ABSTRACT
BACKGROUND:Low-temperature rapid prototyping technology is a new kind of rapid prototyping technology, and it is rapidly used in the preparation of bone tissue engineering scaffolds because it can make scaffold forming control able and can keep the biological activity of the materials, also can easily realize the scaffold with porous of three-dimensional structure and other advantages. OBJECTIVE:To investigate the preparation process of polyethylene glycol-modified polylactic acid-glycolic acid/nano-hydroxyapatite (PLGA-PEG/n-HA) using the low-temperature rapid prototyping, and to test its performance. METHODS:PLGA-PEG/n-HA and PLGA/n-HA were prepared by low-temperature rapid prototyping equipment. Under an electron microscopy, we observed ultra-structure of the scaffolds. Immersion (ethanol) method was used to test the porosity, and electronic testing machine was used to determine the material mechanical properties. Then these two kinds of scaffolds with rat osteoblasts were cultured in vitro, the cel adhesion rate was detected by precipitation method after 12 hours, and cel counting kit-8 method was used to determine the cel proliferation at culture days 1, 3, 5, 7, 9, 12. RESULTS AND CONCLUSION:Both of the two scaffolds had ideal aperture range and high porosity. But the aperture range of PLGA-PEG/n-HA scaffolds had large fluctuations, and the average aperture was smal er than that of PLGA/n-HA. Some pores were closed up. The cel adhesion rate and the cel growth curve of PLGA-PEG/n-HA was better than that of PLGA/n-HA (P<0.05), but the mechanical properties were less than PLGA/n-HA (P<0.05). The results showed the PLGA-PEG/n-HA scaffolds had good cel compatibility.
ABSTRACT
BACKGROUND:Human hypoxia-inducible factor-1 alpha can regulate the expression of osteogenic and angiogenic genes, and promote osteogenic activity. OBJECTIVE:To observe the expression of osteogenic genes in rat bone marrow mesenchymal stem cells carrying human hypoxia-inducible factor-1 alpha slow virus infection. METHODS:Hypoxia-inducible factor-1 alpha was obtained from Hela cells using RT-PCR. Lentivirus expression vector plasmid carrying hypoxia-inducible factor-1 alpha (Lenti-HIF-1α-eGFP) was constructed. 293Ta cells with LentiPac HIV mixed packaging plasmid was packaged, and then lentivirus was obtained. Rat bone marrow mesenchymal stem cells were isolated and cultured using direct whole bone marrow adherent method. Bone marrow mesenchymal stem cells were identified using flow cytometry. Bone marrow mesenchymal stem cells were infected with slow virus for 1, 4, 7 and 14 days. Bone morphogenetic protein-2, osteocalcin, osteopontin and alkaline phosphatase expression levels were detected in bone marrow mesenchymal stem cells using real-time fluorescent quantitative PCR. RESULTS AND CONCLUSION:Bone marrow mesenchymal stem cells were effectively infected with Lenti-HIF-1α-eGFP. Real-time fluorescent quantitative PCR results revealed that bone morphogenetic protein-2, osteocalcin, osteopontin and alkaline phosphatase began to obviously overexpress from 4 days after infection with Lenti-HIF-1α-eGFP until 14 days. Results suggested that hypoxia-inducible factor-1 alpha could elevate the osteogenic activity of bone marrow mesenchymal stem cells.