Author: Caroline Schmidt
Sickle Cell Anemia is an inherited disorder that is caused by a mutation in the protein hemoglobin, which carries oxygen throughout the body. This mutation causes blood cells to change from their regular disc shape into a sickle (crescent) shape. The shape change prevents blood cells from delivering oxygen to organs. The blood cells also become “sticky” and more susceptible to clotting in blood vessels. Currently, the treatment for a sickle cell anemia patient involves a bone marrow transplant. Donors have to be siblings of the patient, and there is a chance that the sibling might not even be a good match. Gene therapy could possibly provide a cure for any anemic person.
Researchers at Boston Children's Hospital have recently started a clinical trial in which they use gene therapy to help cure sickle cell anemia. The primary goal of gene therapy is to increase the amount of fetal hemoglobin produced. A gene called BCL11A stops fetal hemoglobin from being produced shortly after birth. Then, we transition to producing adult hemoglobin. Unhealthy adult hemoglobin can cause sickle cell anemia, while fetal hemoglobin does not sickle.
(1: normal blood cells, 2: sickle cells)
First, blood stem cells are taken from the patients, and then BCL11A is extracted.
Next, the patient undergoes chemotherapy to kill unhealthy red blood cells.
Finally, the patients are given their modified blood stem cells.
This gene therapy method increases fetal hemoglobin while balling sickled adult hemoglobin. So far, this gene therapy has been successful. The first patient, a 21 year old male, is no longer showing signs of sickle cell anemia. A second team of researchers from Harvard Medical School and the Dana-Farber Cancer Institute used a technique called CRISPR-Cas9 in their gene therapy research. Like the other clinical trial, this method also uses blood stem cells and increases fetal hemoglobin. This study uses RNA to alter fetal hemoglobin gene expression (Yirka, 1). So far, this clinical trial has cured 19 people. Both of these studies have been very effective in finding a cure for sickle cell anemia. Gene therapy has shown promise in curing blood diseases, and it could also be used to cure many genetic disorders in the future.