Reprogrammed stem cells cure sickle cell anaemia

Dec 9 2007

Scientists in the U.S. have made a breakthrough in the fight against sickle cell anaemia, a blood disease caused by a defect in a single gene.

Sickle cell anaemia is a serious condition in which the red blood cells can become sickle-shaped instead of smooth and round; they do not move easily through the blood because they are stiff and sticky and can form clumps in the blood vessels.

These clumps block the blood flow in the blood vessels and can cause pain, serious infections and damage to limbs and organs.

Sickle cell anaemia affects millions of people worldwide but is most common in people whose families come from Africa, South or Central America (especially Panama), the Caribbean, Mediterranean countries (such as Turkey, Greece, and Italy), India and Saudi Arabia.

Sickle cell anaemia affects about 70,000 people in the United States mainly African Americans and around 2 million Americans have the sickle cell trait.

The scientists created the stem cells from cells extracted from the skin of mice; by injecting 4 genes into these new stem cells they were able to reprogramme them.

When the reprogrammed cells were reinjected into mice with sickle cell anaemia, the mice were cured.

In order to turn the skin cells into master cells the four genes were delivered using a type of virus called a retrovirus.

The team at the Whitehead Institute of Biomedical Research in Cambridge, Massachusetts, say they have shown that the cells 'pluripotent stem cells' (iPS), have the same potential for therapy as embryonic stem cells, but without the ethical and practical issues.

Lead researcher Rudolf Jaenisch says pluripotent or multipurpose cells, such as embryonic stem cells and the new cells, can morph into any type of cell in the human body.

Jaenisch says the research demonstrates that such reprogramming can be used to correct a major genetic disease.

Researcher Dr. Jacob Hanna says once the 4 genes enter the genome, there is a danger that they can silence some genes that are important or can activate some dangerous genes that should not be activated; one of the four genes used is c-Myc, which is known to cause cancer.

Dr. Hanna says the study is the first evaluation of such cells for therapy after years of work into strategies to generate customized stem cells and using skin cells from the body eliminates the risk of rejection.

Scientists say though the technique is far from perfected, they hope they will be able to use such stem cells to treat a range of diseases such diabetes, Parkinson's disease as well as spinal injuries.

The study is published in the current issue of the journal Science.