“Latest Stem Cells News”

Nerve stem cell transplants may help slow the progression of macular degeneration, the most common cause of blindness in the developed world, U.S. researchers said on Monday.

They said putting nerve stem cells from StemCells Inc near the retinas of rats with a form of macular degeneration helped keep the disease from advancing to blindness for several months.

“These cells improve the chemical environment in the back of the eye,” said Ray Lund of the Casey Eye Institute at Oregon Health & Science University in Portland, whose findings were presented at the Society for Neuroscience meeting in Chicago.

Lund said the mechanism is not clear, but he suspects that when immature nerve cells are placed near the retina, they produce growth factors that protect the cells from damage by the disease.

Deep in the brain, buried in the hippocampus and subventricular zone, reside adult neural stem cells, cells that retain the ability to become other types of neural cells and could serve as possible treatments for ailments ranging from vision impairment to Parkinson’s to spinal cord injuries. Doctors, scientists and patients, however, are understandably hesitant to go digging around for them, their location being “a great deterrent,” Sally Temple, founder of the New York Neural Stem Cell Institute, said at the 2009 World Stem Cell Summit here on Wednesday.

Researchers, therefore, are anxious to uncover other, more accessible neural stem cell candidates. Temple and her team have turned their sights to the retinal pigment epithelium (RPE), a layer of tissue at the base of the retina that comes into being within 30 to 50 days of conception, before many other parts of the neural system differentiate. Cells from this area of the eye can be easily harvested from retinal fluid that is usually discarded during retinal surgery, she explained (…)

from http://www.scientificamerican.com/blog/60-second-science/post.cfm?id=stem-cells-bring-new-insights-to-fu-2009-09-24

Scientists genetically “reprogrammed” human skin cells to possess the same properties as those that make up the retina.

The process involved first turning them into pluripotent stem (IPS) cells, which have the potential to develop into virtually every kind of tissue in the body.

By exposing the IPS cells to a specific cocktail of chemicals, the scientists then caused them to grow into partially developed retina cells – the light-sensitive cells at the back of the eye which transmit nerve signals to the brain.
Although the work, published in the Proceedings of the National Academy of Sciences, is at a very early stage, it paves the way for treatments that allow retinas to be repaired with cells grown from a patient’s own skin.

In the more immediate future scientists could use the cultivated cells to study genetically-linked eye disorders, or screen new drugs for retina conditions.

Study leader Dr David Gamm, from the University of Wisconsin, said: “This is an important step forward for us, as it not only confirms that multiple retinal cells can be derived from human IPS cells. but also shows how similar the process is to normal human retinal development.

“That is quite remarkable given that the starting cell is so different from a retinal cell and the whole process takes place in a plastic dish.

“We continue to be amazed at how deep we can probe into these early events and find that they mimic those found in developing retinas.
“Perhaps this is the way to close the gap between what we know about building a retina in mice, frogs and flies with that of humans.”

Tests showed that the IPS cells gave rise to many types of retina cell, including the photoreceptors that turn light impulses into electrical nerve signals.
In previous research, scientists have succeeded in restoring vision to blind mice by repairing their retinas with stem cells.

Future treatments could help patients with conditions such as macular degeneration, the leading cause of blindness among the elderly.

Another disorder involving damage to the retina is retinitis pigmentosa, which causes tunnel vision and blindness.
* Meanwhile, a new kind of “patch” made from stem cells that can mend a broken heart after an attack has been successfully tested by scientists.

Cells lost from the heart do not grow back naturally, leaving the organ in a weakened and vulnerable state.
Researchers in Israel demonstrated the new patch in rats with injured hearts.

from Telegraph

After much hope and controversy, for the first time stem cells have proven to have the ability to cure a disease. The news comes from a study on age-related macular degeneration (AMD) of the retina, the most common cause of blindness in individuals over the age of 50. The Sunday Times reports that the treatment was developed by a group of British researchers, who say that in the next six to seven years the treatment will become a routine operation, which will not last more than an hour. The treatment involves the replacement of a layer of degenerated cells with new cells created using embryonic stem cells, primitive cells that are able to transform into any type of human tissue.

AMD strikes the central area of the retina, the macula, which progressively deteriorates. Cloned retina cells are placed on an artificial membrane inserted into the posterior retina. The research was conducted by the department of ophthalmology of the University College of London and Morfields Hospital. Ethical controversy is inevitable because in order to create this type of stem cells embryos are used, which is explicitly allowed by British legislation. American pharmaceutical group Pfizer, said the Times, is supporting the study.

Human embryonic stem cells implanted into mice specifically engineered to have a serious retinal dysfunction resulting in blindness have restored the animal’s capacity to sense light during tests.
The results, published in international magazine, Cell Stem Cell, were obtained in the United States by a research group in the Department of Biological Structure at the University of Washington in Seattle. The study, performed by Deepak Lamba, Juliane Gust, and Thomas Reh, demonstrated that it is possible to obtain retina progenitor cells from stem cells derived from the embryo. The researchers observed, “In principle, embryonic stem cells could be a source of photoreceptors” which are specialized nerve cells found on the retina and could be “used to repair the retina”.