What is a Blood Stem Cell Transplant?

A blood stem cell transplant is a procedure where a patient receives an infusion of blood stem cells as a treatment for conditions such as leukemia or other cancers. The material for transplantation comes from donors or patients can have their own marrow harvested and preserved prior to receiving treatments that are destructive to the blood stem cells. Having a blood stem cell transplant can help a patient "re-populate" his or her blood supply with healthy new cells.

Stem cells are special cells that are able to become whichever type of tissue the body needs. Blood stem cells are usually located in the bone marrow, although they are found in minute amounts in the bloodstream. Blood stem cells are able to reproduce an unlimited number of times, and they are also able to develop into any of the cells that make up blood. They can become red blood cells, which carry oxygen in the blood, white blood cells known as leukocytes, which fight disease and infection, or a special type of large cell known as megakaryocytes, which break up into platelets when needed for blood clotting. When transplanted, these stem cells can become any type of blood cell that the patient needs.

There are two types of blood stem cell transplant, and the main distinction between the two is the location cells are collected from within the body. If the cells are taken directly from the bone marrow, the procedure is called a bone marrow transplant, and if they are taken from the bloodstream, it's referred to as a peripheral blood stem cell transplant. Since significant amounts of stem cells are not usually found in the bloodstream, medications are used to stimulate them to leave the bone marrow and enter the blood supply, where they can be harvested for transplantation.

Patients with several medical conditions can benefit from a blood stem cell transplant, including leukemia, lymphoma, and non-cancerous blood diseases. In some cases, these diseases destroy the patient's blood cells; for instance, leukemia attacks the leukocytes. In other instances, treatments like chemotherapy and radiation kill the blood cells. The stem cells are transplanted to help the body replace the lost cells with a supply of healthy ones.

When a patient is in need of a blood stem cell transplant, the cells can come from a compatible donor. The donor needs to have the same blood type, and certain proteins and antibodies also need to match the patient's, so the new stem cells are accepted by the body. If the transplant is necessary because a treatment will be damaging the patient's blood supply, stem cells can be collected while they are still healthy. The blood stem cell transplant is a simple procedure of infusing the new cells into the patient's blood supply. Once transplanted, the stem cells can begin to create healthy new blood cells rapidly.