载药羊膜移植治疗感染性角膜溃疡的实验研究

Efficacy assessment of drug-loaded amniotic membrane transplantation for infectious corneal ulceration

背景 应用羊膜移植术治疗角膜溃疡的方法在临床上已广泛开展,但目前国内有关将羊膜作为药物载体治疗感染性眼表疾病的研究较少见. 目的 探讨载药羊膜在治疗眼表感染性疾病中的缓释性能并评价其疗效.方法 利用体外抑菌实验比较羊膜浸泡不同质量浓度（5、20、30 g/L）的左氧氟沙星不同时间（5、15、30、60 min）后平均抑菌环直径的改变.利用角膜基质层接种法将浊度为0.7麦氏单位的金黄色葡萄球菌菌悬液0.1ml自角膜近中央处注入角膜基质层,形成直径4.0～6.0 mm的混浊区,建立20只家兔单眼感染性角膜溃疡模型,采用随机数字表法将动物模型随机分为单纯羊膜移植联合点药组和载药羊膜移植组,每组各10只,两组家兔造模后24 h分别行单纯羊膜移植术或载药羊膜移植术.单纯羊膜移植联合点药组术后用质量分数0.5％左氧氟沙星滴眼液点眼,每日3次,分别于点眼后0.5、1.0、2.0、3.5、5.5h抽取房水0.1ml,载药羊膜移植组于术后1、3、7、10、14、21d抽取房水0.1ml,用高效液相色谱分析法检测各时间点兔眼房水中左氧氟沙星的质量浓度.各组大鼠在裂隙灯显微镜下观察角膜病变情况及角膜溃疡的面积变化,按照改进的McNeill角膜病变程度分级法对角膜病变进行评分,并于术后4周行兔眼角膜组织病理学检查.结果 左氧氟沙星体外抑菌实验表明,平均抑菌环直径随药物质量浓度的增加而增大,相同质量浓度左氧氟沙星浸泡15 min的羊膜与浸泡5 min相比抑菌环直径增大,差异均有统计学意义（P＜0.01）,但与浸泡30 min、60 min的羊膜相比差异均无统计学意义（P＞0.05）.单纯羊膜移植联合点药组术后房水中左氧氟沙星质量浓度随时间的延长而逐渐降低,0.5h为（0.873 ±0.264） mg/L,5.5h为（0.106±0.027） mg/L;载药羊膜移植组术后1、3、7d房水中左氧氟沙星质量浓度仍高于单纯羊膜移植联合点药组点药后0.5h,差异均有统计学意义（均P=0.00）.载药羊膜移植组家兔用药后1、2、4周角膜病变评分分别为1.7±0.6、1.3±0.5和0.2±0.4,明显低于单纯羊膜移植联合点药组的2.2±0.8、2.0±0.6和1.5±0.8,差异均有统计学意义（F分组=9.49,P=0.01；F时间=22.96,P=0.01）.术后1周载药羊膜移植组角膜溃疡面积明显小于单纯羊膜移植联合点药组,差异有统计学意义[（1.6±0.6）mm2 vs.（3.2±0.8）mm2,t=3.98,P=0.00].组织病理学检查显示,单纯羊膜移植联合点药组术后4周角膜各层排列不规则,出现1～2层新生鳞状上皮,基质层结构紊乱,可见较多炎性细胞浸润及残留血管腔；载药羊膜移植组术后4周角膜有4～5层新生鳞状上皮,排列整齐,仅见少量炎性细胞浸润及残留血管腔.结论 左氧氟沙星载药羊膜移植至角膜后具有一定的药物缓释性能,可以提高房水中的有效药物质量浓度,对金黄色葡萄球菌感染性角膜溃疡的疗效优于点眼的用药方式.

Background Treatment of corneal ulceration by transplanting drug-loaded amniotic membrane has been used widespreadly abroad,however,seldom study is found in China up to now.Objective This study was to explore the sustained release property and the efficacy of the drug-loaded amniotic membrane.Methods The bacteriostatic area of amniotic membrane fragments immersed with different concentrations （5,20,30 g/L） of levofloxacin for different time points （5,15,30,60 minutes） was evaluated by in vitro test.Bacterial corneal ulceration models were established in 20 rabbits by injected 0.7 MCF staphylococcus aureus suspension （0.1 ml） into the central corneal stroma to form the cloudy area of 4.0-6.0 mm.Then the rabbits were randomized into two groups.Regular amniotic membrane transplantation was performed laterally and 0.5% levofloxacin drops was topically administered after operation in the amnion＋levofloxacin drops group,and drug-loading amnion transplantation was used in the drug-loading amnion group.Aqueous humor of 0.1 ml was collected in 30 minutes,1 hour,2,3.5,5.5 hours after levofloxacin was administered and 1 day,3,7,10,14,21 days after operation for the detect of levofloxacin level with high-performance liquid chromatography.The corneal symptom was scored based on McNeill＇s criteria in 1 week,2 weeks and 4 weeks and the ulceration area was assessed under the slit lamp in the first week.The pathological examination was carried out in the fourth week after surgery.Results The mean bacteriostatic area was bigger with the increase of levofloxacin concentration,and bacteriostatic area in amnion immersed for 15 minutes was bigger than that of 5 minutes （P〈0.01）.The levofloxacin concentration of aqueous humor after transplantation was decreased by extending the time,and that in 30 minutes and 5.5 hours after operation was （0.873±0.264） mg/L and （0.106±0.027） mg/L,respectively,in the amnion＋levofloxacin drops group,and that in day 1,3,7 after surgery in the drug-loading amnion group was higher than at 30 minutes in the amnion＋levofloxacin drops group,showing all significant differences （all P =0.00）.In the first,second and fourth week after operation,the corneal symptom score was 1.7±0.6,1.3±0.5,0.2±0.4 in the drug-loading amnion group and 2.2±0.8,2.0±0.6,1.5±0.8 in the amnion＋ levofloxacin drops group,with the significant differences among the different groups and time points （Fgroup =9.49,P =0.01 ;Ftime =22.96,P=0.01）.The corneal ulceration area was （1.6±0.6） mm2 in the drug-loading amnion group and （3.2±0.8） mm2 in the amnion＋levofloxacin drops group 1 week after operation,showing a significant difference between them （t =3.98,P =0.00）.Histopathological revealed that the various layers of cornea tissue appeared irregular arrangement in the amnion ＋ levofloxacin drops group 4 weeks after operation with 1-2 layers of new squamous epithelium.Disorder hypothallus structure,more inflammatory cells and residual vascular cavity were visible.However,new squamous epithelium of 4-5 layers was seen in the drug-loading amnion group,and inflammatory cells and residual vascular cavity were less than the amnion＋levofloxacin drops group 4 weeks after operation.Conclusions Levofloxacin-loaded amniotic membrane can sustained release levofloxacin and maintain an effective drug concentration in aqueous humor,which improves the treating efficacy for staphylococcus aureus corneal ulceration.