Normal disc-shaped red blood cells are flexible and can easily move through large and small blood vessels to deliver oxygen to tissues. In sickle cell disease (SCD), a mutation occurs in a gene called beta-globin, which controls the shape of red blood cells, and helps them carry oxygen to tissues throughout the body. This mutation causes the cells to become distorted into a crescent, or sickle, shape; this can lead to blockages that slow or stop blood flow, preventing oxygen from reaching all tissues, which results in excruciating pain and possible organ damage. This disease is caused by inheriting the “sickle” mutation from both parents.
“Sickle cell disease affects 100,000 people in the U.S. alone.”
Though current technology has improved the treatment and lifespan of SCD patients, the disease still causes recurring pain and ultimately damage to organs. SCD can be cured by blood stem cell transplantation: a patient’s diseased bone marrow (where red blood cells are produced) is eliminated, and blood-forming stem cells–including stem cells from the bone marrow of a healthy donor–are introduced. Over time, they will produce healthy disc-shaped red blood cells that replace the sickle ones, curing SCD. However, access to bone marrow from someone who is a perfect immune system match is extremely rare.
A research team led by Dr. Donald Kohn, at the University of California, Los Angeles (UCLA), has developed a procedure that involves harvesting SCD patients’ stem cells and genetically correcting them to prevent sickling. The scientists have tested this technique in a mouse model of SCD, where the modified stem cells created normal, disc-shaped red blood cells, curing their SCD. A human clinical trial is currently underway at UCLA to test this approach in people. The hope is that this procedure will be less toxic than a full bone marrow transplant, and eventually offer a permanent cure for this debilitating disease.
“Only with continued support for biomedical research can we move this therapy forward and, hopefully, make treatment widely accessible for patients.”
SCD is not the first disease in which Dr. Kohn has made significant strides. In 2015, Dr. Kohn and his team developed a cure for a fatal condition called Severe Combined Immunodeficiency (SCID), also known as “Bubble Boy Disease,” because babies are born without working immune systems, so must remain in completely sterile environments. He is currently advancing this approach in another trial for SCID. Concurrently, he is leading a trial for another type of genetic immune disorder, called Chronic Granulomatous Disease, which is also underway at UCLA.