Using mice models, scientists have transplanted photoreceptor-precursor cells directly into the retina of the eyes, thus restoring visual function.

Rather than injecting undifferentiated and uncommitted stem cells into the retina in hopes they would develop into photoreceptors, researchers introduced cells at a somewhat later stage. These cells are referred to as "precursors": they are immature cells that are "programmed" to be, but have not yet become, functionally mature photoreceptors-the light-sensitive cells in the retina that are essential for sight.

An exact equivalent of this technique may be difficult to carry out in humans as photoreceptor-precursor cells will have to be sourced from fetuses. However, the authors suggest that such cells may be derived from adult of embryonic stem cells. This provides potentials in reversing blindness such as those resulting from retinitis pigmentosa and macular degeneration The study is published in the November 9 advance online issue of Nature. For an overview, see the feature report from NatureNews or the UMHS press release.

[Photo: Rod photoreceptors disassociated from mouse retina expressing green fluorescent protein. Scientists use an NRL gene regulatory element to tag photoreceptor rods and prepare them for transplantation. Amacrine cells in the inner retina are shown in red. Credit: UMHS]