Abstract
Purpose :
Amniotic membrane (AM) has been shown to enhance corneal wound healing and has significant clinical utility as a biological dressing for a number of ophthalmic applications. Most commercially available AM products have strict refrigeration requirements limiting the availability of the tissue. The goal of this study was to develop a sterile, “off-the-shelf” AM tissue scaffold utilizing a novel supercritical carbon dioxide (SCCO2) sterilization process in conjunction with lyophilization for use in corneal wound management.
Methods :
AM was isolated from donated placentas, rinsed in saline, placed epithelial side up on nitrocellulose paper and stored at -80°C (native AM; N-AM). N-AM was sterilized with SCCO2 and refrozen (F-AM) or sterilized with SCCO2, lyophilized for 24 hrs and kept at room temperature (L-AM). Water content and oxygen permeability (Dk) of samples was measured following ISO standard 9913-1. The permeability of AM to antibiotics was assessed using a Franz diffusion cell apparatus. Biocompatibility was evaluated in vitro by culturing human corneal epithelial (CE) cells with membranes or in vivo by placement of membranes over the ocular surface of rabbits.
Results :
The water content of N-AM, F-AM and L-AM was 92%, 92% and 88%, respectively. Using this information the Dk was calculated and found to be greater than 99 x 10-11 mlO2 cm/sec cm2 mmHg for all groups tested. F-AM and L-AM demonstrated increased permeability to antibiotics as compared to N-AM. CE cells attached to all groups evaluated, however, L-AM exhibited increased cell proliferation as compared to F-AM and N-AM. L-AM was secured over the ocular surface of rabbits for six days and did not induce corneal inflammation or swelling as determined by the McDonald-Schadduck scoring system.
Conclusions :
SCCO2 is an emerging tissue sterilization technology that provides a novel method for AM tissue graft preparation and sterilization, and better preserves the inherent biochemical and biophysical properties of the tissue. When combined with a lyophilization step, L-AM exhibits desirable properties of an ocular bandage and demonstrates improved biocompatibility compared to F-AM. Our method of sterilization, combined with lyophilization, renders a tissue graft that can be used as a bandage or a scaffold for ocular therapeutic applications without the need for costly and limiting storage requirements.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.