脊髓损伤后大鼠骨细胞形态学特点

目的：探讨脊髓损伤(Spinal Cord Injury,SCI)后大鼠骨细胞形态学变化特点及在SCI后骨代谢改变中的意义。方法：20只3个月龄SD大鼠均分为SCI组与对照组。SCI组于T10椎体处完全横断脊髓；对照组仅行椎板切除术，6周后处死动物取材。透射电镜观察股骨近段超微结构。原位凋亡染色法计数股骨近段骨细胞凋亡指数。结果：SCI组骨细胞有4种改变：(1)细胞器减少，骨陷窝增大，絮状物质增多、凝聚以及骨陷窝壁嗜锇板层形成等骨细胞性溶骨表现；(2)退变相骨细胞表现为胞质和细胞器出现严重囊性改变如线粒体空泡化，细胞壁不完整，细胞器不清晰；(3)出现核固缩，细胞处于崩解状态为坏死的形态学改变；(4)异染色质凝集、边聚，细胞出芽起泡等典型凋亡样改变。SCI组小梁骨中骨细胞凋亡指数显著高于对照组(P＜0．01)。结论：骨细胞的溶骨、退变、坏死和凋亡样改变是SCI后骨细胞的形态学特征，也可能是SCI后骨代谢偶联失调的细胞学基础。

Morphology Characteristic of Osteocytes in Rats with Spinal Cord Injury

Objective: To study the morphology character of osteocytes in rats with spinal cord injuries and its significance in the bone metabolism. Methods: Twenty 3 month old rats were randomly divided into the SCI group and control group with 10 in each group. Rats in the experimental group underwent spinal cord transection at the tenth thoracic vertebrae, and in the control group, a sham procedure. All animals were sacrificed 6 weeks postoperatively. Ultrastructural investigation of trabecular bone in proximal femur was performed with transmission electron microscopy. The apoptotic osteocytes were detected by using terminal deoxynucleotidyl mediated nick end labeling(TUNEL) technique. Results: Several morphology was detected in the osteocytes in rats of SCI group. First, osteocytic dissolve characterized by decreased organelles, enlargement of bone lacuna, increasing concentrated wadding material and forming of osmium favored stratum. Second, degenerative osteocytes revealed decreased organelles, sake like change and some cells without integrated wall. Third, some typical necrosis cell showed nuclear pycnosis and cell collapsed. Fourth, changs such as bubble and bud, heterochromatin condensation, edge collection of heterochromatin under the nuclear membrane suggested apoptotic osteocytes. Apoptotic index of osteocytes was significantly higher in SCI group than that in control group ( P<0.01) . Conclusion: Dissolve, degeneration, necrosis and apoptosis are the characteristics of osteocytes and probable causes for decoupling in rats with SCI.