成骨蛋白-1对髓核抽吸术后兔腰椎间盘组织病理变化的影响

The influence of osteogenic protein-1 on histologic changes of rabbit lumbar disc induced by aspirating the nucleus pulposus

目的:观察成骨蛋白-1(osteogenic protein-1,OP-1)对髓核抽吸术后兔椎间盘组织病理变化的影响。方法:32只日本大耳白兔,用21号针头行L1/2、L3/4椎间盘后外侧穿刺,抽吸出部分髓核组织,L3/4用微量注射器注射OP-1 25μl作为实验椎间盘(OP-1组),L1/2注射25μl生理盐水作为对照椎间盘(Saline组),L2/3作为正常对照椎间盘(正常组),术后2周、4周、8周、12周分别随机处死8只兔,每只取L1/2、L2/3和L3/4椎间盘,切片,行Masson染色,观察椎间盘组织病理学变化情况。结果:正常对照组椎间盘髓核组织胶原稀疏、排列有序,细胞可呈岛状分布,纤维环胶原纤维排列整齐,无扭曲及无分层现象,术后2周、4周、8周、12周椎间盘组织病理变化不明显。Saline组椎间盘术后2周时髓核部分缺失,胶原排列紊乱,出现大量分布不均匀的无定型颗粒;术后4周髓核组织裂隙形成,出现较多的类软骨细胞,胶原纤维扭曲严重;术后8周髓核组织广泛裂隙,胶原排列极其紊乱,出现介于类软骨细胞及纤维细胞之间的细胞,较明显的分层裂隙,胶原纤维极度扭曲,部分断裂;术后12周凝胶状髓核组织呈现明显纤维化,髓核内出现较多纤维样细胞,类软骨细胞数量明显减少,纤维环出现巨大分层裂隙,伴有部分纤维环断裂。OP-1组椎间盘术后2周髓核胶原排列尚有序,髓核细胞仍较多,纤维环形态接近正常;术后4周髓核组织轻微裂隙,胶原排列紊乱,髓核细胞减少,出现类软骨细胞,内层纤维环胶原纤维轻度扭曲;术后8周髓核组织较多裂隙,胶原扭曲,类软骨细胞增多,内层纤维环胶原纤维明显扭曲,排列紊乱;术后12周时类软骨细胞仍较多,出现少量介于类软骨细胞与纤维细胞之间的细胞,全层纤维环胶原纤维扭曲,排列紊乱,但外层纤维环仍完整,纤维环无巨大裂隙出现。结论:OP-1能延缓后外侧纤维环穿刺髓核抽吸术后兔腰椎间盘髓核细胞及纤维环的退变。

Objectives： To observe the influence of osteogenic protein-l（OP-1） on disc histologic changes in- duced by aspirating the nucleus pulposus. Methods： All the 32 Japanese rabbits＇ posterior annulus fibrosus of L1/2 and L3/4 disc were stabbed by 21-gauge hypodermic needle, then some nucleus pulposus tissues were aspirated out. 25μl 0P-1 was injected into L3/4 disc by using micro-injection syringe as the experi- mental group （OP-1 group）. 25μl normal saline was taken injected into L1/2 as a blank control disc（Saline group）. L2/3 was taken as a normal control disc（normal group）. At 2, 4, 8 and 12 weeks after operation, each 8 rabbits were executed and the disc tissues of L1/2, L2/3, L3/4 were harvested and sliced rapidly, stained by Masson for observation. Results： In the normal intervertebral disc, nucleus pulposus tissue collagen was sparse and lined orderly. The cells were distributed as island. Anulus fibrosus collagen fibers were lined reg- ularly, without distortion and delamination. The intervertebral disc showed no significant pathological change at 2, 4, 8 and 12 weeks after operation. In saline group at 2 weeks after operation, exealation of the nucleuspulposus, collagen disarrangement and a large inhomogeneous amorphous particles could be observed. At 4 weeks after operation, the nucleus pulposus tissue formed cracks. More cartilage ceils appeared. Collagen fibers were seriously distorted. At 8 weeks after operation, nucleus pulposus tissue had wide fissure. Collagen was arranged extremely disorder. A few ceils appeared just between cartilage-like cells and fibroblasts. Layered fissure was formed. Collagen fibers were extremely distorted, with part of fracture evidenced. Gelatinous nucleus pulposus of disc showed significant fibrosis at 12 weeks after operation. Fibroblasts increased in nucleus pulposus region, and the number of cartilage-like cells decreased. The annulus fibrosus appeared huge layered fissure, with part of fracture evidenced. In OP-1 group at 2 weeks after operation, the nucleus pulposus collagen arrangement was ordered. There were still more nucleus pulposus cells. The shape of anulus fibrosus was close to normal. At 4 weeks after operation, the nucleus pulposus tissue formed little cracks, and collagen disarranged. Nucleus pulposus cells decreased, with cartilage-like cells appeared. The inner annulus collagen fibers were distorted slightly. At 8 weeks after operation, nucleus pulposus tissue had more cracks and distortion of collagen. Cartilage-like cells increased. The inner annulus collagen fibers were distorted significantly. At 12 weeks after operation there were still morecartilage-like cells. A few cells appeared just between cartilage-like cells and fibroblasts. The whole layer of the annulus fibrosus collage fibers were distorted and disorganized, but the outer annulus were intact without huge fissure formation. Conclusions： OP-1 can retard disc degeneration of rabbit induced by puncturing lateral annulus fibrosus and aspirating the nucleus pulposus.