^(99)Tc^m-MDP骨显像监测可注射组织工程骨的成骨活性

Osteogenesis of an injectable tissue-engineered bone monitored by ^(99)Tc^m-MDP bone scintigraphy

背景:有关牵张成骨传统的新骨生长形态观察方法如超声、X射线、CT文献报道较多,但有关核素监测的报道较少。目的:探讨经皮注射可注射组织工程骨促进牵张间隙成骨的可行性及放射性核素骨显像对其的早期监测作用。方法:将20只日本大耳白兔以随机数字表法分为实验组和对照组,两组均于右胫骨中下段造成20mm的骨缺损,干骺端截骨。7d后延长,1mm/次、1次/d。造模前实验组分离培养自体骨髓间充质干细胞,传至第2代后诱导成骨。延长达靶位点后,实验组牵张间隙内注射自体干细胞悬液,并同时注射自体富血小板血浆;而对照组只注射等量生理盐水。采用核素骨显像监测移植后2,4,8周时成骨情况。结果与结论:放射性骨显像99Tcm-MDP注入3h后,实验组与对照组可见显像剂明显沉积于牵张间隙区,均较对侧健性部位显影强。骨骼、肾及膀胱显像清楚,骨/软组织的对比度清晰,各组均可见大关节及肌腱附着处有对称性放射性增高区。两组在2,4周时牵张间隙放射性聚集呈现出上升的趋势,实验组上升趋势更为显著;8周时实验组和对照组核素浓聚变弱,但两者差异仍有显著性意义(P<0.01)。结果说明经皮注射移植复合富血小板血浆的可注射组织工程骨能够促进牵张间隙成骨能力,缩短成骨时间。放射性核素骨显像在早期修复过程有比较灵敏的监测效果。

BACKGROUND：Osteogenesis has been commonly observed by ultrasound,X-ray and CT,but nuclide monitor is rarely reported.OBJECTIVE：Using 99Tcm-medronate（MDP） bone scintigraphy to monitor the improvement of osteogenesis in the distracted gap by an injectable tissue-engineered bone to assess the value of radionuclide for monitoring the therapeutic effect of this approach.METHODS：A total of 20 rabbits were divided into experimental and control groups.A 20 mm incision was made in the distal tibia shaft in all rabbits in addition to the metaphysis osteotomy,and stabilized with an self-designed mini external fixator bilaterally.From post-operative day 7,bone fragments were distracted by 1 mm a day.Autologous bone marrow mesenchymal stem cells were isolated and the second passage was used.After elongation,bone marrow mesenchymal stem cells and platelet rich plasma were percutaneously injected in the distracted gap of experimental group,while the control group was injected with the same volume of normal saline.Radionuclide was used to monitor the therapeutic effects at 2,4,and 8 weeks.RESULTS AND CONCLUSION：Radionuclide accumulation was observed in the distraction area in two groups after 3 hours of 99Tcm-MDP injection,which was stronger compared with the healthy side.The bone/soft tissue contrast was clear,and symmetric radioactive increase areas were detected at the big joint and tendon.99Tcm-MDP uptakes and the target to non-target ratios（T/NT） indicated an increasing tendency of radionuclide accumulation in the distracted gap of experimental group and control group at 2,and 4 postoperative weeks.There was a decreasing tendency of radionuclide accumulation in experimental and control groups at 8 weeks,but the differences between two groups were statistically significant（P 0.01）.Results show that percutaneous injection of injectable tissue-engineered bone could improve osteogenesis in the distracted gap,and radionuclide imaging may accurately monitor the new bone formation and maturation in the early phase.