Tuesday, October 2, 2012

Stem cells improve visual function in blind mice

ScienceDaily (Oct. 1, 2012) ? 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 human skin cells but have embryonic properties -- could soon be used to restore vision in people with macular degeneration 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 skin cells are used to replace retina cells destroyed by disease or degeneration," says the study's principal investigator, Stephen Tsang, MD, PhD, associate professor of ophthalmology and pathology & 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 stem cells 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 ophthalmologists 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 cells."

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. The research was supported by NIH grants 5P30CA013696, P30EY019007, and R01EY018213; the Schneeweiss Stem Cell Fund, and the Foundation Fighting Blindness.

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The above story is reprinted from materials provided by Columbia University Medical Center. The original article was written by Susan Conova.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.


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Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of ScienceDaily or its staff.

Source: http://feeds.sciencedaily.com/~r/sciencedaily/most_popular/~3/ttXml6yDcNc/121001141127.htm

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Two female tourists freed after Ecuador kidnap

APTN

Kathryn Cox, left, and Fiona Louise Wilde were abducted as they travelled by canoe through the Cuyabeno nature reserve in the Tarapoa region of Ecuador.

By ITV News and Alastair Jamieson, NBC News

Two female tourists were kidnapped while visiting a nature reserve in north-eastern Ecuador near the border with Colombia, but were released after two days, authorities said Monday.

Kathryn Sara Cox, 23, who is British, and an Australian identified in local media as 32-year-old Fiona Louise Wilde, were seized on Friday by what Ecuadorean authorities said was a Colombian group, according to a BBC report.

Ecuador's interior minister Jose Serrano said the two were rescued Sunday night by police and armed forces.

Read more on this story at ITV News

Britain?s Foreign and Commonwealth Office (FCO) said the safety of Cox was now "top priority" as U.K. and Ecuadorian authorities worked together to find who was responsible.

Two female tourists are free after being kidnapped in Ecuador near the Colombian border and spending two days with captors in the jungle. NBCNews.com's Dara Brown reports.

An FCO spokesman said:

"We are very pleased to be able to confirm that Kathryn Sara Cox, who was kidnapped in a remote part of Sucumbios province, Ecuador, on Friday has been found today. She, along with an Australian national, was found following an intensive search of the area by the police and military. She is now in the care of Ecuadorian and U.K. officials, and her health and safety is our top priority. We are giving full consular assistance to both her and her family."

The incident took place as the women traveled by canoe as part of a tour group in the Cuyabeno nature reserve in the Tarapoa region of Sucumbios province, in the north east of Ecuador close to the border with Colombia, the BBC said.

Officials in Ecuador are searching for suspected arsonists behind the devastating wildfires that have burned thousands of acres of farmland. NBCNews.com's Dara Brown reports.

It reported they were part of a group made up of several foreign tourists and two Ecuadorean guides. Local reports suggested a criminal gang called the Black Eagles, made up of ex-paramilitaries, might have been behind the abduction, according to the BBC.

Australia?s Herald Sun newspaper quoted Wilde as saying:

"We were very scared. We could often hear the helicopters above us and that was very comforting while we were in the jungle.?When the helicopters got right above us, the kidnappers made us hide under bushes and they got scared and they were, we think, close to maybe nearly killing us. For some reason they changed their mind and told us to run and we ran out towards the helicopters, yelling and trying to get their attention.?

The U.S. State Department does not warn against travel in that part of Ecuador, but noted that at least four U.S. citizens have been murdered in Ecuador since 2009.

ITV News is the UK partner of NBC News

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Source: http://worldnews.nbcnews.com/_news/2012/10/01/14170111-two-female-tourists-freed-after-ecuador-kidnap-ordeal?lite

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