骨保护素对兔骨关节炎关节软骨的保护效应

The protective effect of osteoprotegerin on articular cartilage in a rabbit model of osteoarthritis： a histomorphometric study

目的观察关节腔内注射骨保护素对兔骨关节炎关节软骨组织形态的保护作用。方法将60只雄性新西兰大白兔随机分为三组，每组20只。骨保护素组行左侧膝关节前十字韧带离断术，术后4周于左膝关节腔内注射骨保护素溶液0．1mI，每周注射5次，共注射8周；磷酸盐缓冲液组于前十字韧带离断术后4周注射等剂量磷酸盐缓冲液；假手术组显露前十字韧带后缝合切口。术后12周处死动物取左膝关节标本，行大体形态学Pelletier评分，切片番红染色后行Mankin软骨评分并测量软骨厚度。结果大体观察骨保护素组股骨髁软骨评分（1．80±0．89）分，胫骨平台软骨评分（1．80±0．77）分，均低于磷酸盐缓冲液组[分别为（3．10±0．97）、（3．20±0．77）分]，与假手术组比较差异无统计学意义。组织学观察骨保护素组±的软骨结构（2．65±-0．88）分、软骨细胞（1．35±0．71）分、番红染色（1．83±0．83）分、潮线完整性（0．30±0．47）分及Mankin软骨评分总分（6．13±1．97）分，均低于磷酸盐缓冲液组[分别为（4．52±1．09）、（1．85±0．63）、（2．80±0．75）、（0．65±0．49）、（9．83±1．98）分]。骨保护素组Mankin评分总分高于假手术组，但四个分项评分与假手术组的差异无统计学意义。骨保护素组软骨厚度（371．84±38．94）μm，大于磷酸盐缓冲液组（255．09±74．82）μm，小于假手术组（404．68±15．97）μm，差异均有统计学意义。结论骨保护素对关节软骨具有保护效应，可延缓骨关节炎进展。保护效应表现为减轻滑膜炎症反应、减少关节边缘骨赘形成及在一定程度上阻止软骨厚度丢失。

Objective To observe the morphologic protection effect of intra-articular injection of osteoprotegerin （OPG） on articular cartilage in a rabbit model of osteoarthritis （OA）. Methods Sixty male New Zealand rabbits were randomly divided into 3 groups： OPG group （n=20）, sham-operated group （n=20） and PBS group （n=20）. In OPG group and PBS group, each rabbit underwent anterior cruciate ligament transection （ACLT） in left knee joint, then 0.1 ml OPG solution or PBS were injected into the left knee for 8 weeks （5 times a week） in OPG group and PBS group, respectively. In sham-operated group, the anterior cruciate ligament was just exposed without transection, and then the incision was closed. All rabbits were sacrificed 12 weeks after operation, and the left knee joints were obtained. The Pelletier score and Mankin score were used to evaluate the macroscopic and microscopic cartilage morphology. Results The score of femoral condyle cartilage and tibial plateau cartilage was 1.80±0.89 and 1.80±0.77 in OPG group, respectively, and 3.10±0.97 and 3.20±0.77 in PBS group. However, there was no statistical difference in Pelletier score between the sham-operated group and the OPG group. Consistent with the macroscopic data, the OPG group has a significantly lower Mankin score involving cartilage structure （2.65±0.88）, chondrocyte （1.35±0.71）, Safranin O staining （1.83±0.83）, tidemark integrity （0.30±0.47） and total score （6.13±1.97） compared with the PBS group （4.52± 1.09, 1.85±0.63, 2.80±0.75, 0.65±0.49, and 9.83±1.98, respectively）. The OPG group has a significantly higher total Mankin score compared with the sham-operated group （4.80±1.25）, however, there were no statistical differences in four subitem scores between the two groups. Moreover, the cartilage thickness in OPG group was 371.84±38.94μm, 255.09±74.82μm in PBS group, and 404.68±15.97 μm in the sham-operated group, and the differences were statistically significant between three groups. Conclusion OPG has a protective effect on articular cartilage and can slow the progression of OA by reducing the grade of synovitis, decreasing the volume of osteophytes, and suppressing the loss of cartilage thickness.