First Light for Human Embryonic Stem Cell Therapies?


Today the Lancet published a report on the early results of a trial of a treatment based on cells derived from human embryonic stem cells.  Download here.

The article reports on a trial conducted by the Jules Stein Eye Institute at UCLA and funded by the biotech company Advanced Cell Therapies (ACT).  The FDA has approved three clinical trials using cells derived from human embryonic stem cells.  The first, and most famous, was the Geron trial for spinal cord injury.  In November 2011, Geron stopped that trial after treating four patients. Meanwhile, with much less publicity, ACT had received approval to start two different clinical trials to treat macular degeneration, a leading cause of blindness. The first trial focused on a rare, genetic, early-onset version of the disease, known as Stargardt’s macular dystrophy. The second approval was for a treatment of the more common form of the disease, macular degeneration, dry type.  (Wet type macular degeneration makes up about 10 percent of the cases, and, unlike dry type, does show some response to drug treatments.)  All forms of the disease involve the death of cells in the retinal pigment epithelium (RPE) of the eye.

The Lancet piece reports on two – and only two – patients.  One patient had Stargardt’s macular dystrophy and the other had macular degeneration, dry type.  Last July the UCLA researchers transplanted about 50,000 RPE cells that ACT had derived from human embryonic stem cells into the subretinal space in one eye of each of the two subjects.

The trials are primarily intended to show the safety of the process and the article says that, so far, they are safe. But the article also says that the two trial subjects had some improved vision in their treated eyes, but not in their untreated eyes.  Although the improvements in their vision were not great, each subject reported that she found the improvements personally useful.

What does it mean?

My advice – wait and see.  This may or may not means that these cells will be safe, or effective, in treating these diseases, let alone that other cells derived from human embryonic stem cells will be safe and effective in treating other diseases. And, even if these and other trials do work, it may or may not mean that any eventual treatments will use human embryonic stem cells, human adult stem cells, human induced pluripotent cells, or some other form of stem cell.

But, this clearly is some good news for those hoping for treatments from human embryonic stem cells.   Granted, it is only a little good news.  A report on four months of treatment in two patients, with two related but different diseases, cannot bear heavy reliance.  That’s too few patients for too little time to be too exciting. But it is, at least, a little exciting – and in a field that saw its first approved clinical trial stopped two months ago, even a little exciting news is very welcome

When California passed Proposition 71 in November 2004, I was quoted saying that I would be disappointed if there were not some human clinical trials within 5 years and would be further disappointed if there were not some treatments emerging within 10 years.  I did not count on the three year delay in funding from that Proposition caused by frivolous litigation (and courts unwilling to act promptly to dismiss those claims).  Given that CIRM funding did not really start until 2007, I’m going to take (some, little) heart from this report.

Just as these two research subjects have not had normal vision restored, it is far too early to say that that the vision of a medicine transformed by stem cells will soon, or even, be a reality.  But, as with these two subjects, it does seem fair to say that these trials have cast at least two rays of light into the gloom.

Hank Greely