Gibson G, Lin D L, Roque M
Bone and Joint Center, Henry Ford Hospital, Detroit, Michigan 48202, USA.
Exp Cell Res. 1997 Jun 15;233(2):372-82. doi: 10.1006/excr.1997.3576.
During the process of endochondral ossification chondrocytes progress through stages of terminal differentiation culminating in apoptotic death. We have developed a serum-free suspension culture that allows terminal differentiation and facilitates the investigation of factors affecting chondrocyte apoptosis. We have found that chondrocytes not committed to terminal differentiation, i.e., those from the caudal region of chick embryo sterna, a region that remains cartilaginous for some months after the chick hatches, maintained high viability in serum-free suspension culture. A strong dependence of viability on culture density and sensitivity to induction of apoptosis with the protein kinase inhibitor, staurosporine, was consistent with the proposal that these chondrocytes, like nearly all cells, require intercellular communication for survival. Chondrocytes that were committed to terminal differentiation, i.e., those from the cephalic region of chick embryo sterna, a region that is replaced by bone before the chick hatches, expressed the hypertrophic phenotype but maintained their viability in culture for only approximately 6 days. Subsequent cell death was very consistent between cultures and shown to occur by an apoptotic process by analysis of DNA fragmentation and cell morphology. Short-term viability of hypertrophic chondrocytes was independent of culture density and relatively resistant to treatment with staurosporine. Induction of the hypertrophic phenotype in immature chondrocytes committed them to cell death and prevention of expression of the hypertrophic phenotype prevented cell death. We conclude that commitment of chondrocytes to terminal differentiation is associated with a commitment to apoptosis and apoptosis of hypertrophic chondrocytes in growth cartilage does not require initiation by external signals.
在软骨内成骨过程中，软骨细胞经历终末分化阶段，最终以凋亡死亡告终。我们开发了一种无血清悬浮培养方法，该方法可使软骨细胞进行终末分化，并有助于研究影响软骨细胞凋亡的因素。我们发现，未进行终末分化的软骨细胞，即来自鸡胚胸骨尾部区域的软骨细胞（该区域在雏鸡孵化后仍保持软骨状态数月），在无血清悬浮培养中保持高活力。活力对培养密度的强烈依赖性以及对蛋白激酶抑制剂星形孢菌素诱导凋亡的敏感性，与这些软骨细胞（像几乎所有细胞一样）需要细胞间通讯来维持生存的观点一致。已进行终末分化的软骨细胞，即来自鸡胚胸骨头部区域的软骨细胞（该区域在雏鸡孵化前被骨替代），表现出肥大表型，但在培养中仅能维持约6天的活力。随后的细胞死亡在各培养物之间非常一致，通过DNA片段化和细胞形态分析表明其通过凋亡过程发生。肥大软骨细胞的短期活力与培养密度无关，并且对星形孢菌素处理相对抗性。在未成熟软骨细胞中诱导肥大表型会使其走向细胞死亡，而阻止肥大表型的表达则可防止细胞死亡。我们得出结论，软骨细胞向终末分化的转变与凋亡的发生相关，生长软骨中肥大软骨细胞的凋亡不需要外部信号启动。
