A Nanofibrillar Surface Promotes Superior Growth Characteristics in Cultured Human Retinal Pigment Epithelium

Abstract

Background: To evaluate the influence of surface topography on the proliferation of the retinal pigment epithelium (RPE) by comparing nanofibrillar and smooth substrates. Methods: Electrospun polyamide nanofibers (EPN) are an engineered surface mimicking native basement membranes. Commonly used plastic (polystyrene, PS) and glass substrates have a smooth topography. All were analyzed by scanning electron microscopy. RPE cultures were established from fetal and adult donors. Growth curves were established on the above substrates. Cell cycle and growth fractions were analyzed with 5-ethynyl-2′-deoxyuridine (EdU) and 4′,6-diamidino-2-phenylindole (DAPI). Results: At a magnification of ×5,000, EPN showed randomly overlapping fibers and pores. The surface of glass was slightly studded yet regular, in contrast to ideally smooth PS. Polygonal cells grew on nanofibers in a colony-like distribution, while randomly spread spindle-shaped cell morphologies were seen on smooth surfaces. This was observed at all donor ages. Initial proliferation rates were higher on EPN, and similar final cell densities were reached in all age groups, compared to an age-related decline on PS. EdU/DAPI revealed faster cell cycles on EPN. Growth fractions were higher and maintained longer on EPN. Observed substrate differences in growth behavior were statistically significant. Conclusion: Surface topography appears to induce distinct RPE proliferation characteristics.