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Brain Cells Give a Peek at Their Potential
June 1, 2000 -- Contrary to previous belief, cells from adult mouse brains can form a variety of different tissues when transplanted into developing embryos. Results, published in Friday's issue of the journal Science, suggest that these adult cells can form many different types of cells, including heart, gut, liver, and lung cells.
For years, researchers thought that adult cells like brain cells and blood cells were committed to their respective fates, and only cells from very early embryos were versatile enough to form all sorts of different tissues. But recent results from studies involving adult "stem" cells have begun to turn that idea on its head. Stem cells are cells in the bone marrow that are able to turn into many other types of cells in the body. Typically, they turn into various types of blood cells, such as red blood cells or white blood cells.
The finding bolsters the argument of those who believe that cells from adult humans could one day be used instead of cells from early embryos to create replacements for diseased and damaged tissues, experts say.
"It supports the argument that [therapeutic cells and tissues] might be developed from adult stem cell lines. Hence, there may be no need to isolate cells [from human embryos]," says Ronald M. Green, PhD, director of the Ethics Institute at Dartmouth College.
Last year, researchers showed that brain cells from adult mice could become blood cells when implanted into adult mice that had been exposed to radiation that destroyed the immature blood cells in their bone marrow. And other recent studies have shown that bone marrow cells can become immature brain and muscle cells. But researchers had no idea that cells from adult tissues could be this versatile, co-author Diana Clarke tells WebMD. Clarke is a researcher in Jonas Frisén's lab at the Karolinska Institute in Stockholm, Sweden.
Clarke and her co-workers first plucked a particularly versatile line of nerve stem cells from mouse brains and grew them in the lab for a week. Then, they injected the cells into very early mouse embryos. The injected cells huddled among themselves for two and a half days, then mixed with the cells in the developing mouse. Later, when the team examined the embryos, they found that a whole variety of immature mouse tissues, such as heart, stomach, lung, and liver, contained tissue derived from the implanted stem cells.
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