We have previously reported that an osteopontin-derived SVVYGLR peptide exhibited potent angiogenic activity in vitro and in vivo. In the present study, the focus points were on the in vitro effect of SVVYGLR on bone marrow stromal cell proliferation, as well as its in vivo effect on bone tissue formation when grafts made of CO3 Ap-collagen sponge -as a scaffold biomaterial containing the SVVYGLR motif -were implanted. SVVYGLR peptide promoted bone marrow stromal cell proliferation. When a CO3 Ap-collagen sponge containing SVVYGLR peptide was implanted as a graft into a tissue defect created in rat tibia, the migration of numerous vascular endothelial cells -as well as prominent angiogenesis -inside the graft could be detected after one week. These results thus suggested that our scaffold biomaterials including the peptide could be useful for bone tissue regeneration.

In tissue engineering, biodegradable polymer materials with both high biocompatibility and high strength are very important as scaffolds for long term use. Therefore, in this research, we tried to prepare the three types of poly(L-lactic acid) (PLLA)/calcium phosphate (CP) hybrid composite for a scaffold biomaterial. The effects of addition of different CP on both biocompatibility and mechanical properties were evaluated. CP powders and voids were three-dimensionally and uniformly distributed in the solid samples and porous composite samples. These compositions of CP and PLLA greatly improved the cellular adhesiveness, which increased as the volume fraction of CP in the composite increased. For the porous samples, cells migrated into the pores. This study demonstrated that a composite of PLLA and CP is an effective new scaffold material that results in better osteoconductivity, bone regeneration, and mineralization and has moderately high strength.

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Dental caries often causes pulp inflammation once it reaches the dentine. In deep caries, there are many kinds of bacterial components, such as lipopolysaccharide (LPS), that induce the production of proinflammatory mediators, including tumor necrosis factor (TNF)-α. Inflammation in dental pulp tissue is associated with tissue degradation, and matrix metalloproteinases (MMPs) are believed to participate in this destruction. In the present study, we examined whether TNF-α and LPS affect the production of MMP-1 and MMP-3 in human dental pulp cells (HDPCs) of deciduous teeth utilizing RT-PCR and ELISA analyses. Exposure of HDPCs to TNF-α at 10 ng/ml for 6 h significantly increased the gene expression of MMP-1 and MMP-3. MMP-1 gene expression was slightly affected by exposure to LPS, while MMP-3 gene expression was significantly elevated by LPS at 0.1, 1 and 5 µg/ml. TNF-α at 10 ng/ml and LPS at 1 and 5 µg/ml potentiated the protein production of MMP-3, but not MMP-1, in HDPCs. The results of this study suggests that the mechanisms by which TNF-α and LPS induce MMP-3 expression may be important links in the pathogenesis of inflammatory diseases and reparative dentin formation in HDPCs of deciduous teeth.

Inflammation in dental pulp tissue is associated with tissue degradation, and matrix metalloproteinases (MMPs) are believed to participate in this destruction. Elevated levels of some MMPs have been reported in inflamed pulp and periapical lesions. Moreover, in inflamed pulp, many kinds of inflammatory cytokines such as interleukin (IL)-1␤ and tumor necrosis factor (TNF)-␣, are released from inflammatory cells like macrophages, lymphocytes and neutrophils. In the present study, we examined whether TNF-␣ affected the production of MMP-2 in deciduous dental pulp fibroblasts and its signaling pathways utilizing gelatin zymography and western blotting analysis. TNF-␣ increased the expression of MMP-2 in a dose-dependent manner in deciduous dental pulp fibroblasts. LY294002 and Wortmannin, which are PI3-K (phosphoinositide 3-kinase) inhibitors, inhibited the MMP-2 production induced by TNF-␣ in deciduous dental pulp fibroblasts. Moreover, in deciduous dental pulp fibroblasts cultured with TNF-␣, AKT (protein kinase B) was phosphorylated in a time-dependent manner with the maximum phosphorylation at 30 min, and LY294002 and Wortmannin abolished this phosphorylation of AKT in TNF-␣-stimulated deciduous dental pulp fibroblasts. These results suggest that TNF-␣ may enhance pulp tissue destruction during pulp inflammation in part by regulating MMP-2, and that the AKT pathway is involved in MMP-2 production in deciduous dental pulp fibroblasts. including lymphocytes and macrophages. Elevated levels of TNF-␣ have been detected in inflammatory lesions, and this cytokine is highly related to the progression of bone destruction 4). In addition, it has been suggested that TNF-␣ may play an important role in extracellular matrix (ECM) degradation during pulp inflammation 5). Like any other inflammation, pulpitis is associated with tissue degradation. The matrix metalloproteinase (MMP)-dependent pathways have been implicated in inflammatory tissue breakdown. MMPs comprise a family of endopeptidases that degrade ECM proteins along with other substrates. Two gelatinases (MMP-2 and MMP-9) are capable of degrading denatured interstitial collagens (gelatins), lamin, elastin, fibronectin and basement membrane zone-associated collagens 6) , and are involved in normal ECM turnover as well as