What Is Bone Marrow?

Bone Marrow Is Located Inside Bones and Contains Stem Cells

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. Bone marrow stem cells can mature into several different kinds of cells, each of which has its own vital functions within the body.

What does bone marrow do?

As previously discussed, the function of bone marrow is to produce different types of cells that are vital to sustaining life. There are two types of human bone marrow: red bone marrow (myeloid tissue) and yellow bone marrow (fatty tissue).

Red bone marrow

The three types of blood cells formed from the stem cells

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 – Transport oxygen throughout the body
  • White blood cells – Help fight infections within the body
  • Platelets – Prevent 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.

Types of bone marrow tests

If a physician is concerned about a patient’s bone marrow function, they may order a bone marrow test for cancer or another type of disease. There are two types of bone marrow tests, which are typically performed during the same procedure:

  • A bone marrow aspiration involves removing a sample of liquid bone marrow, usually from the patient’s hip bone.
  • A bone marrow biopsy involves removing a small, marrow-filled portion of the patient’s bone (again, usually the hip bone).

Once the samples have been collected, they will be examined under a microscope.

Before the procedure, the provider will administer local anesthesia to numb the area. In some cases, the patient will be given a mild sedative as well. It’s fairly common for patients to experience minor bone pain in the days following a bone marrow test.

Why might you need a bone marrow transplant?

A number of circumstances can affect the health of bone marrow and impair its ability to produce a normal amount of healthy cells. For example, 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

A bone marrow transplant, in which healthy bone marrow is administered to a patient via a central line, may be necessary in these instances. Patients with bone marrow disorders—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.

How does a bone marrow transplant work?

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

How to donate bone marrow or blood

Allogeneic blood and bone marrow transplants require a third-party donor. The recipient’s physician will recommend the approach—either bone marrow or blood—that’s best suited to the patient’s specific needs.

Bone marrow donations

During a bone marrow donation procedure, a surgeon uses hollow needles to extract liquid bone marrow from the rear of the donor’s pelvic bones. The bone marrow donor is given anesthesia and thus doesn’t feel any pain during the collection. Once the removal is complete, the bone marrow is transported to wherever the recipient is located and then transplanted.

Bone marrow donors may experience the following side effects once the procedure is complete:

  • Pain in the back, hips, throat or muscles
  • Headache
  • Dizziness
  • Fatigue
  • Insomnia
  • Nausea
  • Loss of appetite

Donors are often able to go home the same day as the procedure, although some will be kept overnight for observation. Recovery times will vary based on a number of factors, but many bone marrow donors fully recover within approximately one week.

Peripheral blood stem cell donation

Unlike bone marrow donation, peripheral blood stem cell (PBSC) donation is not a surgical procedure. Prior to the collection, the donor begins receiving daily injections of filgrastims, which are proteins that help transport blood-forming cells out of the bone marrow and into the bloodstream. These injections may reduce the donor’s blood platelet count and cause side effects such as:

  • Pain in the bones or muscles
  • Headache
  • Fatigue
  • Difficulty sleeping
  • Nausea

These side effects typically resolve within a few days after the PBSC donation is completed.

During the PBSC donation procedure, a medical provider inserts a needle into one of the donor’s arms to collect their blood. The blood then passes through a machine that filters out the blood stem cells, and then the remaining blood is returned to the donor through a needle inserted in their other arm. Although many PBSC donations are able to be completed in one session lasting up to eight hours, some require two sessions, each lasting around four to six hours.

Bone marrow disease treatment at Moffitt

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 bone marrow cancer and other conditions in which the marrow is affected. Thanks to our providers’ experience and specialization, we’re able to perform transplantations even for patients with potential risks, including advanced age. In fact, we’re one of the only centers offering bone marrow transplants for adults over the age of 70.

If you would like to learn more about cancer of the bone marrow, receiving a bone marrow transplant at Moffitt or becoming a bone marrow donor, call 1-888-663-3488 or fill out a new patient registration form online. We are proud to offer every new patient rapid access to a cancer expert within just one day—a turnaround time faster than that offered by any other cancer hospital across the country. We look forward to speaking with you and helping you take the next step forward.

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