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A new preclinical study published online in the journal Stem Cells shows that a single injection of stem cells can greatly slow the progression of age-related macular degeneration (AMD). AMD is a major cause of vision impairment and blindness in adults over 50 years of age, and affects 30-50 million people worldwide. There are two forms of AMD, known as the “dry” and “wet” forms. Approximately 90% of AMD cases are of the dry form, for which there is currently no effective treatment. Both forms of AMD cause the loss of specialized light-sensitive cells, known as photoreceptors, from the macula, which forms the central part of the retina. The retina is the light-sensitive layer of tissue on the inner surface of the eye. AMD can lead to loss of central vision and profoundly affect visual function, making it difficult or impossible to discern colours and contrasts, read or recognize faces.

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In the current study, scientists at the Cedars-Sinai Medical Center in Los Angeles induced human stem cells to differentiate into neural progenitor cells (iNPCs). iNPCs can then change into different types of cells of the nervous system, of which the visual system is a part. When the iNPCs were transplanted into an animal model of AMD, the treatment greatly slowed the progression of the disease. Transplanted iNPCs migrated within the retina and protected photoreceptors from further deterioration. Visual tests showed that areas protected by the iNPCs were 140 times more light-sensitive than the same areas in untreated eyes. A single dose of iNPCs preserved vision for 130 days in the AMD rats, which is roughly equivalent to 16 years in humans.

Based on the results of the study, the authors are conducting further preclinical testing to establish the safety and efficacy of the treatment, paving the way for testing in human subjects. The authors conclude that the iNPC treatment holds promise to preserve vision in the early stages of AMD, and also plan to test the treatment in patients in later stages of AMD.