Researchers at the Weizmann Institute of Science have discovered a crucial association between the bones and the blood renewal system in the body.
Their study revealed that the cells that work at remodeling the bones play a key role in the ongoing renewal of another system, which is the blood.
The researchers said that bones are actually two systems entwined in one.
The cavities inside bones are filled with spongy bone marrow, in which stem cells divide, whereas their daughter cells differentiate into all kinds of blood cells, including large numbers of immune cells for the body's defense.
The hematopoietic, which are the blood-creating stem cells, give rise to any kind of blood cell, residing in special 'stem cell niches' nestled in the bones' inner walls.
Inside these sheltered nurseries, the stem cells remain undifferentiated; with the help of other nearby cells, they hang on to their youthful qualities.
Only when they leave the niches do they morph into specialized blood cells, possibly becoming immune cells for fighting infection or cells for blood clotting and healing after injury. They can even respond to calls for help from organs such as the liver, migrating through the bloodstream to assist in repairing damage.
Their findings have added a new dimension to the understanding of the blood-forming stem cells, bone, and the immune system. And it may also lead to future improvements in bone marrow transplantation and a better understanding of diseases involving bone or blood renewal.