ORDINARY cells from people with a genetic disease can be 鈥渇ixed鈥� by gene therapy and then reprogrammed to be stem cells that will produce a limitless supply of defect-free cells.
Izpis煤a Belmonte of the Salk Institute in La Jolla, California, knew that stem cells are more useful for gene therapy than ordinary cells, because they produce multiple daughter cells with the modified genes. However, the body does not have many stem cells for doctors to work with.
So Izpis煤a Belmonte and his colleagues harvested fibroblasts, which are far more common than stem cells, from the skin of people with the bone marrow disease . The team used viruses to replace the defective genes that cause the anaemia with normal ones, then used a second virus to insert genes that 鈥渞eset鈥� the cells to a pluripotent state. The reset cells, known as induced pluripotent stem cells (iPS cells), gave rise to healthy precursors of bone marrow stem cells (Nature, ).
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One drawback is that the resetting can trigger cancer. But if efforts to make this step safer succeed, the technique could provide a limitless supply of healthy, personalised iPS cells, says team member .