Differential Distribution of Subchains of the Basement Membrane Components Type IV Collagen and Laminin Among the Amniotic Membrane, Cornea, and Conjunctiva

Abstract

Amniotic membrane transplantation has been reported to be an effective surgical procedure for the reconstruction of the anterior segment of the eye. To understand better the function of transplanted amniotic membrane, we compared the distributions of subchains of type IV collagen and laminin in the amniotic membrane to those in the cornea and conjunctiva. Five human corneas with conjunctivas and three human amniotic membranes were frozen in OCT compound. Cryosections were cut with a cryostat and stained by an indirect immunofluorescent microscopy. We used antibodies of the collagen alpha2(IV) and alpha5(IV) subchains, laminin-1, laminin-5, fibronectin, and type VII collagen. In the conjunctival basement membrane and the amniotic membrane, fluorescence was evident for collagen alpha2(IV) but not for collagen alpha5(IV). By contrast, in the corneal basement membrane, fluorescence was apparent for the collagen alpha5(IV) subchain but not for the collagen alpha2(IV) subchain. Laminin-1, laminin-5, fibronectin, and type VII collagen were present in all the basement membranes examined. The distribution of alpha subchains of type IV collagen in the amniotic membrane was identical to that in the conjunctiva but different from that in the cornea. No difference in the distribution pattern of other basement membrane components was observed. These results demonstrate that the basement membrane of the amniotic membrane and the conjunctiva might share the same components; therefore, the amniotic membrane might be useful as a replacement for the basement membrane of the conjunctiva.