Abstract
Purpose :
Several groups, worldwide are developing methods for subretinal transplantation of scaffold-supported stem cell-derived RPE and photoreceptor sheets as regenerative therapy for macular disease. Subretinal implantation of these constructs is challenging and requires specialized instrumentation designed to accommodate the size and mechanical characteristics of each tissue transplant. Consequently, each prototype tissue/scaffold construct would ideally be inserted using a customized delivery device. In this work we developed a rapid prototyping method that uses readily available office equipment for building microfluidic and actuator-based devices for deploying scaffold-supported tissue transplants into the subretinal space
Methods :
Microfluidic devices were designed using 2-Dimensional (2D) vector-based 2-dimensional (2D) computer-aided design (CAD) software (QCAD freeware (RibbonSoft, GmbH). 3-Dimensional structures were achieved by laminating multiple 2-D layers on top of each other. Each structural layer was fabricated from 180 micron thick polyethylene terephthalate (PTFE) transparency sheets, patterned using a computer-controlled drag-knife cutter used for sign and pattern making (Graphtec FXC4000, Graphtec GB Ltd). Waterproof silicone double-sided adhesive sheets (3M 91022, 3M Corp, MN) cut on FXC4000, were used to laminate each PTFE layer. A heated roller-based laminator was used to assure good film adhesion.
Results :
Prototypes were fabricated that could accommodate tissue constructs between 50 and 700 microns thick between 3 and 5mm wide. Overall device heights were 750 microns (360 micron high lumen) and 1080 microns (720 micron lumen). The prototypes had adequate rigidity and had sufficient durability for multiple uses. Microfluidic and actuator based designs were tested in-vitro for their ability to be loaded and to deploy planar sheets.
Conclusions :
The manufacturing method we report, based upon PTFE film laminates, bonded using double-sided silicone adhesive sheets, is a viable rapid prototyping approach for subretinal tissue delivery devices. This method is inexpensive, rapid and consequently allows for facile design modification (e.g. to accommodate grafts/implants with different dimensions and thickness). Future studies with these devices will examine their effectiveness in delivering subretinal tissue implants, in-vivo.
This is a 2020 ARVO Annual Meeting abstract.