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London (UK), 19 November: A paper in this week’s Nature shows that non-dividing retinal cells implanted into adult mouse retina can generate new photoreceptors, suggesting a possible way to regenerate the photoreceptors lost during many forms of blindness.

Previously, stem cells transplanted into the adult retina have not integrated correctly and it was thought that the retinal environment inhibits regeneration. Robin Ali and colleagues extracted immature retinal cells from newborn mice at a time when many rod photoreceptors are normally being generated, and transplanted them into adult mouse retinas.

They show that the cells differentiate into rods, form synaptic connections and, when transplanted into certain mouse models of inherited retinal degeneration, improve the animals’ response to light. Surprisingly, they found that this was possible only using rod precursor cells during a specific time window of development, when they have stopped dividing (rather than proliferating stem cells). The results suggest that precursor cells grown from human adult or embryonic stem cells might also serve to restore sight, and challenge the assumption that stem cells offer the best prospect for tissue repair.

(ResearchSEA)