Abstract
Abstract: :
Purpose: Amniotic membrane has been widely used as a graft in ocular surface reconstruction and as a substrate for the in vitro expansion of corneal limbal epithelial cells. To determine, whether the specific extracellular niche parameters required for maintaining an undifferentiated phenotype are reflected by this substrate, we comparatively analyzed the basement membrane composition of the human limbal and amniotic membrane epithelia. Methods: Cryosections of human corneoscleral specimens from 10 donor eyes and of 5 amniotic membrane specimens obtained at Cesarean sections were stained by indirect immunofluorescence using a broad panel of antibodies against basement membrane components. Results: Both the limbal epithelial and the amniotic epithelial basement membranes showed positive immunoreactivity for collagen type IV (α1, α2, α5, and α6 chains), laminin (α3, ß1, γ1, and γ2 chains), laminin–1 and –5, perlecan, nidogen–1 and –2, agrin, fibronectin, collagen types VII, XV, XVI, and XVII, matrilin–4, and tenascin–C. Similarly, both basement membranes were negative for collagen type IV (α3 and α4 chains), laminin (α4, ß2, ß3, and γ3 chains), and collagen type V. Differences in distribution patterns of basement membrane components were observed for laminin (α1, α2, and α5 chains), BM40/SPARC, collagen type XVIII, endostatin, and matrilin–2, which revealed positive immunoreactivity in the limbal basement membrane, but negative immunolabeling along the amniotic basement membrane. Conclusions: In spite of minor differences, the basement membrane composition of amniotic membrane largely resembles that of the corneal limbal epithelium suggesting that amniotic membrane provides a proper microenvironment for the maintenance of an undifferentiated phenotype. The findings, therefore, support the concept that epithelially denuded amniotic membrane represents a suitable substrate for the in vitro expansion and transplantation of limbal epithelial cells.
Keywords: cornea: epithelium • cornea: basic science • extracellular matrix