An overview of scaffolds for retinal pigment epithelium research

The reduced capabilities of retinal pigment epithelium (RPE) marks early retinal degenerative diseases and leads to blindness. Regenerating a functional RPE monolayer in vitro becomes significant and promise for developing new therapies. Many research activities have been done to develop new materials, structures and fabrication technologies to mimic native RPE structure for cell attachment and subsequent tissue development. Scaffold-based tissue engineering approaches attract intensive investigation, due to their capability and potential in building preclinical models and developing possible treatment for retinal degenerative diseases. Scaffolds in facilitating regeneration of RPE tissue in vitro has been proved by recent studies. Various materials have been applied, such as synthetic polymers, plant or animal extracted proteins, and composite materials. This review outlines the most recent fabrication progresses using these materials for RPE scaffolds, including both in vitro and in vivo trials, and the challenges in building a whole tissue model construct and transplantation. Additive manufacturing technologies at micrometer- and nanometer-scale are proposed as promising methods to build biomimetic RPE scaffolds in the current studies.