This article will cover several areas of investigation in the use of adult stem cells to treat glaucoma.
Adult stem cells, as discussed in this article, refer to cells that are grown in the laboratory using tissue samples taken from adult patients (typically from skin, blood, bone marrow, or fat cells).
The field of adult stem cell research is indeed very exciting, and particularly so for the eye. After all, the world’s first transplantation of cells that were derived from induced pluripotent stem cells (iPSCs) took place in the eye, when surgeons implanted retinal tissue that was created after reverting the patient's own cells to 'pluripotent' state.
What are Induced Pluripotent Stem Cells?
There are many different types of adult stem cells. One type are pluripotent stem cells. These stem cells are special because they can mature and change into many different types of cells in the body as well as replace themselves.
There are also several types of pluripotent stem cells, including human-induced pluripotent stem cells. These stem cells are created from adult cells, such as skin or blood cells, that have been reprogrammed back into a primitive state, which allows them to develop into any type of human cell needed for therapeutic purposes.
Although progress may seem slow to patients with vision loss who are awaiting a cure, this first transplantation actually took place only ten years after iPSCs were first discovered and made.
All this being said, although there is rigorous and scientifically sound work being done in adult stem cell laboratories all over the world, some stem cell “treatments” are not yet ready to treat glaucoma.
There are many areas of active investigation surrounding adult stem cells and glaucoma. One important feature about stem cells to consider is that the term “stem cells to treat glaucoma” is broad and covers a wide variety of approaches that could be potentially used.
Fixing the Eye’s Drainage System
In primary open-angle glaucoma, for example, the drainage system does not properly drain the fluid inside the eye, and eye pressure can increase. One idea is to take pluripotent stem cells and use them to make the cells that drain fluid out of the eye (trabecular meshwork cells) in an effort to restore the eye’s drainage system. This approach has the potential to lower eye pressure, although we already have many therapies that do the same such as eye drops and laser. However, using an adult stem cell-based approach has the potential to restore and “rejuvenate” the eye’s drainage system.
Retinal Ganglion Cells: A Challenging Problem
The method described above to fix the eye’s drainage system would not help a glaucoma patient who has already lost vision since the vision loss is due to the death of the retinal ganglion cells that comprise the optic nerve.
Retinal ganglion cells are the cells that connect the visual information collected by the retina. Think of it as the “film” that lines the back of the eye and the brain, where visual information is further processed. These retinal ganglion cells die in glaucoma, an irreversible process, which is why at present there is no cure for glaucoma. Healthy retinal ganglion cells are crucial for vision: they are the neurons that extend long cables (or axons) connecting the retina to the brain.
Currently, the only treatment we have is to lower eye pressure, a major risk factor for glaucoma. Lowering eye pressure is a very effective treatment for glaucoma, but it cannot improve or restore vision due to the damage of retinal ganglion cells. Thus, there is excitement around the possibility of using adult stem cells to make retinal ganglion cells and then to transplant these into the eye. This is an extremely challenging problem, however, since any transplanted retinal ganglion cells, for example, would not only need to survive, but also connect with their appropriate partners both in the retina and in the brain.
Scientists around the world are working to tackle this challenge, and we should continue to devote resources to it. The research community is placing significant importance and resources towards this goal; the National Eye Institute’s Audacious Goals Initiative aims to restore vision by retinal regeneration. However, while this particular area of adult stem cell research is important, it is not yet ready for patient care.
[See more: “Dream Team” of BrightFocus Alums Receive Major NIH Vision Research Grant]
While replacing retinal ganglion cells is a “holy grail” in glaucoma, another strategy is to promote survival of these cells. This can be achieved by identifying molecules that are “neuroprotective,” but figuring out how to deliver these molecules in a long-lasting fashion can be a challenge. One approach that has been studied in early clinical trials is a cell-based strategy. With this technology, cells have been engineered to make ciliary neurotrophic factor (CNTF) and are in an encapsulated device that can be surgically implanted in the eye. The concept is that these cells continue to make CNTF in a long-lasting fashion, which could potentially help stressed retinal ganglion cells and preserve vision.
[Learn about BrightFocus-funded research evaluating CNTF to enhance vision or protect against vision loss in glaucoma.]
Finding Clinical Trials
So, if you are a glaucoma patient with vision loss, where might you turn to find stem cell treatments?
Talk with Your Ophthalmologist
You should first talk to your ophthalmologist, which is a very important step. Your ophthalmologist should be up to date in the field,and may be aware of recent advances that even this article will not address, since the field is constantly changing and advancing.
Other patients might Google “stem cells” and “glaucoma.” Some patients may go to a clinical trial website thinking that any study listed on the website has a rubber stamp of approval from the federal government and is based on solid science. Unfortunately, this is not always the case.
Recent news stories have detailed how unsuspecting patients suffered severe vision damage after treatment at certain illegitimate “trials.” If you are considering a stem cell treatment for glaucoma, or for any eye disease, please think about the following very important factors:
In a typical clinical trial, patients are not asked to pay for the treatment. Indeed, for some clinical trials patients are reimbursed for costs associated with study visits, such as parking or travel. Thus, be wary of treatments in which you are asked to pay for the procedure or the stem cells.
A clinical trial or study in which the same stem cell “treatment” is used for many different diseases of the eye and/or that uses many different ways of delivering the stem cells is also concerning. It suggests that there is not a good understanding of how stem cell treatment works.
Treatments that involve both eyes being treated at the same time are also a red flag.
An important question to ask is whether the treatment is FDA approved or whether it is being studied under an “Investigational New Drug” (IND) application with the FDA.
Finally, certain stem cell “clinics” have cropped up that offer unproven treatments, with websites prominently featuring patient testimonials. These clinics often use “autologous” stem cells, where the stem cells are harvested from the patient’s own fat (such as from liposuction) or bone marrow. The Food and Drug Administration (FDA) does not have as strict control over these types of stem cells, so it is important to understand that these treatments have no regulatory protection. These clinics offer treatments that have not had any proper vetting for use in humans.
For more information on clinical trials, view or download Clinical Trials: Your Questions Answered.
It is an exciting time for the adult stem cell field, as the pace of new discoveries and understanding about how stem cells can be used for potential therapies is moving quickly. However, there are currently no FDA-approved stem cell treatments for glaucoma.
Some glaucoma patients, especially if they have very little vision left, may feel that they have little to lose by paying for an unproven treatment using adult stem cells. However, it is possible to lose all vision or even have worse outcomes such as loss of the eye or tumor growth.
Despite these cautions, we should continue investing our resources into legitimate research with adult stem cells, developing potential uses in the treatment of eye disease. We just have to be patient and focus on treatments that have been carefully studied and tested in scientifically rigorous clinical trials.