CRISPR-Cas9 technology can effectively treat rare blood diseases

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In the past two years, CRISPR technology has been in the limelight, and two scientists have won the Nobel Prize in Chemistry for CRISPR gene editing. With the deepening of research, CRISPR gene editing has made great progress. From the treatment of cancer to genetic diseases, CRISPR has begun to successfully enter clinical applications from a basic research tool.

CRISPR technology is adapted from the natural defense mechanisms of bacteria and archaea (the field of single-celled microorganisms). These organisms use CRISPR-derived RNA and various Cas proteins to defend against attacks by viruses and other foreign bodies. CRISPR gene editing, on the other hand, is the specific DNA modification of targeted genes, which has broad application space in blood diseases, tumors and other genetic diseases.

Recently, the European Society of Hematology announced the results of using CRISPR technology to treat two rare genetic blood diseases. The results showed that the CRISPR gene editing technology was safe and effective within three years of treating patients, with a success rate of nearly 100%.

Transfusion-dependent beta-thalassemia (TDT) and sickle cell disease (SCD) are more serious monogenic disorders. Previous studies have found that γ-globin functions similarly to β-globin, which is silenced and no longer expressed in humans in adulthood. If the expression of the γ-globin gene could be reactivated, the loss of β-globin could be compensated for, thereby alleviating or curing both types of hereditary anemias.

Of the 75 treated patients in the experiment, 44 had transfusion-dependent beta thalassemia (TDT) and 31 had severe sickle cell disease (SCD). The researchers used CRISPR technology to make genetic changes that increased fetal hemoglobin levels in red blood cells, and then reinfused the stem cells into the patient. It is worth mentioning that umbilical cord blood is rich in hematopoietic stem cells that rebuild human hematopoietic and immune systems, and can be used for hematopoietic stem cell transplantation to treat more than 80 diseases.

Closer to home, of the 75 patients treated with the breakthrough CRISPR therapy, 42 with TDT were largely cured and no longer required blood transfusions. Two other TDT patients who still required blood transfusions had 75% and 89% less blood transfusions, respectively. All 31 SCD patients were also asymptomatic at long-term follow-up.

Furthermore, in the previous study, 22 patients were treated and all showed a 100% success rate. Even more surprising, seven of the patients did not experience diminished efficacy within 12 months of initial treatment.

In the future, it is hoped that this technology can bring benefits to mankind.