The trial results announced here represent a promising step forward in efforts to regenerate an age-damaged retina, particularly because the patients were in an advanced stage of their degenerative condition and nonetheless achieved a meaningful degree of restored sight. Macular degeneration has a number of different manifestations, and here the wet form was treated, which involves excessive growth of blood vessels in the retina and consequent death of the retinal cells necessary for vision. Researchers have established an approach involving the generation of a patch of engineered retinal cells that can be implanted to restore some of the lost retinal function. Given the details, it is interesting to speculate on the degree to which the transplanted cells are helping by integrating into the retina versus helping by issuing signals that spur local regeneration. In most cell therapies it is the latter, but here the transplanted cells are more organized into a tissue-like structure.
Human embryonic stem cells (ESCs) represent a promising source for cellular replacement therapies owing to their availability, pluripotency, and unlimited self-renewal capacity. However, they also carry risks of neoplastic change, uncontrolled proliferation, and differentiation to inappropriate cell types. The eye is advantageous in investigating hESC-based cell