CRISPR a potential cure for sickle cell disease

Blood smear showing sickle cell disease--Courtesy of Keith Chambers

Sickle cell disease is caused by a mutation in the gene that codes for the protein beta-globin, a component of red blood cells. A group of physicians and researchers have used CRISPR/Cas9 editing to correct the mutation in stem cells taken from the blood of affected patients.

The team, from UC Berkeley, UC San Francisco Benioff Children’s Hospital, Oakland Research Institute and the University of Utah School of Medicine, used CRISPR to fix the mutation in hematopoietic stem cells--cells that mature into red blood cells--that were taken from sickle cell patients, according to a statement. The edited cells produced healthy hemoglobin, which mutated cells do not make.

They also transplanted edited stem cells into mice, where they persisted four months after transplantation, suggesting that a potential therapy based on the approach would be long-lasting, according to the statement. The results are published in Science Translational Medicine.

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“This is an important advance because for the first time we show a level of correction in stem cells that should be sufficient for a clinical benefit in persons with sickle cell anemia,” said co-author Mark Walters, a pediatric hematologist and oncologist and director of UC San Francisco’s Benioff Oakland’s Blood and Marrow Transplantation Program, in the statement.

While “a lot of work” remains before the method reaches the clinic, the team’s goal is to develop genome engineering-based treatments to fix the mutation in a patient’s own stem cells so that the new blood cells produced by the patient are healthy, according to the statement. Current treatments for sickle cell disease include pain relievers and blood transfusions. While a bone marrow transplant is the only potential cure, finding a matching donor is challenging and surgery can be risky.

Further work will include large-scale mouse studies and safety analysis. Walters and Jacob Corn, a senior author and scientific director of UC Berkeley’s Innovative Genomics Initiative, are working to bring the treatment to clinical trials within the next 5 years. And while the team’s initial focus is sickle cell anemia, the approach could be used to tackle other blood disorders, including beta-thalassemia and severe combined immunodeficiency.

“Sickle cell disease is just one of many blood disorders caused by a single mutation in the genome,” Corn said in the statement. “It’s very possible that other researchers and clinicians could use this type of gene editing to explore ways to cure a large number of diseases.”