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Appropriate mechanical loading during occlusion and mastication play an important role in maintaining the homeostasis of periodontal ligament (PDL) tissue. Connective tissue growth factor (CTGF/CCN2), a matricellular protein, is known to upregulate extracellular matrix production, including collagen in PDL tissue. However, the underlying mechanisms of CTGF/CCN2 in regulation of PDL tissue integrity remain unclear. In this study, we investigated the effect of CTGF/CCN2 on osteo/cementoblastic and fibroblastic differentiation of human PDL stem cells using the cell line 1-11. CTGF/CCN2 expression in rat PDL tissue and human PDL cells (HPDLCs) was confirmed immunohisto/cytochemically. Mechanical loading was found to increase gene expression and secretion of CTGF/CCN2 in HPDLCs. CTGF/CCN2 upregulated the proliferation and migration of 1-11 cells. Furthermore, increased bone/cementum-related gene expression in this cell line led to mineralization. In addition, combined treatment of 1-11 cells with CTGF/CCN2 and transforming growth factor-β1 (TGF-β1) significantly promoted type I collagen and fibronectin expression compared with that of TGF-β1 treatment alone. Thus, these data suggest the underlying biphasic effects of CTGF/CCN2 in 1-11 cells, inducible osteo/cementoblastic, and fibroblastic differentiation dependent on the environmental condition. CTGF/CCN2 may contribute to preservation of the structural integrity of PDL tissue, implying its potential use as a therapeutic agent for PDL regeneration. J. Cell. Physiol. 229: 150-159, 2014. © 2014 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Aim To investigate Glial cell line-derived neurotrophic factor ( GDNF) expression in normal and wounded rat periodontal ligament ( PDL) and the effects of GDNF on human PDL cells ( HPDLCs) migration and extracellular matrix expression in HPDLCs. Material and Methods The expression of GDNF and GDNF receptors was examined by immunocyto/histochemical analyses. Gene expression in HPDLCs treated with GDNF, interleukin-1 beta ( IL-1β), or tumour necrosis factor-alpha ( TNF-α) was quantified by quantitative RT- PCR ( qRT- PCR). In addition, we examined the migratory effect of GDNF on HPDLCs. Results GDNF was expressed in normal rat PDL and cultured HPDLCs. HPDLCs also expressed GDNF receptors. In wounded rat PDL, GDNF expression was up-regulated. QRT- PCR analysis revealed that IL-1β and TNF-α significantly increased the expression of GDNF in HPDLCs. Furthermore, GDNF induced migration of HPDLCs, which was blocked by pre-treatment with the peptide including Arg-Gly-Asp ( RGD) sequence, or neutralizing antibodies against integrin αVβ3 or GDNF. Also, GDNF up-regulated expression of bone sialoprotein ( BSP) and fibronectin in HPDLCs. Conclusions GDNF expression is increased in rat wounded PDL tissue and HPDLCs treated with pro-inflammatory cytokines. GDNF enhances the expression of BSP and fibronectin, and migration in an RGD-dependent manner via the integrin αVβ3. These findings suggest that GDNF may contribute to wound healing in PDL tissue. [ABSTRACT FROM AUTHOR]

Repair of injured peripheral nerve is thought to play important roles in tissue homeostasis and regeneration. Recent experiments have demonstrated enhanced functional recovery of damaged neurons by some types of somatic stem cells. It remains unclear, however, if periodontal ligament (PDL) stem cells possess such functions. We recently developed a multipotent clonal human PDL cell line, termed cell line 1-17. Here, we investigated the effects of this cell line on neurocytic differentiation, migration, and survival. This cell line expressed the neural crest cell marker genes Slug, SOX10, Nestin, p75NTR, and CD49d and mesenchymal stem cell-related markers CD13, CD29, CD44, CD71, CD90, CD105, and CD166. Rat adrenal pheochromocytoma cells (PC12 cells) underwent neurocytic differentiation when co-cultured with cell line 1-17 or in conditioned medium from cell line 1-17 (1-17CM). ELISA analysis revealed that 1-17CM contained approximately 50 pg/ml nerve growth factor (NGF). Cell line 1-17-induced migration of PC12 cells, which was inhibited by a neutralizing antibody against NGF. Furthermore, 1-17CM exerted antiapoptotic effects on differentiated PC12 cells as evidenced by inhibition of neurite retraction, reduction in annexin V and caspase-3/7 staining, and induction of Bcl-2 and Bcl-xL mRNA expression. Thus, cell line 1-17 promoted neurocytic differentiation, migration, and survival through secretion of NGF and possibly synergistic factors. PDL stem cells may play a role in peripheral nerve reinnervation during PDL regeneration. J. Cell. Physiol. 227: 2040-2050, 2012. © 2011 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]