目的: 探讨3D打印工艺制造的多孔WE43镁合金支架的生物相容性, 并观察其治疗新西兰大白兔股骨缺损的效果。方法: 利用Sprague Dawley(S-D)大鼠骨髓间充质干细胞进行体外细胞毒性试验, 根据培养液不同将细胞分为100%浸提液组、50%浸提液组、10%浸提液组及对照组, 将各组细胞分别培养1、3及7 d后, 采用细胞计数试剂盒8(cell counting kit-8, CCK-8)法测定各组细胞活性。体内实验中, 随机将3.0~3.5 kg新西兰大白兔分成实验组、骨水泥组与空白组3组, 每组9只, 每只均对左侧股骨外侧髁进行手术, 利用骨钻制造直径5 mm、深6 mm的骨缺损, 其中实验组植入WE43镁合金支架, 骨水泥组植入硫酸钙骨水泥, 空白组不做植入。在术后4、8与12周分别对每组3只进行二氧化碳麻醉法安乐死, 对股骨及重要内脏器官进行取材, 对左股骨外侧髁进行微计算机断层扫描(micro-computed tomography, Micro-CT)。对重要内脏器官制备切片, 并使用苏木精-伊红(hematoxylin-eosin, HE)染色, 对股骨外侧髁制作硬组织切磨片, 使用亚甲基蓝酸性品红染色, 在显微镜下观察。结果: 细胞毒性试验中, 培养1 d时, 100%浸提液组细胞存活率高于对照组(140.56% vs. 100.00%, P＜0.05); 培养3 d时, 各组细胞存活率差异无统计学意义(P>0.05);培养7 d时, 100%浸提液组细胞存活率低于对照组(68.64% vs. 100.00%, P＜0.05)。体内实验中Micro-CT扫描发现实验组在4周时大部分支架均已降解, 高密度的支架所剩很少, 12周时已无明显支架轮廓。在4周时, WE43镁合金支架周围有一定量气体生成, 在8~12周时, 气体明显减少。硬组织切磨片显示, 实验组4周时支架周围有一定量细胞外基质和类骨质生成, 骨水泥组中硫酸钙骨水泥已大部分降解, 8周时实验组支架及其降解产物周围的类骨质明显增多, 12周时实验组支架周围有新生骨与支架接触, 骨水泥组与空白组新生骨较少。结论: 3D打印工艺制造的多孔WE43镁合金支架生物相容性良好, 具有良好的成骨性能, 有潜力成为修补骨缺损的新型材料。

Objective: To investigate the biocompatibility of porous WE43 magnesium alloy scaffolds manufactured by 3D printing technology and to observe its effect in treating femoral defects in New Zealand white rabbits. Methods: In vitro cytotoxicity test was performed using bone marrow mesenchymal stem cells from Sprague Dawley (S-D) rats. According to the different culture media, the cells were divided into 100% extract group, 50% extract group, 10% extract group and control group. After culturing for 1, 3 and 7 days, the cell activity of each group was determined by cell counting kit-8 (CCK-8). In the in vivo experiment, 3.0-3.5 kg New Zealand white rabbits were randomly divided into three groups: Experimental group, bone cement group and blank group, with 9 rabbits in each group. Each rabbit underwent surgery on the left lateral femoral condyle, and a bone defect with a diameter of 5 mm and a depth of 6 mm was created using a bone drill. The experimental group was implanted with WE43 magnesium alloy scaffolds, the bone cement group was implanted with calcium sulfate bone cement, and the blank group was not implanted. Then 4, 8 and 12 weeks after surgery, 3 rabbits in each group were euthanized by carbon dioxide anesthesia, and the femur and important internal organs were sampled. Micro-computed tomography (Micro-CT) scanning was performed on the left lateral femoral condyle. Sections of important internal organs were prepared and stained with hematoxylin-eosin (HE). Hard tissue sections were made from the left lateral femoral condyle and stained with methylene blue acid fuchsin and observed under a microscope. Results: In the cytotoxicity test, the cell survival rate in the 100% extract group was higher than that in the control group (140.56% vs. 100.00%, P < 0.05) on 1 day of culture; there was no statistically significant difference (P>0.05) in cell survival rate among the groups on 3 days of culture; the cell survival rate in the 100% extract group was lower than that in the control group (68.64% vs. 100.00%, P < 0.05) on 7 days of culture. Micro-CT scanning in the in vivo experiment found that most of the scaffolds in the experimental group had been degraded in 4 weeks, with very few high-density scaffolds remaining. In 12 weeks, there was no obvious stent outline. In 4 weeks, a certain amount of gas was generated around the WE43 magnesium alloy scaffold, and the gas was significantly reduced from 8 to 12 weeks. Hard tissue sections showed that a certain amount of extracellular matrix and osteoid were generated around the scaffolds in the experimental group in 4 weeks. In the bone cement group, most of the calcium sulfate bone cement had been degraded. In 8 weeks, the osteoid around the scaffold and its degradation products in the experimental group increased significantly. In 12 weeks, new bone was in contact with the scaffold around the scaffold in the experimental group. There was less new bone in the bone cement group and the blank group. Conclusion: The porous WE43 magnesium alloy scaffold fabricated by 3D printing process has good biocompatibility and good osteogenic properties, and has the potential to become a new material for repairing bone defects.