Stem cell technology may soon enter the mainstream as a treatment for ocular disease, says Leo Semes, OD, FAAO, at this year’s annual SECO 2017 conference.
Atlanta - Stem cell technology may soon enter the mainstream as a treatment for ocular disease, says Leo Semes, OD, FAAO, at this year’s annual SECO 2017 conference.
While stem cell therapy is not yet ready for human application, its advancement may soon provide optometrists with new possibilities for regenerative ocular therapy.
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The excitement over stem cells therapy lies in its versatility in application. One promising area of study is limbal stem cell deficiency.
“If limbal stem cells could be harvested, for example, from the patient’s fellow eye, the better eye, grown appropriately in a medium and then transplanted to the cornea, this limbal stem cell deficiency could be overcome,” Dr. Semes says.
This methodology could theoretically be applied to any physical area of ocular deficiency, provided the stem cells were available.
Fortunately, research suggests that these types of stem cells can be collected from various areas of the body-including areas like the oral mucosa. This would allow practitioners to take cells from analogous tissue rather than directly from the tissue needing treatment, then adapt them for specific medical therapies.
“There are a number of means by which appropriately differentiated stem cells can be generated for application to different areas of the body,” Dr. Semes says.
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Stem cells are known as the “progenitor” cells for each of the body’s tissues. Skin tissue develops from skin stem cells, nervous system tissue develops from neural stem cells, and so on.
Usually, tissue development is limited to its respective type of stem cell. However, there is another form of stem cell with developmental capabilities beyond predetermined tissues: embryonic stem cells.
Embryonic stem cells are the cells from which every other type of stem cell is derived. While embryonic stem cells are not always readily available, certain stem cells (known as induced pluripotent stem cells) can be grown and differentiated to act in the same way-and become specific tissues of medical interest.
For optometrists, these cells could include retinal cells, corneal cells, or nerve tissues that may reverse the damage caused by diseases like glaucoma.
As optometrists know, the primary danger of glaucoma is progressive damage to ganglion cells in the optic nerve. Typical glaucoma therapies involve lowering intraocular pressure (IOP) and managing symptoms as they appear.
There are other glaucoma considerations that optometrists must consider, such as complications with the trabecular meshwork that occur before an IOP spike is noticed, as well as patients with normal tension glaucoma.
“There are pieces to the glaucoma puzzle other than elevated IOP,” Dr. Semes says. And while FDA-approved strategies for glaucoma prevention primarily involve IOP reduction, stem cell technology may be changing the game.
“There might be, in the future, other strategies that would be beneficial,” says Dr. Semes.
There appears to be potential for stem cell therapy in replacing ganglion cells, but practitioners must keep the context of these therapies in perspective. Although stem cells may restore some function to damaged tissue, it is unclear how much overall function would be restored by stem cell therapy. That is still a topic of research and is likely years from a conclusive answer.
“We can make a ganglion cell,” says Dr. Semes. “We can get it to the inner retina, and then how does that hook up with the rest of the visual system? It’s a rudimentary replacement that is life-saving for the patient, and might be vision restoring in a glaucoma situation, but maybe not a perfectly restored visual system,” he says.
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Research into ganglion cell growth may only be the first step. Because glaucoma primarily involves the trabecular meshwork, studies on better medications to address damage in this meshwork may provide neuroprotective benefits outside of stem cell strategies.
Such a development could lead to a complete change in how, or which, existing methodologies are applied.
“If that tissue can be regenerated or rehabilitated in some way, then there may not be a need for ganglion cell replacement,” he says.
Better targeted medications, in addition to advancements in IOP reduction, are providing optometrists with a new means to alter or reverse the damage caused by glaucoma. All of this leads to the faint promise that one day glaucoma could be considered a curable condition.
Although current research is promising, there are still obstacles to overcome in stem cell therapy for ocular disease.
“We’re making progress,” Dr. Semes says. “This is not something that is going to go by the wayside-as some neuroprotective strategies have.”
Moving forward, more research must be done on creating needed cells and placing them in the target site, as well as understanding how the whole entire visual system works together.
“It’s going to be an evolutionary process, not a revolutionary one,” says Dr. Semes. “It’s going to take considerable development, and a lot of time in order to be a viable application for humans.”