The effects of epithelial and spongy layers on transparency of amniotic membrane as a substitute for corneal tissue engineering

The light transmittance through amniotic membrane (AM) has a major effect on the visual acuity after transplantation of this biomaterial for reconstruction of the cornea. In this study, we evaluated role of placental region of extracted AM and histological layers of the amnion on the light transmission ability (transparency).
Material and The AMs were obtained from disk and peripheral (2 cm away from disk edge) regions of the placenta. The light transmission rates of the prepared intact tissues and also of the tissues after removal of the epithelial and spongy layers were measured. We determined the thicknesses of AMs by evaluating the photos of histological sections using software analyses.
Peripheral region of the AM was more transparent than the disk region. Histological studies revealed structural differences between epithelial cells of disk and peripheral regions. Removal of the epithelial cells increased the transparency of AMs and omitted the transparency difference between disk and peripheral regions, while, the thickness of the AMs samples of the two regions had significant differences after removal of the epithelial layer.
The epithelial cells of the AM, which have stem cell characteristics, play a major role in the light transmission ability of the AM, and thickness of the membrane had no significant impact on its light transmission rate.