Eighteen adults with a serious eye disease that were among the first to receive transplants created from human embryonic stem cells (hESCs) still do not have apparent complications with the cells introduced after an average of almost 2 years, according to the latest status report on their health. vision tests also suggest the view of more than half of the subjects had improved, but others have expressed reservations about these results. However, the result may pave the way for transplants derived ocular cells of stem cells called photoreceptors, which could significantly improve vision in people with eye disease if all goes according to plan.
Eye diseases such as age-related macular degeneration, as well as a genetic disease called macular dystrophy Stargardt that afflicts young people-are considered excellent candidates for stem cell therapy because the eye is an immune privileged site, meaning the transplanted cells are not as likely to be rejected as abroad compared with grafts elsewhere. (Volunteers in these trials nevertheless received immunosuppressants for 12 weeks as a precaution.) Such treatment could, in theory, to repopulate the eye with cells which were destroyed, helping to restore lost sight. But there are many obstacles: Among them, enough cells growing in a Petri dish and ensure that they connect to "existing machinery" in the eye, said Hendrik Scholl, who co- directs the Center for stem cell and regenerative medicine Ophthalmic at Johns Hopkins University in Baltimore, Maryland. There have also been security problems facing all hESC studies, including concerns that embryonic stem cells could proliferate out of control.
Today's report, which appears in The Lancet , follows another in the same group in early 2012. Then a team led by Robert Lanza, chief scientist in Chief technology Advanced cell Inc. in Marlborough, Massachusetts, and his colleagues published the first results ever clinical trial using human embryonic stem cells. This study indicated that the first two patients, both legally blind, had suffered no ill effects from the cells.
Now Lanza and Steven Schwartz, who heads the division of the retina at the Jules Stein Eye Institute at the University of California, Los Angeles, and colleagues to share details from initial studies in two different eye diseases. They describe the results on nine people with macular degeneration and nine with Stargardt's age. The volunteers, aged 20 to 88 were injected in their retina of a particular type of cells in the eye, the retinal pigment epithelium (RPE) cells, which were derived from hESCs in the lab. RPE cells have some great benefits for the first hESC Security Studies: Because they are pigmented, they can be tracked. They are also relatively easy to grow, manipulate and control in the laboratory. The downside is that people with these eye diseases lose sight largely because they lose another type of eye cells :. Photoreceptors sensitive to light in the retina
However, the test results offer hope to the distance. After surgery, 13 of the 18 patients had increased pigmentation, suggesting that the transplanted cells have done their work. The authors also reported that 10 patients reported some improvement in their vision, Lanza said was an unexpected result. "In the best case, we thought we could hopefully prevent vision loss in these patients," he said, because the RPE cells are known to help maintain existing photoreceptors in part by digesting debris cell they lose. "We did really expected such a dramatic improvement," says Lanza. He suspects that the transplanted cells are actually restore photoreceptor function "dormant".
However, improvements not correlate with the additional amount detected pigment researchers, Lanza and is careful to point out that, for ethical reasons, the study had no control group that received the transplanted cells without surgery.
Scholl is optimistic that the transplanted cells still appear safe and said that the analysis of cells in the eyes of the recipients are "in fact an indication that something is happening. "The" small signal "this improved vision in this cohort could be because the remaining photoreceptors" are exposed to a healthy environment, "he believes. Or it could be due to cataract surgery many patients in the study received, or the challenges of measuring the vision to start. . Yet Scholl added, RPE cell transplantation "can not be" for these patients, because ultimately they need new photoreceptors to restore vision
Some groups, including Lanza that seek to do exactly it. transplant photoreceptor cells early data show that these cells derived from hESCs, have "an amazing ability" to migrate into the retina and restore vision, Lanza said. But they are more difficult to grow in the laboratory and tests are currently limited to animals. In the long term, it is hoped that the injection of these cells could make a huge difference to people whose sight is disappearing or have already disappeared.
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