Jelic M, Pecina M, Haspl M, Kos J, Taylor K, Maticic D, McCartney J, Yin S, Rueger D, Vukicevic S
Department of Anatomy, School of Medicine, University of Zagreb, Croatia.
Growth Factors. 2001;19(2):101-13. doi: 10.3109/08977190109001079.
The efficacy of osteogenic protein-1 (OP-1; BMP-7) in regeneration of articular cartilage was examined by creating knee chondral defects in sheep. With a specially designed instrument in both knees, two 10 mm (diameter) chondral defects were created: one in the trochlea and the other on the femoral condyle. The recombinant BMP was delivered via an extra-articulary positioned mini-osmotic pump, which was fixed to the femoral diaphysis above the knee joint, and connected by a polyethylene tubing to the articular space. Prior to use, the compatibility of OP-1 with mini-osmotic pumps was tested in vitro by measuring aggregation/precipitation and modification of the released protein by size exclusion and reversed phase HPLC. The average amount of aggregation was 15% and about 5% of OP-1 was modified. However, the biological activity of OP-1 released from pumps over a period of 2 weeks at 37 degrees C was equal to ROS cell assay OP-1 standard. Following surgery, a total of 55 microg (low dose) or 170 microg (high dose) OP-1 in acetate buffer (pH 4.5) was slowly released from the pump over a period of 2 weeks. The pumps connected to control knees were filled with acetate buffer as a vehicle. Twelve animals were operated, six of which were treated with the low OP-1 dose, and six with the high OP-1 dose. Three sheep of each group were killed either at 3 or 6 months following surgery, based on arthroscopical evaluation. The chondral defects in the control knees remained empty during the observation period. At 3 months following surgery, defects treated with both OP-1 doses were filled with connective tissue and cartilage. At 6 months following surgery, both doses of OP-1 stimulated regeneration in treated knees. The boundaries between new and old cartilage were well fused and mechanically resisted animals' weight bearing. The regenerated cartilage was rich in proteoglycans and type II collagen, as demonstrated by toluidine blue staining and immunohistochemistry. No signs of endochondral bone formation above the bony tidemark were observed. We suggest that a recombinant bone morphogenctic protein stimulates ingrowth of mesenchymal cells into the chondral defects which then transform into newly formed articular cartilage-like tissue.
通过在绵羊身上制造膝关节软骨缺损，研究了成骨蛋白-1（OP-1；骨形态发生蛋白-7，BMP-7）在关节软骨再生中的疗效。使用专门设计的器械在双侧膝关节制造两个直径10毫米的软骨缺损：一个位于滑车，另一个位于股骨髁。重组骨形态发生蛋白通过关节外放置的微型渗透泵递送，该泵固定在膝关节上方的股骨干上，并通过聚乙烯管连接到关节腔。使用前，通过测量聚集/沉淀以及通过尺寸排阻和反相高效液相色谱法对释放蛋白的修饰，在体外测试了OP-1与微型渗透泵的兼容性。平均聚集量为15%，约5%的OP-1发生了修饰。然而，在37℃下，泵在2周内释放的OP-1的生物活性与ROS细胞测定OP-1标准相等。手术后，55微克（低剂量）或170微克（高剂量）的OP-1在醋酸盐缓冲液（pH 4.5）中在2周内从泵中缓慢释放。连接到对照膝关节的泵中填充醋酸盐缓冲液作为载体。对12只动物进行了手术，其中6只接受低剂量OP-1治疗，6只接受高剂量OP-1治疗。根据关节镜评估，每组三只绵羊在手术后3个月或6个月处死。在观察期内，对照膝关节的软骨缺损保持为空。手术后3个月，用两种OP-1剂量治疗的缺损均被结缔组织和软骨填充。手术后6个月，两种剂量的OP-1均刺激了治疗膝关节的再生。新旧软骨之间的边界融合良好，并且能够机械抵抗动物的负重。甲苯胺蓝染色和免疫组织化学显示，再生软骨富含蛋白聚糖和II型胶原。在骨嵴上方未观察到软骨内骨形成的迹象。我们认为，重组骨形态发生蛋白刺激间充质细胞长入软骨缺损，然后转化为新形成的关节软骨样组织。
