Bone Marrow and Stem Cell Transplantation 1956

The different types of blood cells develop from hematopoietic (blood-forming) stem cells (HSCs), which are “immature cells”. Most HSCs are found in bone marrow, the spongy tissue inside bones, while some are present in the peripheral blood circulating throughout the body.

A stem cell can renew itself through cell division and produce other specialized cell types. 

• Totipotent stem cells (such as fertilized egg cells) can produce all the differentiated cells in an organism. 
• Pluripotent stem cells cannot develop into a fetus or adult because they cannot form extraembryonic tissues such as the placenta. 
• Multipotent stem cells (such as HSCs) generally produce a limited range of cell types. For example, HSCs can produce infection-fighting white blood cells, oxygen-carrying red blood cells and platelets that cause clotting for wound healing. 
• Various organs, such as the liver, have cells that can be activated when tissue is damaged or new cells are needed, known as dormant stem cells.

People with leukemia, a cancer of the blood or bone marrow, often produce excessive numbers of abnormal white blood cells. During bone marrow transplants (also known as stem cell transplants), physicians generally first destroy the abnormal marrow with chemotherapy or radiation and then inject healthy donor HSCs into the recipient's blood vessels to “reset” the bone marrow. The injected cells then reach the patient's bone marrow. 

If healthy stem cells are to come from a separate donor, clinicians must watch for Graft Versus Host (GVH) disease. GVH disease is a clinical condition that develops 4 to 60 days after allogeneic lymphocytes are given to immunosuppressed patients through procedures such as bone marrow transplantation or blood transfusion. They react against the host, resulting in aplastic anemia (anemia caused by the bone marrow's inability to produce blood) and organ failure. 

In 1956, the American physician Donnall Thomas performed the first successful bone marrow transplant, giving a leukemia patient healthy bone marrow from the patient's twin.

About the Article Image: A microscopic examination of bone marrow cells. Band neutrophils are marked with blue-green dots, a large promyelocyte with a yellow dot, and metamyelocytes with orange dots.

Historical Figures Mentioned in the Article: Edward Donnall Thomas (b. 1920)

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