富血小板纤维蛋白对下颌骨牵引成骨区RANKL表达的影响

目的　通过动物实验，研究应用富血小板纤维蛋白（Platelet-rich Fibrin，PRF）对兔下颌骨牵引成骨区核因子KB受体活化因子配体（receptor activator for NF-KB ligand，RANKL）的影响, 为临床研究与应用提供参考依据。 方法　在20只成年大耳白兔的一侧下颌骨前部行骨切开术，用牵引器延长一侧下颌骨4 mm，牵引间隙放置PRF膜；另一侧下颌骨行骨切开并安置牵引器，作为对照组，稳定期第1、7、14、21、28天，分别处死各组动物，取牵引区新生骨痂行组织学及RANKL免疫组化染色。 结果　下颌牵引延长后牵引间隙均有新骨形成，免疫组织化学显色RANKL主要定位于骨髓基质细胞的胞浆中,其中以稳定期的第1，14天的表达最强。在稳定期第1、14天，实验组较对照组RANKL表达的阳性细胞率及阳性面积百分比差异有统计学意义（P＜0.05），以后逐渐下降，第28 d仅有微弱表达。 结论　动物实验表明，PRF能促进兔下颌骨牵引成骨区新骨的生成，RANKL可能在牵引成骨过程中特别是调控组织细胞应力信号传递的早期发挥破骨作用。

Effects of Platelet-rich Fibrin on mandibular distraction osteogenesis and its RANKL expression

Objective　To investigate the effects of PRF on mandibular distraction osteogenesis and the expression of RANKL in the period of distraction osteogenesis, in order to provide a reference for its clinical research and application.　Methods　unilateral mandibular osteotomies were performed in 20 mature rabbits, the mandibles of 20 rabbits were lengthened by 4 mm using a distractor , PRF were implanted in the osteotomy side of mandibles. Another side of the mature rabbit was cut and a distractor was implanted in the mandible as a control group. The animals were killed on 1, 7, 14, 21 and 8 days of consolidation period. The distracted calluses were harvested and processed for histological and immunohistochemistric study of RANKL.　Results　The regenerated bone was found in the distraction gap after mandibular lengthening, and RANKL were co-localized in bone marrow lining cells, osteoblasts and newly embedded osteocytes. The RANKL expression increased on 1 and 14 days. At the consolidation period of 1 and 14 days there was significant difference between the experiment group and control group(P<0.05). The comparison of positive cells rate and positive area percentage in distracted calluses on the 28th day after the distraction were performed, and the results showed weak RANKL staining in the distracted callus.　Conclusion　PRF could accelerate bone formation of mandibular distraction osteogenesis in rabbit. RANKL may play important roles at the early stage of mandibular distraction.