SAN FRANCISCO--Cells gathered from umbilical cords can develop into brain cells, according to a new study. The cells can migrate to recently damaged tissue in rat brains and allow the animals to recover faster and more thoroughly, researchers reported here on 18 February at the annual meeting of the American Association for the Advancement of Science, ScienceNOW's publisher.
Stem cells haven't yet committed to becoming a particular type of tissue. This makes them therapeutically valuable; for instance, stem cells harvested from umbilical cord blood are already used to replace blood cells in people with leukemia and certain types of anemia. Stem cells from other sources, such as embryos and lab cell lines, repair brain and spinal cord injuries in animals (Science, 24 November 2000, p. 1479). Reasoning that umbilical cord blood might serve as a ready and uncontroversial source of stem cells to treat neurological damage, a research team led by neuroscientist Paul Sanberg at the University of South Florida in Tampa tested whether they could coax such cells to behave like brain cells.
The researchers tweaked the human umbilical cord cells with retinoic acid, a standard technique to send the cells on the path to becoming a neuron. The cells started turning on some of the same genes that are active in the brain's neurons and associated glial cells. Encouraged, the team then injected the umbilical cord blood cells into the bloodstream of rats whose brain had been damaged by an artificial stroke. If the cells were delivered 24 hours after the stroke, Sanberg reported, the rats recovered faster than untreated rats, as measured by their ability to keep their balance in the laboratory equivalent of a log-rolling contest. Injecting the cells 7 or 14 days after the stroke also helped the rats recover, although not as dramatically as the earlier treatment.
Umbilical cord blood is a "logical source" of stem cells that could travel to damaged parts of the brain, says neurologist Evan Snyder of Harvard Medical School in Boston. But it's too early to tell whether gathering stem cells from umbilical cord blood will be efficient or whether the cells will be effective in humans, he says. Because umbilical cells are used in established treatments, Sanberg estimates that they could be tested as a stroke therapy in clinical trials in 2 years.