- Sickle cell disease is an inherited disease that affects hemoglobin, the oxygen-carrying protein that is inside red blood cells.
- People with sickle cell disease do not have enough healthy red blood cells to carry oxygen throughout the body. Normal red blood cells are round, but in sickle cell disease, red blood cells are crescent-shaped, or “sickle” shaped. This abnormality is due to the abnormal hemoglobin in the red blood cells, which causes them to become stuck in blood vessels, blocking them, and restricting blood flow to different parts of the body.
- Complications of sickle cell disease range from fatigue to stroke, infections, and pain in the bones and chest that require hospital visits.
- Sickle cell disease affects about 1 in every 500 African Americans in the United States, about 1 in 1,000 to 1,400 Hispanic Americans and it is the most common genetic disease in the world.
- Sickle cell disease is most common among people whose families come from Africa, South or Central America, Caribbean Islands, Mediterranean countries, India and Saudi Arabia.
- The most common types of sickle cell disease in the United States are:
- Sickle cell anemia
- Sickle hemoglobin C disease (also known as hemoglobin Hb SC disease)
- Sickle beta thalassemia disease
How Stem Cell Research Can be Used to Treat Sickle Cell Disease
There is a currently available and potentially curative stem cell therapy for a limited population of sickle cell patients. Stem cell transplants (SCT) involves the replacement of the sickle cell disease patient’s bone marrow with healthy bone marrow stem cells. There are major limitations to this approach, however, including: age of the recipient, availability of a donor match, use of immunosuppression, etc. This highlights the need for further identification of alternative approaches for older patients who do not have matched siblings. These alternative approaches include:
- Using stem cells from the patients themselves, correcting the genetic defect, and then reintroducing the modified stem cells to the patient to create new and healthy blood systems.
- Identifying safer and less toxic methods of bone marrow eradication to prepare the recipient for new donor stem cells.
CIRM’s Progress: Selected Research Highlights
- CIRM has funded three clinical trials in California:
- In a Phase 1 clinical trial, researchers at UCLA are combining stem cells and gene therapy to remove bone marrow from people with sickle cell disease, isolating the stem cell population, fixing the genetic mutation that causes sickle cell disease so that the cells produce a correct version of hemoglobin. The modified cells are then reintroduced to the patient in order to create a healthy blood system with healthy blood cells.
- In a Phase 1 clinical trial, researchers at City of Hope, Beckman Research Institute are studying a way to eliminate the sickle cell patient’s bone marrow cells with a technique that is much milder and less toxic than standard chemotherapy. By doing so, the patient can then be prepared for a stem cell transplant without high risk of rejection.
- In a Phase 1 clinical trial, researchers at ExCellThera, Inc. are expanding and using cord blood stem cells from healthy donors to mitigate the challenge of donor matching and availability.