Since that time, researchers have been racing to find other sources of viable stem cells -- iPS cells are one outcome of that race.
For this study, Hanna and his colleagues used a process similar to the one revealed two weeks ago, taking skin cells from the tails of mice with sickle cell anemia and using them to produce iPS cells. The researchers then replaced the mutated gene with a healthy gene in the new cells. Once the iPS cells had differentiated into hematopoietic stem cells, they were reintroduced into the mice, where they began to produce healthy blood cells.
Some 10 percent of the human population, mostly blacks, carry the mutation for sickle cell anemia. The exact mutation is well known, as is the protocol for differentiating embryonic stem cells into precursors of bone marrow adult stem cells, making the condition well-suited to study.
In sickle cell anemia, red blood cells become sickle-shaped and can't move easily through the blood vessels.
Although exciting, the process is still fraught with potential danger.
The procedure to turn skin cells into iPS cells could lead to cancer (although none of the mice in this study showed any evidence of tumors). Also, the healthy genes were introduced into the mice via retroviruses, which can introduce other problems.
"Now the major question in the field is can you make iPSs with a safer method, that don't use retroviruses, because viruses can integrate into the DNA and activate dangerous genes or silence necessary genes," Hanna explained.
"I like the fact that they're saying this is a first step, because they're using retroviruses, and they have to show that this is a safe approach," added Sanb
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