Retina stem cells, hopes and obstacles

Figure 1 Origin of the different cell types from embryonic stem cells (ESCs) in the developing embryo. ESCs from the inner cell mass of a preimplantation embryo can give rise to all the cell types and to an entire organism.

Figure 2 Regulatory control of self-renewal and differentiation by transcription factors and microRNAs. Oct4, Sox2 and Nanog prevent microRNA-145 from blocking the self-renewal of SC. Conversely, microRNA-145 promotes cell differentiation by inhibiting expression of Oct4, Sox2 and Nanog. Let-7, another microRNA, promotes differentiation by interfering with cell cycle regulators, and is regulated in turn by microRNA-145 and Lin 28.

Figure 3 microRNA-145 and transcription factors Sox2, Oct4 and Nanog regulate cell renewal and differentiation. Sox2, Oct4 and Nanog interact with microRNA-145 to regulate cell cycle and differentiation of stem cells.

Figure 4 Stem cell properties of Müller glial cells. Photomicrographs of Müller glial cell cultures from rat retina in interphase (left) or mitosis (self-renewal) (right), showing nuclei labeled with the DNA probe DAPI, expression of the stem cell marker nestin (red) and of vimentin (green). Arrows indicate mitotic anaphases. The bar indicates 150 µm.

Figure 5 Activation of gliosis by the JAK2/STAT3 signaling cascade. Jak/Stat signaling cascade is activated by ciliary neurotrophic factor and other factors, generating phosphorylated STAT3 intermediates, which turn on glial fibrillary acidic protein promoter gene to induce gliosis. CNTF: Cliary neurotrophic factor; GFAP: Glial fibrillary acidic protein.