[Effects of OGP(10-14) and its derivative G38I on proliferation and differentiation of rat osteoblasts in vitro].
OBJECTIVE
To investigate the effects of the carboxyl end of osteogenic growth peptide (OGP)-OGP((10-14)) and its derivative G38I on the proliferation and differentiation of osteoblasts (OBs).


METHODS
Osteoblasts were isolated from the calvariae of newborn SD rats and cultured to G3. OGP((10-14)) or G38I of the concentrations of 10(-15) to 10(-7) mol/L were added to culture medium for 48 hours respectively. The number of cells was counted and MTT analysis was used to examine the proliferation of the cells. The ultrastructure of cells was investigated by electron microscopy. The osteoblasts of G3 were divided into experimental groups, treated with OGP((10-14)) or G38I of the concentration of 10(-11) mol/L for 48 hours, and control group. The alkaline phosphatase activity in the culture medium was measured. The protein expression level of type-I collagen was evaluated by immunohistochemistry. The core binding factor 1 (Cbfa1) and type-I collagen mRNA level of osteoblasts were determined by RT-PCR.


RESULTS
With a biphasic effect on, OGP((10-14)) and G38I stimulated the number enhancement of OBs dose-dependently at low concentration and inhibited it at high concentration. The numbers of OB were the highest (37 x 10(4)/ml +/- 7 x 10(4)/ml and 30 x 10(4)/ml +/- 5 x 10(4)/ml respectively) when treated by OGP((10-14)) or G38I of the concentration of 10(-11)mol/L. The rough endoplasm net was flourishing and the secreting vesicle was abounding in the experimental cells. There was calcium crystal in the control cells. The activity of alkaline phosphatase in the culture medium of the OGP (10(-14)) and G38I groups were higher than that in the control group (4.47 U/g and 3.82 U/g vs 2.21 U/g). The protein expression level of type-I collagen was higher and the mRNA levels of Cbfa1 and type-I collagen were higher in the OGP((10-14)) and G38I groups were increased in the experimental groups in comparison with the control group (P < 0.05, P < 0.01, and P < 0.05).


CONCLUSIONS
They stimulated cell number enhancement dose dependently at low concentration and followed by inhibition at high concentration. Just as the native OGP, OGP((10-14)) and its derivative G38I stimulate the proliferation of osteoblasts, and improve their activity, up-regulate the Cbfa1 and type-I collagen mRNA expression levels and increase the collagen synthesis, thus promoting the differentiation and osteogenic effect of osteoblasts.
Liu
Hong-li
HL
Department of Endocrine, General Hospital of Tianjin Medical University, Tianjin 300052, China.
Ding
Xiao-ying
XY
Qiu
Ming-cai
MC
Tian
Gui-jie
GJ
Wang
De-xin
DX
D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D002245:Carbon Dioxide / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects*; D049109:Cell Proliferation / Q000187:drug effects*; D002478:Cells, Cultured; D024042:Collagen Type I / Q000096:biosynthesis / Q000235:genetics; D050657:Core Binding Factor alpha Subunits / Q000096:biosynthesis / Q000235:genetics; D006657:Histones / Q000494:pharmacology*; D036341:Intercellular Signaling Peptides and Proteins / Q000494:pharmacology*; D010006:Osteoblasts / Q000166:cytology*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley
D024042:Collagen Type I; D050657:Core Binding Factor alpha Subunits; D006657:Histones; D036341:Intercellular Signaling Peptides and Proteins; D012333:RNA, Messenger; C074533:osteogenic growth peptide; D002245:Carbon Dioxide; C041069:carboxyl radical; D000469:Alkaline Phosphatase