Stem cell researchers are getting closer to a new treatment for sickle cell disease, moving promising laboratory research into human clinical trials. Millions of people worldwide suffer from this hereditary disease.
Sickle cell disease is a group of disorders that affects hemoglobin, the molecule in red blood cells that delivers oxygen to cells throughout the body. People with this disorder have atypical hemoglobin molecules, which can distort red blood cells into a sickle shape. The sickled cells break down prematurely causing anemia. The sickled cells can also get stuck in small blood vessels depriving the tissues and organs of oxygen-rich blood. The illustration to the right shows a healthy, round, red blood cell next to a sickled cell.
Symptoms of sickle cell disease include anemia (a low number of red blood cells), severe pain, difficulty breathing, strokes, joint pain and arthritis, blockage of blood flow in the spleen or liver and severe infections.
Sickle cell disease is caused by an inherited mutation in the beta-globin gene, and it is here at the source that stem cell scientists are targeting their efforts. Hematopoietic stem cells generate all the cells of the blood and immune system. If the mutation could be corrected in these stem cells, all the red blood cells arising from the repaired stem cells would carry the normal beta-globin and function normally.
Dr. Donald Kohn of UCLA and has demonstrated this approach is feasible by removing the stem cells from the bone marrow of people with sickle cell disease and precisely correcting the genetic mutation in the hemoglobin gene. In the laboratory, these corrected hematopoietic stem cells make normal red blood cells. Ultimately, the goal is to transplant the repaired stem cells back into patients with sickle cell disease. Dr. Kohn and his team are one step closer to this goal having received approval for a phase 1 clinical trial (May 2015) that will assess the safety and initial evidence of effectiveness of treating sickle cell disease patients by transplanting them with their own genetically corrected hematopoietic stem cells. Learn more about clinical trials here.
Sickle cell disease can currently be treated with the transplantation of bone marrow from a healthy donor, which provides a source of new blood-forming stem cells which produce normal red blood cells. However, bone marrow transplantation is dependent on a well-matched donor and comes with the risk that the recipient’s body may reject the transplanted cells. Dr. Kohn’s strategy has the potential to provide a more effective and safe treatment.
