Researchers have developed a method to efficiently turn human stem cells into retinal ganglion cells. Death and dysfunction of these cells cause vision loss in conditions like glaucoma and multiple sclerosis.
The laboratory process, described in the journal Scientific Reports, entails genetically modifying a line of human embryonic stem cells to become fluorescent upon their differentiation to retinal ganglion cells, and then using that cell line for development of new differentiation methods and characterization of the resulting cells.
Using a genome editing laboratory tool called CRISPR-Cas9, investigators inserted a fluorescent protein gene into the stem cells’ DNA. This red fluorescent protein would be expressed only if another gene was also expressed, a gene named BRN3B (POU4F2). BRN3B is expressed by mature retinal ganglion cells, so once a cell differentiated into a retinal ganglion cell, it would appear red under a microscope.
Next, they used a technique called fluorescence-activated cell sorting to separate out the newly differentiated retinal ganglion cells from a mixture of different cells into a highly purified cell population for study. The cells showed biological and physical properties seen in retinal ganglion cells produced naturally.
Researchers also found that adding a naturally occurring plant chemical called forskolin on the first day of the process helped improve the cells’ efficiency of becoming retinal ganglion cells. The researchers caution that forskolin, which is also widely available as a weight loss and muscle building supplement and is touted as an herbal treatment for a variety of disorders, is not scientifically proven safe or effective for treatment or prevention of blindness or any other disorder.
In follow-up studies using CRISPR, the researchers are looking to find other genes that are important for ganglion cell survival and function.
Donald Zack, M.D., Ph.D., at the Johns Hopkins University School of Medicine, is the study lead, with Chung-ha Davis, Vinod Ranganathan, Kellin Krick, Russ Martin, Cynthia Berlinicke, Nicholas Marsh-Armstrong and Hai-Quan Mao of Johns Hopkins; and Jeffrey Diamond and Justin Kerr of the National Institute of Neurological Disorders and Stroke as co-authors.
Edited from source. Featured image credit: Johns Hopkins Medicine