingival graft procedures.

Preliminary research on DNA methylation changes during murine palatogenesis induced by TCDD.

2,3,7,8-Tetrachlrodibenzo-p-dioxin (TCDD) has been shown to induce cleft palate through growth factor and receptor expression changes during palatogenesis. DNA methylation is an important epigenetic modification that can regulate gene expressions and may be involved in TCDD-induced cleft palate. In this study, we investigated the effects of TCDD on the global and CpG DNA methylation status and the expression levels of DNA methyltransferases (Dnmts) in palate tissue of fetal mice. Pregnant C57BL/6J mice were administered with corn oil or TCDD 28 µg/kg at gestation day 10.5(GD10.5), and sacrificed at GD13.5, 14.5, 15.5. Fetal palates were collected for molecular analysis. Global DNA methylation status was detected by Methylamp™ Global DNA Methylation Quantification Ultra Kit. The expression of DNA methyltransferases were examined by quantitative real-time PCR(q-PCR). Methylation Specific PCR (MSP) was performed to analyze CpG methylation status of Dnmts. We found that the global DNA methylation level and the expression of Dnmt3a were higher at GD13.5 in the TCDD group. The methylation level of CpG site 2 in the promoter region of Dnmt3a in the control group was higher than that of the TCDD group at GD13.5. The low CpG methylation level of Dnmt3a at GD13.5 which causes the up-expression of Dnmt3a may induce global hypermethylation in fetal palate tissue. The aberrant global methylation status at GD13.5 may be the cause of palate malformation in fetal mice induced by TCDD.