July 2, 2014
News Review From Harvard Medical School -- Transplant May Help Adults with Sickle Cell
A partial transplant of bone-marrow stem cells may reverse sickle cell disease in adults, a new study finds. People with sickle cell disease have abnormally shaped red blood cells. They get stuck in blood vessels. This causes organ damage, pain and other medical problems. The new study included 30 adults with severe sickle cell disease. Each of them had a brother or sister who was a suitable match for a bone-marrow stem cell transplant. The sibling donor's cells were mixed with some of the patient's own cells. During 3.4 years of follow-up, the partial transplant reversed sickle cell disease in 26 out of 30 people, researchers said. In these patients, the bone marrow began making normal red blood cells. Fifteen people also were able to stop taking drugs to prevent rejection of the transplant. Overall, people were much less likely than before to need hospital treatment for the disease. Use of narcotic drugs for pain also was greatly reduced. The Journal of the American Medical Association published the study. HealthDay News wrote about it July 1.
By Howard LeWine, M.D.
Harvard Medical School
What Is the Doctor's Reaction?
In the United States, more than 90,000 people are affected by sickle cell disease. Most of them are African-American. Worldwide, the number is much higher. About 300,000 babies are born with this genetic disease every year.
In sickle cell disease, the red blood cells made in the bone marrow are abnormal. Instead of having a normal round shape, the cells are curved and stiff. This causes the red blood cells to get stuck inside blood vessels before they reach the tissues. The result:
- Damage to organs
- A high risk of strokes
- Loss of vision
- Frequent episodes of very severe pain
Sickle cell disease used to be thought of as incurable. No longer. Bone marrow stem cell transplant has been shown to be more than 90% successful in children. But the treatment requires a complete wipe-out of bone marrow cells. After the transplant, the child must stay on drugs that suppress the immune system indefinitely. This is needed to prevent rejection of the bone marrow transplant. These drugs put the child at high risk for severe infections.
Another serious problem that can occur after stem cell transplant is graft-versus-host disease. The transplanted red cells from the donor attack the child's body. This causes a wide variety of medical problems.
Adults with severe sickle cell disease already have organ damage. Therefore, a full wipe-out of the bone marrow has seemed too risky for them. But what if a stem cell transplant could be performed without totally wiping out the bone marrow? In this new study, researchers recruited 30 adults with severe sickle cell disease who were willing to undergo this partial bone marrow wipe-out and stem cell transplant.
Although the study includes only a small number of patients, the results are dramatic. After 3.4 years, 1 person died. That death was probably unrelated to the stem cell transplant. The amount of medicine needed after the transplant to treat sickle cell pain fell by 80%. And the number of times people needed hospital treatment for severe pain episodes also decreased significantly.
People's quality of life improved. Half of them also were able to stop anti-rejection drugs after a year. The patients still had some of their original bone marrow cells. These cells and the donors' bone marrow cells were able to work together naturally to produce enough normal red cells to treat the disease.
What Changes Can I Make Now?
Most adults with sickle cell disease will not be candidates for this treatment. They need to have a brother or sister who is a match for a bone-marrow stem cell donation. This means the sibling's cells have to be genetically very similar to the patient's cells. This doesn't happen very often.
If you do have sickle cell anemia, it's important to do what you can to stay healthy. Here are some things you can do:
- Take folic acid pills. This vitamin is needed to make red blood cells.
- Get vaccinated against influenza, pneumonia and other infections.
- Get regular eye exams. Early detection of injury to the retina can lead to vision-saving laser treatment.
- Consider hydroxyurea treatment. This medicine may reduce painful episodes, called "sickle crises." You also may need fewer blood transfusions.
- Get prompt medical care if you have fever or severe pain. Treatment may include fluids, oxygen, transfusions and pain medicines.
What Can I Expect Looking to the Future?
Future research will look at whether a parent can act as the stem cell donor. This will require new techniques that either:
- Alter the parent's donor stem cells to more closely match the patient's cells OR
- Prevent the patient from rejecting the parent's donated stem cells
This would be a tremendous advance. Many more sickle cell patients might be eligible for stem cell transplant.