Purpose  

To investigate by immunohistochemical observation the effects of amniotic membrane (AM) patching on myofibroblastic differentiation and matrix metalloproteinase (MMP) expression in the corneal stroma after an alkali burn in vivo.

Methods  

A corneal alkali burn was made by placing a circular piece of filter paper containing 1 N NaOH on the central cornea of rabbits. Burning was done unilaterally in each rabbit. Immediately after the wounding, in the AM group, AM was sutured onto the cornea and removed on day 1. Rabbits with no AM patching were controls. On day 14, corneas were excised and immunohistochemical observation was carried out using antibodies against α-smooth muscle actin (α-SMA), vimentin, MMP-1, MMP-2, MMP-9, and membrane-type1 (MT1)-MMP. Observation after Masson trichrome staining was also performed.

Results  

In the AM group, α-SMA positive cells were noticeably fewer, and MMP-2, MMP-9, and MT1-MMP expression was clearly inhibited. Also, collagen fibers were more regularly arranged than in control eyes. The more proximate the cells were to the epithelial side, the fewer α-SMA-positive cells were observed in the AM group.

Conclusions  

AM patching suppressed myofibroblastic differentiation and MMP expression in the stroma after an alkali burn. An inhibition gradient suggests that AM may release unknown soluble factors possessing some antiscarring capability. Jpn J Ophthalmol 2007;51:3–9 © Japanese Ophthalmological Society 2007