A Study On Preparation Of3-D Porous Carbon Scaffold And The Effects Of The Scaffold On Osteogenic Genes Of Human Osteoblast-like MG63Cells

Bone defects reparation and replacement are regarded as a big challenge ofclinical orthopedics. In order to overcome intrinsic disadvantages of current bonesubstitute materials, including autologous and allogenous grafts, a novel way, tissueengineered approach, has been established to produce the ideal bone substitutematerials. In vitro construction of tissue engineered bones requires numerous cellswith high viabilities. Since only a limited amount of cells could be collected frompatients, it is crucial to enhance the proliferation of those cells and maintain theirdifferentiation state by proper cell culture methods in vitro.3-D cell culture plays akey role in tissue engineering, which demands various3D scaffolds with porousnetwork. In this study, an optimized method of preparing porous carbon scaffolds hasbeen reported. Our data demonstrate that those porous carbon scaffolds promote theproliferation of human osteoblast-like MG-63cells, indicating that it is suitable for3D cell culture. Furthermore, to understand the molecular mechanism of increasedcell growth induced by the porous carbon scaffolds, the mRNA level of severalcellular proliferation and differentiation related genes were determined by RT-PCRassay.In the first part of this study, our aim is to find the optimal method of porouscarbon scaffolds preparation. To acquire interconnected porous structure,polyurethane foams were used as templates, whilst phenolic resin as precursors wasbuilt the main body of porous carbon scaffolds. After phenolic resin was added topolyurethane foams by drops, samples were treated by a120oC curing and a subquent900oC carbonization process to obtain porous carbon scaffolds. My results show thatporous carbon scaffolds prepared by this method possess a high apparent porosity andpoor mechanical performance. A series of experiments were carried out to find theoptimal process conditions, including polyurethane foam pre-treated methods,thickness of solid phenolic resin and the carbonization temperature effects apparentporosity and mechanical properties of porous carbon scaffolds. The optimal process isdescribed as follows; polyurethane foams were treated by99%ethanol for30minutes;after phenolic resin was suspended on polyurethane foams, it was cured by microwave;this above process was repeated for4-5times; samples were carbonized at900oC.Porous carbon scaffolds with both ideal machinery properties and apparent porositywere obtained by using this method. In the second part, the biocompatibility of porous carbon scaffolds was detected.After osteoblast-like MG-63cells were cultured on the porous carbon scaffolds, cellmorphology and cellular proliferation were tested by ESEM. The figures display thatMG-63cells grow well and occupy the full surface of scaffolds after6days culture,implying that porous carbon scaffolds possess good biocompatibility. Compared withcell culture plates, porous carbon scaffolds significantly promote the proliferation ofMG-63cells, illustrating that those scaffolds could be applied for3D cell culture. Thetranscription of cellular proliferation or differentiation related genes (including ColI,BGN, ON, etc) alters during the whole culture period. However, compared with cellculture plates, porous carbon scaffolds influence transcriptional alteration of thosegenes in a different pattern.