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 future.
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 African- Americans, 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 one 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 to 30 years.
A 1997 report published in Public Health Reports found that a study group of 1,189 sickle cell patients generated more than $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
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, other types of stem cell therapies could provide cures to many more sickle cell sufferers.
Bone marrow contains adult stem cells that can turn 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. Although recent trials show that this procedure can be successful, genetically matching bone marrow donors can only be found for about 20% of sickle cell patients.
Discarded umbilical cords also contain adult type blood-forming stem cells and recent research indicates that transplants of those stem cells could provide effective treatments for sickle cell disease. The use of umbilical cord stem cells could also provide genetically matching stem cell transplants for a larger percentage of sickle cell patients than bone marrow transplants alone can provide.
The issue of genetic compatibility could someday be addressed even more effectively with treatments provided by the new frontier in stem cell research, which involves early, or "embryonic," stem cells (ES cells). There is mounting evidence that ES cells may be less "immunogenic" than adult stem cells, meaning that they may be less prone to immune system rejection than adult stem cells.
The consensus of the medical and patient community is that all types of stem cell research should be pursued in the effort to find cures for diseases and injuries - including sickle cell disease - and that ES cells can play an important role in this effort.
That's why ES cell research is strongly supported by the overwhelming majority of medical researchers; medical organizations, like the American Medical Association, American Society of Hematology and National Medical Association; by leading research institutions, like the Stowers Institute for Medical Research; and by dozens of disease and patient advocacy groups.
Links to More Information:
Sickle Cell Disease Association of America
Sickle Cell Disease Association of America - San Diego Chapter
Sickle Cell Society
American Society of Hematology Statement in Support of All Avenues of Stem Cell Research
"Bone Marrow and Cord Blood Stem Cell Transplant."
The Sickle Cell Information Center
"Stem Cells Stem Sickle Cell."
“Treatments Aimed at Sickle Cell Disease.”
University of Maryland
“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