Triggering receptor expressed on myeloid cells-2 stimulates osteoclast differentiation and bone loss in periodontitis.

OBJECTIVE: To investigate the expression of triggering receptor expressed on myeloid cells 2 (TREM-2) in the healthy and diseased tissue, including gingivitis or periodontitis, and then to assess whether it has an impact on the development of periodontitis. METHODS AND MATERIALS: The gingival tissues from healthy controls, gingivitis, and periodontitis underwent hematoxylin-eosin and immunohistochemical staining, and the association of TREM-2 expression or TREM-2+ cell counts with clinical parameters was assessed. An anti-TREM-2 antibody was used to block the osteoclastogenesis in vitro and during the experimental periodontitis by injection into the gingiva. The relative gene expression of TREM-2 in different gingival tissues was analyzed by quantitative PCR. RESULTS: In the gingival tissues of periodontitis, TREM-2 expression and TREM-2+ cell counts were significantly higher than those of gingivitis and healthy controls (p<0.05). In the group of periodontitis showing moderate signs, the gingival tissues displayed significantly lower TREM-2 expression, in contrast with the group with advanced periodontal symptoms (p < 0.05). Consistently, blocking TREM-2 significantly decreased osteoclast formation both in vitro and in vivo (p < 0.05). CONCLUSION: Increased TREM-2 expression and TREM-2+ cells were positively associated with the development of periodontitis. Osteoclast differentiation and stimulating alveolar bone loss were partly relied on TREM-2, which could be a target to be blocked for attenuating osteoclastogenesis in periodontitits.

The detection of Gper1 as an important gene promoting jawbone regeneration in the context of estrogen deficiency.

Numerous studies have demonstrated that estrogen deficiency inhibit the proliferation and differentiation of pre-osteoblasts in skeleton by affecting osteogenic signaling, lead to decreased bone mass and impaired regeneration. To explore the mechanisms maintaining bone regeneration under estrogen deficiency, we randomly selected 1102 clinical cases, in which female patients aged between 18 and 75 have underwent tooth extraction in Stomatological Hospital of Tongji University, there is little difference in the healing effect of extraction defects, suggesting that to some extent, the regeneration of jawbone is insensitive to the decreased estrogen level. To illuminate the mechanisms promoting jawbone regeneration under estrogen deficiency, a tooth extraction defect model was established in the maxilla of female rats who underwent ovariectomy (OVX) or sham surgery, and jawbone marrow stromal cells (BMSCs) were isolated for single-cell sequencing. Further quantitative PCR, RNA interference, alizarin red staining, immunohistochemistry and western blotting experiments demonstrated that in the context of ovariectomy, maxillary defects promoted G protein-coupled estrogen receptor 1 (Gper1) expression, stimulate downstream cAMP/PKA/pCREB signaling, and facilitate cell proliferation, and thus provided sufficient progenitors for osteogenesis and enhanced the regeneration capacity of the jawbone. Correspondingly, the heterozygous deletion of the Gper1 gene attenuated the phosphorylation of CREB, led to decreased cell proliferation, and impaired the restoration of maxillary defects. This study demonstrates the importance of Gper1 in maintaining jawbone regeneration, especially in the context of estrogen deficiency.

Interactions of Fibroblast Subtypes Influence Osteoclastogenesis and Alveolar Bone Destruction in Periodontitis.

Background: To analyze the fibroblasts subtypes in the gingival tissues of healthy controls, gingivitis and periodontitis patients, as well as the effects of interaction between subtypes on alveolar bone destruction. Methods: Gingival tissues were divided into three groups according to clinical and radiographic examination, and the immunostaining of EDA+FN was assessed. Fibroblasts from gingiva developed colony formation units (CFUs) and induced Trap+MNCs. The expression of osteoclastogenesis-related genes was assessed by real-time PCR. Variances in the gene profiles of CFUs were identified by principal component analysis, and cluster analysis divided CFUs into subtypes. The induction of Trap+MNCs and gene expression were compared among individual or cocultured subtypes. The fibroblast subtypes exerted critical effect on Trap+MNCs formation were selected and edited by CRISPR/Cas to investigate the influence on osteoclastogenesis in the periodontitis in mice. Results: Most periodontitis samples exhibited intensive EDA+FN staining (P < 0.05), and these fibroblasts also induced most Trap+MNCs among three groups; consistently, fibroblasts from periodontitis highly expressed genes facilitating osteoclastogenesis. According to gene profiles and osteoclastogenic induction, four clusters of CFUs were identified. The proportion of clusters was significantly different (P < 0.05) among three groups, and their interaction influenced osteoclastogenic induction. Although Cluster 4 induced less osteoclasts, it enhanced the effects of Clusters 1 and 3 on Trap+MNCs formation (P < 0.05). EDA knockout in Cluster 4 abrogated this promotion (P < 0.05), and decreased osteoclasts and alveolar bone destruction in experimental periodontitis (P < 0.05). Conclusion: Heterogeneous fibroblast subtypes affect the switch or development of periodontitis. A subtype (Cluster 4) played important role during alveolar bone destruction, by regulating other subtypes via EDA+FN paracrine.

Vascularized nanocomposite hydrogel mechanically reinforced by polyelectrolyte-modified nanoparticles.

Vascularization plays an important role in the initial stage of triggering bone defect repair. The combination of bioactive small molecule drugs and biomaterials has been a powerful strategy for vascularization in bone tissue engineering. In this study, an in situ crosslinked aldehyde hyaluronic acid (AHA)/N,O-carboxymethyl chitosan (NOCC) nanocomposite hydrogel doped with sphingosine 1-phosphate (S1P)-loaded polyelectrolyte-modified mesoporous silica nanoparticles (MSNs) was developed. The alginate/chitosan polyelectrolyte-modified MSNs (MSNs-ALG/CHI) were prepared via the electrostatic interaction. The incorporation of MSNs-ALG/CHI not only achieved a sustained release profile of the angiogenic drug, but also improved the mechanical property of the AHA/NOCC hydrogel due to the Schiff base reaction between the amino group in chitosan and the aldehyde group in AHA. In addition, in vitro cell experiments demonstrated that the nanocomposite hydrogel provided favorable support for cell adhesion and proliferation, and the S1P-loaded nanocomposite hydrogel was able to recruit endothelial cells. More importantly, the chicken chorioallantoic membrane (CAM) assay confirmed that the S1P-loaded nanocomposite hydrogel could significantly enhance capillary formation. More cell infiltration and better angiogenesis in the S1P loaded nanocomposite hydrogel were observed compared to the group without S1P loading after being implanted subcutaneously for 2 weeks. Furthermore, the subcutaneous implantation experiment further demonstrated that the incorporation of the S1P-loaded nanocomposite hydrogel could improve the tissue infiltration and new vessel formation within the macroporous poly(L-lactic acid)/polycaprolactone scaffold. Our results suggest that the nanocomposite hydrogel will be an excellent drug delivery system and the S1P-loaded nanocomposite hydrogel has great potential for vascularized bone regeneration application.

Study of the differentially expressed genes in pleomorphic adenoma using cDNA microarrays.

Recent studies have determined that gene expression profiling using microarray technology can be used to identify tumor-related molecules. The objective of this study was to screen the differentially expressed genes between pleomorphic adenoma (PA) and the normal tissue adjacent to PA using cDNA microarrays and to further validate the differentially expressed genes by real-time PCR. In this study, we selected five pairs of PA and the surrounding normal salivary gland tissues. The total RNA was isolated from tumor and normal tissues and purified to mRNA. The mRNA was reverse-transcribed to cDNA with the incorporation of fluorescent-labeled dUTP to prepare the hybridization probes. The mixed probes were hybridized to Whole Human Gene Expression Microarrays by Agilent. Tumor-related genes were screened by analyzing the fluorescence intensity. As a result, a total of 447 genes were found to be differentially expressed between PA and normal tissue adjacent to PA. Among them, 185 genes were up-regulated and 262 genes were down-regulated in PA. By constructing a network from the differentially expressed genes, some genes, such as Gli2 and CTNNB1, were identified as being at the core of the network. In addition, differential gene expression was validated for 2 up-regulated genes, Gli2 and LOX, using real-time PCR and the results were consistent with those of the cDNA microarray analysis thus verifying the credibility of the microarray data. Therefore, our microarray data may provide clues for finding novel genes involved in the development of PA, and shed light on finding new targets for diagnosis and therapy of PA. Further characterization of these differentially expressed genes will be useful in understanding the genetic basis for PA.

[Biocompatibility between bone-marrow stem cell and beta-TCP: an experimental study].

PURPOSE: To study the biocompatibility between bone-marrow stem cell (BMSC) and bio-ceramic material, and the influence of bio-ceramic on the intracellular calcium of BMSC. METHODS: BMSC was taken from four canines, and the induced cells were combined with the bio-ceramic, then intracellular calcium and OD value were measured, the data was analyzed using SAS 8.0 software package. RESULTS: After combination with stent material, intracellular calcium of osteoblast-like cell(OBL)was significantly elevated (P<0.05), and the proliferation rate was also enhanced. CONCLUSIONS: BMSC has multi-differentiation potential with certain osteoblast capability. After combination with beta-tricalcium phosphate, the proliferation ability is seen in BMSC.