Abstract
Purpose: :
Corneal chemical burns are a common cause of potential vision loss. Alkaline agents, found in caustic soda lime, have both hydrophilic and lipophilic properties allowing them to pass cell membranes easily making them particularly damaging and able to gain access to the anterior chamber quicker. Hydroxyl ions cause saponification of cell membranes, disrupt extracellular matrix, and ultimately cell death. Alkali burns revoke the immune privilege of the cornea and may also result in limbal stem cell deficiency. In this study we aim to visualize and assess immune cell infiltration of the cornea after alkali insult and the immunomodulatory affects of amniotic membrane transplantation (AMT).
Methods: :
C57 mice receive a corneal alkali burn of 0.5M NaOH for 20s and then thoroughly flushed until a resulting corneal surface pH of 7-7.4 is reached. Mice then receive AMT (AmbioDry2) with running 11-0 Nylon suture. Control groups include alkali burn only, and alkali burn plus suture (no AMT). Mice were clinically scored on clarity, vascularity, scar formtion, and fluorescein staining on post operation days (POD) 0, 1, 3, 5, 7, 10, 14, 21, 28. Eyes were then harvested and used for H & E staining and immunohistochemistry. Neutrophils, macrophages, and B & T cells were stained for imaging and localization. Chimeric eGFP mice were also utilized to assess in vivo cell migration into the cornea after alkali burn. These eyes were scored using the methods above with the addition of fluorescent imaging to visualize eGFP expressing cells.
Results: :
Mice treated with amniotic membrane had lower corneal clarity scores (clearer corneas; 1.7 vs. 3.15 at POD25) and had less corneal vascularity than control and suture groups. Differences in groups began at POD10 and continued through until the end of the experiment. Both control and AMT treated mice had high levels of neutrophil infiltration at POD3, with no significant difference. However, AMT treated mice had fewer macrophages, B & T cells than mice in the alkali burn only group at POD 28. Less eGFP cells were also noted in AMT treated mice versus alkali burn only or suture/burn mice.
Conclusions: :
AMT is used in the treatment of many ocular surface disorders. In this study we show the effect of AMT to decrease immune cell infiltration into the cornea after alkali insult.
Keywords: transplantation • immunomodulation/immunoregulation • cornea: epithelium