Cross-linking of human amniotic membrane by ultraviolet A-riboflavin / 中华实验眼科杂志

ABSTRACT

BackgroundStudies confirmed that ultraviolet A (UVA)- riboflavin photodynamic therapy can control keratoconus progresses by altering the physicochemical property of cornea.The collagen components of amniotic membrane transplantation is similar to that of cornea and amniotic membrane transplantation has been widely used to ocular surface reconstruction.However,the study on UVA riboflavin-induced-collagen crosslinking for amniotic tissue is less now.ObjectiveThis study was to investigate the role of UVA-riboflavin on frozen-preserved human amniotic membrane.Methods Human amnions were obtained in informed consent and prepared into 2 mm×15 mm pieces and were then divided into 4 groups using lottery method and 6 pieces for each group.The first 3 groups were treated with the photosensitizer riboflavin and UVA-irradiation ( wavelength370 nm ; irradiation energy1,2 or 3 mW/cm2,distance10 mm) for 30 minutes,and the untreated fourth group was as control group.Biomechanical stress-strain test was performed using a microcomputer-controlled biomaterial tester and the stress(mN) was recorded when the strains were set to 5％,10％ and 15％.The 7 mm diameter of human amniotic membrane pieces were trephined and divided into 4 groups(5 pieces for each group) with the treated method as mentioned above,and then the buttons were exposed to 0.1％ collagenase Ⅰ solution.The transparency was scored and the complete dissolving time was record.In histological evaluation,three groups (3 pieces for each group) of human amniotic membranes were treated using UVAriboflavin(3 mW/cm2),0.1％riboflavin,normal saline for 30 minutes respectively and examined under the transmission electron microscopy.This study was performed under the permission of the Ethic Commission of Beijing Tongren Hospital.ResultsWhenthestrainwas 5％,10％,15％,thestressof controlgroupand1,2,3 mW/cm2UVA group were statistically signifcantly different ( F =3.411,P =0.037; F =9.927,P =0.001;F=11.118,P=0.000).The tensile strength of human amniotic membrane cross-linked with UVA-riboflavin was statistically significantly increased in comparison to the control group (P＜0.05 ),and the tensile strength of human amniotic membrane became stronger as UVA power increased.The complete dissolve time was (8.6± 1.8 ) hours for the control group,(39.6± 2.3 ) hours for 1 mW/cm2 UVA group,(71.4±0.9 ) hours for 2 mW/cm2 UVA group,(78.8± 1.8 ) hours for 3 mW/cm2 UVA group,showing the enhanced anti-enzyme ability of human amniotic membrane after cross-linking(P＜0.01 ).The collagen density in the UVA-riboflavin treated group was increased,the connection among the collagen fibers as well as between the stroma and the epithelium became tighter than those of control group.ConclusionsCollagen cross-linking with UVA-riboflavin make the biomechanical strength and enzymatic resistance of human amniotic membrane enhance and ultrastructure change of human amniotic membrane.