Abstract
Purpose::
A new type of retinal prostheses (Okayama University Type Retinal Prosthesis) utilize photoelectric dye molecules which absorb the light and convert photon energy to electric potentials. One of these dyes coupled to polyethylene film surface, as a prototype of retinal prostheses, could induce the response in chick embryonic retinal cells. In this study, we observed by scanning electron microscopy the surface of the original and modified types with cultured neurons and glial cells to search for a better tissue-prosthesis interface.
Methods::
The extruded-blown film of high density polyethylene was used as the original polyethylene film. Polyethylene film surface was modified either by coupling with type 1 collagen or by recrystallization from the melt of the original polyethylene film. A photoelectric dye, 2-[2-[4-(dibutylamino)phenyl]ethenyl]-3-carboxymethylbenzothiazolium bromide, was coupled to these different types of polyethylene films through amide linkage. Retinal cells from 12-day chick embryos were cultured on the surface of the dye-coupled films. Cell types, either neurons or glial cells, on the film surface, were detected by immunocytochemistry and observed by scanning electron microscopy.
Results::
Chick embryonic retinal cells, including both neurons and glial cells, could be cultured on the surface of the original dye-coupled film, collagen-coated dye-coupled film, and dye-coupled recrystallized film, and dye-"un"coupled plain film. By immunocytochemistry, the number of retinal neurons on the surface of the collagen-coated dye-coupled film and dye-coupled recrystallized film was significantly larger than the number of neurons on the dye-"un"coupled plain film (P<0.0004, ANOVA, P<0.05, Tukey-Kramer test). By scanning electron microscopy, Muller cell-like large cells covered the original dye-coupled film and collagen-coated dye-coupled film, and neuron-like small cells formed colonies on the Muller cell-like cells. In contrast, neuron-like small cells settled directly on the surface of the dye-coupled recrystallized film and few Muller cell-like cells adhered to its surface.
Conclusions::
Combining the results obtained by immunocytochemistry and scanning electron microscopy, the dye-coupled recrystallized film is a better candidate for retinal prostheses because of less adherence of glial cells to the surface.
Keywords: retinal glia • microscopy: light/fluorescence/immunohistochemistry • microscopy: electron microscopy