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Eye Trials Give Hope for Stem Cells

Preliminary data from human embryonic stem cell trials for two degenerative eye disorders are promising, but challenges remain for more complex tissues.

By | January 24, 2012

FLICKR, LENI MURPHY

After the pioneering stem cell company Geron, which launched the first-ever clinical trial for a human embryonic stem cell (hESC) therapy in 2010, shuttered its stem cell program last November for financial reasons, a shadow fell over the field of stem cell medicine. But yesterday, optimism rose as the stem cell research company Advanced Cell Technology (ACT) published in The Lancet preliminary data from two human patients, each with a different degenerative eye disorder, showing safety and perhaps even some efficacy of an hESC treatment.

“This is a milestone that will offer tremendous encouragement to the field, and promises hope for many families,” said George Daley, director of the stem cell transplantation program at Children’s Hospital Boston who was not involved in the research, in an email to The Scientist. “But these are still very early days of an uncontrolled and unblinded trial, and we have much more to learn about the safety and effectiveness of this new treatment before we can claim success.”

ACT currently has two clinical trials in the US to study hESC therapies underway, and both are treating degenerative eye disorders. Dry age-related macular degeneration and Stargardt’s macular dystrophy, the former affecting older adults and the latter a genetic disorder affecting children, both lead to blindness and originate from the breakdown of a one-cell-thick protective layer under the retina called the retinal pigment epithelium (RPE).

Replacing this RPE with a fresh layer of stem cells to halt disease progression was the goal of ACT’s Chief Scientific Officer Robert Lanza and his colleagues from the Jules Stein Eye Institute at the University of California, Los Angeles. They induced hESCs into early-stage bone and nervous tissue cells, which then differentiated into retinal epithelial cells with more than 99 percent purity. Around 50,000 of these dissociated cells were injected under the retina of two patients, the first from each trial: a woman in her 70s with dry age-related macular degeneration, and a middle-aged woman with Stargardt’s, both of whom were legally blind.

After 4 months, the researchers observed that the RPE had been replaced physically, and asked the women to perform some basic tests such as reading an eye chart to measure their vision. “There was structural evidence to confirm that cells were able to survive and persist throughout the study, and measureable improvement in their vision,” Lanza said. Regarding the visual improvement, he noted that “there could be some placebo component, but clearly there’s a biological component as well.”

Lanza will begin treating more patients in the coming weeks, for a total of 12 per early-stage trial, and treated the first patient in a similar European trial last week.

A strategic eye

Teratomas with three differentiated layers from stem cells visible.
Teratomas with three differentiated layers from stem cells visible.
WIKIMEDIA COMMONS

Though the results are promising so far, there are still many challenges ahead for the stem cell community because the eye, in many ways, is an alluring testing ground for stem cell therapy. Most obviously, the eye is easily accessible and visible, and thus “can be operated on very easily” compared to internal organs in case anything goes wrong, said Sheng Ding, a stem cell biologist at the Gladstone Institutes who was not involved in the study. The eye is also an immune-privileged site in the body, along with parts of the brain and central nervous system. Few pathogens troll the brain, said Ding, so the immune system has little presence in the area and doesn’t cross the blood-brain barrier from the body to the eyes and brain. This makes immune system rejection, the Achilles’ heel of most hESC therapies and organ transplants, a non-issue, and the first two patients in the ACT trials were taken off of preemptive immunosuppressant drugs after just 6 weeks.

Working with the eye also evades another major risk of stem cell therapy: tumor formation. Tumors can form if undifferentiated stem cells are accidentally injected into a patient along with the derived cells of interest, and then differentiate within the body to form a small tumor resembling malformed tissue called a teratoma. Most stem cell therapies require tens or hundreds of millions of cells to be injected into the body, said Ding, increasing the chances that a few undifferentiated cells could sneak through quality control and turn cancerous. But because replacing the retinal epithelium only requires 50,000 cells, the risk of teratoma formation decreases significantly. Just to be sure, however, ACT does employ an assay that can detect one undifferentiated cell in a million, said Lanza.

But these two patients still need continued surveillance for teratoma formation, argued Ding. If just a few undifferentiated stem cells are injected, “you may not see [an effect] at all, or you may be able to see it over a much longer period of time,” he said. The 4-month follow-up received by the trial patients thus far is “very short in this regard, and I think the patients need a much, much longer-term follow up to make sure there’s no tumor cells.”

But Lanza is hopeful that the news, however preliminary, will provide the stem cell field the boost it needs after losing the Geron trial. The trials in the eye “definitely pave the way for other pluripotent stem cell therapies,” he said. “The fact that these pluripotent stem cells can be differentiated, go into the eye, and behave well—knock on wood—has significance for the entire field.”

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Comments

Avatar of: Shi V. Liu

Shi V. Liu

Posts: 1457

January 24, 2012

I think it is too early to claim this result as a "milestone".  As a matter of fact, how many "milestones" have been collected out in the stem cell research field but the road to regenerative medicine is still unpaved?

Avatar of:

Posts: 0

January 24, 2012

I think it is too early to claim this result as a "milestone".  As a matter of fact, how many "milestones" have been collected out in the stem cell research field but the road to regenerative medicine is still unpaved?

Avatar of:

Posts: 0

January 24, 2012

I think it is too early to claim this result as a "milestone".  As a matter of fact, how many "milestones" have been collected out in the stem cell research field but the road to regenerative medicine is still unpaved?

Avatar of:

Posts: 0

February 23, 2012

Typical USA stem cell article, trying to prove useless embryonics have a shot when they have none---but politically correct, Ms. Hannah.  Too bad you are never allowed to tell the truth and still get published, because Big Medicine's bosses don't want stem cells which actually help people.  The truth would reduce their profits on always-useless standard medicine, and every writer stays well in line, as do you.

Big fuss about two patients with rare conditions for which there is no market, on every controlled website and in every major newspaper in our (LOL) "Free" Press; but absolute silence all over North America about Adult Stem Cells which have successfully treated hundreds of optic patients, even moving legally blind patients to drivers licenses!  Pharma is pleased and you should be proud to have excited optic patients about embryonic cures which will never come in their lifetime.

You also did your little bit for them in your breast-replacement article, which was spot-on until you got to the last paragraph, about stem cells.  God forbid you should explain the difference as to why the patients own stem cells could never "leak" and do damage.  Again, Pharma is proud of you and the hundreds of writers of your ilk who put politics and profits ahead of patients.

Don Margolis, Chairman
Repair Stem Cell Institute

Avatar of:

Posts: 0

February 23, 2012

Hi
I am concerned about Mr Margolis' comments re 'rare conditions for which there is no market'. I live in Australia and my 17 year old daughter has Stargardt's. There is a market for this therapy. Please do not make us give up hope that there is 'cure' in sight. (pardon the pun). I would love to know the treatments given to legally blind patients that have successfully treated them and allowed them to get a licence. Please let me know.
Yvonne Lane

Avatar of:

Posts: 0

February 23, 2012

Typical USA stem cell article, trying to prove useless embryonics have a shot when they have none---but politically correct, Ms. Hannah.  Too bad you are never allowed to tell the truth and still get published, because Big Medicine's bosses don't want stem cells which actually help people.  The truth would reduce their profits on always-useless standard medicine, and every writer stays well in line, as do you.

Big fuss about two patients with rare conditions for which there is no market, on every controlled website and in every major newspaper in our (LOL) "Free" Press; but absolute silence all over North America about Adult Stem Cells which have successfully treated hundreds of optic patients, even moving legally blind patients to drivers licenses!  Pharma is pleased and you should be proud to have excited optic patients about embryonic cures which will never come in their lifetime.

You also did your little bit for them in your breast-replacement article, which was spot-on until you got to the last paragraph, about stem cells.  God forbid you should explain the difference as to why the patients own stem cells could never "leak" and do damage.  Again, Pharma is proud of you and the hundreds of writers of your ilk who put politics and profits ahead of patients.

Don Margolis, Chairman
Repair Stem Cell Institute

Avatar of:

Posts: 0

February 23, 2012

Hi
I am concerned about Mr Margolis' comments re 'rare conditions for which there is no market'. I live in Australia and my 17 year old daughter has Stargardt's. There is a market for this therapy. Please do not make us give up hope that there is 'cure' in sight. (pardon the pun). I would love to know the treatments given to legally blind patients that have successfully treated them and allowed them to get a licence. Please let me know.
Yvonne Lane

Avatar of: Don Margolis

Don Margolis

Posts: 1457

February 23, 2012

Typical USA stem cell article, trying to prove useless embryonics have a shot when they have none---but politically correct, Ms. Hannah.  Too bad you are never allowed to tell the truth and still get published, because Big Medicine's bosses don't want stem cells which actually help people.  The truth would reduce their profits on always-useless standard medicine, and every writer stays well in line, as do you.

Big fuss about two patients with rare conditions for which there is no market, on every controlled website and in every major newspaper in our (LOL) "Free" Press; but absolute silence all over North America about Adult Stem Cells which have successfully treated hundreds of optic patients, even moving legally blind patients to drivers licenses!  Pharma is pleased and you should be proud to have excited optic patients about embryonic cures which will never come in their lifetime.

You also did your little bit for them in your breast-replacement article, which was spot-on until you got to the last paragraph, about stem cells.  God forbid you should explain the difference as to why the patients own stem cells could never "leak" and do damage.  Again, Pharma is proud of you and the hundreds of writers of your ilk who put politics and profits ahead of patients.

Don Margolis, Chairman
Repair Stem Cell Institute

Avatar of: Yvonne Lane

Yvonne Lane

Posts: 1457

February 23, 2012

Hi
I am concerned about Mr Margolis' comments re 'rare conditions for which there is no market'. I live in Australia and my 17 year old daughter has Stargardt's. There is a market for this therapy. Please do not make us give up hope that there is 'cure' in sight. (pardon the pun). I would love to know the treatments given to legally blind patients that have successfully treated them and allowed them to get a licence. Please let me know.
Yvonne Lane

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