A bone marrow transplant, also known as a haemopoietic stem cell transplant, replaces damaged bone marrow with healthy bone marrow stem cells.

Bone marrow is a spongy tissue found in the hollow centres of some bones. It contains specialist stem cells, which produce the body's blood cells.

Stem cells in bone marrow produce three important types of blood cells:

• red blood cells – which carry oxygen around the body
• white blood cells – which help fight infection
• platelets – which help stop bleeding  

Why are bone marrow transplants needed?

Bone marrow transplants are often needed to treat conditions that damage bone marrow. If bone marrow is damaged, it is no longer able to produce normal blood cells. The new stem cells take over blood cell production.

Conditions that bone marrow transplants are used to treat include:

• severe aplastic anaemia (bone marrow failure)
• leukaemia – cancer of the white blood cells
• non-Hodgkin lymphoma – cancer of the lymphatic system
• certain genetic blood and immune system disorders – such as sickle cell anaemia, thalassaemia and some severe immune system conditions

Read more about why a bone marrow transplant is needed.

What does a bone marrow transplant involve?

A bone marrow transplant involves taking healthy stem cells from the bone marrow of one person and transferring them to the bone marrow of another person.

In some cases, it may be possible to take the bone marrow from your own body. This is known as an autologous transplantation. Before it is returned, the bone marrow is cleared of any damaged or diseased cells.

A bone marrow transplant has five stages. These are:

• physical examination – to assess your general level of health
• harvesting – the process of obtaining the stem cells to be used in the transplant
• conditioning – preparing your body for the transplant
• transplanting the stem cells
• recovery period – during which you'll be monitored for any complications or side effects

Having a bone marrow transplant can be an intensive and challenging experience. Many people take up to a year to fully recover from the procedure.

Read more about what happens during a bone marrow transplant.

Who can have a bone marrow transplant?

Bone marrow transplants are usually only recommended if:

• the recipient is in relatively good health despite their associated condition (which is why they're often carried out when cancer is in remission)
• stem cells are available from a brother/sister or, less commonly, another family member, or an unrelated donor with the same or similar tissue type (this reduces the chances of the bone marrow being rejected)
• the associated condition isn't responding to other forms of treatment and it's believed that it would respond to a transplant and could get worse without one
• the benefits of a transplant are believed to outweigh the risks

Read more about who can have a bone marrow transplant.

Risks

Bone marrow transplants are complicated procedures with significant risks.

In some cases, the transplanted cells (graft cells) recognise the recipient's cells as "foreign" and try to attack them. This is known as graft versus host disease (GvHD). 

The risk of infection is also increased because your immune system is weakened when you're conditioned (prepared) for the transplant.  

Read more about the risks of having a bone marrow transplant.