Eyeing A Cure: Stem Cell Treatments For Macular Degeneration

(Posted on Thursday, August 17, 2023)

Originally published on Forbes on 8/11/2023

This story is part of a series on the current progression in Regenerative Medicine. This piece is part of a series dedicated to the eye, and it marks the first of a three-part series on dry age-related macular degeneration.

In 1999, I defined regenerative medicine as the collection of interventions that restore to normal function tissues and organs that have been damaged by disease, injured by trauma, or worn by time. I include a full spectrum of chemical, gene, and protein-based medicines, cell-based therapies, and biomechanical interventions that achieve that goal.

Age-related macular degeneration is a global health issue with two significant subtypes: dry and wet macular degeneration. Dry macular degeneration can cause geographic atrophy, which may be irreversible. 

A comprehensive review by the University of Nevada investigated dry age-related macular degeneration and the latest investigational therapeutics for treating the disease. One of the therapeutic approaches they reviewed is stem cell therapy for advanced macular degeneration and geographic atrophy.

Understanding Geographic Atrophy

Geographic atrophy is an advanced form of dry age-related macular degeneration. It causes the death of cells in the retina’s macular region, leading to central vision loss. Geographic atrophy is characterized by grey or white patches in the macula, the part of the retina responsible for central vision. 

Currently, there are no approved treatments for geographic atrophy. The lack of adequate and effective treatment options significantly impacts the quality of life for those affected. Also, the damage caused by geographic atrophy is irreversible. Fortunately, several clinical trials are ongoing to slow the progression of age-related macular degeneration, and some methods can provide some relief to those with geographic atrophy.

Current Treatments for Geographic Atrophy

and Dry Macular Degeneration 

One of these approaches is to reduce oxidative stress in the retina, which will slow the progression of geographic atrophy. One can use antioxidants like vitamins C and E to mitigate oxidative stress. These powerful agents act as protective shields against free radicals. Free radicals are particles produced by the body’s metabolism. Other supplements, such as zinc, have also shown some promise in supporting retinal function.

Other approaches for macular diseases include laser photocoagulation and photodynamic therapy. These make use of lasers and light to target abnormal blood vessels selectively. Laser photocoagulation seals leaking blood vessels in the retina, while photodynamic therapy uses light alongside a laser to do the same. Ultimately, both treatment methods focus on minimizing the amount of light reaching the retina, thereby reducing the damage to cells and blood vessels in the macula.

Further treatments for macular degeneration are currently being studied. These additional approaches include complement inhibitors that prevent inflammation and cell damage and stem cell therapies that replace the damaged cells.

Stem Cell Therapies for Geographic Atrophy

Stem cells are cells with the potential to grow or differentiate into any cell type in the body. These cells can treat a variety of different diseases, including retinal disorders.

Research by the National Natural Science Foundation of China has shown that stem cells can regenerate retinal pigment epithelium and photoreceptor cells, essential components in a healthy retina. Geographic atrophy and dry macular degeneration impact these retinal cells, so stem cell therapies may be an ideal approach to reversing the once irreversible vision loss associated with them. 

The typical process involved in using stem cell therapies is to take a specific type of stem cell from a patient, direct it to become the needed cell type or cell type precursor and inject it directly into the eye to replace or regenerate the damaged cells. Another method is to use what are called induced pluripotent stem cells. 

An induced pluripotent stem cell is unique because it is an adult stem cell reverted to an embryonic stem cell that can differentiate into any cell type. Stem cell treatments greatly benefit from this cell type since obtaining adult stem cells from patients is more feasible. This type of cell therapy also reduces the likelihood of immune rejection because the cells come directly from the patient.

The results of stem cell therapies for age-related macular degeneration and geographic atrophy are promising. Animal studies and clinical trials have seen improved vision; further clinical trials are underway.

One example of a recent clinical trial currently investigating stem cell therapy for geographic atrophy is OpRegen. This trial tests the safety and tolerability of embryonic stem cell-derived retinal pigment epithelium cells. The trial showed that this treatment has a favorable safety profile with no reports of inflammatory or immune responses. Also, there was a marked increase in visual function.

Still, careful consideration is needed when determining the appropriate cell type for each patient, as derivation and transplantation techniques must be optimized. Furthermore, long-term clinical trial data is necessary to evaluate the feasibility of wide-use stem cell therapies for retinal disorders.

Looking Toward the Future

Personalized stem cell and gene therapies are likely necessary when treating severe retinal disorders like dry age-related macular degeneration and geographic atrophy. Also, while there are no FDA-approved treatments for geographic atrophy, we will likely see some in the future. Research continues to develop, and ophthalmologists are conducting more studies to find the most effective treatment for vision loss.

This research will support an improved understanding of geographic atrophy secondary to dry age-related macular degeneration. It will aid in correctly diagnosing patients, reducing disease burden, and prolonging visual function. 

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