含镁多孔支架材料的体外抗菌活性和生物相容性

In vitro antibacterial activity and biocompatibility of a porous scaffold containing magnesium

背景:将多聚物材料与生物陶瓷材料复合制成有机/无机复合三维支架材料,可赋予支架骨传导所必需的理化特性,同时强化材料的力学性能,但大多数骨替代材料无法预防缺损部位的感染。研究发现由于镁的降解可产生局部碱性环境,使镁具有一定的抗菌活性。目的:探讨含镁多孔支架材料的体外抗菌活性和细胞相容性。方法:应用低温快速成型技术制备聚乳酸/β-磷酸三钙/镁多孔支架材料,其中β-磷酸三钙与镁的质量比分别为2∶1和1∶2,分别设为PTM(2∶1)组、PTM(1∶2)组;同时应用低温快速成型技术制备聚乳酸与聚乳酸/β-磷酸三钙多孔支架材料,分别设为P组、PT组。检测4组支架的表面形貌、孔径、孔隙率及压缩模量。将金黄色葡萄球菌(ATCC 35923)接种于4组支架表面24 h,通过涂板计数法和激光共聚焦显微镜观察材料的抗菌活性。将小鼠前成骨细胞MC3T3-E1分别与4组支架材料共培养,通过CCK-8法分析材料对细胞黏附和增殖的影响。结果与结论:①4组支架材料表面都形成相对均匀的多孔结构,4组支架间孔径大小和孔隙率比较差异均无显著性意义(P>0.05);②PTM(2∶1)组和PTM(1∶2)组压缩模量明显高于P组、PT组(P<0.05),PTM(1∶2)组明显高于PTM(2∶1)组(P<0.05);③涂板计数实验显示,PTM(2∶1)组、PTM(1∶2)组菌落形成单位明显低于P组、PT组(P<0.05),其余组间比较差异无显著性意义(P>0.05);④培养6 h,PT组、PTM(2∶1)组、PTM(1∶2)组黏附细胞数量多于P组(P<0.05),PTM(2∶1)组和PTM(1∶2)组比较差异均无显著性意义(P>0.05);⑤培养1 d时,仅PT组细胞增殖优于P组(P<0.05);培养4,7 d时,PT组、PTM(2∶1)组、PTM(1∶2)组细胞增殖均优于P组(P<0.05),PTM(2∶1)组和PTM(1∶2)组比较差异均无显著性意义(P>0.05);⑥结果表明,聚乳酸/β-磷酸三钙/镁多孔支架材料不但具有良好的抗菌活性,而且具有优良的细胞相容性和一定的抗压能力。

BACKGROUND:The three-dimensional organic/inorganic scaffold materials using polymer/bioceramic composites can endow the necessary physical and chemical properties and enhance the mechanical properties of the materials.However,most bone substitution materials cannot prevent infection at the defect site.It has been found that the degradation of magnesium can produce local alkaline environment,so that magnesium has certain antibacterial activity.OBJECTIVE:To investigate the in vitro antibacterial activity and cytocompatibility of magnesium-containing scaffolds.METHODS:Polylactic acid/β-tricalcium phosphate/magnesium porous scaffolds were prepared by low-temperature rapid prototyping technology.The PTM(2∶1)and PTM(1∶2)groups referred to two mixing mass ratios(β-tricalcium phosphate∶magnesium=2∶1 and 1∶2),respectively.Two scaffolds of polylactic acid(P group)and polylactic acid/β-tricalcium phosphate(PT group)were also prepared by low-temperature rapid prototyping technology.The surface morphology,pore size,porosity and compression modulus of the scaffolds were measured.Staphylococcus aureus(ATCC 35923)was seeded on the scaffolds of each group for 24 hours.The antibacterial activity of the scaffolds was observed through spread plate method and confocal laser scanning microscopy.Mouse preosteoblasts MC3T3-E1 were co-cultured with the scaffolds of each group.The cell attachment and proliferation were evaluated by cell counting kit-8 assay.RESULTS AND CONCLUSION:(1)A relatively uniform porous structure was found on the scaffold surfaces in each group.There were no significant differences in the pore size and porosity among groups(P>0.05).(2)The compression modulus in the PTM(2∶1)and PTM(1∶2)groups were significantly higher than those in the P and PT groups(P<0.05),and those in the PTM(1∶2)group were significantly higher than those in the PTM(2∶1)group(P<0.05).(3)The results of the spread plate method showed that the bacterial colony formation unit in the PTM(2∶1)and PTM(1∶2)groups was significantly lower than that in the P and the PT groups(P<0.05),and the difference among the other groups was insignificant(P>0.05).(4)After 6 hours of culture,the number of attached cells in the PT,PTM(2∶1)and PTM(1∶2)groups was greater than that in the P group(P<0.05),and there was no significant difference between PTM(2∶1)and PTM(1∶2)groups(P>0.05).(5)At 1 day of culture,the cell proliferation in the PT group was superior to that in the P group(P<0.05).At 4 and 7 days,the cell proliferation in the PT,PTM(2∶1)and PTM(1∶2)groups was superior to that in the P group(P<0.05),and there was no significant difference between PTM(2∶1)and PTM(1∶2)groups(P>0.05).(6)These results indicate that the polylactic acid/β-tricalcium phosphate/magnesium scaffold not only possesses good antibacterial activity,but also exhibits excellent cytocompatibility and certain anti-compressive ability.