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A new study is the first of its kind to prove long-term safety of embryonic stem cell transplants used to treat human disease. The involved 18 people who received transplants as a means of treating different forms of macular degeneration, the number one cause of vision loss.
Not only did the transplants restore some degree of sight in about 50% of participants, it appeared to be safe three years after completion of the procedure.
Findings of this study were noted in the October publication of The Lancet and according to Dr. Robert Lanza, chief scientific officer at Advanced Cell Technology, there is great potential for embryonic stem cells to become virtually any cell within the body.
However, when it comes to transplantation, several problems have surfaced to include cell rejection due to a compromised immune system and risk the cells could promote teratomas, a specific type of cancer. Teratoma develops when stem cells transform into several different kinds of cells and then form incompatible tissue such as hair and teeth.
Lanza further explains that based on these known issues, scientists who work with embryonic stem cell therapy usually focus on areas of the body that do not naturally produce a strong immune response, to include the eyes.
In the study, researchers first prompted embryonic stem cells to develop into eye cells known as pigment epithelial cells. The cells were then transplanted into 18 patients, nine with dry atrophic age-related macular degeneration and nine who have Stargardt’s macular dystrophy.
For three years after the transplants, patients were monitored. During that period, no signs of immune system rejection or cancer-like cell growth were found in any of the treated eyes. The team also conducted a 22-month follow-up, which revealed that adverse effects were associated only to the actual eye surgery or suppression of the immune system, not the transplanted cells.
As noted by Dr. Steven Swartz, co-lead author of the study and doctor with the Jules Stein Eye Institute in California, the results of this study suggest that human embryonic stem cells used to alter progressive loss of vision in people with degenerative diseases is both promising and safe long-term.
The study’s findings are also an exciting step forward in using stem cells as a safe method of treating a number of different medical conditions that require replacement or repair of tissue. Dr. Anthony Atala, director of the Wake Forest Institute for Regenerative Medicine and Wake Forest School of Medicine agrees that this new study is a huge accomplishment.
There are a few scientists who prefer to take a more cautious approach to include Dr. C. Michael Samson, co-director of Ocular Immunology and Uveitus Service at the Eye and Ear Infirmary of Mount Sanai in New York. He said that loss of vision caused by a damaged retina, regardless if from diabetes or macular degeneration, cannot be reversed with treatment options currently available.
In support of the study, Dr. Samson stressed that stem cell technology offers the best hope in recovering lost vision and that according to this pilot study, incredible progress is being made. Dr. Mark Fromer, ophthalmologist at Lenox Hill Hospital in New York agreed that using stem cell transplants to treat cases of degenerative diseases in the future is promising.
