Breakthrough: Origin of Blood Stem Cells Discovered |
Timeline of development of HSCs from embryo to bone marrow |
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Editors published 1/18/2009 11:50:00 AM
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The timeline of development of blood (hematopoietic) stem cells (HSCs) from the embryo to bone marrow has been proven in mice by a research team led by Nancy Speck, PhD, Professor of Cell and Developmental Biology at the University of Pennsylvania School of Medicine.
HSCs are found in the bone marrow of adults and generate all of the blood cell types in the body.
During development, some endothelial cells generate the protein Runx1, producing clusters of HSCs inside major blood vessels. HSCs release and enter the blood circulation and travel to the foetal liver, and upon birth they relocate to the bone marrow.
“The ultimate goal for stem cell therapies is to take embryonic stem cells and push them down a particular lineage to replace diseased or dead cells in human adults or children,” says Speck. For instance, in theory embryonic stem cells could be tweaked in a lab to provide a patient with bone marrow failure a fresh supply of compatible HSCs.
The researchers also showed that at least 95 percent of all adult HSCs (and therefore almost all adult blood) originate in the endothelium, during this short window of time during development.
“This study helps illustrate a very important step in the transitional stage from embryonic stem cells to HSCs – the need to move through endothelial cells as an intermediary,” Speck says.
Understanding the location and developmental timeline of the origin of blood stem cells will help guide future efforts to coax embryonic stem cells to produce mature blood cells, she says.
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