Abstract
Abstract: :
Purpose: To investigate factors that promotes the development of photoreceptors in retinal neurospheres, and to study tissue integration of photoreceptors in cultured adult retina. Methods: Retinal progenitor cells were isolated from embryonic rat retinas and expanded in vitro into neurospheres in the presence of bFGF, EGF, and leukemia inhibitory factor (LIF). An in vitro system was designed to maintain a co–culture of neurospheres and adult retina for up to one week. The neurospheres were labeled with a fluorescent lipophilic dye prior to culture. All neurospheres and sectioned co–cultures were analyzed using immunohistochemistry. Results:By excluding LIF from the original culture paradigm, subsets of rhodopsin+–cells developed in the neurospheres. About 20 rhodopsin+–cells was observed in each neurosphere. Examination of co–cultures showed that the neurospheres integrated into the surrounding retinal tissue. Slender neuronal cell processes were found to project into the retina after one week of culture. Conclusions: Cell contacts in the neurospheres and omission of LIF seem to promote the development of rhodopsin+–photoreceptors. Neurospheres cultured without LIF showed a tendency of improved tissue integration into adult retina, perhaps as a result of their neuronal content.
Keywords: retinal culture • retina • retina: distal (photoreceptors, horizontal cells, bipolar cells)