Stem cell transplantation is one of the great achievements of modern medicine. It is still under extensive research for most organs, especially for spinal cord surgery after transection of the spinal cord. On the other hand, the most advanced type of stem cell transplantation as of now is that of the bone marrow.
What is the bone marrow?
The bone marrow is the tissue located within the cavity of bones especially long bone like your thighs and arm bones and the axial skeleton including your hip bone and ribs. The bone marrow is a collection of cells and blood vessels with some bony trabeculations supporting the cavity. The main function of the bone marrow is the production of blood elements including red blood corpuscles, white blood cells and platelets. It may also function as the site of destruction of cells albeit in a much lesser extent than the spleen.
When we are born, most of our bone marrow is of the active or “red” type, which means that all of it produces cells actively, but as we grow older, most of that red marrow is replaced by inactive or “yellow” marrow. It is called yellow because of its high fat component. By adulthood, the active marrow becomes limited to the axial skeleton and some long bones like the femur (thigh bone). This is, however, reversible and in some cases when blood loss or red cell destruction is evident, the active marrow can expand to reach similar levels to those found in the newborn. This proves how adaptive and “plastic” our bone marrow is.