股骨头创伤性缺损模型修复过程的同步辐射硬X线相位衬度成像

Application of phase-contrast imaging with synchrotron radiation hard X-ray in repair of traumatic femoral defect

目的 采用同步辐射硬X线相位衬度显微成像技术对胶原基纳米骨（nanohydroxyapatite/collagen,nHAC）和骨髓间充质干细胞（mesenchymal stem cells,BMSCs）修复兔股骨头创伤性缺损的过程进行比较观察.方法应用新西兰白兔建立双侧股骨头内骨缺损模型,并按完全随机设计方法分为三组：A组为制作缺损而不填充任何材料,B组为单纯填充nHAC,C组填充nHAC和骨髓间充质干细胞的复合材料.植入后4,8,12周的股骨头行同步辐射类同轴全息相位衬度显微成像和衍射增强成像,观察nHAC和骨髓间充质干细胞对组织的修复作用以及降解替代过程. 结果 同步辐射硬X线相位衬度显微成像技术可以清晰地观察骨缺损修复情况和nHAC降解及骨细胞替代过程.4周时,A组缺损区未愈合,部分发生塌陷,B组和C组出现植入nHAC降解和新骨替代,无塌陷;8周时,A组缺损区未愈合,可见纤维组织形成,B组和C组缺损区初步修复,可见成骨和材料降解;12周时A组缺损区仍未愈合,出现纤维组织替代,B组和C组缺损区修复,C组骨小梁结构形成.B组和C组在股骨头缺损修复成骨方面与A组有显著差异,C组成骨更佳. 结论同步辐射硬X线相位衬度成像技术可检测到兔股骨头坏死模型骨缺损修复情况,显示骨组织显微水平上的修复过程,为骨缺损修复提供新的检测手段,对组织工程的发展将起到不可替代的作用.

Objective To compare the effectiveness of nano-hydroxyapatite/collagen （nHAC）and autologous mesenchymal stem cells （AMSCs） for the repair of femoral defect in a rabbit model with femoral defect under the monitoring of the synchrotron radiation hard X-ray. Methods The rabbit models of traumatic bone defect were established and completely randomized into three groups. The femoral defects filled with nothing were used as control group （Group A） , the femoral defects filled with nHAC as Group B and the femoral defects filled with nHAC ＋ AMSCs as Group C. Phase-contrast imaging with synchrotron radiation hard X-ray was applied to detect the degradation and repair process of each group at postoperative weeks 4, 8 and 12, respectively. Results Phase-contrast imaging with synchrotron radiation hard X-ray could display the reparative process. Four weeks after operation, there was collapse in some defect areas in Group A, and the degradation of nHAC and new bone formation were observed in Groups B and C. Eight weeks after operation, fibrous tissues were observed in the defect area in Group A, while osteogenesis and nHAC degradation were more obvious in Groups B and C. Twelve weeks after operation, the defect areas were still unhealed and were substituted by fibrous tissues in Group A, tissue densities of defect areas in Group C were identical with periphery areas, and trabecular bones were formed in Group C. There were statistical differences in the osteogenesis between Group A and Groups B and C,with Group C the best. Conclusion Phase-contrast imaging with synchrotron X-ray can detect the reparative process at a micro-level and plays an important role in the development of tissue engineering.