During a bone marrow transplant, doctors remove bone marrow that is either not working properly or was destroyed by radiation or chemotherapy, and they replace it with healthy bone marrow stem cells, explains MedlinePlus. There are three types of bone marrow transplants, and they all require a different process.
Patients can receive an autologous bone marrow transplant, an allogeneic bone marrow transplant or an umbilical cord blood transplant, notes MedlinePlus. For autologous procedures, healthy stem cells are removed from the patient before chemotherapy or radiation treatment, and they are frozen and stored. After treatment, the patient's cells are placed back into the body, where they regenerate and develop into normal blood cells.
Allogenic transplants require a stem cell donor, and the donor's genes must match the genes of the patient. Brothers, sisters, children and parents are ideal donors for this type of transplant, but a person who is not related to the patient can also be a match, according to the National Cancer Institute. Doctors perform blood tests to determine if a donor is a good match for a specific patient. If so, some of the donors stem cells are removed and frozen, and they are eventually implanted into the patient's body, where they ultimately develop into normal blood cells.
An umbilical cord bone marrow transplant is when healthy stem cells are taken from the umbilical cord of a newborn baby shortly after birth and then frozen until they are needed for bone marrow surgery, explains MedlinePlus.