Evaluating a prototype transplantation device to deliver scaffolds into the rodent subretinal space

Abstract

Purpose : Synthetic scaffolds can promote the organized delivery of cells for stem cell based replacement therapies. Animal testing is often performed in rodents, however, subretinal scaffold transplantation into the small rodent eye is technically challenging. The purpose of this study was to evaluate a custom made transplantation device that can fold scaffolds into a small insertion tip designed to reduce surgically induced trauma.

Methods : Scaffolds made from SU-8 were generated using standard photolithography techniques. These scaffolds were 8µm thick with 5µm pores, and punches 1mm in diameter were created for transplantation. Prior to delivery, a small incision was made in the rat sclera, and a subretinal bleb of HBSS buffer was created with a 33 gauge Hamilton microsyringe. Scaffolds were then placed into the loading port of the transplantation device. The tip of the device was then inserted through the scleral hole, and the scaffold was ejected and unfolded in the subretinal space. Rats were monitored for up to 1 month and eyes were enucleated and processed for immunocytochemistry.

Results : Previously, we have used a proprietary transplantation device (PCT/US10/60622) to deliver scaffolds as a flat sheet, however this required a large incision for the insertion of the flat plastic tip (1.5mm in diameter). By comparison, the present proprietary prototype (PCT/US2015/060219) device required a much smaller entry point, and induced much less trauma and bleeding. These scaffolds were well tolerated in the subretinal space, with minimal gliosis apparent at one month post-surgery.

Conclusions : In this study, we demonstrate successful scaffold insertion into the rat subretinal space with minimal trauma. Our prototype instrument makes scaffold transplantation into the rodent retina more feasible, and may reduce the need to use more expensive large animal models. Current studies are underway examining the transplantation of scaffolds seeded with stem cell-derived RPE and photoreceptors.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.