美國有一百七五萬人因年齡增長得到黃斑點退化症(macular regeneration),造成視力永久的損失.此外,約有十萬人得到視網膜色素變性(retinitis pigmentosa),造成視力逐漸喪失,並會遺傳到下一代.
對於這兩個疾病的治療,目前沒有有效的方法.美國Nebraskau大學的醫學中心(UNMC)花了四年的時間,利用小鼠與大鼠模式,研究成體幹細胞對視網膜的治療.發現打入特定化學組成物(chemical combination)於老鼠的視網膜內,可以再生視網膜細胞上的光學接收器,將光刺激轉為視覺訊號傳遞致大腦產生視力.
這項成功的發現,使科學家下一步要運用在猴子,研究哺乳類動物的視力再造.
Stem cell work targets eye disease
By Rick Ruggles Published Monday September 6, 2010
WORLD-HERALD STAFF WRITER
Scientists at the University of Nebraska Medical Center hope they are homing in on a strategy to use adult stem cells to treat certain diseases that cause blindness.
The strategy, which so far has been effective in rats and mice, uses a chemical process to coax stem cells in the back of the eye into becoming like light-capturing cells that have deteriorated.
Dr. Iqbal Ahmad, the lead scientist on the project, said the process is several years or more from providing treatment for age-related macular degeneration and retinitis pigmentosa in humans. Age-related macular degeneration affects more than 1.75 million Americans and retinitis pigmentosa about 100,000.
“I think we are quite far away from this,” Ahmad said of human treatments. Currently there is no effective treatment to reverse those diseases, he said.
The findings of Ahmad, Dr. Carolina Del Debbio and their colleagues offer hope for treatments for eye diseases that will increase in number as baby boomers age. They published the results of their study recently in PLoS One, a science journal through the Public Library of Science.
The findings also generally reflect the potential of adult stem cell research, which is being conducted by various UNMC scientists and carries none of the controversy of research using embryonic stem cells.
The diseases in question involve the degeneration of photoreceptors, which are cells in the retina at the back of the eye that capture light from objects. They convert that light to visual signals, which are passed on to the brain by other cells in the retina.
Adult stem cells are healing cells that are created throughout an animal's life. But scientists believed that while other creatures, such as fish and frogs, have stem cells in the retina, mammals didn't have such cells.
UNMC scientists discovered four years ago, though, that stem cells in the retinas of rats and mice could be activated by the right chemical combination. The retina in mice and rats is similar to the human retina. The chemicals are injected into the eye, although they might eventually be applied through eyedrops, Ahmad said.
Ahmad said that among other things, he needs to increase the efficiency with which the chemicals convert the stem cells into photoreceptors. Also, scientists will have to test the strategy on monkeys before using it on humans.
