Investigators from Massachusetts General Hospital (MGH) have found a subpopulation of hematopoietic stem cells, the source of all blood and immune system cells, that reproduce much more slowly than previously anticipated.
Use of these cells may improve the outcome of stem cell transplants – also called bone marrow transplants – for the treatment of leukemia and other marrow-based diseases. The report will appear in the journal Nature Biotechnology and is being released online to coincide with a similar study in the journal Cell .
"Hematopoietic stem cell transplantation saves many lives every day and is the most established therapeutic application of stem cells, but ironically we know very little about the cells that have made this clinical success possible," says Hanno Hock, MD, PhD, of the MGH Center for Regenerative Medicine, who led the study. "If we can improve our understanding of the biology of these cells, we should be able to offer our patients more therapeutic options."
It has been believed that the entire population of hematopoietic stem cells (HSCs) in the bone marrow reproduce at a rate of about 7 percent per day, with each cell dividing every two weeks. But previous investigations of stem cell proliferation appear to have missed the fact that some cells divide much less frequently. The MGH team developed a mouse model in which HSCs could be induced to express a green fluorescent label for a limited period of time. Tracking how long cells retained the label after its expression was halted indicated how long a cell remained in a resting phase between cell divisions.