Using a type of human stem cell, researchers at Johns Hopkins University School of Medicine in the US say they have created a three-dimensional complement of human retinal tissue in the laboratory that includes functioning photoreceptor cells capable of responding to light – the first step in the process of converting it into visual images.
“We have basically created a miniature human retina in a dish that not only has the architectural organisation of the retina but also has the ability to sense light,” says study leader Dr M Valeria Canto-Soler, an assistant professor of ophthalmology at the Johns Hopkins University School of Medicine. She says the work, reported online in the journal Nature Communications, “advances opportunities for vision-saving research and may ultimately lead to technologies that restore vision in people with retinal diseases”.
Like many processes in the body, vision depends on many different types of cells working in concert, in this case to turn light into something that can be recognised by the brain as an image. Canto-Soler cautions that photoreceptors are only part of the story in the complex eye-brain process of vision, and her lab hasn’t yet recreated all of the functions of the human eye and its links to the visual cortex of the brain. “Is our lab retina capable of producing a visual signal that the brain can interpret into an image? Probably not, but this is a good start,” she says.
According to the Johns Hopkins newsroom, the achievement emerged from experiments with human induced pluripotent stem cells (iPS) and could, eventually, enable genetically engineered retinal cell transplants that halt or even reverse a patient’s march toward blindness. The iPS cells are adult cells that have been genetically reprogrammed to their most primitive state. Under the right circumstances, they can develop into most or all of the 200 cell types in the human body. In this case, the Johns Hopkins team turned them into retinal progenitor cells destined to form light-sensitive retinal tissue that lines the back of the eye: ergo, retina in a dish.
Source: Johns Hopkins