Abstract
Purpose :
Future treatments for macular disease include the use of various forms of regenerative tissues. Sources of regenerative tissue are autologous, allografts, xenografts, and various stem-cell related constructs. Macular O-Rings (MORs) are a biocompatible structure, designed to serve as a platform technology to support tissue within the submacular space. The MORs are made of nitinol, a material with shape-memory properties. The memory of the nitinol is activated by temperature. The second generation MOR was refined with an austenite-finish (Af) temperature just below body temperature that optimizes the clamping capacity formed by shape memory and allows for surgical clamping of tissue.
Methods :
Two design phases of the MOR device (using Good Manufacturing Practice: GMP) were tested ex-vivo using fresh porcine globes, dissected to expose sections of choroid, Bruchs membrane, and retinal pigment epithelial (RPE) cells or CBR grafts. We tested the MORs (2 devices) ex-vivo for clamping CBR grafts from porcine specimens. Scanning electron microscopy (SEM) was used to image the tissue.
Results :
We tested two MOR devices. SEM confirmed that both devices were capable of clamping tissue. Due to the Af of the first generation MOR1, external thermal energy (cautery) was required to active the shape memory property and clamp CBR grafts. Next, using the second generation MOR2, a warmed, intraocular balanced salt solution (BSS; Alcon, Ft. Worth TX) was irrigated over the rings at a physiologic temperature (37° C), and tissue clamping (Af) was enabled without using thermal cautery. SEM was used to illustrate the ability of the devices to support a tissue graft, minimize folding, provide a support structure, and maintain an intact RPE cell layer integrity. SEM also showed some artifact from the device teeth may result in localized RPE injury.
Conclusions :
MORs represent a novel technology capable of supporting regenerative tissue grafts in the submacular space, can be thermally activated to clamp autologous CBR grafts, and still require further, pre-clinical in-vivo studies before they can be considered for human use.
This is a 2020 ARVO Annual Meeting abstract.