Mesh-supported submicron parylene-C membranes for culturing retinal pigment epithelial cells

In this work, a mesh-supported submicron parylene-C membrane (MSPM) is proposed as an artificial Bruch's membrane for the therapy of age-related macular degeneration (AMD). Any artificial Bruch's membrane must first satisfy two important requirements. First, it should be as permeable as healthy human Bruch's membrane to support nutrients transportation. Secondly, it should be able to support the adherence and proliferation of retinal pigment epithelial (RPE) cells with in vivo-like morphologies and functions. Although parylene-C is widely used as a barrier layer in many biomedical applications, it is found that parylene-C membranes with submicron thickness are semipermeable to macromolecules. We first measure the permeability of submicron parylene-C and find that 0.15-0.30 μm parylene-C has similar permeability to healthy human Bruch's membranes. Blind-well perfusion cell viability experiments further demonstrate that nutrients and macromolecules can diffuse across 0.30 μm parylene-C to nourish the cells. A mesh-supported submicron parylene-C membrane (MSPM) structure is design to enhance the mechanical strength of the substrate. In vitro cells culture on the MSPM (with 0.30 μm ultrathin parylene-C) shows that H9-RPE cells are able to adhere, proliferate, form epithelial monolayer with tight intracellular junctions, and become well-polarized with microvilli, which exhibit similar characteristics to RPE cells in vivo. These studies have demonstrated the potential of the MSPM as an artificial Bruch's membrane for RPE cell transplantation.