Studies of Changes of Bone Tissue with Aging

以往的研究表明，大鼠骨髓基质细胞在地塞米松（一种人工合成的糖皮质激素）存在下，可以在体外产生类骨矿化组织。为了确定其他类固醇激素是否具有相同的效果，我们做了以下实验。将雄性Wistar大鼠（5周龄）股骨骨髓细胞培养在添加不同浓度类固醇激素的培养基中。泼尼松龙、去炎松、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效应一致，而与盐皮质激素效应无关。氢化可的松在生理浓度（100 nM）下诱导矿化组织。我们的结论是，在糖皮质激素存在下，在这种培养系统中矿化组织的形成是生理性的，这种系统对骨研究是有用的。 ...更多信息 骨组织中骨祖细胞数量的减少是骨老化的背景之一。我们以不同浓度培养不同年龄大鼠的骨髓细胞，然后测量矿化组织。结果表明，随着年龄的增长，骨髓组织中骨祖细胞的数量急剧减少，由于最近的体内研究表明，给予前列腺素E2（PGE 2）增加骨量，我们研究了PGE 2对骨髓细胞培养系统中矿化组织形成的影响。PGE 2对矿化组织形成的影响依赖于浓度和时间。高浓度的PGE_2（1 μ M）完全抑制矿化组织的形成。有趣的是，在细胞生长的第3 - 5天，脉冲加入PGE_2，可以显著增加矿化组织的数量和矿化结节的数量。结果表明，PGE 2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