Abstract
Purpose: :
Photoelectric dyes absorb the light and convert photon energy to electric potentials. We have screened photoelectric dyes using embryonic chick retinal cells in culture and calcium imaging, and showed the feasibility of these dyes as components for retinal prostheses. One of these dyes coupled to polyethylene film surface, as a prototype of retinal prostheses (Okayama University Type Retinal Prostheses), could induce intracellular calcium elevation in chick embryonic retinal tissues which have not yet developed photoreceptor outer segments. Furthermore, chick embryonic retinal cells cultured on the surface of the prototype also showed the response. In this study, we assessed neuronal and glial colony formation on the original and modified types of retinal prostheses to search for better interface between the tissue and the prostheses.
Methods: :
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 chick embryos at the 12–day embryonic stage were cultured on the surface of the dye–coupled films. The response of retinal cells to the dye–coupled films was observed by calcium imaging. Cell types, either neurons or glial cells, were detected by immunocytochemical staining.
Results: :
Intracellular calcium elevation was observed in both neurons and glial cells on the surface of the original dye–coupled film, collagen–coated dye–coupled film, and dye–coupled recrystallized film, in contrast with no response of cells cultured on the dye–"un"coupled plain film. Retinal neurons grew upon the colonies of glial cells settling on the surface of all different types of the films. The number of retinal neurons on the collagen–coated film and the recrystallized film was significantly larger than the number of neurons on the dye–uncoupled plain film (P<0.0004, ANOVA, and P<0.05, Tukey–Kramer test).
Conclusions: :
Retinal neurons and glial cells were cultured directly on the different types of the dye–coupled polyethylene films and showed the response. The photoelectric dye–coupled polyethylene films could be used as prototypes of retinal prostheses.
Keywords: retinal culture • immunohistochemistry • calcium