Estrogen enhances progesterone-induced stimulation of proliferation and differentiation of osteoprogenitors in cell populations derived from adult human bone

以往的实验证明，成年雌性大鼠腰椎外植体来源的骨细胞群含有骨祖细胞，需要地塞米松(Dex)或孕酮(Prog)才能增殖和分化为完全分化的成骨细胞。这项研究是为了确定在老鼠身上发现的这些发现是否也在使用人类细胞的人身上观察到。首先，本研究旨在确定细胞群体中Dex和Prog反应性骨祖细胞的频率和/或数量。通过连续继代培养、有限稀释度分析和菌落分析，确定了最多六种继代培养的祖细胞类型的频率和数量。在含地塞米松的培养液中，继代培养的第二代细胞中对地塞米松敏感的成骨细胞总数比第一代细胞增加10%。从第三代传代开始，骨祖细胞的频率呈线性…下降。经过5次继代培养后，观察到更多的ER和没有观察到的Er。在含有Prog的介质中也得到了类似的结果。在地塞米松存在下的极限稀释分析表明，在第一代传代细胞中，1.81%的细胞代表集落形成单位-成纤维细胞，0.25%的细胞代表成骨细胞。在Prog存在下，第一代传代细胞中有1.75%的细胞代表集落形成单位成纤维细胞，0.09%的细胞代表成骨细胞。其次，我们发现，在性成熟后的女性骨骼中可以检测到Prog依赖的群体，并可以通过在含有17β-雌二醇(10-9-10-8M)的培养液中培养骨祖细胞来诱导。这表明依赖Prog的成骨细胞的存活和/或其增殖能力依赖于雌激素的存在。在女性骨骼中，维持骨量的机制之一与雌激素和Prog对一类骨祖细胞对Prog反应的影响有关。这些发现可能为人类骨骼中一类特定的Prog依赖的骨祖细胞的意义以及雌激素对它们的调控提供新的见解。较少

Previous experiments have demonstrated that bone cell populations derived from explants of lumbar vertebral bone of adult female rats contain osteoprogenitors that require dexamethasone (Dex) or progesterone (Prog) to proliferate and differentiate into fully differentiated bone-forming osteoblasts. This study was conducted to determine whether these findings found in rat are also observed in human using human cells. First, the present study was undertaken to determine the frequency and/or number of Dex and Prog-responsive osteoprogenitors in cell populations. Frequencies and numbers of progenitor types were determined for up to six subcultures using continuous subculturing, limiting dilution analysis, and colony assays. In Dex-containing medium, subculturing resulted in a 10% increase in the total number of Dex-responsive osteoprogenitors in second subculture cells over first subculture cell. From the third subculture onward, the frequency of osteoprogenitors decreased in a linear mann … More er and none were observed after five subcultures. Similar results were obtained in Prog-containing medium. Limiting dilution analysis in the presence of Dex indicated that 1.81% of cells represented a colony forming unit-fibroblast and 0.25% represented an osteoprogenitor in first subculture cells. In the presence of Prog indicated that 1.75% of cells represented a colony forming unit-fibroblast and 0.09% represented an osteoprogenitor in first subculture cells. Second, we show that the Prog-dependent population can be detected in female bone after sexual maturation, and can be induced by culturing the osteoprogenitors in media containing 17 β-estradiol (10-9-10-8m). This suggested that the survival of the Prog-dependent osteoprogenitors and/or their ability to proliferate is dependent on the presence of estrogen. The results presented here are compatible with the view that in the female skeleton one of the mechanisms maintaining bone mass is related to effects of both estrogen and Prog on a class of osteoprogenitors responsive to Prog. These findings may provide new insight into the significance of a specific class of Prog-dependent osteoprogenitors and of their regulation by estrogen in the human skeleton. Less