The researchers have identified embryonic cells in the brain that can multiply indefinitely in the test-tube yet develop into fully mature nerve cells when they are transplanted into a damaged region of the brain.
Finding and culturing the so-called "stem cells" of the human brain is the holy grail of neurosurgery, because it raises the prospect of reviving dead regions of the brain that were, until now, considered to be beyond repair.
Evan Snyder, an assistant professor of biology at Harvard Medical School in Boston, said he had isolated the stem cells from foetal brain tissue and they survive and replicate outside the body.
There appears to be no limit to the number of brain cells he can grow in the laboratory from the line of stem cells he has established for transplant operations.
"This is the first report of a rigorously defined stem cell of the human brain that can be grafted into the brain. We hope to show that we can integrate them in a seamless fashion into the fabric of the brain," Professor Snyder said.
One possibility is that the stem cells can be genetically engineered to possess the genes that are not functioning in patients who are afflicted with inherited defects.
A transplant with the engineered stem cells could result in rectification of the genetic fault and recovery from the disorder, Professor Snyder said.
Research published in the journal Nature Biotechnology shows that when Professor Snyder and his colleagues injected the stem cells into mice, the human cells developed into fully mature nerve cells.
A separate research team, led by Oliver Brustle of the University of Bonn, demonstrated that the human stem cells were so versatile that they could be fully integrated into the developing brain of rats to create a human-rodent chimeric brain.
Professor Snyder said the next stage of the research is to investigate safety by injecting the stem cells into the brains of laboratory monkeys. Attempts at a human transplants could begin within the next five years.Reuse content