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G. Thumann, S. Tholl, B. Sellhaus, P. Walter, A. K. Salz; Comparison of Ultrathin Bovine Collagen Membranes and Human Amniotic Membranes for Ocular Applications. Invest. Ophthalmol. Vis. Sci. 2010;51(13):5250.
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© ARVO (1962-2015); The Authors (2016-present)
Reconstruction of corneas, chronic ulcer coverage, maculoplasty and other novel ophthalmic therapeutic approaches require implantation of biodegradable materials. Here we have compared characteristics of ultrathin bovine collagen and human amniotic membranes in vitro and in vivo after subconjunctival implantation in rabbits.
Bovine collagen 1 and human amniotic membranes stained with a non-toxic fluorescent dye for visualization were evaluated for diffusion properties, ability to support growth of BCE and RPE. Viability and morphological characteristics were evaluated using light and fluorescence microscopy. Diffusion kinetics of bromophenol blue (M.W. 692) were measured using a modified Ussing chamber. Membranes were transplanted subconjunctivally in rabbits to examine biocompatibility and degradation by clinical follow-up and histology. Inflammation was classified as acute or chronic by enumerating inflammatory cells in three 400x microscopic fields.
Both membranes were flexible, stable to handling and transparent when wet. BCE and RPE adhere spread and proliferated well on both membranes and reached confluence after 7 days when plated at 20.000 cells/cm2. Viability for both cell types on both membranes was greater than 98%. Diffusion coefficients were 2,79x10-7 for collagen and 6,76x10-8 for amniotic membranes indicating better diffusion characteristics for collagen. After subconjunctival transplantation membranes became enveloped by a delicate capsule and degradation was accompanied by invasion of giant cells one week after implantation. Degradation of amniotic membranes was completed between 11 and 13 weeks whereas degradation of collagen was completed by about 5 weeks.
Both collagen and amniotic membranes are suitable as ophthalmic bioengineering materials since both support cell growth and elicit only very mild inflammation. Availability of collagen from many sources should make collagen the preferred material, whereas the use of amniotic membranes will be limited by problems with obtaining human tissue and possibility of viral transfer from donor to recipient.
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