Differential distribution of subchains of the basement membrane componentstype IV collagen and laminin among the amniotic membrane, cornea, and conjunctiva

Purpose. Amniotic membrane transplantation has been reported to be an effec tive surgical procedure for the reconstruction of the anterior segment of t he eye. To understand better the function of transplanted amniotic membrane , we compared the distributions of subchains of type TV collagen and lamini n in the amniotic membrane to those in the cornea and conjunctiva. Methods, Five human corneas with conjunctivas and three human amniotic membranes we re frozen in OCT compound. Cryosections were cut with a cryostat and staine d by an indirect immunofluorescent microscopy. We used antibodies of the co llagen alpha 2(IV) and alpha 5(IV) subchains, laminin-1, laminin-5, fibrone ctin, and type VII collagen. Results, In the conjunctival basement membrane and the amniotic membrane, fluorescence was evident for collagen alpha 2(I V) but not for collagen alpha 5(IV). By contrast, in the corneal basement m embrane, fluorescence was apparent for the collagen alpha 5(IV) subchain bu t not for the collagen alpha 2(IV) subchain. Laminin-1, laminin-5, fibronec tin, and type VII collagen were present in all the basement membranes exami ned. Conclusion. The distribution of alpha subchains of type IV collagen in the amniotic membrane was identical to that in the conjunctiva but differe nt from that in the cornea. No difference in the distribution pattern of ot her basement membrane components was observed. These results demonstrate th at the basement membrane of the amniotic membrane and the conjunctiva might share the same components; therefore, the amniotic membrane might be usefu l as a replacement for the basement membrane of the conjunctiva.