Abstract
Abstract: :
Purpose: To study the development of the postnatal gerbil retina in order to compare it with that of mouse and rat. Based on this knowledge, we attempted a reconstruction of the postnatal gerbil retina from dissociated cells, as a model for future tissue engineering of a human retina. Dissociated embryonic retinal cells of the chick are well suited to reaggregate and establish 3–dimensional spheres (see refs.). However, attempts to reaggregate retinal cells from mammals (mouse, rat) and to form highly organised retinal spheres, so far mostly were limited. Methods: Using a number of immunohistochemical markers, a series of retinal sections from P1–P20 were analysed. Further, we describe experiments using dissociated retinal cells of the newborn (P1) Mongolian desert rat (Gerbil, or Meriones unguiculatus). By systematically adjusting culturing parameters, we have succeeded in producing two types of histotypically organised spheres. Cell types within spheres were characterised by immunohistochemistry Results: The developmental study shows significant spatial, temporal and cell–type specific differences of retinal development in gerbil when compared with mouse and rat. In particular, this applies to the expression of calcium binding proteins calretinin, calbindin and parvalbumin. Our in vitro study shows that if retinal cells alone are reaggregated, regions homologous to the inner half of the retina are discernible, while photoreceptors are not detectable. A major structural improvement is achieved with a second set–up, where retinal cells are reaggregated in presence of supernatants from cultures of mouse retinal pigmented epithelium (RPE). All spheres are covered by an outer layer of cells, which are characterised as ganglion cells. This GCL is separated from an inner core of cells by a well established IPL. In the inner cell core amacrine and horizontal cells, but no photoreceptors are discernible. Conclusions: We have managed to generate highly organised retinal spheres from the postnatal Gerbil, consisting of a GCL, an IPL and an INL, but no ONL. This represents a major breakthrough towards tissue engineering of a mammalian retina. References: Layer, P.G. et al. (2001). From stem cells towards neural layers... NeuroReport 12(7), A39–46. Layer, P.G. et al. (2002). Of layers and spheres: the reaggregate approach in tissue engineering. Trends Neurosci. 25(3), 131–134.
Keywords: retina • photoreceptors • regeneration