Evolution Research - General Evolution News

From Nature journal: Using a technique that may one day help blind people to see, researchers have shown in mice that retinal cells from newborns transplanted into the eyes of blind adults wire up correctly and help them to detect light.

The finding challenges conventional biological thinking, because it shows that cells that have stopped dividing are better for transplantation than the stem cells that normally make new cells.

For decades, researchers have sought a way to replace the light-detecting cells that carpet the back of our eyes - and which break down in diseases such as retinitis pigmentosa and macular degeneration. But they have struggled to find cells that will work normally after being transplanted into the eye. [More]

Also reported by New Scientist: "Cell transplant may restore lost sight"

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Based on "Retinal repair by transplantation of photoreceptor precursors" by Robert Maclaren et. al

Nature 444, 203-207 (9 November 2006) | doi:10.1038/nature05161; Received 2 June 2006; Accepted 10 August 2006

Abstract

Photoreceptor loss causes irreversible blindness in many retinal diseases. Repair of such damage by cell transplantation is one of the most feasible types of central nervous system repair; photoreceptor degeneration initially leaves the inner retinal circuitry intact and new photoreceptors need only make single, short synaptic connections to contribute to the retinotopic map. So far, brain- and retina-derived stem cells transplanted into adult retina have shown little evidence of being able to integrate into the outer nuclear layer and differentiate into new photoreceptors1, 2, 3, 4. Furthermore, there has been no demonstration that transplanted cells form functional synaptic connections with other neurons in the recipient retina or restore visual function. This might be because the mature mammalian retina lacks the ability to accept and incorporate stem cells or to promote photoreceptor differentiation. We hypothesized that committed progenitor or precursor cells at later ontogenetic stages might have a higher probability of success upon transplantation. Here we show that donor cells can integrate into the adult or degenerating retina if they are taken from the developing retina at a time coincident with the peak of rod genesis5. These transplanted cells integrate, differentiate into rod photoreceptors, form synaptic connections and improve visual function. Furthermore, we use genetically tagged post-mitotic rod precursors expressing the transcription factor Nrl (ref. 6) (neural retina leucine zipper) to show that successfully integrated rod photoreceptors are derived only from immature post-mitotic rod precursors and not from proliferating progenitor or stem cells. These findings define the ontogenetic stage of donor cells for successful rod photoreceptor transplantation.

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