A team of international researchers has transferred eye tissue from newborn to adult mice. It lets the blind adults detect light. The scientists say it challenges conventional wisdom on stem cells, because the successful cells had already stopped dividing before they were transferred.
Stem cells are primal cells that retain the ability to renew themselves through cell division and can differentiate into a wide range of specialized cell types. Research in the stem cell field grew out of findings by Canadian scientists Ernest A. McCulloch and James E. Till in the 1960s.
The two categories of stem cells include embryonic stem cells and adult stem cells and possibly a third, cord-blood-derived embryonic-like stem cells (CBEs). In a blastocyst of a developing embryo, stem cells differentiate into all of the specialised embryonic tissues. In adult organisms, stem cells and progenitor cells act as a repair system for the body, replenishing specialized cells. As stem cells can be readily grown and transformed into specialized tissues such as muscles or nerves through cell culture, their use in medical therapies has been proposed.
Blind mice regained some ability to see after getting transplants of cells taken from the eyes of other mice, strengthening the prospect that it may someday be possible to restore vision in some people who have lost most or all of their eyesight, scientists reported.
Researchers in London and Michigan who did the work warned that it would be years before similar efforts might be tried in people who have lost their vision from macular degeneration, the kind of blindness addressed in the mouse study.
But they said the new study showed for the first time that light-detecting retina cells ? which in this case were taken from other animals but which scientists have begun to grow from human embryonic stem cells ? can orient themselves properly after being injected into a blind eye, connect to other nerve cells and communicate appropriately with visual centers in the brain.