颈椎间盘退变动物模型的制备及终板软骨细胞迁移规律的研究

目的制备双后足大鼠增龄颈椎间退变的动物模型并研究颈椎间盘自然老化及退变过程中髓核中软骨样细胞的来源及其规律。方法4周龄SD大鼠76只,随机分成两组。实验组40只大鼠通过截除前肢制备双后肢大鼠颈椎间盘退变的动物模型,按术后3、6、9、12个月4个时间段分组,每组10只;对照组36只大鼠未予处置,按实验开始后4、8、12、16个月分4组,每组9只。每组大鼠处死后摄颈椎正侧位X线片并制备C4～5、C5～6和C6～7椎间盘中矢状面组织学切片,行HE、番红．0染色,研究观察颈椎间盘退变情况及终板软骨细胞向髓核迁移的规律。结果截除双前肢后,双后肢大鼠全部存活,实验组大鼠术后9、12个月影像学及组织学检查均出现颈椎间盘退变的典型征象。颈椎间盘老化的过程中,终板的软骨细胞向髓核不断迁移,在髓核、终板与内纤维环的交界区,软骨细胞沿胶原纤维排列的方向向髓核边缘迁移;在髓核的中央区域,软骨细胞平行或垂直于终板向髓核迁移,脊索性髓核向心性皱缩并最终完全被纤维软骨性髓核取代。在颈椎间盘退变的过程中,这一过程完成得更快、更早。结论双后足大鼠颈椎间盘退变模型不损伤动物靶器官正常的解剖结构,成功率高、重复性好,符合人类颈椎间盘退变规律;髓核中的软骨样细胞由终板软骨细胞迁移而来,在髓核的不同部位及椎间盘老化和退变的不同时期表现出不同的迁移规律。

Intervertebral disc degeneration model and the rule of migration associated with chondrocytes in the nucleus pulposus in rat cervical disc

OBJECTIVE: To develop a scientific and reproducible degenerative disc rat model for the study on the cervical disc and study the rule of migration associated with the chondrocytes in the nucleus pulpusus. METHOD: The degenerative cervical disc animal model was developed in 40 infancy SD rats by means of forelimb amputation. Thirty-six normal rats in the same age served as the control. When the rats in the experimental group were 3, 6, 9 and 12 months (named E3, E6, E9 and E12 group respectively) and in the control group were 4, 8, 12 and 16 months (named C4, C8, C12 and C16 group respectively) postoperatively, the vertebral columns from C4-5 to C6-7 were removed and observed under radiographic and histological examination after the rats were sacrificed. RESULT: Light microscopy revealed that aging rat undergoes a chronological transition from a notochordal to a fibrocartilaginous NP. The chondrocytes found in mature nucleus pulposus originate and migrate from the cartilage endplate. The origin of chondrocytes proceeded in a centripetal direction from the periphery toward the center of the NP. In the periphery of NP, chondrocytes migrate along collagen fibers; in the center part of NP, chondrocytes migrate from endplate to NP in a parallel or vertical direction. Overload on the cervical spine elicited by this surgical intervention accelerated the process and resulted in cervical intervertebral disc degeneration thereafter. CONCLUSION: The availability of this experimental model should be valuable for comprehensive understanding of the pathogenesis of cervical degeneration. The degeneration process of the bipedal rats'discs is in agreement with that of human beings. Chondrocytes in the rat NP originated and migrated from the cartilage endplate. There are different rules of the chondrocytes migrating from endplate associated with different period of degeneration and different region of nucleus pulposus.