Stem cells improve visual function in blind mice

October 1, 2012 by Susan Conova
Central vision is lost in age-related macular degeneration after cells in the retina deteriorate. New research by Stephen Tsang suggests special adult stem cells could restore sight or prevent vision loss.

An experimental treatment for blindness, developed from a patient's skin cells, improved the vision of blind mice in a study conducted by Columbia ophthalmologists and stem cell researchers.

The findings suggest that induced pluripotent stem (iPS) cells – which are derived from adult but have embryonic properties – could soon be used to restore vision in people with and other diseases that affect the eye's retina.

"With eye diseases, I think we're getting close to a scenario where a patient's own are used to replace destroyed by disease or degeneration," says the study's principal investigator, Stephen Tsang, MD, PhD, associate professor of and & cell biology. "It's often said that iPS transplantation will be important in the practice of medicine in some distant future, but our paper suggests the future is almost here."

The advent of human iPS cells in 2007 was greeted with excitement from scientists who hailed the development as a way to avoid the ethical complications of embryonic and create patient-specific stem cells. Like embryonic stem cells, iPS cells can develop into any type of cell. Thousands of different iPS cell lines from patients and healthy donors have been created in the last few years, but they are almost always used in research or drug screening.

No iPS cells have been transplanted into people, but many say the eye is the ideal testing ground for iPS therapies.

"The eye is a transparent and accessible part of the central nervous system, and that's a big advantage. We can put cells into the eye and monitor them every day with routine non-invasive clinical exams," Tsang says. "And in the event of serious complications, removing the eye is not a life-threatening event."

In Tsang's new preclinical iPS study, human iPS cells – derived from the skin cells of a 53-year-old donor—were first transformed with a cocktail of growth factors into cells in the retina that lie underneath the eye's light-sensing cells.

The primary job of the retina cells is to nourish the light-sensing cells and protect the fragile cells from excess light, heat, and cellular debris. If the retina cells die – which happens in macular degeneration and retinitis pigmentosa – the photoreceptor cells degenerate and the patient loses vision. Macular degeneration is a leading cause of vision loss in the elderly, and it is estimated that 30 percent of people will have some form of macular degeneration by age 75. Macular degeneration currently affects 7 million Americans and its incidence is expected to double by 2020.

In their study, the researchers injected the iPS-derived retina cells into the right eyes of 34 mice that had a genetic mutation that caused their retina cells to degenerate.

In many animals, the human cells assimilated into mouse retina without disruption and functioned as normal retina cells well into the animals' old age. Control mice that got injections of saline or inactive cells showed no improvement in retina tests.

"Our findings provide the first evidence of life-long neuronal recovery in a preclinical model of retinal degeneration, using stem cell transplant, with vision improvement persisting through the lifespan," Tsang says. "And importantly, we saw no tumors in any of the mice, which should allay one of the biggest fears people have about stem cell transplants: that they will generate tumors."

Tsang hopes to begin a clinical trial for macular degeneration patients in the next three years, after more preclinical testing in animal models.

Already a similar trial – testing retina cells derived from embryonic stem cells – has seen encouraging preliminary results. A paper from this study, published earlier this year, reported that the stem cells are safe and have potential to improve the vision of two patients with macular degeneration.

"These results are encouraging, but iPS cells could be a more attractive option than embryonic stem cells," Tsang says, "because patients may not need drugs to prevent rejection of the transplanted ."

Regardless of which cell works better, the prospect of stem cell transplants may mean many people with macular degeneration may never lose their vision.

"We have a good idea which patients will eventually lose their vision. In the early stages of macular degeneration we can tell by looking in the eye, and new genetic tests can now predict vision loss with 70 percent accuracy even before those signs emerge," Tsang says. "If the therapy is safe, we could intervene very early to prevent much vision loss."

The study was published online in advance of print in the journal Molecular Medicine.

Explore further: Sections of retinas regenerated and visual function increased with stem cells from skin

Related Stories

Sections of retinas regenerated and visual function increased with stem cells from skin

May 16, 2011
Scientists from Schepens Eye Research Institute are the first to regenerate large areas of damaged retinas and improve visual function using IPS cells (induced pluripotent stem cells) derived from skin. The results of their ...

Recommended for you

Want to win at sports? Take a cue from these mighty mice

July 20, 2017
As student athletes hit training fields this summer to gain the competitive edge, a new study shows how the experiences of a tiny mouse can put them on the path to winning.

'Smart' robot technology could give stroke rehab a boost

July 19, 2017
Scientists say they have developed a "smart" robotic harness that might make it easier for people to learn to walk again after a stroke or spinal cord injury.

Engineered liver tissue expands after transplant

July 19, 2017
Many diseases, including cirrhosis and hepatitis, can lead to liver failure. More than 17,000 Americans suffering from these diseases are now waiting for liver transplants, but significantly fewer livers are available.

Lunatic Fringe gene plays key role in the renewable brain

July 19, 2017
The discovery that the brain can generate new cells - about 700 new neurons each day - has triggered investigations to uncover how this process is regulated. Researchers at Baylor College of Medicine and Jan and Dan Duncan ...

New animal models for hepatitis C could pave the way for a vaccine

July 19, 2017
They say that an ounce of prevention is worth a pound of cure. In the case of hepatitis C—a disease that affects nearly 71 million people worldwide, causing cirrhosis and liver cancer if left untreated—it might be worth ...

Omega-3 fatty acids fight inflammation via cannabinoids

July 18, 2017
Chemical compounds called cannabinoids are found in marijuana and also are produced naturally in the body from omega-3 fatty acids. A well-known cannabinoid in marijuana, tetrahydrocannabinol, is responsible for some of its ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

Sonhouse
not rated yet Oct 01, 2012
Do you think it could work for all three of them?

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.