Endogenous hydrogen sulfide is involved in osteogenic differentiation in human periodontal ligament cells.

OBJECTIVE: Endogenous hydrogen sulfide (H2S) has recently emerged as an important intracellular gaseous signaling molecule within cellular systems. Endogenous H2S is synthesized from l-cysteine via cystathionine ß-synthase and cystathionine γ-lyase and it regulates multiple signaling pathways in mammalian cells. Indeed, aberrant H2S levels have been linked to defects in bone formation in experimental mice. The aim of this study was to examine the potential production mechanism and function of endogenous H2S within primary human periodontal ligament cells (PDLCs). DESIGN: Primary human PDLCs were obtained from donor molars with volunteer permission. Immunofluorescent labeling determined expression of the H2S synthetase enzymes. These enzymes were inhibited with D,L-propargylglycine or hydroxylamine to examine the effects of H2S signaling upon the osteogenic differentiation of PDLCs. Gene and protein expression levels of osteogenic markers in conjunction with ALP staining and activity and alizarin red S staining of calcium deposition were used to assay the progression of osteogenesis under different treatment conditions. Cultures were exposed to Wnt3a treatment to assess downstream signaling mechanisms. RESULTS: In this study, we show that H2S is produced by human PDLCs via the cystathionine ß-synthase/cystathionine γ-lyase pathway to promote their osteogenic differentiation. These levels must be carefully maintained as excessive or deficient H2S levels temper the observed osteogenic effect by inhibiting Wnt/ß-catenin signaling. CONCLUSIONS: These results demonstrate that optimal concentrations of endogenous H2S must be maintained within PDLCs to promote osteogenic differentiation by activating the Wnt/ß-catenin signaling cascade.

[Effects of LPS-stimulated monocyte culture supernatant on the OPG/RANKL of osteoblastic cells].

PURPOSE: To investigate the influence of Pg-LPS stimulated monocyte (RAW264.7) culture supernatant on the OPG/RANKL expression of osteoblastic cells (MC3T3-E1). METHODS: The culture supernatant of monocytes stimulated with Pg-LPS was applied to osteoblasts MC3T3-E1 with different diluted concentrations (10%, 20%, 30%, 40% and 50%) simultaneously for 24h, then RT-PCR was used to detect the expression changes of OPG/RANKL mRNA. Western blot was used to detect the expression changes of OPG/RANKL protein. The data was analyzed by ANOVA using SPSS 17.0 software package. RESULTS: After stimulation of different concentrations of inflammatory supernatant, the expressions of OPGmRNA and protein significantly decreased (P<0.05), whereas the expressions of RANKLmRNA and protein significantly increased(P<0.05), both of them were in a concentration-dependent manner. CONCLUSIONS: These results indicate that Pg-LPS stimulated RAW264.7 culture supernatant can inhibit the osteogenesis and differentiation of the osteoblasts through inhibiting the expression of OPGmRNA and protein of osteoblastic cells, while increasing the expression of RANKLmRNA and protein in a concentration-dependent manner.

[Effect of tensile strain on perlecan expression of human periodontal ligament cells].

PURPOSE: To investigate the perlecan expression of human periodontal ligament cells (hPDLCs) under cyclic tensile strain in vitro, and learn the molecular mechanism of periodontal remolding during tooth movement. METHODS: hPDLCs isolated by enzyme digestion were loaded with 12% elongation, 1 Hz of uniaxial tensile strain for 12, 24 and 48 h. The unloaded cells were used as control. Real-time PCR and enzyme-linked immune sorbent assay (ELISA) were applied to analyze the mRNA and protein expression of perlecen in each sample respectively. The data was analyzed with SPSS 19.0 software package. RESULTS: Within 12 h, mRNA expression was transiently elevated, but no significant difference was detected compared with the control. After 12 h, the mRNA expression was significantly decreased. It would decreased to (0.28±0.049) at lowest level of control at lowest level at 48 h (P<0.05). The protein expression of perlecan was time-dependently decreased. Specifically, it was downregulated from (14.03±0.71) pg/mL (control) to (11.06±0.15) pg/mL at lowest level at 48 h (P<0.05). CONCLUSIONS: Tensile strain time-dependently down-regulates perlecan expression, indicating perlecan may play a pivot role in PDLCS responding to mechanical loading in vitro.

[Root and alveolar bone status of maxillary labial inverted impacted incisor in mixed dentition after orthodontic treatment].

OBJECTIVE: To study the alveolar bone surrounding situation and the length of the root of the maxillary labial inverted impacted incisor in mixed dentition after orthodontic treatment. METHODS: Fourteen cases with maxillary labial inverted impacted incisor in mixed dentition were collected. Modified Nance arch and conventional appliance were used. Cone-bean CT (CBCT) was taken after the treatment. Simplant13.0 three-dimensional reconstruction and multi-planer reconstruction (MPR) method were used to observe the labial and lingual alveolar bone crest morphology, besides, the labial and lingual length from the alveolar bone crest to cemento-enamel junction (CEJ) of the impacted incisor and the homonym tooth after treatment, along with their root length and their labial and lingual length ratio of the root surrounded by the alveolar bone to the total root length were measured. The idependent samples t-test were used to analyze the variable differences. RESULTS: The labial and lingual alveolar bone of fourteen cases crest of the diseased tooth after treatment presented general symmetry U shape from qualitative observation through the three-dimensional reconstruction. The labial and the lingual length of the diseased incisor from alveolar bone crest to CEJ [(2.47 ± 1.35) and (1.47 ± 0.84) mm] was significant increased than those of the homonym incisor [(1.03 ± 0.35) and (0.90 ± 0.37) mm] (P < 0.05); the length of the diseased incisor's post-treatment root [(9.82 ± 2.82) mm] was no statistically significant decreased than that of the homonym incisor root [(10.28 ± 1.38) mm, P = 0.59]; the labial and the lingual length ratio of the impacted tooth's root surrounded by the alveolar bone to the total root length [(72.83 ± 17.16)% and (85.32 ± 5.98)%] was statistically significant decrease than those of homonym teeth[(89.66 ± 3.98)% and (90.84 ± 4.61)%] (P < 0.05). CONCLUSIONS: The diseased tooth's root had gotten enough length after the treatment. The labial and lingual alveolar bone of the maxillary labial inverted impacted incisor in mixed dentition can't offer sufficient adaptive hyperplasia after treatment, of which labial alveolar bone is more apparent, prompting careful protection when they were used.