RESUMO
Objective The nano-zirconia scaffolds we previously prepared had a good 3-dimensional ( 3D ) connectivity but did not achieve the ideal sintering rate and compressive strength .The objective of this study was to explore the enhancing effect of polyvinyl butyral ( PVB) as a dispersant on the compressive strength of 3D nano-zirconia porous scaffolds for bone tissue engineering . Methods We prepared the slurry containing different concentrations of PVB and ana-lyzed the improving effect of PVB on the mechanical properties of the scaffolds by sediment experiment , compressive strength test and scan-ning electron microscopy . Results The sediment experiment showed no significant stratification in the slurry with 0.2wt%PVB, white suspension in the upper layer and white precipitate in the lower layer , with a significantly higher compressive strength of the scaffold ([0.324 ±0.030] MPa) than that of the scaffold prepared by adding other concentrations of PVB to the slurry (P <0.01).And the compressive strength of the scaffold constructed by adding no dispersant ([0.109 ±0.021] MPa) was remarkably lower than that of the scaffold constructed by adding PVB to the slurry (P<0.05).Scanning electron microscopy demonstrated that the scaffold prepared by adding 0.2wt%PVB to the slurry had a complete porous structure with the fewest and most sparsely distributed surface cracks as compared with other PVB concentration groups . Conclusion PVB can signifi-cantly improve the stability of zirconia slurry , enhance the compressive strength of the nano-zirconia porous scaffold , and make the scaf-fold more applicable to bone tissue engineering .
RESUMO
Objective:To examine the expression of odontoblast related proteins in dental pulp stem cells(DPSCs)induced by BMP-7.Methods:DPSCs were cultured in the common culture medium or medium supplemented with 1 00 ng/ml BMP-7.Electron microscope,CCK8 and immunohistochemical staining were carried out to estimate the cell morphology and differentiation.Results:In-duced by BMP-7,the morphology of DPSCs was not changed,the proliferation of DPSCs was slower than that of the cells without BMP-7 treatment.DPSCs were negative for the expression of DSPP,DMP-7 and ALP.However,DPSCs were found strongly positive for DSPP,DMP-7 and ALP after the induction of BMP-7.Conclusion:BMP-7 induction may promote the differentiation of DPSCs.
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Objective Nowadays, in the field of bone tissue engineering , searching for a kind of scaffold , which is both strong enough and biocompatible , is still a hot topic .Objective of this study is to evaluate the three-dimensional nano-zirconia porous scaffold′s effect on bone marrow stromal cells early attachment and proliferation . Methods Preparing nano-zirconia porous scaffold and testing its porosity and its mechanical strength .Hemolysis experiment was taken to evaluate its biosafety .Canine bone marrow stromal cells ( BM-SCs) were extracted from an adult beagle and cultured in vitro.The third generation cells were seeded onto the scaffold and induced to os-teoblasts under condition medium .Cells early attachment on scaffold was observed by SEM .MTT and ALP tests were taken to evaluate cells proliferation and osteogenesis within two weeks . Results Nano-zirconia porous scaffold in our study presented a porous structure with a well connected inner .Its porosity and compressive strength were (92.667 ±0.324)%and 4.38 MPa, respectively.Hemolysis rate was 2.19%, which was demonstrated to be safe to human body .Canine BMSCs could colonize the surface of the materials , bridge macro-poros-ity and proliferate on the scaffold .A values taken by the method of MTT showed that cells could proliferate quickly on the scaffold after 3, 6, 9, 12 d (A values were 0.604 ±0.059, 1.215 ±0.019, 1.385 ± 0.254, and 1.506 ±0.050), comparing with that on the first day (A value was 0.261 ±0.034).Statistical difference was found (P <0.01) .The ALP level raised up significantly on day 7 and 14 ( A val-ues were 0.032 ±0.002 and 0.062 ±0.007), comparing with that on the first day (A value was 0.016 ±0.003).Statistical difference was found (P<0.01). Conclusion The three-dimensional nano-ZrO2 porous scaffold in our study presented satisfactory biocompati-bility.It could offer a microenvironment for osteoblasts growth and secreted osteogenesis marker in vitro .