American biologists have moved a step closer to the treatment of degenerative diseases of the retina: they implanted blind mice blockoptions cells obtained by reprogramming of fibroblasts. Thus it was possible to restore light sensitivity in almost half the cases. Moreover, the effect was noticeable even in the later stages of retinal degeneration when their own sticks in the retina of mice have left — this means that implantable cells acted by themselves and not merged with existing ones. Work published in the journal Nature.
Among the many tissues and organs, which scientists are trying to grow from the stem cells, the retina stands out. The problem is that the human eye generally some stem cells, so the “spare components” to get through the reprogramming. In other words, first the patient take cells other tissue, most commonly fibroblasts, and then they are converted into the analog germ cells (induced pluripotent cells), and then differentiat into cells of the desired type. Thus was able to obtain the pigment epithelium (the layer that contains the photoreceptors) and the cornea.
However, the retina is its structure is so complex that so far no one managed to grow it in vitro. Savala SAI (Sai Chavala) from the health Center at the University of North Texas, along with colleagues decided to go the other way and fix it work in vivo. As a model they took mice with a mutation in the gene rd1, which causes the destruction of the sticks — photoreceptor cells responsible for the perception of light intensity. By the end of the month sticks in their retina no longer remains, and they cease to respond to light.
New cones, the researchers decided traditionally to of fibroblasts. However, they decided to avoid the stage of induced pluripotent cells, because it increases the risk of tumour formation. And instead of the classic reprogramming used transdifferentiation — that is, tried to get sticks of fibroblasts directly.
To do this, they took another line of mice that have no mutations in rd1, but sticks which Express green fluorescent protein. These animals took the fibroblasts and treated them with protein shake to gain neurons. It turned out that by themselves are four protein from the cocktail does not allow you to turn the fibroblasts into sticks, but adding another protein, the authors received blockoptions cells, employing genes to the retina.
These cells were placed under the retina of a 24-day mice. To check how this method is effective, the researchers measured the pupillary reflex: what percentage of reduced pupil size in reaction to light. In 6 of the 14 eyes were operated on, they noticed improvements: the pupil began to shrink when such an intensity that the mouse that received no treatment, did not recognize. In addition, those animals in which scientists have noticed improvements of steel in half to spend more time in the dark when choosing between light and dark room, that is, behave in this respect just like a sighted mouse.