Hypoxic preconditioning effects on the ability of bone marrow mesenchymal stem cells tolerant to ischemia and hypoxia / 中国组织工程研究

BACKGROUND:According to the previous studies, it is known that bone marrow mesenchymal stem cells live in the physiological environment of lower oxygen concentration compared with the common culture concentration (20%-21%). Hypoxia can promote bone marrow mesenchymal stem cells proliferation and maintain the characteristics of differentiation potential. OBJECTIVE:To understand the biological characteristics of bone marrow mesenchymal stem cells after hypoxic preconditioning, and search for in vitro basis for bone marrow mesenchymal stem cells therapy in vivo with hypoxic preconditioning strategy. METHODS:After passage and inoculation, bone marrow mesenchymal stem cells were cultured in the hypoxic incubator (1%O2, 5%CO2). Bone marrow mesenchymal stem cells cultured in the normoxic incubator (20%O2, 5%CO2) served as controls. RESULTS AND CONCLUSION:Compared with bone marrow mesenchymal stem cells cultured under normoxia (20%O2), bone marrow mesenchymal stem cells cultured under hypoxia (1%O2) began to display exponential growth phase after a longer incubation period. Hypoxia (1%O2) was not the lethal condition for bone marrow mesenchymal stem cells. cellsurvival rates of both groups reduced over time, while those of bone marrow mesenchymal stem cells cultured under normoxia reduced faster (P<0.05). Surface markers expression of bone marrow mesenchymal stem cells, including CD29(+), CD90(+), CD31(-), CD45(-), after hypoxic preconditioning did not change greatly when compared with the results before hypoxic preconditioning. The hypoxia preconditioned bone marrow mesenchymal stem cells did not differentiate into vascular endothelial cells. Hypoxia-inducible factor-1αprotein expression was promoted after 24 hours to 48 hours hypoxic preconditioning, and there was significant difference between the two time points (P<0.05). Vascular endothelial growth factor expression increased at both transcriptional and protein levels after 48 hours hypoxic preconditioning (P<0.05). Culture under hypoxia (1%O2) does not produce a lethal effect on bone marrow mesenchymal stem cells and can be used for hypoxic preconditioning. Surface markers of bone marrow mesenchymal stem cells after 48 hours hypoxic preconditioning exhibit no great changes and the hypoxia preconditioned bone marrow mesenchymal stem cells maintain the characteristics of stemness. Hypoxic preconditioning can promote the ability of bone marrow mesenchymal stem cells to survive under hypoxia/ischemic condition. The activation of the hypoxic response signal transduction pathway through hypoxia-inducible factor-1αmay explain this.

The Measurement of Mandibular Thickness and Its Clinical Significance Relative to the Mandibular Plasty by Three-dimensional CT / 实用放射学杂志

Objective To measure the mandibular thickness relative to the osteotomy line of mandibular angle plasty so that to provide the anatomical basis for operation.Methods 37 youth women patients mandible were scanned by spiral CT,then the three-dimensional reconstruction was done,the thickness of the mandible around osteotomy line were measured on the planes corresponding to the posterior margin of mandibukar ramus,the middle part of the mandibular ramus,the posterior line of the third molar,the line between the second and third molar,the line between the second and first molar and the line between the first molar and the second premolar.The data were analyzed by Spss 11.5.Results The thichest bone around the osteotomy line was under the second and third molar,then the bone thickness became thinner forward and backward.The thinnest bony was on the middle part of the mandibular ramus.Conclusion The result of this study is of significant for guiding operation and reducing the complications.