Chondrocyte specific regulation by BMP inhibitors in a medsodermal stem cell C1 and skeletal cells

成骨细胞和成软骨细胞来源于共同的间充质祖细胞。BMP在体外诱导间充质细胞分化为成骨和成软骨途径。其抑制剂noggin在地塞米松存在下培养的中胚层C1细胞的软骨分化过程中表达，但在抗坏血酸和β-GP存在下培养的C1细胞的成骨分化过程中不表达。我们推测noggin可能以谱系特异性方式发挥作用以阻断BMP作用。为了验证这一假设，我们构建了表达noggin的重组腺病毒（Ad/noggin）C1细胞，该细胞来源于胚胎癌细胞1003，具有中胚层细胞的特征。当C1细胞在分化培养基中以聚集体形式培养时，它们分化成软骨形成细胞、成骨细胞和成脂细胞。当我们在诱导分化前将Ad/noggin感染到C1细胞中时，与Ad/IacZ感染的C1细胞相比，这些细胞中的内源性碱性磷酸酶水平没有改变。当Ad/noggin感染的C1细胞被诱导分化为软骨形成谱系时，Sox 9和X型胶原mRNA的表达降低，显示noggin抑制软骨形成。与此相反，在诱导C1细胞成骨谱系，成骨细胞表型标志物，骨钙素和碱性磷酸酶mRNA的表达水平，没有广告/头蛋白和lacZ感染的细胞之间的差异。我们通过胚胎长骨的器官培养进一步研究了noggin是否可能影响骨骼组织的发育。当我们将Ad/noggin感染到15-5dpc的后肢骨中时，与Ad/lac Z感染的肢骨相比，软骨形成生长受到抑制。这些结果表明，noggin是软骨分化，而不是成骨分化的中胚层干细胞系Cl和骨骼细胞的调节剂。

Osteoblast and chondroblast are derived from common mesenchymal progenitors. BMP induces mesenchymal cell differentiation into both osteogenic and chondrogenic pathways in vitro. Its (inhibitor, noggin, is expressed during the chondrogenic differentiation of mesodermal C1 cells cultured in the presence of dexamethasone, but it is not expressed during the osteogenic differentiation of C1 cells cultured in the presence of ascorbate and beta-GP We hypothesize that noggin may function in lineage-specific manner to block BMP action. To lest this hypothesis, we constructed an recombinant adenovinis to express noggin ( Ad/noggin) C1 cells are derived from an embryonal carcinoma cell 1003 and have characteristics of mesodermal cells. When C1 cells are cultured in aggregate form in differentiation medium, they differentiate into chondrogenic, osteogenic and adipogenic cells. When we infected Ad/noggin into C1 cells before induction of differentiation, endogenous alkaline phosphatase level in these cells was not altered compared with Ad/IacZ infected C1 cells. When Ad/noggin-infected C1 cells were induced to differentiate into chondrogenic lineage, expression of Sox9 and type X collagen mRNAs was reduced, showing noggin inhibition of chondrogenesis. In contrast, upon induction of C1 cells into osteogenic lineage, expression levels of osteoblast phenotypic markers, osteocalcin and alkaline phosphatase mRNAs, did not differ between Ad/noggin and lacZ- infected cells. We further examined if noggin may affect skeletal tissue development by using organ cultures of embryonic long bones. When we infected Ad/noggin into 15-5dpc hind limb bones, chondrogenic growth was inhibited compared with Ad/lac Z infected limb bones. These results suggest that noggin is a regulator of chondrogenic differentiation, rather than osteogenic differentiation, of mesodennal stem cell line Cl and skeletal cells.