Dexamethasone induces osteoblast conversion of bone morphogenic protein-2 modified bone marrow mesenchymal stem cells in rabbits
- VernacularTitle:地塞米松诱导联合骨形成蛋白2基因修饰兔骨髓间质干细胞的成骨转化
- Author:
Yan LI
;
Lu YAN
;
Min SHEN
- Publication Type:Journal Article
- From:
Chinese Journal of Tissue Engineering Research
2008;12(2):377-380
- CountryChina
- Language:Chinese
-
Abstract:
BACKGROUND: Mesenchymal stem cells (MSCs) can differentiate into osteoblasts in the action of dexamethasone; Meanwhile, bone morphogenetic protein-2 (BMP-2) can promote the cell proliferation and differentiation, and matrix secretion in the process of bone repair. BMP-2 plays an important role in treating fracture and bone defects by inducing bone formation both in vivo and in vitro.OBJECTIVE: To analyze whether dexamethasone induction in vitro could enhance the ability of BMP-2 modified MSCs in osteogenic conversion.DESIGN: A randomized paired design.SETTING: Xijing Hospital of the Fourth Military Medical University of Chinese PLA.MATERIALS: The experiments were carried out in the Orthopaedic Oncology Institute of Chinese PLA, the Fourth Military Medical University of Chinese PLA from February to August in 2004. Twenty 20-month-old New Zealand rabbits were provided by the experimental animal center of the Fourth Military Medical University of Chinese PLA [Certificate number: 2005C00117]. The rabbits were raised normally at room temperature with normal humidity. The samples were collected bilaterally, the cells from the left limb were taken as the dexamethasone-induced group, and those from the right limb as the control group.METHODS: MSCs treated and untreated with dexamethasone were transfected with BMP-2 gene, then the BMP-2 expression was determined by reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemical staining. The growths of the MSCs were observed, and the activity of alkaline phosphatase (ALP) and osteocalcin of MSCs were determined with ALP kit and osteocalcin radioimmunoassay kit after Ad-BMP-2 transfection.MAIN OUTCOME MEASURES: ① BMP-2 expression in MSCs; ② Morphological changes of the MSCs; ③ ALP activity and osteocalcin content in the MSCs. RESULTS: ① Expressions of BMP-2 gene could be observed in MSCs both treated and untreated with dexamethasone after transfection. ② The forms were irregular in most of the MSCs treated with dexamethasone, appeared as triangular or polygonal changes.They grew more slowly than those cultured with basic medium. There were no obvious changes of cellular forms after gene transfection. ③ Five days after transgene, the ALP activity in the MSCs supernatant in the dexamethasone-induced group was higher than that in the control group [(134.36±8.84), (104.02±7.83) nkat/L, t =3.350 6, P ＜ 0.01, n =20]. The amount of osteocalcin secretion in MSCs in the dexamethasone-induced group was higher than that in the control group [(14.68±0.73), (6.52±1.21) μg/L, t =3.568 2, P ＜ 0.01, n =20].CONCLUSION: Dexamethasone induction before transgene can promote the proliferation of BMP-2 modified MSCs and the conversion into osteoblasts.
