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

Abstract

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. Key words: Sustained release; Amniotic membrane/drug-loading amnion; Corneal ulceration; Levofloxacin; Ocular surface reconstruction