BMP responsiveness in human mesenchymal stem cells
BMP responsiveness in human mesenchymal stem cells
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DOI：
10.1080/03008200390181825
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发表时间：
2003-01-01
影响因子：
2.9
通讯作者：
Leboy, PS
中科院分区：
文献类型：
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作者：
Diefenderfer, DL;Osyczka, AM;Leboy, PS
骨形态发生蛋白（BMPs）在动物模型中诱导骨形成，并且可以促进从大鼠和小鼠骨髓分离的多潜能间充质干细胞（MSC）培养物中的成骨。然而，骨形成蛋白的临床试验表明，骨形成蛋白是相对无效的人类成骨诱导剂。我们实验室最近的研究表明，当将人骨髓MSC置于原代培养物中时，地塞米松（Dex）可以诱导成骨，而BMP-2、-4或-7不能诱导成骨。因此，我们研究了人MSC中BMP信号通路的组成部分。将来自进行髋关节置换手术的患者的骨髓的第一代细胞与抗坏血酸磷酸盐一起培养，并用100 nM地塞米松（Dex）、100 ng/ml BMP或两者处理。6天后，测量细胞提取物的碱性磷酸酶活性，并提取RNA用于mRNA水平的RT-PCR分析。在来自十几名患者的人类MSC样本中，只有一名患者的样本在暴露于BMP后显示碱性磷酸酶显着升高;其余的对Dex有反应，但对BMP无反应。从培养的人MSC的mRNA的分析表明，而地塞米松治疗引起碱性磷酸酶的mRNA水平的增加，BMP没有。Noggin是一种BMP结合蛋白，可被BMP上调。BMP处理的人MSC培养物没有显示出增加的碱性磷酸酶，但表达了升高水平的头蛋白mRNA，表明细胞能够进行一些BMP反应。我们的研究结果表明，BMP信号在间充质干细胞利用一个以上的转录激活系统。大多数人MSC不能激活碱性磷酸酶基因的转录，这意味着诱导成骨细胞表型所需的系统存在缺陷。
Bone morphogenetic proteins (BMPs) are well known to induce bone formation in animal models and can promote osteogenesis in cultures of multipotential mesenchymal stem cells (MSC) isolated from rat and mouse bone marrow. However, clinical trials of BMPs suggest that BMPs are relatively ineffective inducers of osteogenesis in humans. Recent studies from our lab indicate that when human bone marrow MSC are placed in primary culture, osteogenesis can be induced by dexamethasone (Dex), but not by BMP-2, -4, or -7. We have therefore investigated components of BMP signaling pathways in human MSC. First passage cells, derived from the bone marrow of patients undergoing hip replacement surgery, were cultured with ascorbate phosphate and treated with 100 nM dexamethasone (Dex), 100 ng/ml BMP, or both. After 6 days, alkaline phosphatase activity of cell extracts was measured, and RNA was extracted for RT-PCR analysis of mRNA levels. Among human MSC samples from more than a dozen patients, only one patient sample showed significantly elevated alkaline phosphatase after exposure to BMP; the rest responded to Dex but not BMP. Analysis of mRNA from cultured human MSC indicated that, while Dex treatment caused increased levels of mRNA for alkaline phosphatase, BMP did not. Noggin is a BMP-binding protein that is upregulated by BMPs. BMP-treated human MSC cultures that did not show increased alkaline phosphatase did express elevated levels of noggin mRNA, indicating that the cells are capable of some BMP response. Our results suggest that BMP signaling in mesenchymal stem cells utilizes more than one system for transcriptional activation. The inability of most human MSC to activate transcription of the alkaline phosphatase gene implies that a defect exists in the system required for induction of the osteoblast phenotype.