Adhesion Structures in Human Corneas After Amniotic Membrane Transplantation (AMT)

Abstract

Abstract: : Purpose: The exact time course, and patterns of corneal wound healing and integration of amniotic membrane (AM) into the cornea following AMT are not clearly established. The aim of the study was to investigate the formation of adhesion structures between AM and corneal epithelium. Methods: Penetrating keratoplasty (PKP) was carried out on 14 eyes of 14 patients (age 65.8+/–13.5 years) 19.3+/–20.7 (0.3 to 77) weeks after cryopreserved human AMT. The residual AM and the corneal buttons after PKP were examined by transmission electron microscopy (TEM) with special attention to structure and density of desmosomes and hemidesmosomes as well as continuity and thickness of basement membrane in different patterns of AM integration. Results: Remnants of AM integrated into the anterior cornea were found up to 77 weeks after AMT. Regenerating corneal epithelial cells were connected to each other by desmosomes at a density of 21.2+/–5.3 per 10µm membrane length. Corneal epithelial cells were attached to the underlying AM by well developed hemidesmosomes at a density of up to 16.5+/–2.3 per 10µm. AM basement membrane, which measures normally 182.1+/–13.4 nm in thickness was replaced by short segments of corneal epithelial basement membrane, which measured about 17.2+/–4.9 nm in thickness. Conclusions: AM integrates into the host corneal tissue after AMT. The formation of adhesion structures such as hemidesmosomes is important for anchoring and for the stability of the regenerating epithelium. The magnitude of the desmosome formation suggests, that AM is equivalent to the original corneal basement membrane. Our findings support the clinical experience obtained with the use of AM as substrate for epithelial regeneration.

Keywords: cornea: epithelium • cell adhesions/cell junctions • microscopy: electron microscopy