Studies of Changes of Bone Tissue with Aging

先前的研究表明，大鼠骨髓基质细胞在合成糖皮质激素之一地塞米松存在的情况下，可以在体外产生骨样矿化组织。为了确定其他类固醇激素是否有同样的效果，我们做了以下实验。5周龄雄性Wistar大鼠股骨骨髓细胞在添加不同浓度类固醇激素的培养基中培养。强的松龙、曲安奈德、氢化可的松和醛固酮也能诱导矿化组织，这些激素的诱导能力与糖皮质激素作用相对应，而与矿皮质激素作用不一致。氢化可的松以生理浓度（100nM）诱导矿化组织。我们得出结论，在糖皮质激素存在的情况下，矿化组织在培养系统中形成是生理的，该系统对骨研究是有用的。骨组织随着年龄的增长发生了各种变化，我们的工作假设是骨组织中骨祖细胞数量的增加是骨老化的背景之一。以不同浓度培养不同年龄大鼠骨髓细胞，测定矿化组织。结果表明，随着年龄的增长，骨髓组织中成骨细胞的数量明显减少。由于最近的体内研究表明前列腺素E2 （PGE2）可以增加骨量，我们研究了PGE2对骨髓细胞培养系统中矿化组织形成的影响。在该培养体系中，PGE2对矿化组织形成的影响取决于浓度和时间。高浓度的PGE2 （1muM）完全抑制矿化组织的形成。而100-10nM的PGE2对其有刺激作用。有趣的是，脉冲添加PGE2，在该培养体系的细胞生长阶段3 - 5天，大大增加了矿化组织的数量和矿化结节的数量。结果表明，PGE2在骨组织中的合成代谢作用部分是由于骨祖细胞的增加。少

Previous studies have shown that stromal cells of rat bone marrow can produce bonelike mineralized tissue in vitro in the presence of dexamethasone, one of the synthetic glucocorticoids. To determine whether other steroid hormones have the same effect, we did the following experiment. Bone marrow cells of femora from male Wistar rats (5 weeks old) were cultured in the medium supplemented with various concentrations of the steroid hormones. Predonisolone, triamcinolone, hydrocortisone and aldosterone also induced mineralized tissue and the induction ability of these hormones corresponds with glucocorticoid effect, not mineralocorticoid effect. Hydrocortisone induces mineralized tissue at a physiological concentration (100nM). We conclude that mineralized tissue formation in this culture system in the presence of a glucocorticoid is physiological and this system is useful for bone research.Various changes in bone tissue with aging have been reported and our working hypothesis is that dec … More rease of the number of osteoprogenitors in bone tissue is one of the backgrounds of bone aging. We cultured bone marrow cells from rats of different ages at different cell concentration and then measured mineralized tissue. The results indicates the dramatic decrease of the number of osteoprogenitors in bone marrow tissue with aging.Since recent in vivo studies have shown that administration of prostaglandin E2 (PGE2) increases bone mass, we investigated the effects of PGE2 on mineralized tissue formation in bone marrow cell culture system. Effects of PGE2 on mineralized tissue formation in this culture system depend on concentration and time. High concentration of PGE2 (1muM) completely inhibited the mineralized tissue formation. However, 100-10nM of PGE2 stimulated it. Interestingly, pulse addition of PGE2, from 3 to 5 days, cell growth stage in this culture system, greatly increased the amount of mineralized tissue and the number of mineralized nodules. The results indicates that anabolic effect of PGE2 in bone tissue is partly due to the increase of osteoprogenitors. Less