Development of a new culture model for the screening of a agent to increase the bone formation

生长因子对老年大鼠成骨细胞骨结节形成的影响：1.碱性成纤维细胞生长因子（bFGF）在成骨细胞生长期的短时间内对骨结节形成有促进作用; 2.在5 ng/ml时，对骨结节形成的促进作用最大。3.在体外培养条件下，加入aFGF、FGF、IGF-I、IGF-II、PDGF、TGF-β等生长因子后，bFGF、aFGF、IGF-I、IGF-II、PDGF、TGF-β均能促进成骨细胞的分裂，但只有bFGF、PDGF能促进成骨细胞的骨结节形成。地塞米松对老年大鼠成骨细胞骨结节形成的影响经过对其他生长因子和激素的广泛筛选，我们发现地塞米松显著地恢复了来自老年大鼠的成骨细胞中的骨结节形成活性，当地塞米松和bFGF同时加入时，在骨结节形成过程中碱性磷酸酶活性也增加。另一方面，当地塞米松与bFGF同时加入时，仅略微增加FOB中的骨结节形成和碱性磷酸酶，这是因为bFGF本身具有增加FOB中的骨结节形成的强烈作用。在成骨样细胞系的情况下，如ROS 17/2.8、MC 3 T3-E1和UMR 106，没有观察到地塞米松和bFGF增加碱性磷酸酶活性的协同作用。从上述结果，我们认为，在AOB中存在一种独特的能对bFGF和地塞米松产生反应的成骨细胞。该模型的建立将有助于研究老年动物骨形成的机制。

Effects of Growth factors on the bone nodule formation in osteoblasts from aged rats.1.We found that the basic fibroblast growth factor (bFGF) is potent to increase the bone nodule formation, when added to the culture medium, in the short period of the growth phase of osteoblasts.2.The Fffect to increase the bone nodule formation is maximal at 5ng/ml. This effect is more remarkable in osteoblasts from fetal rats (FOB) than those of aged rats (AOB).3.When other growth factors, such as aFGF,FGF,IGF-I,IGF-II,PDGF,TGF-beta, was added to the culture medium, bFGF,aFGF,IGF-I,IGF-II,PDGF,and TGF-beta increased the cell division, but only BFGF and PDGF enhances the bone nodule formation in FOB.In the case of AOB,the effect on the cell division was similar to the results of FOB,but only bFGF enhanced the bone nodule formation.Effects of Dexamethasone on the bone nodule formation in osteoblasts from aged rats.After the extensive screening of the other growth factors and hormones, we found that dexamethasone remarkably recovered the bone nodule formation activity in the osteoblasts from aged rats, when added simultaneously with bFGF.Dexamethasone and bFGF also increased the alkaline phosphatase activity in the course of bone nodule formation. In other hand, dexamethasone only slightly increased the bone nodule formation and alkaline phosphatase in FOB,when added simultaneously with bFGF.This was because of the results that bFGF itself has strong effects to increase the bone nodule formation in FOB.In the case of osteoblast-like cell line, such as ROS 17/2.8, MC3T3-E1 and UMR106, synergistic effect of dexamethasone and bFGF to increase the alkaline phosphatase activity was not observed.From the result described above, we suggests that there is a distinct species of osteoblast which is able to respond to bFGF and dexamethasone in AOB.This in vitro culture experimental model will be useful to investigate the mechanism of the bone formation in aged animals.