SummaryOxidative stress regulates cellular functions in multiple pathological conditions, including bone formation by osteoblastic cells. However, little is known about the cellular mechanisms responsible for the effects of oxidative stress on osteoblast functions in senescence. To clarify the inhibitory effects of oxidative stress on osteoblastic mineralization, we examined the relationship between the antioxidant system and bone formation in MC3T3-E1 cells. After a single exposure to H 2 O 2 within range of a non-toxic concentration for cells, the mineralization level was diminished half. Under the same conditions, gene expression of the transcription factor Nrf2, which regulates antioxidant enzymes, was upregulated. In addition, gene expression for the osteogenic markers Runx2, ALP, and BSP was lower than that in non-treated cells, whereas expression of the osteocalcin gene was up-regulated following H 2 O 2 exposure. These results suggest that reduced mineralization by MC3T3-E1 cells after H 2 O 2 exposure is the result of an up-regulated antioxidant system and altered osteogenic gene expression.
Fibronectin (FN) can be immobilized directly on titanium surfaces using tresyl chloride activation technique. The key advantage of tresyl chloride activation technique lies in its simplicity. In this study, we examined the cell attachment and gene expression of MC3T3-E1 cells on FN-immobilized titanium using GeneChip. Cells attached on FN-immobilized titanium at a higher rate than untreated titanium. FN altered the gene expression profile, whereby 62 genes were found to be up-regulated, while 56 genes were found to down-regulate to over twice the level on day 14. FN not only enhanced the expression levels of IBSP and OMD, but also decreased SULF1 mRNA level. Taken together, the immobilization of FN on tresylated titanium promoted early matrix mineralization and bone formation.
Enhanced adhesion and migration of osteoblastic cells on titanium (Ti) surface is believed to increase the success rate of implant therapy. A GRGDSP peptide derived from fibronectin was coated on Ti surfaces using a tresyl chloride activation technique, and then MC3T3-E1 osteoblastic cells were cultured on the Ti surfaces. After 15 days, total RNA was isolated from the cells and gene expression level were analyzed by Affymetrix GeneChip system. The expression levels of many genes in MC3T3-E1 cells cultured on GRGDSP-coated Ti surface were altered when compared to uncoated Ti. In particular, the elevated mRNA levels of bone sialoprotein (BSP) and osteocalcin (OC) were successfully confirmed by reverse transcription-polymerase chain reaction (RT-PCR) and real-time PCR. In light of the results obtained, GRGDSP-coated Ti presented the potential of evolving into a useful biomaterial for successful implant therapy.
Our data demonstrate that P. gingivalis LPS-induced macrophages increased NO secretion. The activated macrophage CM inhibited HN4 cell proliferation and promoted invasion of all HNSCC cell lines.
Background/purpose
Various chemical titanium (Ti) surface modifications have been reported for enhancing cellular activities that promote early osseointegration. The purpose of this study was to determine if sandblasted Ti coated with or without fibronectin (FN) or FN-derived peptides stimulated osteoblast-like cell adhesion, spreading, proliferation, and differentiation.
Materials and methods
Osteoblast-like cells (MC3T3-E1) were cultured on sandblasted Ti disks immobilized with FN or FN-derived peptides [GRGDSP (Gly-Arg-Gly-Asp-Ser), PHSRN (Pro-His-Ser-Arg-Asn), or GRGDSP/PHSRN]. Surface topography, cell morphology, cell adhesion, cell proliferation, analysis of osteogenesis-related genes and protein expression, alkaline phosphatase, and alizarin red staining of mineralization were evaluated.
Results
The sandblasted Ti coated with FN or FN-derived peptides enhanced cell adhesion and cell proliferation. However, the Ti coated with FN or FN-derived peptides groups were similar in cell spreading. Osteogenic differentiation was observed in the peptide-modified Ti surface groups, compared with that of the noncoated Ti group. FN and GRGDSP/PHSRN coating enhanced the gene and protein expression of Runx2, osteocalcin, and bone sialoprotein. Alkaline phosphatase activity and matrix mineralization were also markedly enhanced in the Ti coated groups.
Conclusion
The sandblasted Ti coated with FN or FN-derived peptides (GRGDSP/PHSRN) markedly enhance adhesion, proliferation, and differentiation of osteoblast-like cells compared with uncoated sandblasted Ti.
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