Converted stem cells may one day restore vision

"Our work could lead not only to a better understanding of the biology of the optic nerve, but also to a cell-based human model that could be used to discover drugs that stop or treat blinding conditions," says Donald Zack. "And, eventually it could lead to the development of cell transplant therapies that restore vision in patients with glaucoma and MS." Above, human retinal ganglion cells at day 50. Fluorescence microscopy image. (Credit: Valentin Sluch/Johns Hopkins Medicine)

Researchers have found a way to efficiently convert human stem cells into a nerve cell critical for vision, which could open a path to restoring sight lost to disease.

This newly demonstrated ability to create new retinal ganglion cells in the lab may eventually help doctors repair retinas damaged by conditions like glaucoma and multiple sclerosis, researchers say. Retinal ganglions are the nerve cells that send visual signals from the eye to the brain.

“Our work could lead not only to a better understanding of the biology of the optic nerve, but also to a cell-based human model that could be used to discover drugs that stop or treat blinding conditions,” says study leader Donald Zack, professor of ophthalmology at Johns Hopkins University.

“And, eventually it could lead to the development of cell transplant therapies that restore vision in patients with glaucoma and MS.”

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The laboratory process, detailed in the journal Scientific Reports, is a modified version of a procedure developed by other researchers using stem cells to create light-detecting eye cells. Zack and his team also discovered that adding a naturally occurring plant chemical called forskolin on the first day of the process improved the efficiency of the conversion to retinal ganglion cells.

Forskolin is sold as a weight loss and muscle building supplement and touted as an herbal treatment for a number of disorders. The researchers for the new study emphasize it is not scientifically proven safe or effective in treatment or prevention of blindness or other disorders.

Zack’s team also inserted a fluorescent protein gene into the stem cells’ DNA. This red fluorescent gene is activated only if another gene–expressed by mature retinal ganglion cells–is also activated. In other words, the researchers could see when they had succeeded in making retinal ganglion cells because they would appear red under a microscope.

They then used a technique called fluorescence-activated cell sorting to separate out the new retinal ganglion cells from a mixture of different cells.

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“By the 30th day of culture, there were obvious clumps of fluorescent cells visible under the microscope,” says lead author Valentin Sluch, a former Johns Hopkins graduate student and now a postdoctoral scholar at the pharmaceutical company Novartis. Sluch completed this research at Johns Hopkins.

“I was very excited when it first worked,” Sluch says. “I just jumped up from the microscope and ran [to get a colleague]. It seems we can now isolate the cells and study them in a pure culture, which is something that wasn’t possible before.”

“We really see this as just the beginning,” Zack adds. In follow-up studies, his lab is looking to find other genes that are important for ganglion cell survival and function. “We hope that these cells can eventually lead to new treatments for glaucoma and other forms of optic nerve disease.”

The Maryland Stem Cell Research Fund, the National Institutes of Health, Research to Prevent Blindness Inc., the Guerreri Family Foundation, and Robert and Clarice Smith funded the work.

Source: Johns Hopkins University