Ekanayake S, Tuan R S
Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, PA 19107.
Differentiation. 1994 Nov;58(1):19-27. doi: 10.1046/j.1432-0436.1994.5810019.x.
The mechanisms of chondrogenic differentiation are generally studied in vitro by analyzing the action of agents that promote or affect chondrogenesis in embryonic mesenchyme, such as cells of the embryonic limb bud. However, it is not known whether progenitor cells of the craniofacial skeleton, which are of a different embryonic origin and derived from the neural crest, are similarly responsive to such agents. To gain insight into the regulation of chondrogenic differentiation in cells derived from neural crest, we have treated chick embryonic neural crest explants in vitro with poly-L-lysine (PL, M(r) 380 kDa) or bovine bone extract (BBE), two agents known to enhance chondrogenesis of limb mesenchymal cells. Both cephalic (normally chondrogenic) and trunk (normally nonchondrogenic) neural crest cells were analyzed. Chondrogenic differentiation was determined by histological, immunohistochemical and autoradiographic methods. Our results indicate that both PL (380 kDa) and BBE significantly enhance chondrogenesis of cephalic neural crest cells, suggesting that the mechanism of chondrogenesis of these ectodermally derived cells is similar to that of mesodermally derived limb mesenchymal cells. However, trunk neural crest cells did not undergo chondrogenesis in response to PL or BBE. These data show that chondrogenesis can be enhanced in cranial ectodermal neural crest cells in a manner similar to that in the limb mesenchyme. However, since nonchondrogenic trunk neural crest cells are not responsive, an inherent potential for cartilaginous differentiation is necessary for exogenous stimulation of chondrogenesis.
软骨形成分化的机制通常是在体外通过分析促进或影响胚胎间充质（如胚胎肢芽细胞）中软骨形成的因子的作用来进行研究的。然而，尚不清楚源自神经嵴、具有不同胚胎起源的颅面骨骼祖细胞是否对这类因子有类似反应。为了深入了解源自神经嵴的细胞中软骨形成分化的调控机制，我们在体外使用聚-L-赖氨酸（PL，相对分子质量380 kDa）或牛骨提取物（BBE）处理鸡胚神经嵴外植体，这两种因子已知可增强肢体间充质细胞的软骨形成。我们分析了头部（通常具有软骨形成能力）和躯干（通常无软骨形成能力）的神经嵴细胞。通过组织学、免疫组织化学和放射自显影方法确定软骨形成分化。我们的结果表明，PL（380 kDa）和BBE均显著增强头部神经嵴细胞的软骨形成，这表明这些外胚层来源细胞的软骨形成机制与中胚层来源的肢体间充质细胞相似。然而，躯干神经嵴细胞对PL或BBE没有发生软骨形成。这些数据表明，颅外胚层神经嵴细胞的软骨形成可以以类似于肢体间充质的方式增强。然而，由于无软骨形成能力的躯干神经嵴细胞没有反应，因此软骨分化的内在潜力对于软骨形成的外源刺激是必要的。
