Bone marrow is the spongy tissue inside your bones where blood cells are made. The "parent cells" of all blood cells are called hematopoietic stem cells. Stem cells divide and form the different cells that make up your blood and your immune system. Stem cells make millions of blood cells every day.

The three main types of blood cells are: 

Red blood cells: These cells form the "blood" we’re most familiar with. Red blood cells travel from the heart and lungs, carrying oxygen to the rest of your body. The oxygen is carried on molecules called hemoglobin. Most of your blood cells are red blood cells. Anemia is a low number of red cells (or low hemoglobin). It can make you tired or breathless.

White blood cells: White blood cells fight infection and, therefore, are an important part of the immune system. A low white blood cell count (neutropenia) increases the risk of developing an infection. There are several kinds of white blood cells. Neutrophils are important white cells that help fight infections caused by bacteria and yeasts. Others, called lymphocytes, carry the immunologic memory to protect against viral and other infections, especially those for which people receive vaccinations.

Platelets: Platelets help your blood to clot when you have an injury. A low platelet count increases the risk of bleeding and bruising. If your platetet counts are low, we will give you platelet transfusions to reduce the risk of bleeding.

To prepare the for BMT, you will receive drugs (called chemotherapy) with or without radiation. The goal is to destroy cancer or disease and to suppress your immune system. This helps prevent your body from rejecting the transplant. An intravenous infusion (transplant) of stem cells should restore your ability to make blood cells. These new cells are either previously donated by you or by a donor, or come from umbilical cord blood. The stem cells plant themselves in your bone marrow, almost like seeds in the ground, and reproduce, making new bone marrow and new blood cells.

The term BMT is a bit confusing. It sounds like an operation, like an organ transplant, but it is not a surgical procedure. It’s more like a blood transfusion.You may wonder, too, what the difference is between bone marrow transplant, peripheral blood stem cell transplant, and umbilical cord blood transplant. The main difference is the source of the stem cells and how they are collected. Regardless of their source, stem cells are given to the patient in the same way: by intravenous (IV) infusion.

Transplant Cell Sources: Bone Marrow, Peripheral Blood, Umbilical Cord Blood
The term blood and marrow transplant (BMT) is used for any transplant involving stem cells, regardless of their source. A more accurate way to say this is a hematopoietic stem cell transplant.

In a bone marrow transplant, hematopoietic stem cells are collected from your own bone marrow or from a donor’s. Bone marrow is aspirated from the pelvic bones using a special needle and syringe.

Stem cells are more often collected from blood. These stem cells are referred to as peripheral blood stem cells. We collect or "harvest" them using a peripheral intravenous (IV) catheter or a special IV catheter called a central venous catheter. In a peripheral blood stem cell harvest, the blood circulates through a special centrifuge. It removes the white blood cells along with the stem cells and then returns the red blood cells to the body. This procedure is often referred to as apheresis or, more specifically, leukapheresis. We do this procedure on an outpatient basis.

A third source of stem cells is blood from the umbilical cord and placenta of a newborn. This blood is a particularly rich source of stem cells. These cells can be collected by draining the blood from the umbilical cord and placenta after a baby is born. The baby is not hurt in the process. This blood is normally thrown away with the placenta. Some hospitals collect cord blood (with parental consent) for donation to cord blood banks. Cord blood banks will do human leukocyte antigen typing of the cord blood (to match patients and donors). They will then freeze and store the blood. 

Cord blood can come from a related baby, such as a sibling. But the baby and patient are usually unrelated. If an HLA match is close enough, these cord blood cells can be used for BMT.