What Are Bone Marrow Stimulators Used For?

A blood test, known as a complete blood count (CBC) measures red blood cells (RBCs), white blood cells (WBCs), and platelets. When cell counts are low or expected to become low, bone marrow stimulating drugs can be given to boost your body’s production of these blood cells.

These agents have potentially serious risks and side effects, and not all cases of "low counts" are treated with these drugs. In the treatment of cancer, the use of bone marrow boosting drugs is considered supportive care, meaning that the drug does not directly fight cancer, but helps in other ways.

Your Bone Marrow, Up Close

Bone marrow is the living tissue that is packed inside the hollows of certain bones, especially the hipbones and the vertebrae, or the bones of the spinal column.

The bone marrow is where most of your hematopoietic stem cells are located. Hematopoietic stem cells divide and give rise to all of the different kinds of blood cells, including RBCs, WBCs, and platelets.

Cancer and the Bone Marrow

Bone marrow may be unhealthy for a variety of reasons. In the case of certain blood cancers, the cancer cells grow in the bone marrow. And many chemotherapy drugs are toxic to the bone marrow.

Without healthy bone marrow, blood cell production suffers, and new blood cells can’t be made to keep pace with the natural recycling of blood cells. This can be an especially serious problem when blood cells rapidly die as a side effect of cancer treatment.

What Is Bone Marrow Stimulation?

Healthy bone marrow responds to the body’s chemical signals that trigger blood cell production. Scientists have learned to make treatments that replicate these chemical signals, and they can be used medically to boost production. They are often given in larger doses than the body normally produces.

Different “families” or progenitors of blood cell types in the marrow may respond to different chemical signals. One general term for a chemical signal that boosts production is hematopoietic growth factor. Not all drugs that boost the bone marrow are growth factors, however.

Why Is Bone Marrow Stimulation Done?

There are specific circumstances that necessitate the use of bone marrow stimulation.

Raising Low Counts

Stimulating the body to produce more new blood cells can be helpful when one or more of your blood cell counts are low or your counts are expected to become very low. For instance, sometimes the bone marrow is stimulated in advance, as a preventive measure, when counts are expected to fall due to planned cancer therapy.

If you receive cytotoxic chemotherapy, you can have extremely low counts for long periods of time. Levels of neutrophils, a type of WBC, are carefully tracked.

Preparing to Donate Stem Cells

Healthy people may be given bone marrow stimulation treatments in preparation for donating stem cells to another person, for a peripheral blood stem cell transplant.

A small number of blood-forming hematopoietic stem cells can be found in the bloodstream. In some instances, volunteers can donate their stem cells for a marrow/stem cell transplant simply by giving blood. Part of this process involves boosting the bone marrow so that more stem cells can be collected from the circulating blood.

According to the National Marrow Donor Program, or “Be The Match,” a person donating stem cells receives injections of filgrastim, a growth factor, over a period of 5 days prior to donation. Filgrastim is used to increase the number of blood-forming cells in the bloodstream. Then, on the day of donation, the volunteer’s blood is drawn through a needle on one arm and passed through a machine that collects the stem cells. The remaining blood is returned to the volunteer through the other arm.

Types of Bone Marrow Stimulating Medications

Growth factors are usually given through injections beneath the skin. Some may also be given intravenously, into a vein. Your healthcare team can administer the medication by injection, and sometimes individuals and family members learn to administer them, too.

Growth Factors to Boost White Blood Cells

Growth factors or “colony-stimulating factors” that help boost WBCs include the following:

• Filgrastim and lenograstim are granulocyte colony-stimulating factors (G-CSFs)
• Pegfilgrastim is a long-acting form of G-CSF. It works in the same way as filgrastim but can be given less often.
• Sargramostim is a granulocyte macrophage-colony stimulating factor (GM-CSF).

Both types of growth factors—G-CSFs and GM-CSFs—can improve WBC production. Most medical institutions use G-CSF, and this is the most established type and one that has been studied the most.

When Would You Get Growth Factors to Boost WBCs?

G-CSFs may be given during the first cycle of chemotherapy to help prevent neutropenia throughout all of the chemotherapy cycles. G-CSFs also help limit the incidence of neutropenic fever, and they may reduce the need for hospitalization.

They can also be used to allow higher doses of chemotherapy, in scenarios where lowering the chemotherapy dose might lead to a worse prognosis.

G-CSFs are sometimes given during chemo re-treatment when a previous cycle of chemotherapy caused a neutropenic fever, and also to shorten the length of time a person has severe neutropenia from chemo when there is no fever. G-CSFs may also be given when a person already has a fever and neutropenia.

Growth Factors to Boost Red Blood Cells

Growth factors that help boost erythrocytes (RBCs), include the following:

• Erythropoietin is a growth factor that boosts red blood cell production.
• Darbepoetin is a long-acting form of erythropoietin that works in the same way but can be given less often.

Erythropoietin treatment can help some people avoid transfusions of RBCs. Getting treatment with erythropoietin and G-CSF improves the response to the erythropoietin.

Boosting Platelets

Romiplostim, eltrombopag, avatrombopag, and lusutrombopag are treatments that can help boost platelets. The indications include treatment of low platelets that are caused by chronic immune thrombocytopenia (ITP). They may also be used in rare cases of chemotherapy-induced thrombocytopenia, and some of these drugs are approved to help raise the platelet counts in people who have chronic liver disease.

Romiplostim is not a naturally occurring growth factor, but it works by mimicking thrombopoietin, a growth, and development factor that boosts platelets.

When to See Your Healthcare Provider

If you are taking a bone marrow stimulating medication, notify your healthcare provider if you begin to develop any concerning symptoms.

Contact your healthcare provider immediately if you experience any of the following:

• Fever of 100.4° F (38° C) or higher, chills—possible signs of infection
• Shortness of breath
• Rapid heartbeat
• Bleeding that does not stop after a few minutes
• Any new rashes on your skin
  

A Word From Verywell

Researchers are examining the best ways to tell which patients might benefit from growth factors that boost blood cell and platelet production. There is also a lot of interest in determining the best way to combine growth factors with each other and with chemotherapy and hormone therapy.

If you have been told you have low counts and are wondering why you are not receiving blood-boosting medication, bring these questions up with your healthcare team. Often, there are very specific criteria for such therapy, and decisions are made in view of your particular illness, medical history, and treatment plans. Not everybody is a good candidate, but in the right scenario, these medications can help prevent serious neutropenia, fevers, and infections.