Age-related macular degeneration, aka AMD, is the leading cause of irreversible blindness in the industrialized world. It affects 11 million people in the U.S. and 170 million globally. We can’t cure it, and we don’t treat it very successfully, but we’re getting there. A couple of breakthroughs, in stem cell transplantation and novel medication, could signal a new age for AMD patients.
Here’s what we know. AMD is a neurodegenerative disease that affects the middle of the retina (the macula) and gradually causes loss of sight in the central visual field. AMD comes in two varieties, wet and dry. In wet AMD, blood vessels leak into the eye, causing damage; in dry AMD, they don’t, but lipid/calcium deposits accumulate in the eye and destroy surrounding tissue. Wet AMD always starts as dry AMD.
Risk factors also come in two varieties: those you can change and those you can’t. There isn’t much to do about being over age 50, having a family history of the disease, or being Caucasian. You can, however, reduce your risk by not smoking, losing weight, treating cardiovascular conditions like high blood pressure, wearing sunglasses to protect against ultraviolet light, and avoiding medications (like hydroxychloroquine, recently vaunted, incorrectly, to treat COVID-19) that are known to exacerbate AMD development.
We don’t really have an effective therapy to treat AMD deterioration, but a new stem cell therapy to replace damaged retinal tissue is showing promise. Stem cells have been used experimentally for this purpose for some time, but they’ve always carried the risk of mutating into cancerous tumors. Now, researchers at the Unit on Ocular and Stem Cell Translational Research, National Eye Institute, NIH, in Bethesda, MD, have developed oncogenic mutation-free stem cells from the blood cells of three AMD patients. They grew new tissue from the cells, and transplanted it into animal subjects, where it demonstrated a powerful therapeutic effect. That’s an enormous advance. Next step: human subjects.
Also, Scientists at the Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, in La Jolla, CA, are looking at a new target for medicinal treatment of AMD. The human blood protein vitronectin is a major component of the abnormal deposits associated with age-related macular degeneration, Alzheimer’s disease, atherosclerosis, and other age-related disorders. It turns out that vitronectin binds with lipids and soluble calcium in the formation of these deposits, and so these researchers are now on a search for medicines that can mediate vitronectin expression. If they find one, we may move into a new era in treating these previously untreatable age-related diseases.