Bone marrow is the soft, sponge-like material found inside bones. It contains immature cells known as hematopoietic or blood-forming stem cells. Hematopoietic stem cells are different from embryonic stem cells. Hematopoietic stem cells divide to form more blood-forming stem cells, they mature into one of three types of blood cells: white blood cells, red blood cells, and platelets. Blood in the umbilical cord also contains hematopoietic stem cells. BMT and PBSCT are most commonly used in the treatment of leukemia and lymphoma.