Blood and marrow transplant

During a blood and marrow transplant (BMT), doctors replace your bone marrow system with healthy blood stem cells. These stem cells are young, immature cells that grow into more specialised, mature blood cells. During the transplant, your bone marrow absorbs the healthy stem cells. Once inside the bone marrow, the cells start to produce healthy blood cells. This process is called engraftment.

You may need a BMT because:

• you have too few blood stem cells
• your blood cells do not work properly
• it is part of your cancer treatment
• your cancer has relapsed and it is part of your immunotherapy.

There are 2 types of transplant:

• Allogeneic stem cell transplant – In an allogeneic stem cell transplant, you receive stem cells from a donor. In many cases, the donor is a family member, such as a sibling (brother or sister).
• Autologous stem cell transplant – In an autologous stem cell transplant, you donates your own blood stem cells.

Healthy blood stem cells can come from 3 different parts of our body:

Bone marrow

The spongy tissue inside our bones is called bone marrow. We have blood stem cells inside the marrow of our breastbone, skull, hips, ribs and spine. Our bone marrow contains the largest amount of stem cells in our body. To collect blood stem cells directly from the marrow, the donor will be asleep – they will have a general anaesthetic. Doctors then inject a needle into the top of the hip bone and harvest stem cells directly from the bone marrow.

Circulating (peripheral) blood

Your healthcare team can also collect donor blood stem cells indirectly from the blood that circulates in our body. This is called a peripheral blood stem cell harvest. The protein moves the blood stem cells from the marrow into the bloodstream. The healthcare team then harvest the stem cells using an apheresis machine. This machine can separate the stem cells from the donor's blood.

Cord blood

Doctors can also collect blood stem cells from the umbilical cord, which connects a baby to their mother's placenta. The healthcare team collects them from the umbilical cord and placenta after the baby is born.

Your bone marrow produces blood cells, called red blood cells, platelets, and white blood cells.

Read more about blood counts.

Inside the marrow, blood cells start off as young, immature cells called stem cells. Once they develop, blood cells do not live for a long time inside your body. This is why your marrow continuously produces all 3 types of blood cells to keep you healthy.