Is Age-Related Macular Degeneration Incurable? Stem Cells Therapy Gives Hope

Age-related macular degeneration (AMD) is an eye disease of significant central visual impairment resulted from accumulation of extracellular deposits along with degeneration of photoreceptors and adjacent tissues.

AMD ranks third as a cause of blindness after cataract and glaucoma. This common age-related eye problem usually occurs in the elder. As many as 10 to 20 percent of people over the age of 85 are affected, with most of them in developed countries.

AMD can be classified into two categories: dry and wet. Almost 90% of the patients have the dry form. Dry AMD develops in gradual stages as protein deposits accumulate under the macula and drive the macula to be thinner and drier. Wet AMD is less common but can cause serious vision loss. It happens when blood vessels beneath the retina begin to leak fluid, thus creating a big blind spot in the central vision region. Dry AMD of any stage has the potential to turn into wet AMD, but neither of which is curable with only treatment for wet AMD available by injecting anti-vascular endothelial growth factor to slow down the progression.

The risk for AMD increases as one gets older, and will be even greater if there is a family history. Suggestions to lower the risk of AMD are as follows.

• Don’t smoke.
• Get enough physical exercise.
• Keep blood pressure and cholesterol levels within normal range.
• Wear sunglasses to protect eyes from UV.
• Eat healthy foods, like vegetables, nuts and fish.
• Have regular eye examinations.

As a multifactorial disease encompassing a complicated interaction among senility, environmental factors and genetic susceptibility, AMD’s exact pathological mechanism has not been fully understood yet. The major obstacle may be lacking access to in vitro models to reflect the natural process and phenotype of ocular degenerative diseases.

A research team from National Eye Institute has implemented the first clinical trial in Dec, 2019 to conduct efficacy and safety assessment of a novel patient-derived stem cell-based dry AMD therapy. The therapy acts by identifying and separating stem cells from a patient’s blood cells and converting into induced pluripotent stem cells (iPSCs) that can differentiate into any type of cells in human body. The iPSCs are programmed into retinal pigment epithelial cells (RPE)? the primary caretaker of photoreceptor health and function.

Before they are transplanted, the iPSC-derived RPE are grown in sheets one cell thick, replicating their natural structure within the eye. This monolayer of iPSC-derived RPE is grown on a biodegradable scaffold designed to promote the integration of the cells within the retina. Surgeons position the patch between the RPE and the photoreceptors using a surgical tool designed specifically for that purpose.

Under the phase I/II clinical trial protocol 12 patients with advanced-stage geographic atrophy will receive the iPSC-derived RPE implant in one of their eyes and be closely monitored for a period of at least one year to confirm safety.

This therapy is an effective attempt to prop up the health of residual photoreceptors by substituting dying RPE with well-functioning iPSC-derived RPE. Should early safety be confirmed, later study phases will include more patients to assess the efficacy of the implant to prevent blindness and restore vision in patients with geographic atrophy.

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