大鼠自体微小颗粒骨移植骨诱导活性的实验观察

Experiment study on rat autologous tiny morselized bone grafts＇ osteoinduction

目的 观察大鼠微小颗粒骨修复骨缺损的过程中骨生长因子的表达。探讨微小颗粒骨的骨诱导活性和成骨机制。方法 取雄性DA大鼠120只，切除双侧前肢桡骨中段4mm骨质，建立大鼠双侧桡骨骨缺损模型。取自体髂骨进行移植，根据移植骨块的大小，分为块状骨组和微小颗粒骨组（直径分别为2mm和300．500μm）。将块状骨植入左侧骨缺损中，微小颗粒骨植入右侧骨缺损中。对照组取出髂骨，不进行骨移植（n=8）。术后1、4天和1、2、4、6、10周进行X线检查，观察骨缺损的修复程度。同时于移植处取骨．光镜下观察组织学改变；RT—PCR观察骨形态发生蛋白-2（BMP-2）、转化生长因子β1（TGF-β1）的表达。结果 术后10周。X线检查块状骨组骨缺损区，可见有骨性连接，但骨髓腔未完全再通；微小颗粒骨组骨缺损已修复，骨髓腔再通完全。光镜下块状骨组骨吸收缓慢，编织骨和新生的骨小梁形成晚；微小颗粒骨组骨吸收早。移植2周时可见大量的成骨细胞、间充质细胞、新生的血管和新生的骨质；术后10周时板层骨形成，骨髓腔再通。微小颗粒骨BMP-2mRNA和TGF-β1mRNA的表达高峰出现早，持续时间长，在术后2周时，微小颗粒骨组为1．380±0216和1．492±0．261，块状骨组为0．793±0．147和1．065±0．121，组间比较差异有统计学意义（t=22．482、7．495。P〈0．05）。结论 微小颗粒骨与块状骨相比具有更强的骨诱导活性和成骨效果。

Objective To investigate the expression regularity of bone growth factors in tiny morselized bone grafts during repairing bone defects and its＇osteoinduction and osteogenesis mechanism. Methods The rat model of 4 mm bone defect was established in the middle shaft of the radius. One hundred and twenty male DA rats were divided into 3 groups randomly： bulk bone graft group, tiny morselized bone graft group and control group. Ilium were made into bulk bone grafts and tiny morselized bone grafts whose diameters were 2 mm and 300 - 500 μm respectively. Bulk bone grafts were transplanted into the left radial defects and tiny morselized bone grafts were transplanted into the fight ones in DA rats. No bone grafts were given into control group. Samples were harvested on 1,4 days, 1, 2, 4, 6 and 10 weeks after transplantation. The expression of bone morphogenetic proteins-2（BMP-2） and transforming growth factor-betal （TGF-β1） were semiquantified by RT-PCR. Histological and radiographic changes were studied at each time point. Results X-rays manifested that the bone defect treated with tiny morselized bone grafts were repaired completely at the end of 10 weeks after operation, however that with bulk bone grafts did not. Histology indicated tiny morselized bone grafts repaired bone defects better and faster than bulk bone grafts did at each time point. Tiny morselized bone grafts were absorbed quickly, bringing about faster peak of the expressions of BMP-2 mRNA and TGF-β1 mRNA than bulk bone grafts did, which were much more higher during the first 2 weeks（P 〈 0.05）. Conclusion Tiny morselized bone grafts have better osteoinduction and osteogenesis effect than bulk bone grafts.