Wednesday, October 5, 2011

A cure for SCD?

Researchers at John Hopkins University in Maryland have used a patient’s stem cells to amend the genetic alteration that causes sickle cell disease. This blood disorder is most prevalent in African Americans. In a test tube, the corrected stem cells were coaxed into becoming immature red blood cells that then activated a normal version of the gene.

It is important to remember that this research is still being carried out in laboratories and may still be years away from clinical use in patients, however it should provide tools for developing gene therapies for sickle cell disease and a variety of other blood disorders.
The disease is caused by a single DNA letter change in the gene for adult hemoglobin, the principle protein in red blood cells needed to carry oxygen. In people who inherit two copies—one from each parent—of the genetic alteration, the red blood cells are sickle-shaped, rather than round. The misshapen red blood cells clog blood vessels, leading to pain, fatigue, infections, organ damage, and premature death.
Although there are drugs and painkillers that control SCD symptoms, the only known cure has been bone marrow transplant. But because the vast majority of SCD patients are African-American and few African-Americans have registered in the bone marrow registry, it has been difficult to find compatible donors.

Using one adult patient as their first case, the researchers first isolated the patient’s bone marrow cells. After generating induced pluripotent stem (iPS) cells—adult cells that have been reprogrammed to behave like embryonic stem cells—from the bone marrow cells, they put one normal copy of the hemoglobin gene in place of the defective one using genetic engineering techniques. (see wacky scientist)
In their process, his team converted the corrected iPS cells into immature red blood cells by giving them growth factors. Further testing showed that the normal hemoglobin gene was turned on properly in these cells, although at less than half of normal levels.

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