[Effects of electrospun collagen nanofibrous matrix on the biological behavior of human dental pulp cells].

OBJECTIVE: To compare cell adhesion, proliferation and odontoblastic differentiation of human dental pulp cells (hDPCs) on electrospun collagen nanofibrous matrix (Col_NFM) with that on collagen flat film (Col-FF), to investigate the biological effect of collagen nanofibrous matrix on hDPCs. METHODS: The surface morphology of the two different collagen scaffold was analyzed by scanning electron microscopy (SEM), and the contact angle and the swelling ratio were also measured. Then hDPCs were implanted on the two different collagen scaffolds, the cell morphology was observed using SEM and laser scanning microscope (LSM), and cell proliferation was evaluated by the CCK-8 assay. After hDPCs cultured on the two different collagen scaffold with odontoblastic medium for 14 days, the expression of odontoblastic differentiation related genes was detected by real-time PCR, and alizarin red staining was used to test the formation of mineralized nodules. RESULTS: From the SEM figures, the fibers' diameter of Col_NFM was (884±159) nm, and there were abundant three dimensional connected pore structures between the fibers of Col_NFM, while the surface of Col_FF was completely flat without pore structure. The contact angle at 0 s of Col_NFM was 85.03°±4.45°, and that of Col_FF was 98.98°±5.81°. The swelling ratio of Col_NFM was approximately 3 folds compared with dry weight sample, while that of Col_FF was just 1 fold. Thus Col_NFM indicated better hydrophilicity and swelling property. SEM and LSM showed that hDPCs on Col_NFM presented an irregular and highly branched phenotype, and could penetrate into the nanofibrous scaffold. In contrast, the cells were spread only on the surface of Col_FF with a spindle-shaped morphology. CCK-8 assays showed that hDPCs on Col_NFM showed higher proliferation rate than on Col_FF. After hDPCs were cultured on the two different collagen scaffolds with odontoblastic medium for 14 days, more expressions of odontoblastic differentiation related genes, such as dentin sialophosphoprotein (DSPP) and dentin matrix proten-1 (DMP1) were determined in Col_NFM group (P<0.05), and more mineralization depositions were also observed in Col_NFM group according to the results of alizarin red staining. CONCLUSION: Col_NFM with nanoscale microstructure achieves better hydrophilic and swelling properties than Col_FF, and hDPCs cultured with Col_NFM present higher activity on cell adhesion, proliferation and odontoblastic differentiation.

Indicator microorganisms and pathogens removal function performed by copepods in constructed wetlands.

Removal efficiency of indicator and pathogenic microorganisms in constructed wetlands were analyzed, and microorganisms removal function performed by copepods was determined. The results showed that the constructed wetlands effectively reduced Escherichia coli, fecal streptococci, total coliforms, and fecal coliforms, the Salmonella spp. removal efficiency was relatively low and the Clostridium perfringens removal was the least. At copepods concentrations of 3.0 x 10(2)/L, and 6.0 x 10(2)/L, high die-off rates were observed for indicator and pathogenic microorganisms compared to the control group, and indicator and pathogenic microorganisms in samples with higher concentration of copepods decreased much more rapidly than those in samples with lower concentration. These results suggest that predation by copepods is an important mechanism for the removal of bacteria in constructed wetlands.