Sickle cell anemia ,is a genetic conditions that effects millions across the globe. Headquartered in Cambridge, MA, Bluebird bio is a biotech company which actively works in the field of gene therapies. The company in its recent gene therapy works has been able to cure patients suffering from sickle cell anemia.
What is Sickle Cell anemia?
Caused by a single genetic mutation, sickle-cell is an inherited blood disorder that affects millions around the world.
Sickle cell anemia is an inherited condition that causes the red blood cell to acquire a sickle shape and breakdown. The early death of sickle shaped RBC causes a shortage in the number of blood cell in the body and therefore the person becomes severely anemic and also suffers from pain due to blood flow blockage.
sickle cell disease is a group of disease that affects the hemoglobin and thereby affecting its function of delivering oxygen to the cell throughout the body. People with this disorder have atypical hemoglobin molecules called hemoglobin S, which can distort red blood cells into a sickle,or crescent, shape.
Anemic condition triggers other symptoms such as shortness of breath, fatigue, and delayed growth and development in children. The rapid breakdown of red blood cells may also cause yellowing of the eyes and skin, which are signs of jaundice. The disease can lead to severe pain as the stiff sickle shaped blood vessel block the smaller blood vessels, which in turn deprives the tissues and organs of oxygen rich blood. This condition may lead to organ damage especially the lungs, kidneys , brain and spleen. A particularly serious complication of sickle cell disease patients is high blood pressure in the blood vessels that supply the lungs (pulmonary hypertension) and can lead to heart failure.
The only cure for genetic condition is gene therapy. Although complicated Bluebird bio has been able to help 17 patients eliminate pain. For over 21 months, none needed the transfusions that are a common treatment and none of those who previously suffered from pain attacks experienced any. More than 40% of the hemoglobin in their red blood cells came in a healthier form that was produced by the gene therapy.
The treatment doesn’t ensure a 100% normal production of blood cells. But ensures enough production of normal red blood cells for the body to survive without pain and other symptoms.
The first case of Bluebird bio company was of a teenage boy in France who was cured using gene therapy.
Scientists removed the stem cells from the patient’s bone marrow and modified them by introducing normal genes, thereby preventing the production of sickle shaped cells. The treated stem cells where then infused back into the body. This technique decreased the intensity of the disease by producing normal RBC from the bone marrow cells. More than two years after the treatment the boy still produces enough RBCs to evade any side effects from the disease.
In its series of researches Bluebird bio has generated “Lentiglobin“. A single infusion of Bluebird Bio’s Lentiglobin has eliminated pain and the need for repeated transfusions.
Although there are other drugs such as Novartis AG’s Adakveo and Global Blood Therapeutics Inc.’s Oxbryta, the single infusion is far more promising than repeated administration of drugs. The drug Adakveo , a monthly infusion helps reduce pain whereas Oxybryta works by slowing the progression of the disease. Crispr Therapeutics AG and Vertex Pharmaceuticals Inc. are also working on a novel approach to treat sickle cell disease, using gene-editing tools. The companies reported promising data in the first sickle cell patient to receive CTX001, a one-time treatment that allows the body to resume making a healthier form of hemoglobin normally produced by infants.
There are positive effects at the whole organism level. Carriers of the sickle cell allele are resistant to malaria, because the parasites that cause this disease are killed inside sickle-shaped blood cells.
Molecular level Analysis
A person with sickle cell disease has one different substance in the way it makes hemoglogin. A point mutation in the Beta globin chain of hemoglobin produces amino acid valine in one spot where there should be glutamic acid. This generates an altered protein that is misfolded. This one change causes hemoglobin to form long strings when it lets loose of its’ oxygen. This causes the red cell to become deformed into a “sickle” shape.
A normal blood cell lives for 120 days whereas the mutated sickle blood cell has a life span of 20 days or less.
Sickle cell disease is a autosomal recessive disorder . People with two copies of the sickle cell gene have the disease. People who carry only one copy of the sickle cell gene do not have the disease, but may pass the gene on to their children.