The selection of scaffold materials and the optimization of scaffold morphological and mechanical properties are critical for successful bone tissue engineering. We fabricated porous scaffolds of nano-sized zirconia using a replication technique. The study aimed to explore the relationship between porosity, pore size, mechanical strength, cell adhesion, and cell proliferation in the zirconia scaffolds. Macro- and micro-structures and compressive strength were comparatively tested. Beagle bone marrow stromal cells were seeded onto the scaffolds to evaluate cell seeding efficiency and cell proliferation profile over 14 d of incubation. The zirconia scaffolds presented a complex porous structure with good interconnectivity of pores. By increasing the sinter cycles, the porosity and pore size of the scaffolds decreased, with mean values ranging from 92.7-68.0% and 830-577 μm, respectively, accompanied by increased compressive strengths of 0.6-4.4 MPa. Cell seeding efficiency and cell proliferation over the first 7 d of incubation increased when the porosity decreased, with cell viability highest in the scaffold with a porosity of 75.2%. After 7 d of incubation, the cell proliferation increased when the porosity increased, highest in the scaffolds with a porosity of 92.7%. These results showed that the zirconia scaffold with a porosity of 75.2% possesses favorable mechanical and biological properties for future applications in bone tissue engineering.
BackgroundNotch-1 promotes invasion and metastasis of cancer cells but its role in salivary adenoid cystic carcinoma (SACC) remains unelucidated. Here, we sought to investigate the effect of Notch-1 knockdown on the invasion and metastasis of SACC cells.MethodsStable ACC-M cells whose Notch-1 was silenced by lentiviral vectors were established. Cellular proliferation was evaluated by the MTT assays and clonogenic assays, apoptosis by flow cytometry and the migration of ACC-M cells by Transwell assays. Metastasis was evaluated by examining the number of lung nodules in Balb⁄c nu⁄nu nude mice bearing subcutaneous SACC xenografts.ResultsOur MTT assay revealed that Notch-1 knockdown significantly suppressed the proliferation of ACC-M cells compared with non-infected or scrambled control cells. Clonogenic assays further showed that Notch-1 knockdown significantly suppressed the clonogenic growth of ACC-M cells (p < 0.01 vs. controls). Our flow cytometry demonstrated that Notch-1 knockdown was associated with a significantly higher proportion of late apoptotic and necrotic cells (p < 0.01 vs. controls). Transwell assays revealed that Notch-1 knockdown markedly reduced the migratory capacity of ACC-M cells (p < 0.01 vs. controls) and xenograft studies showed that the number of metastatic nodules in the lung surface was significantly lower in nude mice bearing xenografts with Notch-1 knockdown compared to those bearing control xenografts (p < 0.01 vs. controls).ConclusionNotch-1 knockdown suppresses the growth and migration of SACC cells in vitro and the metastasis of SACC cells in vivo. Notch-1 may be a new candidate target in SACC.
Objective This study investigated the anti-cariogenic effect of fluoride iontophoresis on sound human enamel under different working conditions. Methods One hundred and five enamel blocks were prepared and randomly assigned to seven different groups: Fluoride iontophoresis under different working conditions, including: different electric current intensities (0.2, 0.4, 0.6 mA) and durations of current application (3, 6, 9 min); No fluoride treatment (negative control); Fluoride immersion without iontophoresis (positive control). After 7 days of pH-cycling, morphology changes on enamel surfaces were examined by scanning electron microscopy (SEM), and Vickers surface microhardness (VH) values of enamel blocks before and after treatments were assessed using a Vickers microhardness tester. KOH-soluble fluoride (KOH-F) uptakes were measured by a fluoride ion-selective electrode. Results Distinctly roughened enamel surfaces were showed in all treatment groups, with the greatest extent damaged surface in negative control group and the least in all the fluoride intophoresis groups. All the fluoride iontophoresis groups (except for the group under 0.2 mA) showed smaller reduction of VH values (p < 0.05) and greater KOH-F (p < 0.05) when compared with the negative and positive control groups. There was an increasing trend in the loss of VH and in fluoride uptakes with an increasing current intensity. Meanwhile, the reduction of VH values and KOH-F in Group I3 ( 0.6 mA) were significantly greater (p < 0.05) than those in Group I1 ( 0.2 mA). No significant differences of reduction of VH and KOH-F presented among the three groups applied with fluoride iontophoresis under different current durations . Conclusions Fluoride iontophoresis resulted in a significantly increased KOH-F and a reduced loss of VH after the 7 days pH-cycling procedure, and its effectiveness was influenced by different electric current intensities but not influenced by different current durations.
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