A Bone Marrow Disease With a Brighter Prognosis
New drugs, transplantation helping people with aplastic anemia live longer, fuller lives
SUNDAY, March 23, 2008 (HealthDay News) -- Blood is life. And the rare disease known as aplastic anemia robs the body of life by robbing the body of blood.
The aplastic anemia patient's blood thins as the bone marrow slows its production of blood cells. The results can range from chronic fatigue to heart disease or from endless infections to cuts that won't clot, depending on the type of blood cells that are lacking.
But there's hope: Considered fatal as recently as two decades ago, aplastic anemia is becoming a far more manageable disease. Advances in drug therapies and improvements in the field of transplantation have slashed the death toll, allowing patients to live longer, fuller lives.
"We are getting better at treating aplastic anemia, either in getting rid of it or treating its symptoms," said Dr. Jaroslaw P. Maciejewski, with the Cleveland Clinic's Department of Hematologic Oncology and Blood Disorders.
And those advances are helping doctors gain greater insights into other, more prevalent, health conditions, such as heart disease and leukemia.
An estimated 50,000 people develop aplastic anemia in the United States each year, according to the U.S. National Institutes of Health. (A related blood disorder, myelodysplastic syndrome, or MDS, occurs when the bone marrow begins to produce poorly functioning or immature blood cells. About 20,000 to 30,000 new cases of MDS occur each year.)
It's important to note that many symptoms of aplastic anemia, such as fatigue and infection, can also be caused by other diseases, said Dr. Ronald Paquette, a blood disease researcher with the University of California, Los Angeles' Jonsson Comprehensive Cancer Center.
"If everyone who was fatigued thought they had aplastic anemia, we'd be swamped," Paquette said.
Bone marrow -- the spongy material inside bones -- produces stem cells that normally develop into the three main types of blood cells -- red blood cells, white blood cells, and platelets.
"Essentially, the bone marrow is a factory of blood," Maciejewski said.
In patients with aplastic anemia, the stem cells have been damaged, slowing or stopping the production of all blood cells.
The cause of the damage to stem cells remains unknown in more than half of people with aplastic anemia. Some research has suggested that stem cell damage occurs when the immune system attacks the body's own cells by mistake, according to the National Institutes of Health.
Aplastic anemia has also been linked to exposure to toxins such as pesticides, arsenic and benzene. Some infectious diseases also can cause the disorder, including hepatitis, Epstein-Barr virus, cytomegalovirus, parvovirus B19, and HIV, as well as autoimmune diseases like lupus and rheumatoid arthritis. Finally, some genetic disorders have been linked to it.
Symptoms vary depending on the type of blood cells in shortage:
- Too few red blood cells can mean not enough oxygen is carried to the body, according to the NIH. People who have a low red blood cell count often feel tired. Because the heart has to work harder to pump blood to get enough oxygen to the body's organs and tissues, heart disease can develop over time.
- Too few white blood cells weaken the body's defense against infection. The patient may become ill more often, and the illness can be severe.
- Too few platelets hamper the blood's ability to clot. Patients with a low platelet count may bruise or bleed easily, and their bleeding may be hard to stop.
Once aplastic anemia is detected, swift treatment is essential, Paquette said. "Because it's a rare disease, it's important to be treated at a specialized center," he said. "The most important thing is to be seen by someone with a lot of experience treating the disease early on."
For patients younger than 30, stem cell transplantation is often the preferred treatment. For those with a matched sibling donor, stem cell transplantation replaces the defective bone marrow with healthy cells, and as many as 80 percent of patients enjoy a complete recovery, according to the Aplastic Anemia & MDS International Foundation Inc.
Advances in stem cell research and anti-rejection drugs have meant that transplantations from unrelated donors also are becoming more successful, Paquette said.
One promising avenue of treatment involves transplantation using stem cells harvested from the umbilical cord of new mothers. "The cells can be cryopreserved [frozen] and saved, then given to unrelated donors," Paquette said. "It's quite encouraging."
For these patients, again, speed is of the essence. "The data show the earlier you do a transplant, the better the outcome," Paquette said.
Patients whose transplants fail, or for whom transplantation is not an option, often receive successful immunosuppressive therapy with agents like anti-thymocyte globulin and cyclosporine. Response rates typically range from 70 percent to 80 percent, according to the Aplastic Anemia & MDS International Foundation Inc.
Blood transfusions from matched donors also are used to keep blood counts high and help relieve symptoms, although they are not an effective long-term treatment.
"Whether we cure the disease or not, patients are getting better across the board," Maciejewski said. "We now can maintain life, keep these patients alive longer."
To learn more, visit the Aplastic Anemia & MDS International Foundation Inc.