FDA approves second human embryonic stem cell trial

For only the second time in history, the Food and Drug Administration has approved human trial of a therapy developed from embryonic stem cells.

William Caldwell, CEO of Massachusetts-based Advanced Cell Technology (ACT), tells CNN that 366 days after filing the application, the FDA granted approval for his company to start a clinical trial using cells grown from human embryonic stem cells.  The treatment will be for an inherited degenerative eye disease.

"Were still absorbing the fact that we finally got the approval" says Caldwell.  "The real work lies ahead."  Getting the trial going is the next big step, says Caldwell.  He hopes the first patients can be enrolled by the first quarter of the next year.

In July the FDA gave the Geron Corporation the final go-ahead for its study, which led to the first human being injected with cells derived from human embryonic stems last month. In that study a newly paralyzed patient had a stem cell treatment directly injected into the spinal cord. While the immediate goal is to test the safety of these cells, the ultimate goal in Geron's trial is to permanently repair damage cause by a spinal cord injury.

When ACT's clinical trial gets under way, it,too, will first test the safety of the cells they're injecting.  The company is hoping to find a cure for Stargardt Macular Dystrophy, the most common form of juvenile macular degeneration, for which there is currently no cure.  It affects about 1 in 10,000 children. People with this disease usually start losing their sight between the ages of 8 to 10 years and can be legally blind by the time they reach their 30s says Caldwell.

Embryonic stem cells are only four to five days old and have the ability to turn into any cell in the body.  But the cells patients will receive in both of these clinical trials aren't pure human embryonic stem cells.  Geron has coaxed its cells into becoming a type of cell that insulates nerve cells.  ACT's stem cells have been turned into healthy retinal pigment epithelium (RPE) cells.   RPE cells are naturally found behind the neural retina and it's the death of these cells that leads to blindness in patients with macular degeneration.  The company says their animal studies found vision restored after these new RPE cells were injected.

If this treatment works, Caldwell believes it could be applied to other diseases that lead to blindness, including age-related macular degeneration, which affects millions of Americans and will only increase as baby boomers continue to get older.

ACT's  method of removing stem cells from an embryo is different from Geron's. ACT developed a method in which only one stem cell is removed from an embryo, similar to a method  used in some fertility clinics to test an embryo for genetic abnormalities.  That stem cell is then used to grow many more stem cells.  By removing only one stem cell, the embryo is not destroyed. Destruction of embryos  is the main reason that embryonic stem cell research has been so controversial.