组织工程化骨构建及其修复羊跖骨标准性骨缺损的放射学评估

Roentgenographic evaluation of tissue engineered bones on critical bone defects of metatarsus in sheep

目的:从放射学角度探讨用多孔β-磷酸三钙和自体骨髓间充质干细胞(MSC)复合植入绵羊体内修复标准性骨缺损的效果.方法:从羊髂嵴处抽取10～15ml骨髓组织,用Percoll分离液按梯度离心法分离出间充质干细胞,培养、增殖后种植在多孔β-磷酸三钙上,构建组织工程化骨,植入8只羊的左后肢跖骨缺损区(21mm)作为实验组:单纯植入多孔β-磷酸三钙陶瓷材料的8只羊作为对照组:另取3只羊在同样部位制造同样大小的骨缺损,但不做处理,作为空白对照组.分别在术后即刻及1、3、6个月摄片观察,用放射影像学评分和图像分析X线阻射影比较骨缺损的修复情况.空白对照组6个月取材.结果:实验组骨缺损放射影像学评分以及新生骨痂的密度在1、3、6个月均优于对照组.空白组术后6个月骨缺损均无愈合.结论:多孔β-磷酸三钙和自体MSC复合植入羊体内,可使大节段骨缺损较快修复;放射学评分及骨缺损密度测量是一种简便易行的观察骨缺损修复情况的方法.

Objective:To construct tissue-engineering bone with porous β tricalcium phosphate (β TCP) ceramic and autologous bone marrow mesenchymal stem cells (MSC), and to investigate the effect of this composite on healing segmental bone defects by roentgenographic analysis. Method: 10～15mL bone marrow aspirates were harvested from the iliac crest of sheep,and enriched for MSC by density gradient centrifugation over a Percoll cushion (1.073g/mL).After cultured and proliferated, tissue-engineering bones were constructed with these cells seeded onto porous β TCP, and then the constructs were implanted in 8 sheep left metatarsus defect(21mm in length) as experimental group. Porous β TCP only or loaded fresh bone marrow were implanted to bridge same size and position defects in 8 sheep respectively as control group, and 21mm segmental bone defects of left metatarsus were left empty in 3 sheep as blank group. Sheep were sacrificed at the 1 st , 3 rd , and 6 th month postoperatively and the reparative effects of bone defects were evaluated by roentgenographic analysis. The 3 sheep in blank group were sacrificed at the 6 th month postoperatively. Result: Roentgenographic scores and callus density at bone defects in experiment group were better than those in control group at postoperative 1 st , 3 rd , 6 th months.The bone defects in blank group were non-healed. Conclusion:Tissue engineered bones constructed with MSC are capable of repairing segmental bone defects in sheep metatarsus earlier and faster as compared with porous β TCP only.Roentgenographic analysis is a good and easy method to observe the process of bone defect healing.