Ectopic bone formation as a complication of surgical rehabilitation in patients with Moebius’ syndrome

T Lymphocytes Influence the Mineralization Process of Bone

Bone is a unique organ able to regenerate itself after injuries. This regeneration requires the local interplay between different biological systems such as inflammation and matrix formation. Structural reconstitution is initiated by an inflammatory response orchestrated by the host immune system. However, the individual role of T cells and B cells in regeneration and their relationship to bone tissue reconstitution remain unknown. Comparing bone and fracture healing in animals with and without mature T and B cells revealed the essential role of these immune cells in determining the tissue mineralization and thus the bone quality. Bone without mature T and B cells is stiffer when compared to wild-type bone thus lacking the elasticity that helps to absorb forces, thus preventing fractures. In-depth analysis showed dysregulations in collagen deposition and osteoblast distribution upon lack of mature T and B cells. These changes in matrix deposition have been correlated with T cells rather than B cells within this study. This work presents, for the first time, a direct link between immune cells and matrix formation during bone healing after fracture. It illustrates specifically the role of T cells in the collagen organization process and the lack thereof in the absence of T cells.

Osteogenic differentiation of human periodontal ligament stem cells expressing lentiviral NEL-like protein 1

NEL-like protein 1 (NELL1) is a newly identified secreted protein involved in craniosynostosis and has been found to promote osteogenic differentiation of mesenchymal stem cells. The objective of this study was to investigate the effect of NELL1 on osteogenic differentiation of human periodontal ligament stem cells (hPDLSCs) and the potential underlying mechanism. hPDLSCs underwent lentivirus-mediated NELL1 transfection (Lenti-NELL1) and markers of osteogenesis were assessed [alkaline phosphate (ALP), osteocalcin (OCN) and calcium deposition] to evaluate the effect of NELL1 on the differentiation of these cells. Quantitative polymerase chain reaction (qPCR) was employed to measure the mRNA expression of Msx2 and Runx2, and Lenti-enhanced green fluorescent protein (EGFP) served as a control. Western blot analysis and qPCR analyses confirmed that Lenti-NELL1-transfected hPDLSCs could express NELL1. Compared with the Lenti-EGFP group, ALP, OCN, calcium deposition and Msx2 mRNA expression were markedly increased (P<0.01), but there was no significant difference in Runx2 mRNA expression between the two groups (P>0.01). hPDLSCs can be transfected by Lenti-NELL1 and can stably express NELL1. NELL1 is able to promote the osteogenic differentiation of hPDLSCs, which may be related to the downregulation of Msx2 expression. Lenti-NELL1 transfection can be used during in vitro gene therapy for periodontal regeneration.