Researchers at the University of Wisconsin (USA) have grown retinal cells from stem cells that are able to connect and transmit information between them. This advance opens the door for clinical trials of this tissue, which can begin in people with degenerative eye diseases. If successful, these could be used to restore patients’ vision.
According to the institution, this achievement is the result of nearly a decade of work growing organized groups of cells similar to those of the retina, called organoids, from human skin cells that have been reprogrammed to function as mother cells. After years of research, they finally succeeded in converting these cells into photoreceptor cells that are able to form synapses, i.e. pass information on to neighboring cells.
Cells in the retina and brain communicate via synapses, so to confirm that lab-grown retinal cells have the ability to take over diseased cells and transmit sensory information, the researchers had to show that they could.
Retinal cells reconnect
In earlier studies, the experts had already shown that plated retinal cells, so-called photoreceptors, react to different wavelengths and light intensities like those of a healthy retina. They can also reach their new neighbors via axons, a type of biological cord that connects cells.
To test for the existence of synaptic connections between the cells, the researchers divided the retinal organoids into individual cells and waited a week for the cells to form new axons.
After completion of this experimental phase, a modified rabies virus was added to the medium, which migrated between the retinal cells for a week. This indicated that synaptic connections had been made.
Evidence of development of synaptic connections between cellsGAMM LAB
After confirming that the cells formed the means to communicate with each other, the scientists analyzed the cells involved and discovered that the most common types of cells in the retina that make connections are photoreceptor cells called rods and cones.
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“The final piece of the puzzle was to see if these cords have the ability to connect to or shake hands with other types of cells in the retina,” explained David Gamm, one of the authors of the study published in the Proceedings of the National Academy of Sciences.
After the successes achieved in the laboratory, Gamm commented, human clinical trials are the next step in research. If successful, these tissues could be used to treat degenerative eye diseases such as glaucoma, optic nerve lesions or macular degeneration, among other things.