Using a distinct type of human stem cell, researchers from the Johns Hopkins University School of Medicine have created a three–dimensional match of the human retinal tissue in the laboratory.
Scientists have used human induced pluripotent cells (iPS) that can be genetically reprogrammed to their most primitive stage and can be developed into either most or all the 200 cell types in the human body under right circumstances. In this case, the team programmed the iPS to foster the growth of retinal progenitors. The retinal cells and tissue grew in petri dishes and their growth corresponds in its timing and duration to the retinal development in a human foetus in the womb. The retina took 28 weeks to develop after which, the scientists tested them. These cells possessed photoreceptors, which are essential to absorb light in the retina. Scientists placed an electrode in a single photoreceptor cell and then shone a pulse of light on it, which reacted in a biochemical pattern, similar to the behaviour of photoreceptors in the human retina.
Researchers stated that their lab–grown retinas do act like natural ones, but they cannot produce a visual signal which the brain can interpret. Yet, scientists have marked this as an important step in vision–saving and restoring technologies.