A second company has requested permission from the U.S. Food and Drug Administration (FDA) to conduct a human clinical trial using embryonic stem cells.

Human embryonic stem cells Image: Wikimedia commons, Nissim Benvenisty

Advanced Cell Technology (ACT) filed an Investigational New Drug (IND) application yesterday (November 18) to conduct a phase I/II trial using hESCs to treat a genetic eye disease.

"I'm cautiously optimistic," said Marco Zarbin of the Institute of Ophthalmology & Visual Science of University of Medicine and Dentistry of New Jersey, who would participate in the proposed trial. "Of all the places in the body where I can imagine cell-based therapy working, first -- because it's so seemingly simple -- is in the eye."

If approved, this would be only the second clinical trial involving hESCs. The first -- Geron's study of stem cell treatment for spinal cord injury -- has been on hold by the FDA since August due to microscopic cysts that developed in an animal study, and doesn't expect to resume until the third quarter of next year.

The proposed trial aims to treat patients with Stargardt's Macular Dystrophy (SMD) -- a genetic eye disease for which there is currently no treatment and one of the most common causes of juvenile blindness. The disease results in the degeneration of the retinal pigment epithelium (RPE) -- cells that support the photoreceptors needed for vision -- which in turn causes the degeneration of the photoreceptors and leads to vision impairment. ACT proposes to transplant hESCs that have been differentiated into retinal pigment epithelial cells into SMD patients in hopes of improving visual acuity.

Previous work at ACT has shown dramatic improvement in the visual performance of rats who received implants of these differentiated RPE cells, according to a 2006 study. Furthermore, they found no adverse effects (such as teratomas) in hundreds of treated animals, and the cells are "almost 100% RPE," said Robert Lanza, ACT's chief scientific officer, meaning there are virtually no undifferentiated cells that could potentially behave differently after implantation.

"From the data that we've seen, I think we're in a good position to take this into the clinic in an effective and safe fashion," said Peter Francis of the Casey Eye Institute in Portland, OR. The Casey Eye Institute is one of the clinics that would participate in the study, and Francis also contributed to the preclinical research leading up to this IND.

"We're in good shape," agreed Lanza. "I'm sure [the FDA is] going to have some questions and want some additional information, but, knock-on-wood, we'll be able to start early next year with the clinical trial."

The trial will involve a total of 12 patients and three clinical sites, Lanza said. "Once you show that the patients tolerate the cells, we can go in to larger numbers."

In addition, given the similar pathological processes between Stargardt's Macular Dystrophy and age-related macular degeneration, ACT also hopes to file an IND in the next few months to use hESCs in age-related macular degeneration, a disease that affects millions worldwide.


Related stories:

Geron trial may resume next year
[30th October 2009]

Profiting from Pluripotency
[February 2009]

FDA mulls embryonic stem cell therapy
[11th April 2008]