Opening Doors to a Sickle Cell Cure -- Research Summary

BACKGROUND: Sickle cell anemia is one of the most common genetic diseases in the United States, affecting about 70,000 Americans. The disease also afflicts millions of people worldwide, says the National Heart, Lung and Blood Institute. Not everyone who carries the disease shows signs of it. That means about 2 million Americans, or one in 12 African Americans and one in 16 Hispanic Americans, carry the sickle cell trait, says the American Sickle Cell Anemia Association. Sickle cell anemia takes place when hemoglobin -- a component of red cells in the blood -- is defective and causes red blood cells to become stiff and assume a sickle shape. Since these oddly shaped red blood cells can't fit through small blood vessels, they stack up and cause blockages that deplete the supply of oxygen to organs and tissue. In addition, sickle-shaped red blood cells die after about 10 to 20 days, whereas normal red blood cells last about 120 days. That means the cells can't be replaced fast enough, and anemia takes place.

A LIFELONG BATTLE: Sickle cell anemia is a painful condition and often cuts life short. However, the life expectancy of those with the disease is improving. The National Heart, Lung and Blood Institute says sickle cell disease patients now live into their 40s or 50s and longer. A 1994 New England Journal of Medicine study found 50 percent of those with sickle cell anemia lived past 50. It also found most of those who died from the disease died during an acute episode of pain, chest syndrome or stroke. Those are three of the major complications that can occur with sickle cell anemia. Because sickle-shaped cells die too quickly, jaundice and gallstones are common in people with the disease. The limited blood flow caused by sickle cell anemia can result in lung tissue damage and priapism, or painful, prolonged erection. Other organs that can be damaged by the disease include the kidney, liver and spleen. Complications of sickle cell disease also include hand-foot syndrome, which occurs when blood flow is limited in the hands and feet, and delayed growth. When sickle cell anemia damages the spleen, the patient is more vulnerable to infections. This is why the most common cause of death in children with the disease is pneumonia.

TREATMENT: Treatments for sickle cell are mainly aimed at reducing pain and preventing complications like infections and anemia. Pain is most often treated with over-the-counter medicine and heating pads. During episodes of severe pain, fluids and pain-killing medicines like narcotics are administered in the hospital. To prevent infections in babies and young children, parents are often advised to give daily doses of penicillin. Patients with severe sickle cell anemia may need to receive a medicine called hydroxyurea, which reduces the number of painful crises that take place. Blood transfusions are commonly used to treat worsening anemia and complications associated with the disease.

REPLACING BAD BLOOD: The only cure for sickle cell anemia that exists is bone marrow transplantation, but this only works in a small number of cases. Recent research has looked into ways to make the treatment more widely available and make the process safer. A recent study at the Children's Hospital of Pittsburgh looked into a form of bone marrow transplantation that uses reduced-intensity conditioning prior to the transplant. The goal of conditioning is to prepare the body to receive something foreign, like donor bone marrow. The preparation itself carries complications like organ damage and sterility. Reduced-intensity conditioning reduces the risk of these complications by using lower doses of drugs. This type of conditioning makes bone marrow transplantation available to patients with severe sickle cell disease, who already have compromised immune systems. Another study is ongoing at St. Louis Children's Hospital that is incorporating reduced-intensity conditioning. The study is also allowing patients with severe sickle cell disease to receive bone marrow and umbilical cord blood from unrelated donors.

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FOR MORE INFORMATION, PLEASE CONTACT:

Jackie Ferman-Grothe
St. Louis Children's Hospital
(314) 286-0304