The protective effect of osteoprotegerin on articular cartilage in a rabbit model of osteoarthritis: a histomorphometric study / 中华骨科杂志

ABSTRACT

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 groupsOPG 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±38.94 μm,255.09±74.82 μm 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.