What Is Bone Marrow?
Bone marrow is the soft, spongy tissue that is located in the medullary cavities (centers) of certain large bones. Healthy bone marrow is an essential part of the body, as it contains stem cells that produce blood cells and the cells that make up the immune system. The stem cells contained in the bone marrow can mature into several different kinds of cells, each of which has its own vital functions within the body. There are two types of bone marrow – red bone marrow (myeloid tissue) and yellow bone marrow (fatty tissue).
Red bone marrow
Red bone marrow is primarily found in the medullary cavity of flat bones such as the sternum and pelvic girdle. This type of bone marrow contains hematopoietic stem cells, which are the stem cells that form blood cells. Hematopoietic stem cells can turn into three types of blood cells, all of which have important functions that help keep a person alive and healthy. The three types of blood cells formed from the stem cells within red bone marrow are:
- Red blood cells – Transports oxygen throughout the body
- White blood cells – Helps fight infections within the body
- Platelets – Prevents excessive bleeding by helping blood to clot after an injury
Yellow bone marrow
The second type of bone marrow found in the body is yellow bone marrow, which gets its name from its high concentration of fat cells, which appear yellow in color. This type of bone marrow can be found in the medullary cavity in the shaft of long bones and is often surrounded by a layer of red bone marrow. Yellow bone marrow contains mesenchymal stem cells (marrow stromal cells), which produce cartilage, fat and bone. Yellow bone marrow also aids in the storage of fats in cells called adipocytes. This helps maintain the right environment and provides the sustenance that bones need to function.
What is the function of bone marrow?
As previously discussed, the function of bone marrow is to produce different types of cells that are vital to sustaining life. A number of circumstances can affect the health of bone marrow and impair its ability to produce a normal amount of healthy cells. A bone marrow transplant, in which healthy bone marrow is administered to a patient via a central line, may be necessary in these instances. A bone marrow transplant can help to:
- Replace nonfunctioning bone marrow that has been damaged due to certain health conditions
- Restore the bone marrow’s function after it has been damaged due to treatments such as high-dose chemotherapy or radiation therapy
- Prevent further damage caused by certain genetic diseases
- Regenerate an immune system in order to fight existing or residual cancers such as leukemia
Why might you need a bone marrow transplant?
At Moffitt Cancer Center, the experts in our Blood and Marrow Transplant and Cellular Immunotherapy Program perform bone marrow transplants as a treatment option for certain types of cancer and other conditions in which the marrow is affected. Bone marrow may become damaged or malfunction due to:
- Leukemia, lymphoma, multiple myeloma or other types of cancer
- Aplastic anemia
- Chemotherapy or other medications
- Inherited abnormalities of red blood cells, such as sickle cell anemia and thalassemia)
- Inherited abnormalities of white blood cells that cause an immune deficiency
- Inherited abnormalities of platelets that lead to bleeding problems
Patients with disorders that primarily affect the marrow, such as leukemia, aplastic anemia or inherited disorders, may require a blood or bone marrow transplant from a donor, also called an allogeneic transplant. Patients with lymphoma, multiple myeloma and some other cancers may require an autologous blood or bone marrow transplant, in which the patient serves as his or her own donor. At Moffitt, our team can help explain which type of transplant is best for you.