Abstract
Purpose:
Due to its anti-inflammatory properties, amniotic membrane has developed into a mainstay of treatment of patients with exposure keratopathy due to burns, to help maintain the ocular surface when skin grafting is delayed. However, due to a host of factors, to include elevated room temperature, desiccation, and inflammatory cytokines in the tear film, the amniotic membrane breaks down rapidly, lasting only 1-3 days. Utilizing our previously described exposure keratopathy model, this study utilized two methods to crosslink amniotic membrane to determine if it was possible to increase its resistance to degradation without reducing its anti-inflammatory properties.
Methods:
Thirty-six New Zealand White Rabbits were included in this study. Utilizing our previously reported model of exposure keratopathy, the right upper and lower eyelids were subjected to maximal blepharoplasty and the nictitating membrane was removed. One week following the rabbit was returned to the operating room where cryopreserved amniotic membrane, diimide covalently crosslinked or rose Bengal photocrosslinked amniotic membrane was draped over the cornea and sutured to the limbal conjunctiva and followed for 28 days (n=12) for each arm. The rabbits were returned to the operating room to resuture, patch or replace the amniotic membrane whenever exposure occurred. Histopathological analysis, as well as the number and type of procedures were recorded for each rabbit. Additionally chemokine/ cytokine tear film analysis was conducted using the multiplex immunoassay.
Results:
HIstopathological analysis was performed using a 5 point grading system. The results were then analyzed utilizing an ANOVA with Tukey adjustment. Preliminary results revealed no significant difference between the groups. Additionally Kaplan survival analysis was performed to evaluate the degradation of the amniotic membranes. Both crosslinked membranes performed statistically better than the native amniotic membranes. MMP-9 levels were not statistically different between the groups.
Conclusions:
Moderate amounts of crosslinking (diimide covalent crosslinking or rose Bengal photocrosslinking) of amniotic membrane appears to improve its ability to withstand degradation, and reduce surgical interventions, while not sacrificing its inherent anti-inflammatory properties.