Researchers say they may have developed a potential solution for dry eye—inserting regenerative cells into the lacrimal gland (LG), where tears get their start.
Without healthy LGs, the eyes don't produce enough quantity and quality of tears to spread across the front surface of the eye and keep it smooth and protect against dust, germs and other foreign matter. Located under the eyebrow of each eye, the glands also nourish the eyes.
An estimated 5 million people over 50 years of age in the U.S. suffer from dry eye, according to the National Eye Institute (NEI).
In the recent Scripps Research Institute-led study, researchers took endogenous progenitor cells in mice—which were about to become epithelial tissue—and injected them into the almond-shaped glands of mice with Sjogren's syndrome, an autoimmune disease linked to dry eye.
The progenitor cells, similar to stem cells, help the glands repair themselves. The study, "Lacrimal Gland Repair Using Progenitor Cells," was published in Stem Cells Translational Medicine on Aug. 15.
According to researchers, the study provides the "first evidence" that injection of the cells may repair nontear-secreting LGs in humans. LGs of mice were injected with progenitor cells in the study.
"Overall, our study shows that uninjured adult LGs contain epithelial cell progenitors that we define as EPCPs (epithelial cell progenitors)," the researchers say. "These EPCP cells could successfully engraft into ductal and acinar compartments of 'diseased' LGs and restore acinar structure.
"We also found that EPCPs could increase tear secretion in TSP-1-/- mice with chronic LG dysfunction," it concludes. "Our work provides an important first step toward identifying and characterizing an epithelial-specific progenitor population able to restore function in the LG."
Further research is needed.
Kelly Nichols, O.D., Ph.D., M.P.H., dean of the School of Optometry at The University of Alabama at Birmingham, noted that studies involving mice are the first step in translating results to humans. Dr. Nichols called this early experiment with lacrimal regeneration promising and novel.
"They (researchers) offer hope that regeneration of the tissue can occur, that the progenitor cells will morph or modify themselves into functional cells that will produce tears," says Dr. Nichols, noting its advantage over foreign transplanted LG tissue in the eye, and that would very much help many dry eye patients.
"We ultimately may have some more tools in our toolbox," she says of doctors of optometry.
In July, the U.S. Food and Drug Administration approved a new medication—Xiidra—for the treatment of dry eye disease. Patients' quality of life could improve dramatically with more treatment options, Dr. Nichols says. Studies have shown the impact dry eye has on patients, including a decline in productivity at work. Unfortunately, she says, people choose to live with dry eye rather than seek out the best treatment option.
Earlier intervention could prevent progression to more severe dry eye disease, Dr. Nichols says. Untreated, dry eye can lead to pain, damage to the cornea and decreased quality of life, she says.
"People don't have to live with dry eye," Dr. Nichols adds.
About dry eye
According to the NEI, symptoms for dry eye include:
- Stinging or burning eyes.
- A sandy or gritty feeling in the eye.
- Episodes of excess tears following very dry eye periods.
- A stringy discharge from the eye.
- Pain and redness of the eye.
- Episodes of blurred vision.
- Heavy eyelids.
- Inability to cry when emotionally stressed.
- Discomfort wearing contact lenses.
- Decreased tolerance of reading, working on the computer, or any activity that requires sustained visual attention.
- Eye fatigue.
Dry eye is caused by any number of factors: age, gender, medications, medical conditions, environmental factors and longtime use of contact lenses.
Among the treatments are over-the-counter tear solutions; blocking tear ducts via surgery or tiny silicone or gel-like plugs; eye drops that boost tear production; or treating the contribution eyelid or ocular surface inflammation with eye drops, ointments, warm compresses or lid massage or eyelid cleaners to reduce inflammation.
Patients also can reduce their own symptoms by:
- Blinking regularly.
- Increasing the humidity in the air.
- Wearing sunglasses.
- Taking nutritional supplements.
- Staying hydrated.
Read more about how doctors of optometry are helping patients with dry eye in the 2015 July/August edition of AOA Focus.
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