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--Findings May Aid in Bone Marrow Transplants, Blood Diseases--
PHILADELPHIA, Aug. 5 /PRNewswire-USNewswire/ -- New research sheds light on the biological events by which stem cells in the bone marrow develop into the broad variety of cells that circulate in the blood. The findings may help improve the success of bone marrow transplants and develop better treatments for life-threatening blood diseases.
"As we better understand the biological pathways that regulate the growth of stem cells, we may identify new approaches for treating blood disorders," said study leader Wei Tong, Ph.D., a hematology researcher at The Children's Hospital of Philadelphia. Her study appeared online July 10 in the Journal of Clinical Investigation.
Hematopoietic stem cells (HSCs) develop into all types of blood cells: red blood cells, white blood cells, platelets, and immune cells. HSCs, like other stem cells, have the ability to self-renew: each can give rise to more mature, developed cells with more specific functions, as well as a new stem cell. (Everyone carries HSCs in their bone marrow, unlike embryonic stem cells, which exist only in embryos.)
In her study, conducted in mice, Tong focused on a protein called Lnk that helps control HSC expansion. When a growth factor in the blood called thrombopoietin (TPO) acts on its cell receptor, it triggers signals along a pathway that includes another protein, JAK2. JAK2, in turn, causes stem cells to increase their numbers.
Tong's group and others previously found that Lnk is a negative regulator for HSCs, acting as a brake on stem cell expansion. In the current study, they found that mice genetically engineered to lack the Lnk protein had 10 times the normal amount of HSCs in their bone marrow. Without Lnk to directly interact with JAK2 and inhibit its activity, TPO made stem cell production go into overdrive.
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