Researchers at Johns Hopkins University have developed a method to convert human stem cells into retinal nerve cells, which are nerve cells located in the retina that transmit visual signals to the brain. The death or disorder of these cells can cause vision loss, such as glaucoma and multiple sclerosis (MS).
"Our research not only gives people a deeper understanding of the biological functions of the optic nerve, but also provides a cell model for the development of drugs to prevent and treat vision diseases," said the researcher Dr. Donald Zack, who is the Johns Hopkins University School of Medicine Professor of Ophthalmology. "Moreover, this is also conducive to the development of cell transplantation methods to restore the vision of patients with glaucoma or MS."
The detailed process of the entire experiment was published in the journal Science and Technology Reports. A series of human embryonic stem cells were modified to have fluorescent properties to distinguish retinal nerve cells, and then such cells were used to distinguish the generated cells.
Researchers used a genome editing technology called CRISPR-Cas9 to insert fluorescent protein genes into stem cell DNA. This red fluorescent protein will only be expressed when another gene BRN3B (POU4F2) is expressed. BRN3B is expressed by mature retinal nerve cells, so once the stem cells become retinal nerve cells, it will appear red under the microscope.
Next, they used fluorescence activated cell screening to isolate and purify newly generated retinal nerve cells. Zack said that the newly generated cells exhibited the same biological and physical properties as naturally occurring retinal nerve cells.
Researchers also found that adding a chemical substance called forskolin on the first day of the experiment helped to increase the efficiency of retinal nerve cell production. The researchers reminded that forskolin is widely used for weight loss and muscle shaping, and is often used as a traditional Chinese medicine to treat various disorders, but it is not necessarily safe and effective for preventing vision loss and other disorders.
"On the 30th day of culture, you can see obvious clusters of fluorescent cells under the microscope," said lead researcher Dr. Valentin Sluch, who was a former student of the Department of Biochemistry and Cellular and Molecular Biology at Hopkins University and now works. At Novartis. Sluch completed the research before joining Novartis.
"I was very happy the first time I succeeded," Sluch said. "I almost jumped up and ran to tell a colleague of mine. It was as if the cells could be isolated for research right away, which was impossible before."
"We know, this is just the beginning," Zack added. In subsequent research, his laboratory aimed to identify other genes related to the survival and function of optic nerve cells. "We hope these cells can provide new methods for the treatment of glaucoma and other types of optic nerve diseases."
In order to be able to use these cells to treat MS, Zack is collaborating with Peter Calabresi, who is the director and professor of neurology at the Multiple Sclerosis Research Center at Hopkins University.