The Potential for Stem Cell-Derived Treatments for Glaucoma
Glaucoma is a condition in which increasing intraocular pressure compresses the optic nerve and other structures in the eye, which leads to the irreversible, progressive loss of vision. While researchers continue to develop treatments and devices to improve the management of the disease, the ultimate goal is to find a cure.
One area with the greatest potential for curing the disease remains adult stem cell treatment. Several types of adult stem cells exist. In the context of the eye, research has focused on pluripotent stem cells, which can transform into a variety of different types of cells as they mature. The first transplantation of induced pluripotent stem cells occurred in the eye.
Induced pluripotent stem cells come from the skin or the blood. These cells have been reprogrammed to exist in a primitive state so they can then develop into a variety of different types of human cells. Currently, researchers are investigating the use of stem cells to treat glaucoma from a number of different angles, such as fixing the drainage systems of the eye, which often underlies the development of glaucoma, as well as repopulating retinal ganglion cells. Individuals with glaucoma should note that these approaches remain experimental and currently are not commercially available. Furthermore, these treatments take a long time to develop, so they may not be available for quite some time.
Two Primary Approaches to Stem Cell Use in Glaucoma
One approach to treating glaucoma using pluripotent stem cells aims to lower eye pressure by improving the drainage system in the eye. When the drainage system stops working, the fluid in the eye begins to build up, which leads to increased pressure. Stem cells could be induced to form trabecular meshwork cells to replace the damaged systems in a patient’s eyes. However, some drawbacks exist to this treatment approach. Clinicians already have a variety of pharmaceutical and surgical options to relieve pressure in the eye, so it is not clear whether this approach would produce a durable cure for the condition. Furthermore, this approach would only treat patients with primary open-angle glaucoma and not other forms of the disease.
The other major issue with this approach is it would not restore lost vision among patients who already have advanced glaucoma. The loss of vision relates to the death of retinal ganglion cells comprising the optic nerve. Retinal ganglion cells connect the retina — the back of the eye that processes visual information — to the brain, where data can be interpreted. When these cells die, they cannot be restored, which is why glaucoma has no cure. Adult stem cells could potentially be induced to develop into retinal ganglion cells that could then be transplanted into the eye to restore vision.
However, some serious challenges exist in terms of using stem cells to form retinal ganglion cells. The biggest hurdle is the fact that transplanted cells would need to connect to both the retina and the brain, a difficult feat to achieve. Scientists around the world are working on this issue, although there is no date in sight when such a therapy would be available. At the same time, it remains a worthwhile pursuit for medical researchers, and a significant amount of money continues to be dedicated to exploring ophthalmologic applications of stem cells.
Issues Surrounding Human Stem Cell Clinical Trials
In the meantime, patients with glaucoma who have experienced vision loss may benefit from stem cell treatments in the more immediate future through clinical trials. Interested patients should bring up the subject with their ophthalmologists and work in conjunction with their care providers to find a trial that might have therapeutic benefit. Patients should be cautious about participating in any clinical trial that offers the same approach to treat a variety of diseases or, alternately, several different strategies for treating the same disease.
Unfortunately, due to fairly loose controls on certain stem cell practices by the U.S. Food and Drug Administration, organizations branding themselves as stem-cell clinics have popped up across the country. These clinics have little regulatory oversight, and as such they may use approaches that have not been properly tested in humans. This fact highlights the importance of approaching such clinical trials in conjunction with an ophthalmologist who is familiar with the legitimate research being undertaken.
