“Mega” cells promote regeneration of blood stem cells

Patients recovering from chemotherapy or organ transplantation often have dangerously low levels of blood cells, leaving them weak and vulnerable to infection. Research findings from the lab of Stowers Investigator Linheng Li, PhD, describe new insights that could potentially lead to treatments for patients with low blood cell counts.

Li, who led the study, explains that megakaryocytes, “mega” cells found in bone marrow, regulate the function of hematopoietic stem cells—adult stem cells that form blood and immune cells and constantly renew the body’s blood supply. He and his colleagues found that in mouse bone marrow, megakaryocytes tell blood stem cells when their services aren’t needed and when they need to start proliferating to meet increased demand.

“Megakaryocytes can directly regulate the amount of hematopoietic stem cells by telling the stem cells when they need to stay in the quiescent stage, and when they need to start proliferating to meet increased demand,” says Li. “Maintaining that delicate balance is important. You don’t want to have too many or too few hematopoietic stem cells.”

Engineering a megakaryocyte niche (a special environment in which stem cells live and renew) that supports the growth of hematopoietic stem cells in culture is the next step for the researchers. Meng Zhao, PhD, a postdoctoral fellow at the Institute and first author on the study, and his colleagues are also investigating whether a megakaryocyte niche can be used clinically to jump-start adult stem cell regeneration and to expand cultured cells for adult stem cell transplants.

These findings were published in the October 19, 2014, issue of Nature Medicine.