Stem Cell Find May Alter Field

A recent breakthrough in stem cell research by seven Harvard affiliates could revolutionize treatment for diseases such as leukemia, for which the only existing cure is bone marrow transplant.

A new study, released last week in “Nature Biotechnology,” found that some hematopoietic stem cells in bone marrow differentiate more slowly than others.

According to the study’s principal investigator, Harvard Medical School Professor Hanno R. Hock, such a discovery is “the holy grail of bone marrow transplant therapy.”

This new study defies the established dogma in the field of stem cell research, which previously assumed that all stem cells divide once every two to four weeks.

Hock’s research team discovered that 20 percent of stem cells divide less often than expected, only once every 100 days or more.

Harvard Medical School Professor Vincent J. Carey, a co-author of the study, said he used statistical methods to confirm that “some stem cells are living much longer than anyone expected.”

These slower-dividing cells constitute a purer population of stem cells—one that could be useful in bone marrow transplant therapy, according to Harvard Medical School research fellow Adlen Foudi, one of the study’s lead co-authors.

“The less [the cells] divide, the more potent and functional they are,” he said.

While researchers said they are uncertain about the significance of this new finding, Hock suggested the slower stem cell division could be a biological mechanism to preserve the integrity of the cells. Since genetic mutations accumulate as cells divide, slower division could reduce the rate of mutation, he said.

The study is a major stride forward in stem cell research, added Hock.

“These cells are very poorly understood,” according to Hock, who said the surprising results could help develop better clinical applications of stem cell therapy in the future.

The experiment entailed a novel labeling procedure that allows researchers to examine the rate of stem cell division.

Hock tagged stem cells with a green marker and then observed that some cells retained a higher label intensity, suggesting that they divided less frequently.

“We think this [slower division] is the way the body protects the best stem cells,” Hock said.

However, the new discovery is just the beginning of a new area of research. Foudi said he plans to continue studying these slow-dividing stem cells, the topic of his next paper.