Engraftment is when the donated stem cells become part of your body.

After the donated stem cells are put into your blood, they travel to where your bone marrow lives inside your bones. The cells become your new blood-making stem cells. They grow and multiply.

Your stem cells will make new blood cells:

• Red blood cells. They will be healthy ones, not sickle cells. These carry oxygen to all the other cells in your body.
• White blood cells. These fight germs and are also called immune system cells.
• Platelets. These help your blood clot (stop bleeding) when you have a cut.

Graft versus host disease (GvHD) is a common problem.

• The donated stem cells make immune cells that ‘attack’ your body.
• These new white blood cells can get confused because your body is not the same as the donor’s body. This is why they can attack your body.
• It can cause problems for a few days or months, but some people have problems that last for years.
• The bone marrow transplant can still work, even if you have this problem.
• Your doctors will give you medicine to try to prevent it or stop it if it happens.
• People may need to take these medicines to prevent or treat GvHD for several months after transplant.
• The medicine does not work for some people, and they can get very sick or die.

Graft rejection is not common.

• Your body ‘attacks’ the donated stem cells (graft rejection).
• It can make you very sick. You will not be able to make any blood cells on your own and will need blood transfusions.
• Your sickle cell disease could come back.
• It means the bone marrow transplant did not work.
• Your doctors might want to try bone marrow transplant again, or a different treatment option.
• It is not common. Less than 1 out of every 10 people experience graft rejection. But the risk of death for those who have graft rejection is very high.

Veno-occlusive disease (VOD) is a common problem.

• Chemotherapy can damage your liver (a part for the body that cleans your blood) and this can cause veno-occlusive disease.
• People who have a lot of iron from blood transfusions or people who have liver damage are at a higher risk for veno-occlusive disease.
• Your doctors will watch for signs: your skin or eyes turn yellow, you gain weight, your body keeps too much fluid (water) inside, or your liver gets big.
• Your doctors know how to stop or treat veno-occlusive disease. They can give you medicine (defibrotide, ursodiol, or heparin). They may also limit the amount of fluid (water) they give you.
• Even with treatment, some people can also die from uncontrolled veno-occlusive disease (VOD).

You will be very immunosuppressed (unable to fight germs).

• Chemotherapy kills your blood-making stem cells. This means you will not have enough functional white blood cells (immune system cells) for a few months.
• The donated stem cells will start making new white blood cells, but you can still get very sick from germs for a few weeks or months after chemotherapy.
• For the first few weeks, you are at the highest risk of getting very sick from germs. In the hospital, they take extra care to keep germs away from you.
• Your doctors will also give you medicine to fight germs.