Bone Marrow Transplant

A bone marrow transplant renews the bone marrow, the spongy tissue inside bones that produces the body's blood cells, when it can no longer make enough healthy ones. The treatment uses blood-forming, or haematopoietic, stem cells, the master cells that mature into red cells that carry oxygen, white cells that fight infection and platelets that help blood to clot. These stem cells are collected from the patient's own healthy cells or from a donor, and after the diseased or failing marrow has been treated, the new cells are infused into the bloodstream. They travel to the bones, settle in the marrow and begin producing healthy blood again, a process called engraftment. In this way the transplant restores the body's ability to make normal blood and treats the underlying disease.

A bone marrow transplant is one of the most important treatments for cancers of the blood and is widely used in acute and chronic leukaemia, Hodgkin and non-Hodgkin lymphoma and multiple myeloma. It is also used for non-cancerous conditions in which the marrow does not work properly, including aplastic anaemia and other bone marrow failure syndromes, myelodysplastic syndromes, inherited immune deficiencies and certain inborn errors of metabolism. In some of these diseases, high-dose chemotherapy clears the abnormal cells and the transplant then rescues and rebuilds the marrow; in others, healthy donor cells replace a marrow that is failing or genetically faulty. The decision rests with a transplant team after detailed testing of the disease, the patient's general health and, when a donor is needed, the search for a suitable match.

The process has several stages. First, a thorough assessment over several days confirms the patient is ready, and a soft tube called a central line is placed into a large vein in the chest or neck to give medicines, fluids and the stem cells. The type of transplant depends on where the cells come from: an autologous transplant uses the patient's own stem cells, collected and stored beforehand, while an allogeneic transplant uses cells from a donor, often a matched brother or sister, an unrelated matched donor or umbilical cord blood. Before the transplant, a conditioning phase of chemotherapy, sometimes with radiotherapy, clears the diseased marrow and makes room for the new cells. The stem cells are then infused through the central line, much like a blood transfusion, with no need for surgery or general anaesthesia for the recipient. Over the following two to four weeks the cells engraft in the marrow and begin making new blood, while the patient is cared for in a protected unit.

Both the patient and, for an allogeneic transplant, the donor are assessed thoroughly. The patient has detailed tests of the disease, of heart, lung, liver and kidney function and of any infection, to confirm they can withstand the conditioning treatment and the recovery. When donor cells are needed, tissue typing finds the best-matched donor, ideally a sibling, and the donor undergoes their own health checks before giving cells, either from the bloodstream after a few days of injections or, less often, from the marrow under brief anaesthesia. A suitable cord blood unit can also be used. Suitability for an autologous transplant depends largely on the patient's fitness and the disease responding well enough beforehand. For international patients, much of the disease review and matching workup can begin remotely, with records, scans and pathology reviewed before travel, so that the plan and donor strategy are clear on arrival.

A bone marrow transplant requires a long, carefully supervised stay. After the cells are infused, the weeks until engraftment are the most demanding, because the new immune system is not yet working and the patient is very vulnerable to infection; this time is spent in a protected unit with strict hygiene, frequent blood tests and transfusion and medication support. Most patients stay in hospital for about 3 to 5 weeks, and are then advised to remain in the destination city for roughly 2 to 3 months after the transplant for close outpatient monitoring until the new marrow is securely established. The immune system continues to rebuild over the following 6 to 12 months, during which crowded places and infection risks are avoided and vaccinations are gradually renewed. Once home, follow-up combines a local haematologist with remote review by the transplant team, and international patient services commonly provide interpreters and coordinators throughout the extended stay.

A bone marrow transplant is an intensive treatment, and although it offers the prospect of a lasting cure, it carries significant risks that are managed by an experienced team in a specialised unit. The period of low blood counts after conditioning brings a real risk of infection and bleeding, which is why patients are nursed in a protected environment with close support. In an allogeneic transplant, the donor cells can react against the patient's tissues, a condition called graft-versus-host disease, which the team prevents and treats with medication; this risk does not arise with the patient's own cells. There is also a chance that the new marrow is slow to engraft or that the original disease returns. Careful donor matching, a protected unit and diligent follow-up keep these risks as low as possible. For the right patient, a successful transplant restores healthy blood production and can give a lasting cure or long-term control of the disease.