Massachusetts researchers have identified a source of all blood and immune system cells, subpopulation of hematopoietic stem cells. It works reproduce much more slowly than previously anticipated. Use of these cells may improve the outcome of stem cell transplants.

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. While 80 percent of the labeled HSCs were observed to proliferate at the expected rate, 20 percent of cells reproduced much more slowly, dividing once every 100 days or longer.

Another experiment found that a gene believed to keep HSCs in a resting state was not required to maintain the reduced rate of cell division in these slow-cycling HSCs, and a mathematical model of HSC proliferation only matched what was actually seen in the labeled mouse model if it assumed two populations of HSCs with differing rates of cell division.

Hanno Hock, MD, PhD, of the MGH Center for Regenerative Medicine, who led the study said,

“Our results suggest that we understand a lot less about HSCs than we thought. If we can find more markers for these slow-cycling cells and identify them in human bone marrow, we may be able to make more of them and find additional clinical applications.”

Source: Science Daily