The basics of transplantation

In a blood stem cell transplantation, a patient’s defective stem cells are replaced with healthy ones. Blood stem cells are mostly found in the bone marrow, a spongy tissue inside the bones. Small numbers of stem cells also are found in the blood and in the umbilical cord (the cord that connects a foetus to its mother’s placenta). Stem cells develop into the three types of blood cells that the body needs:

  • red blood cells, which carry oxygen throughout the body;
  • white blood cells, which fight infections; and
  • platelets, which help the blood to clot.