A bone marrow donation is a relatively straightforward medical procedure.

Diseased or damaged bone marrow can be replaced by donated bone marrow cells, which help treat and often cure many life-threatening conditions, including:

• bone marrow failure (severe aplastic anaemia)
• leukaemia – cancer of the white blood cells, which has several sub-types
• non-Hodgkin's lymphoma – cancer of the lymphatic system
• certain genetic blood and immune system disorders such as sickle cell anaemia, thalassaemia and some severe immune system diseases

Read more about the uses of a bone marrow transplant.

After the donation, as long as the transplant is successful, the new bone marrow will begin to make healthy blood cells and the person receiving the donation will start to get better.

What is bone marrow?

Bone marrow is a spongy tissue found in the hollow centres of some bones. It contains stem cells which can grow into any of our normal 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 

The need for donors

Ideally, bone marrow stem cells are best donated from a close family member, such as a brother or sister, because there needs to be a close match between tissue types. However, only around one in three people have a close relative with a matching tissue type.

For this reason a number of bone marrow registers have been set up listing people who are willing to donate bone marrow stem cells if required.

When a donation is needed, doctors search the bone marrow register to try to find a donor with a matching tissue type.

In England, there are two bone marrow registers, which work closely together:

• the British Bone Marrow Registry, which is part of the NHS
• the Anthony Nolan Trust register, which is operated by the charity the Anthony Nolan Trust

You can apply to join the British Bone Marrow Registry when you donate blood.

It is possible for most people to find a donor on the registers, but a small number of people with rare tissue types may find it very hard or impossible to find a suitable match.

How it is performed

Firstly you will be asked to provide a small sample of blood to determine your tissue type. This information is kept on the register.

You will be contacted if you are a potential match for a person requiring a transplant.

The most widely used method of donating bone marrow is known as a peripheral blood stem cell donation (PBSC). You will need to receive injections for four days in a row to increase the number of stem cells in your circulating blood before this type of donation.

You will have to visit the hospital or clinic for four days in a row to receive injections which stimulate the production of stem cells. 

On the fifth day you will be connected to a cell-separator machine without the need for a general anaesthetic. The machine usually collects the stem cells from your blood through a vein in one arm, returning the blood to your body through a vein in your other arm. This takes about four or five hours and may need to be repeated the following day.

Read more about what happens during a bone marrow donation.

Who can donate bone marrow

If you would like to become a potential bone marrow donor, you must be:

• 18 to 49 years of age to join the British Bone Marrow Registry
• 16 to 30 years of age to join the Anthony Nolan Trust register
• in good general health
• over 7 stone 12 pounds (50kg) in weight
• have a body mass index (BMI) lower than 40

It is best to join the bone marrow register at a young age. The younger you are when you join, the more chance there is of your tissue type being matched to that of someone who needs it.

Read more about who can donate bone marrow.