Mesenchymal stem cells derived from human exfoliated deciduous teeth (SHEDs) induce immune modulatory profile in monocyte-derived dendritic cells.

BACKGROUND: Mesenchymal stem cells have prominent immune modulatory properties, which may have clinical applications; however their major source, bone marrow, is of limited availability. On the other hand, mesenchymal stem cells derived from human exfoliated deciduous teeth (SHEDs) are readily accessible, but their immune regulatory properties have not been completely investigated. This study was designed, therefore, to evaluate the SHEDs influence on DCs differentiation, maturation, ability to activate T cells and to expand CD4(+)Foxp3(+) T cells. METHODOLOGY/PRINCIPAL FINDINGS: The experiments were based in cellular co-culture during differentiation and maturation of monocyte derived-DCs (moDCs), with, or not, presence of SHEDs. After co-culture with SHEDs, (moDCs) presented lower expression of BDCA-1 and CD11c, in comparison to DC cultivated without SHEDs. CD40, CD80, CD83 and CD86 levels were also decreased in mature DCs (mDCs) after co-cultivation with SHEDs. To assess the ability of SHEDs-exposed moDCs to modulate T cell responses, the former were separated from SHEDs, and co-cultured with peripheral blood lymphocytes. After 5 days, the proliferation of CD4(+) and CD8(+) T cells was evaluated and found to be lower than that induced by moDCs cultivated without SHEDs. In addition, an increase in the proportion of CD4(+)Foxp3(+)IL-10(+) T cells was observed among cells stimulated by mature moDCs that were previously cultivated with SHEDs. Soluble factors released during co-cultures also showed a reduction in the pro-inflammatory cytokines (IL-2, TNF-α and IFN-γ), and an increase in the anti-inflammatory molecule IL-10. CONCLUSION/SIGNIFICANCE: This study shows that SHEDs induce an immune regulatory phenotype in moDCs cells, evidenced by changes in maturation and differentiation rates, inhibition of lymphocyte stimulation and ability to expand CD4(+)Foxp3(+) T cells. Further characterization and validation of this phenomenon could support the use of SHEDs, directly or indirectly for immune modulation in the clinical practice.

Mecanismos celulares e moleculares envolvidos na reabsorção radicular fisiológica de dentes decíduos / Cellular and molecular mechanisms involved in the physiological root resorption of primary teeth

Introdução: A reabsorção fisiológica dos dentes decíduos constitui um fenômeno fisiológico complexo não completamente conhecido; assunto de grande interesse clínico. Os mecanismos celulares e moleculares envolvidos no fenômeno de reabsorção radicular fisiológica parecem ser similares aos mecanismos envolvidos na reabsorção óssea, mediada por osteoclastos. As principais células responsáveis pela reabsorção ativa dos tecidos dentais são os odontoclastos, também denominados de clastos ou osteoclastos; células gigantes multinucleadas originadas de precursores hematopoiéticos de monócitos ou macrófagos. Avanços recentes na literatura específica têm mostrado que a diferenciação e atividade dos osteoclastos, fenômeno também conhecido como osteoclastogênese, são iniciadas e reguladas por diferentes estímulos e sinalizadores moleculares como as citocinas, quimiocinas, produtos de degradação liberados pela superfície radicular afetada, moléculas de adesão, metaloproteinases e pelo sistema RANK/RANKL/OPG. Ainda, o contato físico entre os precursores de osteoclastos e osteoblastos ou células estromais também parece ser necessário para a ativação da osteoclastogênese. Entretanto, o papel específico dos fatores envolvidos no início e modulação da reabsorção radicular dos dentes decíduos permanece desconhecido. Objetivo: Realizar uma revisão de literatura sobre os mecanismos celulares e moleculares envolvidos no processo de reabsorção fisiológica dos dentes decíduos, enfatizando suas implicações clínicas.

Conclusão: Uma complexa interação entre osteclastos, osteoblastos, macrófagos, citocinas, quimiocinas, metaloproteinases, moléculas de adesão e o sistema RANK/RANKL/OPG parecem contribuir para a reabsorção dentária fisiológica. O conhecimento dos mecanismos celulares e moleculares envolvidos no processo de reabsorção fisiológica dos dentes decíduos pode contribuir para o estudo da imunopatogenia das reabsorções dentárias e futuramente resultar na aplicação clínica de mediadores moleculares para atrasar ou mesmo inibir esse processo

Introduction: The physiological resorption of primary teeth is a complex physiological phenomenon that is not completely known and is a subject of great interest. The cellular and molecular mechanisms involved in the phenomenon of physiological root resorption seem to be similar to those involved in bone resorption mediated by osteoclasts. The main cells responsible for the active resorption of the dental tissues are the odontoclasts, which are also known as clasts or osteoclasts; multi nucleated giant cells originated from hematopoietic precursors of monocytes or macrophages. Recent advances published in the literature have shown that the differentiation and activity of osteoclasts, a phenomenon that is also known as osteoclastgenesis, are initiated and regulated by different stimuli and molecular signalizing agents such as cytokines, chemokines, products of degradation released by the affected root surface, adhesion molecules, metalloproteinases, and the RANK/RANKL/OPG system. Moreover, the physical contact between the osteoclasts and osteoblast precursors or stromal cells also seems to be necessary for the activation of osteoclastgenesis. However, the specific role of the factors involved in the initiation and modulation of root resorption of the primary teeth remains unknown. Objective: To perform a review of the literature about the cellular and molecular mechanisms involved in the process of physiological resorption of the primary teeth, emphasizing their clinical implications.

Conclusion: A complex integration among osteoclasts, osteoblasts, macrophages, cytokines, chemokines, metalloproteinases, adhesion molecules and the RANK/RANKL/OPG system seems to contribute to the physiological resorption of teeth. Knowing the cellular and molecular mechanisms involved in the process of physiological root resorption of primary teeth may contribute to the investigation of the immunepathogenesis of dental resorptions, and allow for the clinical application of molecular mediators to delay or even inhibit this process

Loss of deciduous teeth and germs of permanent incisors in a 4-year-old child. An atypic prepubertal periodontitis? A clinical, microbiological, immunological and ultrastructural study.

A 4-year-old child was referred, in April 1988, to Rennes Dental School (France) for deciduous tooth mobility with premature loss of 4 deciduous teeth and germs of 2 permanent incisors. Microbiological examinations by culture revealed the presence of the periodontal pathogen Actinobacillus actinomycetemcomitans. Immunofluorescence of plaque samples revealed the presence of Porphyromonas gingivalis that had not been isolated by culture. Neutrophil functions were within normal ranges. Transmission electron microscopy of gingiva showed a disorganised epithelium. The connective tissue was infiltrated by inflammatory cells. The basement membranes were normal, but the connective tissue-epithelium interface was mainly composed of short rete pegs. Scanning electron microscopy of extracted deciduous teeth revealed lack of cementum, lacunae in the cementum and lack of fibrillar insertion on the middle part of the root. Skin lesions, mainly situated on face, were observed. Treatment was by extraction of mobile deciduous teeth combined with 3-week courses of metronidazole. Clinical and microbiological follow-up was continued over a 7-year period. No periodontal lesions have been detected since eruption of the permanent teeth. The present subgingival and lingual microflora (December 1995) is composed of bacteria associated with periodontal health. However, the future appearance of a hitherto undetected systemic disease is still possible.