Sickle Cell Disease
Sickle cell disease is an inherited genetic blood disease that can cause severe pain, damage to vital organs and death. It results from a defect in a protein (hemoglobin) that enables red blood cells to carry oxygen throughout the body. Normal red blood cells are flexible and disk shaped. People with sickle cell disease have red blood cells that become hard and pointed instead of soft and round.
These irregular, inflexible sickle-shaped cells have difficulty passing through small blood vessels and can create blockages in the circulatory system, preventing the normal flow of oxygen to tissues. Tissue that does not receive normal blood flow eventually becomes damaged. This is what causes many of the complications of sickle cell disease, such as stroke, lung tissue damage and damage to many other organs, including the spleen, kidneys and liver.
Sickled red blood cells that do pass through blood vessels are often
destroyed in the liver or spleen, causing a constant thinning of the
red blood cell supply that results in anemia.
Basic treatment of sickle cell complications includes antibiotics, pain management, intravenous fluids, blood transfusion, drugs and surgery.
Although there is currently no universal cure for sickle cell disease,
stem cell transplants have already been shown to provide cures in
some cases and offer great potential in the years ahead. Gene therapy
is another option that may lead to new cures for this disease in the
Human and Social Costs
Sickle cell disease currently affects an estimated 72,000 people in the U.S. Each year, about 1,000 babies in our country are born with the disease. It is most common among people of African ancestry, but also affects people whose families come from Central and South America, the Mediterranean, Arabia, Italy, the Caribbean, the Middle East and India.
A person can carry the gene for the sickle cell trait without having sickle cell disease. In fact, about 2.5 million people in America, including 1 in 12 African-Americans, carries the sickle cell gene. These people rarely manifest any of the health problems associated with the sickle cell gene. However, when two people with the sickle cell gene have a child, their child can develop sickle cell disease.
The effects of sickle cell disease can be extremely painful and debilitating and can lead to an early death. Although the average life expectancy of a person with sickle cell disease has improved, most victims die by their mid-40s. In 1994, The Cooperative Study of Sickle Cell Disease showed that sickle cell disease decreased life expectancy among African-Americans by 25-30 years.
A 1997 report published in Public Health Reports found that a study
group of 1,189 sickle cell patients generated more that $59 million
in health care costs during a two-year period. Based on those findings
and a U.S. patient population of more 70,000 people, the annual health
care costs created by sickle cell disease in the U.S. could be well
over $1.5 billion.
The Potential for Stem Cell Cures and Therapies
Bone marrow transplants, one of the first forms of stem cell therapy, are already providing cures for some victims of sickle cell disease. Scientists believe that, with further research, stem cells could provide cures to many sickle cell sufferers.
Bone marrow nurtures stem cells that mature into red and white blood cells and platelets. By destroying the sickle cell patient's diseased bone marrow and then transplanting healthy bone marrow from a genetically-matched donor (such as a brother or sister), normal blood cells can be produced. Recent trials show that this procedure is generally successful, but it is limited to a relatively small percentage of patients by the availability of genetically compatible donors.
Other recent research indicates that the use of cord blood stem cells from donated umbilical cords could expand stem cell transplantation to a larger number of patients. Roughly 20% of sickle cell patients are found to have a matched sibling donor, and bone marrow banks typically house a narrow pool of minority-matched samples, making it difficult to find suitable transplant material for many sickle cell patients. By providing healthy cells to patients who do not have genetically matched donors for bone marrow transplants, cord blood stem cells may expand treatment access within communities impacted most severely by sickle cell disease.
Early trials are also reporting some success with a process by which
a mixture of patient and donor bone marrow is used. The procedure
has fewer side effects than traditional bone marrow transplants because
all of the patient’s original bone marrow is not destroyed.
Although some sickle blood cells remain, small studies indicate that
the patients are still free of the typical infections and pain of
Partial list of sources:
Sickle Cell Disease Association of America
Sickle Cell Disease Association of America - San Diego Chapter
Sickle Cell Society
"Bone Marrow and Cord Blood Stem Cell Transplant." The
Sickle Cell Information Center
"Stem Cells Stem Sickle Cell." CBS News
"Treatments Aimed at Sickle Cell Disease." University of
"New Treatment Strategies For Sickle Cell Disease."
Article by doctors A. Olujohungbe, A. Yardumian and K.I. Cinkotai
"Management and Therapy of Sickle Cell Disease: Hematopoietic
Cell Transplantation." Mark Walters, M.D., Oakland Children's
Hospital, Oakland, California
"Bone Marrow Transplantation for Sickle Cell Disease."
New England Journal of Medicine