May 12, 2004
Scientists have transplanted adult stem cells from the bone marrow of rats into the brains of rat embryos and found that thousands of the cells survive into adulthood, raising the possibility that someday developmental abnormalities could be prevented or treated in the womb.
Dr. Ira Black, chairman of the department of neuroscience at the University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, said the cells took on the properties of brain cells, migrating to specific regions and taking up characteristics of neighboring cells.
"They exhibited the same flexibility in the living brain as we had observed in culture," said Black, director of the school's Stem Cell Center. His findings were published today in the Journal of Neuroscience.
Over the past few years, scientists have debated the theory that bone marrow stem cells, plentiful throughout the human life cycle, could, with coaxing, become many types of brain cells. Many reports have disputed this, asserting bone marrow stem cells merely fuse to nearby brain cells. Other scientists believe marrow stem cells don't actually trigger new cells to grow in the adult brain, but work like factories to pump new life into remaining cells.
But Black and his colleagues injected adult bone marrow stem cells into the brain ventricles of embryonic rats and watched them migrate throughout the brain. When they reached their destination, they expressed the same genes as other cells in the area. Thousands per cubic millimeter survived into adulthood.
Black and his colleagues used a specific type of bone marrow cell called a stromal cell, taken from the leg bones of adult rats. "We see this potentially as an appropriate treatment for prenatal disease, mental retardation and congenital conditions," Black said.
The hope is that a patient's own bone marrow might someday be the source for replacing brain cells lost to illness and brain trauma, experts say, eliminating the need to use human embryonic stem cells.
In a separate study, Dr. Alexander Storch of the University of Ulm, Germany, recently took bone marrow stromal cells from six healthy people and converted the cells into immature neural stem cells. He presented the findings at the American Academy of Neurology meeting last month. "A single cell culture could grow all major brain cell types," said Storch, who used specific growth factors to help them differentiate. They lost half the cells during the conversion process, yet still generated a high number of new cells.
Storch is now transplanting the cells into mice with multiple sclerosis,
Parkinson's disease and stroke symptoms. In the stroke study, the labeled
adult stromal cells migrated to the area surrounding the stroke damage,
he said. They had all of the chemical, electrical and functional properties
of brain cells.
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