How bone marrow transplants treat leukemia

Healthy bone marrow is a soft tissue inside some bones in your body that is responsible for making nearly all the components of your blood.
Certain cells, called hematopoietic stem cells, have the unique ability to differentiate and develop into billions of red and white blood cells and platelets every day. Throughout your lifetime these stem cells replenish and maintain your blood cell population to support your immune system, oxygen transport, and blood clotting. However, blood, like other parts of the body can become diseased.
Healthy stem cells hold a powerful key for treating diseases like leukemia, a cancer of the white blood cells. Leukemia is one of the most common forms of cancer worldwide and can affect people of all ages, but it is more common in older adults. Radiation therapy and chemotherapy are methods designed to target and destroy rapidly dividing cancer cells. However, they can also affect healthy cells, including the ones in bone marrow. Bone marrow can be transplanted, removed from one place and restored or transferred to another. This process is used to treat some types of leukemia where bone marrow is compromised and allow cancer patients to survive high or potentially fatal doses of chemo and radio therapy. Hematopoietic stem cell transplantation, or HSCT, is a medical term for bone marrow transplant. Before administering radiation or chemicals, some bone marrow is extracted from the patient or a healthy donor and the stem cells are isolated.
Over time, a donor's body will naturally produce new stem cells to replace those that have been removed. After radiation or chemotherapy are complete, the collected stem cells are infused into the patient's bloodstream, similar to a blood transfusion. The infused stem cells travel to the bone marrow and gradually replace the recipient's diseased tissue, restoring normal blood cell production.