Therapy with the use of human embryonic stem cells improves vision in two patients
Two patients having vision disorders had their vision improved after the transplantation of retinal epithelium cells derived from human embryonic stem cells, a preliminary study funded by Advanced Cell Technology Inc.—the company that developed the treatment—says. The study results have been recently published online in the journal Lancet
The study conducted by University of California, Los Angeles (UCLA), involved two patients. The one had dry age-related macular degeneration, and the other Stargardt’s macular dystrophy. Both diseases are known to cause blindness and in both retinal photoreceptor cells are involved.
To treat the diseases, the researchers decided to replace damaged cells with new retinal epithelium cells made from embryonic stem cells. In the study, they aimed to test the safety of the method chosen. As embryonic stem cells are known to cause tumor formation, the dose of injected cells was intentionally low and equaled about 50,000 cells. The injection was made in one eye only to leave the other one as a control. Due to the fact that the eye is protected by a blood-ocular barrier, meaning that the cells transplanted are not able to travel to other tissues, only low doses of immunosuppression were used.
Despite the low dose of cells injected, both patients reported vision improvement. The vision of the patient with macular degeneration improved from 20/500 to 20/320, the perfect vision being 20/20. Now the patient distinguishes 33 letters on an eye chart instead of only 20 before the treatment. The person with Stargardt disease could distinguish only hand movements before the transplantation. Two weeks after the treatment, the patient could start reading letters on an eye chart and was able to read the five letters on it with the treated eye in the following months. Her vision improved to 20/800. Given the progressive nature of both diseases, these results are impressive.
As the initial aim of the study was to estimate its safety, the researchers concentrated on finding trouble signs. However, no tumor formation, cell rejection, hyperproliferation or other adverse effects were observed in any patient during the 4-month follow-up period. Instead, stem cell differentiation was under control in both patients.
As immune suppression, though in low doses, was used, it remains unknown whether the transplanted cells would be rejected without it. It is also under question how long the treatment effects will last. The company plans another two trials involving 12 patients each to test the safety and tolerability of transplantation of retinal photoreceptor epithelial cells derived from embryonic stem cells.
Fetal stem cells treatment results depend on: disease's severity, age of the patient, adherence for the medications and regime. Treatment results, presented on this site, are individual for each clinical case.