Disease-Specific Stem Cell Lines Developed

The current paper in Cell describes a similar process, taking cells from patients aged 1 month to 57 years and suffering from one of 10 conditions including Down Syndrome, Parkinson's, Huntington's disease, muscular dystrophy and type 1 diabetes, and using iPS to produce pluripotent, undifferentiated stem cells.

These cells, of course, will then have to be coaxed into tissues of different types. "That is where all of the science will go on over the next many, many years," added Daley, who is associate director of the Stem Cell Program at Children's Hospital Boston.

The recent successes will not likely obviate the need for controversial stem cells, however, the scientists said.

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"Even though the iPS methodology gives us a facile way for making disease-specific lines, it does not eliminate the value or need for continuing to study human embryonic stem cells," Daley said. "Those are really the gold standard for pluripotent stem cell types. They have no genetic modifications and, at least for the foreseeable future, and I would argue beyond that, are going to be extremely valuable tools. . . Human embryonic stem cells allow you to ask questions that we never can ask with iPS cells."

The iPS method requires the use of viruses, limiting the therapeutic potential of the lines.

"Whether or not we're going to be able to figure out how to do it without viruses so we can use the cells therapeutically is, as of today, an unanswered question," Daley said. "I'm confident we're going to get there and that within the next year or two, we will have several strategies for reprogramming cells without viruses, and when that happens, we may have cells in our hands that may be valuable for cell replacement therapy."

The number of lines ultimately generated will depend on a host of factors.

"In these complex genetic diseases, we're so ignorant at the moment, we don't even know if patients who get type 1 diabetes all get it the same way. There could be 50 different ways to get type 1 diabetes," Melton said.

If there are 50 ways to get the disease, scientists are going to want to develop more stem cell lines to reflect that variety. If there are only one or two ways, then fewer lines will be needed.

More information

The National Institutes of Health has more on stem cells.