Correcting Sickle Cell Disease With Stem Cells

Sickle cell disease (SCD) is an autosomal recessive genetic blood disorder that is characterized by an abnormal, sickle shape in red blood cells. It causes complications due to decreasing the cells' flexibility and is caused by a single letter mutation on the hemoglobin gene.

There are many drugs and painkillers to control SCD symptoms, but the only cure, which doesn't have a high success rate, is a complete bone marrow transplant. This poses a problem because the majority of disease carriers are African-American and few are registered in the bone marrow registry awaiting transplantation. It is also very hard to find suitable and compatible donors. For this reason, a research team at Johns Hopkins Institute for Cell Engineering is developing a method where treatment uses the patients own stem cells, eliminating the compatibility issue altogether.

A research team at Johns Hopkins have successfully corrected the anomaly in vitro by using stem cells from a patient's own bone marrow. First they prepared the induced pluripotent stem cells (iPS), or cells that have been reprogrammed to behave like embryotic stem cells. Then they placed one normal, nonmutated copy of the hemoglobin gene in place of the defective one using standard genetic bioengineering techniques.

They sequenced the DNA of 300 different samples of iPS cells to identify ones that had correct copies of the hemoglobin gene and initially only found four, but three of them did not pass further testing and were excluded from the test.

To convert the corrected iPS cells into immature red blood cells, growth factors were used. Further testing showed that the hemoglobin is functional and working properly. The only problem is the fact that immature blood cells only output half of what the mature counterparts would. The researchers believe it has something to do with the fact that immature red blood cells still behave like embryonic cells and therefore are looking for ways to properly and fully convert iPS cells to fully mature red blood cells.

This article was interesting to me because it gave me insight into more uses and ways stem cells are beneficial to the treatment and care of many anomalies. Although the use of stem cells in correcting sickle cell disease is not yet been tested on humans, this is yet another huge step toward providing tools for developing gene therapies for SCD and many other blood disorders.

Link to article:

http://www.sciencedaily.com/releases/2011/09/110928180416.htm