Retinal Transplantation of Neural Precursor Cells and Their Gene-Modification

Abstract

Abstract: : Purpose: In mammals, matured retina does not show regenerative capacity after injury. Development of renewable cell source is required for retinal transplantation therapy. This study was conducted in an attempt to investigate possibility of gene-modified neural precursor cells (NPCs), as a potential cell source is required for retinal transplantation. Methods: NMDA (4mM, 5ul) was injected into the intravitreal space of adult rat to induce retinal cell death. NPCs were prepared from the telencephalic neuroepithelium of EGFP (enhanced green fluorescence protein) transgenic mice on embryonic day 14. Cell suspension (5x105 cells) was injected into intravitreal or subretinal space of NMDA-treated eyes. At 1, 2 or 4 wk after transplantation, sections were prepared for immunohistochemistry. Overexpression of neurogenin (ngn) 2, a basic helix-loop-helix transcriptional factor, in NPCs was performed with a retrovirus vector encoding ngn2-IRES-EGFP. Results: NPCs prepared from EGFP transgenic mice have a potential to differentiate into GFAP-positive (glial) and bÖ°-tubulin-positive (neuronal) cells. Retinal transplantation of NPCs revealed that the transplanted cells survive for at least 28 days and differentiate into both glial and neuronal cells with a preference of the former. Markers for retinal cell types were not expressed in the transplanted cells. Retrovirus-mediated gene expression of ngn 2 in NPCs led to appearance of more neuronal cells in vitro. Our in vivo experiments showed the possibility and usefulness of retinal transplantation of gene-modified NPCs as a novel cell source for retinal regenerative therapy. Conclusions: We demonstrated that the transplanted NPCs are viable in the matured retina for at least 28 days. We also showed neurogenic differentiation of NPCs by ngn 2 expression.

Keywords: transplantation • cell adhesions/cell junctions • retinal connections, networks, circuitry