Using a recently developed technique for turning skin cells into stem cells, scientists have cured mice of sickle cell anemia — the first direct proof that the easily obtained cells can reverse an inherited, potentially fatal disease.
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researchers also cautioned that aspects of the new approach will have to be changed before it can be tried in human patients. Most important, the technique depends on the use of gene-altered viruses that have the potential to trigger tumor growth. “The big issue is how to replace these viruses,” said Rudolf Jaenisch of the Whitehead Institute for Biomedical Research in Cambridge, Mass., who led the new work with co-worker Jacob Hanna and Tim M. Townes of the University of Alabama Schools of Medicine and Dentistry in Birmingham.
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The researchers converted those skin cells into iPS cells by infecting them with viruses engineered to change the cells’ gene activity so they would resemble embryonic cells. Using DNA splicing techniques in those cells, the researchers then snipped out the small mutated stretches of DNA that cause sickle cell disease and filled those gaps with bits of DNA bearing the proper genetic code.

Next, the researchers treated the corrected iPS cells with another kind of virus — this time one designed to induce a genetic change that encouraged the cells to mature into bone marrow cells.

Finally, each mouse that gave up a few skin cells at the beginning of the experiment was given an infusion with the corrected marrow cells created from its own skin cells. Those cells set up permanent residence in the animals’ bones and began producing blood cells — the major function of marrow cells — and releasing them by the millions into the circulatory system.

But now the blood cells being produced were free of the sickle cell mutation.