Authors:
M. E. Zuber, E. Solessio, Y. Lyou, A. S. Viczian
Summary:
Pluripotent cells are a potential starting point from which to generate organ specific stem cells. For example, conversion of pluripotent cells to retinal stem cells could provide an opportunity to treat retinal injuries and degenerations. Although pluripotent cells have been induced to express some retinal markers, it is not known if retinal stem cells form, or if induced cells can generate functional retina. We took advantage of the relatively simple Xenopus laevis animal cap system to address these questions. Previous work demonstrated that a group of transcription factors (the eye field transcription factors; EFTFs) are coordinately expressed in the embryonic eye field, form a self-regulating feedback network and are essential for eye formation. Primitive ectoderm cells isolated from the animal pole of blastula stage embryos are pluripotent. When cultured in isolation, then transplanted to developing embryos, the cells differentiate into epidermis. However, if treated with the appropriate inducer, they can form cell types of all three germ layers. Using microarray analysis we found that cultured, EFTF-expressing primitive ectoderm has a transcriptional profile similar to the endogenous eye field. EFTF-expressing cells also appear determined to form retinal tissue since they generate retinal cells and eye-like structures when transplanted to the embryonic flank. We show the cells are self-renewing as they continue to proliferate in the peripheral retina where adult retinal stem cells are normally located. As a test of multipotency, we replaced one of the two endogenous eye fields with EFTF-expressing pluripotent cells. Donor cells differentiated into all seven retinal cell classes of the mature retina, including retinal ganglion cells, which extended axons to the host brain. Using both the electroretinogram and a phototropic behavioral assay we show the eyes that form from induced retinal cells are functional. Since EFTF-expressing pluripotent cells are both multipotent and self-renewing, we have named these cells induced retinal stem cells (iRSCs). Our results demonstrate the fate of pluripotent cells can be purposely altered to generate multipotent retinal stem cells, which differentiate into functional retinal cell classes and form a neural circuitry sufficient for vision.
Source:
Society for Neuroscience 2008; Washington Convention Center, Room 147B, 4:00 PM–4:15 PM, Abstract 407.13, Page 5-6 (11/17/08)