Aplastic anemia
Disease information
Overview
Aplastic anemia is a serious condition where the bone marrow does not produce enough new blood cells, including red blood cells, white blood cells, and platelets. This happens because there's a decrease in the number of hematopoietic stem cells, which are the cells in the bone marrow responsible for producing blood cells. The disease is often caused by an abnormality in the immune system that affects these stem cells, preventing them from dividing and turning into different types of blood cells as they should. Aplastic anemia is more commonly diagnosed in East Asian countries, such as Korea, than in Western countries. In its most severe forms, it poses a significant threat to life. However, there is hope for those affected. With treatments such as allogeneic hematopoietic stem cell transplantation, where stem cells are transferred from a donor, or immunosuppressive therapy, which calms the immune system, many patients—about 80-90%—can achieve a cure.
▲ Findings from the bone marrow biopsy of patients with aplastic anemia
▲ Findings from the bone marrow biopsy of a healthy individual
Treatment
For individuals diagnosed with aplastic anemia, particularly those under the age of 50, hematopoietic stem cell transplantation (HSCT) is a critical treatment to consider. The decision to proceed with HSCT is often based on the severity of the disease and the results of human leukocyte antigen (HLA) compatibility testing with a sibling. In cases of severe aplastic anemia, if there is an HLA-matched sibling donor, HSCT is the recommended course of action for patients under 50. For older patients, those with a moderate form of the disease, or when an HLA-matched sibling donor is not available, the treatment of choice is usually immunosuppressive therapy. This approach helps to suppress the abnormal immune response that is attacking the bone marrow.
▲ Korean Journal of Internal Medicine, Seung-Hwan Shin and Jong-Wook Lee, Recent advances in treatment of aplastic anemia, 2014
In the treatment of aplastic anemia, autologous hematopoietic stem cell transplantation, which involves using the patient's own stem cells, is not an option due to the disease's nature affecting the bone marrow's ability to produce healthy cells. Instead, allogeneic transplantation is used, where stem cells are sourced from a donor. The best chance of success typically comes from using hematopoietic stem cells from a sibling with matching human leukocyte antigens (HLA), but if a matched sibling is not available, cells from an unrelated donor or a family member with half-matched HLA, known as a haploidentical donor, may be used.
For patients with severe aplastic anemia who do not have a matched sibling donor, the initial treatment is usually immunosuppressive therapy. If the patient doesn't respond to this therapy, an allogeneic hematopoietic stem cell transplantation from an unrelated donor is considered. When a compatible unrelated donor cannot be found, a haploidentical transplant from a family member may be the next step. Thanks to improvements in transplant procedures and post-transplant care, the success rates for sibling donor transplants are now approximately 90-95%. Unrelated and haploidentical family donor transplants also have high success rates, around 90%.