Sickle Cell Disease (SCD) is a genetic blood disorder that afflicts millions of people worldwide. Although there is currently no cure, one gene-editing technique could soon change the way we treat SCD and other genetic diseases.
Hemoglobin is the oxygen-carrying protein that normally gives a red blood cell its circular shape. In SCD patients, however, the hemoglobin forms a rigid skeleton and the red blood cell becomes sickle-shaped as a result. In most cases, SCD is caused by mutated hematopoietic stem cells which are precursors to the hook-shaped hemoglobin in affected red blood cells. Sickle cells stick to blood vessel walls and can cause blockages. Consequently, nearby tissues don’t receive oxygen and complications manifest in the form of anemia and debilitating pain. SCD is inherited when both parents contribute an abnormal hemoglobin gene. A carrier of the sickle cell trait is described as having one abnormal and one healthy hemoglobin gene. These patients do not experience the same symptoms as those that suffer from SCD.
In the U.S., about 100,000 people show symptoms of the disease, while 3.2 million suffer worldwide. Interestingly, a relatively high percentage of sickle cell carriers exist in malaria-endemic regions like Sub-Saharan Africa, as the mutation grants the carrier a natural resistance to the pathogen.
CRISPR-cas9 to Cure Sickle Cell Disease
Researchers from the University of California, Berkeley, UCSF Benioff Children’s Hospital Oakland Research Institute (CHORI), and the University Of Utah School Of Medicine have succeeded in correcting the hematopoietic mutation responsible for SCD using gene “scissors” CRISPR-Cas9. The team then reintroduced the genetically repaired stem cells back into SCD affected mice. Surprisingly, the SCD-affected mice began producing normal hemoglobin. Furthermore, the corrected stem cells continued to function for almost four months, suggesting that CRISPR editing could provide lasting therapy.
While the technique has not yet been tested on humans, the team carried out tests on diseased human blood. Results showed a high number of healthy hemoglobin, which could help alleviate symptoms in SCD patients.
Immediate Applications of CRISPR Gene Therapy
Gene editing’s success in curing mice of SCD is promising for the prospect of testing on humans, despite further animal testing still being required. Hopefully, more research yields safe treatment for humans that more effectively treats or even completely cures the condition. According to Jacob Corn, one of the lead researchers, the CRISPR-cas9 scissors could be used to cure any number of genetic diseases.