Change of calpain and effect of mechanical stress on chondrocyte tube culture

Rat chondrocyte cultures grown in centrifuge tubes with intermittent centrifugation differentiateinto hypertrophic chondrocytes and form calcification. This文化系统provides an extracellularmatrix mineralization which is produced by chondrocytes per se，我们可以测试这个文化系统作为一个模型在我们体内的endochondral ossificationprevious study m-calpain was demonstrated immunohistichemically in epiphyseal chondrocytes，and immunoreactive m-calpain content in cells increased with terminal differentiation intohypertrophic cells. Using this文化系统我们examined whether various degree of centrifugation changed the pattern of the endochondralossification. Growth-plate chondrocytes were isolated from the rib cartilages of 5-week-old malewister rats,and the cell suspension was transferred into a 15-ml plastic centrifuge tube at a density of16x10 D14 D1 cells/ml/tube and centrifuged at 1, 500 rpm for 5 minutes. In the following，我们分开三个组：group A was centrifuged at 3, 000 rpm for 30分钟每一天，group B was centrifuged at 1，500 rpm for 5分钟每一天group C是added no centrifugation. group C also had the increase of alkaline phosphataseactivity and terminal differentiation like group A and B. There were no significant differences indna content,proteoglycan content and alkaline phosphatase activity of all three groups. Calcium content of groupA was significantly larger than that of group B at 3-week-文化，but at 4-week-文化，there was no significant difference between them。

Rat chondrocyte cultures grown in centrifuge tubes with intermittent centrifugation differentiate into hypertrophic chondrocytes and form calcification. This culture system provides an extracellular matrix mineralization which is produced by chondrocytes per se, and we can assess this culture system as a model for the endochondral ossification in vivo. In our previous study, m-calpain was demonstrated immunohistichemically in epiphyseal chondrocytes, and immunoreactive m-calpain content in cells increased with terminal differentiation into hypertrophic cells. Using this culture system, we examined whether various degree of centrifugation changed the pattern of the endochondral ossification. Growth-plate chondrocytes were isolated from the rib cartilages of 5-week-old male Wister rats, and the cell suspension was transferred into a 15-ml plastic centrifuge tube at a density of 16X10ィイD14ィエD1 cells/ml/tube and centrifuged at 1, 500 rpm for 5 minutes. In the following, we divided three groups : group A was centrifuged at 3, 000 rpm for 30 minutes every day, group B was centrifuged at 1, 500 rpm for 5 minutes every other day, and group C was added no centrifugation. Group C also had the increase of alkaline phosphatase activity and terminal differentiation like group A and B. There were no significant differences in DNA content, proteoglycan content and alkaline phosphatase activity of all three groups. Calcium content of group A was significantly larger than that of group B at 3-week-culture, but at 4-week-culture, there was no significant difference between them.