Mesenchymal stem cells-conditioned medium protects PC12 cells against 2,5-hexanedione-induced apoptosis via inhibiting mitochondria-dependent caspase 3 pathway.

Studies suggested that the conditioned medium of mesenchymal stem cells (MSC-CM) inhibited the increased apoptosis in various cells. However, there are no reports underlying the protection of MSC-CM against 2,5-hexanedione (HD)-induced apoptosis in neural cells. In the present study, the viability was observed in PC12 cells that received HD alone or with MSC-CM by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Apoptosis was estimated by Hoechst 33342 staining and flow cytometry. Mitochondrial transmembrane potential was examined by rhodamine 123. Moreover, we investigated the expression of Bax and Bcl-2, cytochrome c translocation, and caspase 3 activity by real-time polymerase chain reaction, Western blot, and immunochemistry. Nerve growth factor (NGF) was examined in MSCs and MSC-CM. Our results showed that MSC-CM promoted cell survival and reduced apoptosis in HD-exposed PC12 cells. Moreover, MSC-CM significantly reversed disturbance of Bax and Bcl-2, ameliorated disruption of mitochondrial transmembrane potential, and reduced release of cytochrome c and activity of caspase 3 in HD-exposed PC12 cells. In the meantime, NGF was detected in MSCs and MSC-CM. These findings demonstrate that MSC-CM protects against HD-induced apoptosis in PC12 cells via inhibiting mitochondrial pathway. Our results indicate that NGF in MSC-CM may be involved in the protection of MSC-CM against HD-induced apoptosis. Our study clarifies the protection of MSC-CM on HD neurotoxicity and its underlying mechanism.

Effects of fluoride-ion-implanted titanium surface on the cytocompatibility in vitro and osseointegatation in vivo for dental implant applications.

As an attractive technique for the improvement of biomaterials, Plasma immersion ion implantation (PIII) has been applied to modifying the titanium material for dental implant application. The present study investigated the cytocompatibility and early osseointegration of fluoride-ion-implanted titanium (F-Ti) surface and implants, both characterizing in their composition of titanium oxide and titanium fluoride. The cytocompatibility of F-Ti was evaluated in vitro by using scanning electron microscope, Cell Counting Kit-8 assay, alkaline phosphatase activity assay, and quantitative real-time polymerase chain reaction. The results showed that the F-Ti weakened the effects that Porphyromonas gingivalis exerted on the MG-63 cells in terms of morphology, proliferation, differentiation, and genetic expression when MG-63 cells and Porphyromonas gingivalis were co-cultured on the surface of F-Ti. Meanwhile, the osteogenic activity of F-Ti implants was assessed in vivo via evaluating the histological morphology and estimating histomorphometric parameters. The analysis of toluidine blue staining indicated that the new bone was more mature in subjects with F-Ti group, which exhibited the Haversian system, and the mean bone-implant contact value of F-Ti group was slightly higher than that of cp-Ti group (p>0.05). Fluorescence bands were wider and brighter in the F-Ti group, and the intensity of fluorochromes deposited at the sites of mineralized bone formation was significantly higher for F-Ti surfaces than for cp-Ti surfaces, within the 2nd, 3rd and 4th weeks (p<0.05). An indication is that the fluoride modified titanium can promote cytocompatibility and early osseointegration, thus providing a promising alternative for clinical use.

[Resistance to cyclic fatigue of pulpless teeth with flared root canals restored with different post-and-core materials].

OBJECTIVE: To investigate the resistance to cyclic fatigue of maxillary incisors with flared canals restored with different post-and-core materials. METHODS: Thirty human maxillary central incisors were assigned randomly to two main groups (non-ferrule and 1-mm ferrule) of 15. Each main group was then divided into 3 groups of 5 specimens and restored with custom cast post-and-core (MPC), resin composite post-and-core (RCP), and resin composite core combined with prefabricated carbon fiber post (FRC), respectively. Every group was subjected to a cyclic fatigue test, and recorded the numbers of load cycles that occurred tooth fracture. All data were analyzed with two-way ANOVA and the Tukey HSD test at alpha = 0.05. RESULTS: FRC revealed significantly higher fatigue strength than the other groups (P < 0.05). Preparing a dentin ferrule increased significantly fatigue resistance (P < 0.05). The favorable (retrieval) fracture pattern of the tested specimens was discovered only in RCP. CONCLUSIONS: Using FRC may get a long fatigue life in restoring pulpless teeth with flared canals. Dentin ferrule preparation is necessary to enhance resistance of the restorations to cyclic fatigue.