Researchers have found stem cells in optic nerve that carries signals from the eye to the brain. This discovery will help to better understand the development of the most common form of glaucoma and could be a potential treatment for one of the main causes of vision loss.
The results of the study by scientists from the University of Maryland School of Medicine (UMSOM) were published on July 28 in the journal Proceedings of the National Academy of Sciences (PNAS).
“We believe these cells, called neural progenitor cells, are present in the optic nerve tissue at birth and remain for decades, helping to nourish the nerve fibers that form the optic nerve”, – said study leader Steven Bernstein, MD, PhD, Professor and Vice Chair of the Department of Ophthalmology and Visual Sciences at the University of Maryland School of Medicine. “Without these cells, the fibers may lose their resistance to stress, and begin to deteriorate, causing damage to the optic nerve, which may ultimately lead to glaucoma”.
More than 3 million Americans suffer from glaucoma, which results from damage to the optic nerve, causing blindness. Nerve damage is usually associated with increased pressure in the eye due to a buildup of fluid that is not drain properly. Blind spots may form in the patient’s field of vision, which gradually increase over time.
“This is the first time that neural progenitor cells have been discovered in the optic nerve. Without these cells, the nerve is unable to repair itself from damage caused by glaucoma or other conditions. This may lead to permanent vision loss and disability”, – said Dr. Bernstein. “The presence of neural stem/progenitor cells opens the door to new treatments to repair damage to the optic nerve, which is very exciting news.”
During the experiment, Dr. Bernstein and his team examined a narrow strip of tissue called the optic nerve lamina. A lamina less than one millimeter wide is located between the light-sensitive tissue of the retina at the back of the eye and the optic nerve. The long fibers of neurons extend from the retina through the lamina to the optic nerve. The researchers found that the lamina progenitor cells are responsible for isolating fibers as soon as they leave the eye, maintaining connections between neurons on their way to the brain.
Stem cells in the lamina niche act on these neurons with growth factors and also contribute to the formation of an insulating sheath. The researchers were able to confirm the presence of these stem cells using antibodies and genetically modified animals by identifying specific protein markers on neuronal stem cells.
“It took 52 trials to successfully grow the lamina progenitor cells in a culture”, – said Dr. Bernstein, “so this was a challenging process.”
Dr. Bernstein and his colleagues needed to choose the right combination of growth factors and other cultivation conditions that would be most favorable for the growth and reproduction of stem cells. Ultimately, the research team found that stem cells could be made to differentiate into several different types of nerve cells. These include neurons and glial cells, which are known to be important for cell repair and replacement in various areas of the brain.
This discovery may be a turning point in the treatment of diseases affecting the optic nerve. Dr. Bernstein and his research team plan to use genetically modified mice to see how depleting the lamina progenitor niche promotes diseases such as glaucoma and inhibits regeneration.
Further research is also needed to investigate the mechanisms of neural precursor repair.
“If we can identify the critical growth factors that these cells secrete, they may be potentially useful as a cocktail to slow the progression of glaucoma and other age-related vision disorders”, – Dr. Bernstein added.