[Effect of sustained increasing fibroblast growth factor signal on development of epiphyseal plate cultured in vitro].
OBJECTIVE
The biological effects of fibroblast growth factor (FGF) may be different under different intensities and durations. To investigate the impact of sustained increasing FGF signal upon the development of epiphyseal plate.


METHODS
Epiphyseal plates cultured in vitro were obtained from embryonic C57BL/6J mice, and were divided into control group (0.1% DMSO), basic FGF (bFGF) group (100 microg/L bFGF and 0.1% DMSO), and PD98059 group (100 microg/L bFGF and 50 micromol/L PD98059 with 0.1% DMSO). The total length (TL) and ossified tissue length (OSL) of the cultured bones were measured with Calcein staining 6 days after culture. The expressions of Indian hedgehog (Ihh), collagen type II (Col II), and Col X genes were detected by real-time fluorescent quantitative PCR 7 days after culture.


RESULTS
The embryonic bones cultured in vitro continued growth. At 6 days after culture, there was no significant difference in increased percentage of TL between bFGF group and control group (P > 0.05), the increased percentage of OSL in bFGF group was significantly less than that in control group (P < 0.05). There was no significant difference in the increased percentage of TL and OSL between PD98059 group and control group (P > 0.05), but they were significantly higher than those of bFGF group (P < 0.05). At 7 days after culture, the gene expressions of Ihh, Col II, and Col X in bFGF group significantly decreased when compared with those in control group (P < 0.05). There was no significant difference in the gene expressions of Col II and Col X between PD98059 group and control group (P > 0.05), but the gene expressions were significantly higher than those of bFGF group (P < 0.05); the expression of Ihh in PD98059 group was significantly higher than that in control group and bFGF group (P < 0.05).


CONCLUSIONS
Sustained increasing FGF signal may affect the Col II and Col X expressions by down-regulating Ihh, which may lead to the development retardation of epiphyseal plate cultured in vitro. The external signal regulated kinase pathway may play an important role in the process.
Yin
Liangjun
L
Department of Orthopaedics, Second Affiliated Hospital, Chongqing Medical University, Chongqing 400010, PR China. Albertyin.21@163.com
Shen
Yue
Y
Deng
Zhongliang
Z
Lu
Xianhong
X
Yan
Zhengjian
Z
Nie
Mao
M
Chen
Lin
L
D000818:Animals; D004838:Epiphyses / Q000254:growth & development*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D016222:Fibroblast Growth Factor 2 / Q000378:metabolism*; D006132:Growth Plate / Q000378:metabolism*; D050279:Metacarpal Bones / Q000196:embryology; D051379:Mice; D008810:Mice, Inbred C57BL; D009924:Organ Culture Techniques; D015398:Signal Transduction
D016222:Fibroblast Growth Factor 2; D048049:Extracellular Signal-Regulated MAP Kinases