Effects of hypoxia on the immunomodulatory properties of human gingiva-derived mesenchymal stem cells.

The environment of bone marrow mesenchymal stem cells (MSCs) is hypoxic, which plays an important role in maintaining their self-renewal potential and undifferentiated state. MSCs have been proven to possess immunomodulatory properties and have been used clinically to treat autoimmune diseases. Here, we tested the effects of hypoxia on the immunomodulatory properties of MSCs and examined its possible underlying mechanisms. We found that hypoxic stimulation promoted the immunomodulatory properties of human gingiva-derived mesenchymal stem cells (hGMSCs) by enhancing the suppressive effects of hGMSCs on peripheral blood mononuclear cells (PBMCs). The proliferation of PBMCs was significantly inhibited, while the apoptosis of PBMCs was increased, which was associated with the Fas ligand (FasL) expression of hGMSCs. The in vivo study showed that systemically infused hGMSCs could enhance skin wound repair, and 24-h hypoxic stimulation significantly promoted the reparative capacity of hGMSCs. For mechanism, hGMSC treatment inhibited the local inflammation of injured skin by suppressing the inflammatory cells, reducing the pro-inflammatory cytokine tumor necrosis factor-α (TNF-α), and increasing anti-inflammatory cytokine interleukin-10 (IL-10), which was promoted by hypoxia. Hypoxia preconditioning may be a good optimizing method to promote the potential of MSCs for the future cell-based therapy.

Immunomodulatory properties of dental tissue-derived mesenchymal stem cells.

In addition to their well-established self-renewal and multipotent differentiation properties, mesenchymal stem cells (MSCs) also possess potent immunomodulatory functions both in vitro and in vivo, which render them a potential novel immunotherapeutic tool for a variety of autoimmune and inflammation-related diseases. The major mechanisms may involve (1) the secretion of an array of soluble factors such as prostaglandin E2 (PGE2 ), indoleamine 2, 3-dioxygenase (IDO), transforming growth factor-ß (TGF-ß), and human leukocyte antigen G5 (HLA-G5); (2) interactions between MSCs and immune cells such as T cells, B cells, macrophages, and dendritic cells. Recently, increasing evidence has supported that MSCs derived from dental tissues are promising alternative sources of multipotent MSCs. We here provide a thorough and extensive review about new findings in the immunomodulatory functions of MSCs derived from several dental tissues, including dental pulp, periodontal ligament, gingiva, exfoliated deciduous teeth, apical papilla, and dental follicle, respectively. The immunomodulatory properties of dental MSCs place them as a more accessible cell source than bone marrow-derived MSCs for cell-based therapy of immune and inflammation-related diseases.

Comparison of methods for localization of impacted maxillary canines by panoramic radiographs.

OBJECTIVES: The objective of this study was to compare three methods for localization of impacted maxillary canines using only conventional panoramic radiographs. METHODS: The panoramic radiographs of 94 patients (102 impacted maxillary canines) were reviewed and evaluated using the methods magnification, angulation and superimposition. The actual positions of them were decided with cone beam CT images. The predicted positions of impacted canines from the magnification and angulation methods were compared using the McNemar χ(2) test. Sensitivity, specificity, accuracy, positive-likelihood ratio and negative-likelihood ratio were calculated. The canine-incisor index values and α angles of palatally and bucally non-rotated impacted canines were compared using the Mann-Whitney U test. RESULTS: The statistical analysis revealed that there was a significant difference between the magnification and angulation methods (p < 0.01). Using the magnification method, 68.00% of buccal canines and 69.57% of palatal canines could be localized correctly. The results of the angulation method were 28.57% and 84.91%, respectively. The sensitivity of the angulation method for buccal canines was very low. In the superimposition method, 82.98% of the superimposing samples were palatal. CONCLUSIONS: The magnification and angulation methods were not reliable methods for locating the impacted canine with a single panoramic radiograph. Magnification was more successful than the angulation method. Further research is needed on the magnification method. The image superimposition method could be used as an adjunct to others.