Source: Johns Hopkins University
Date: January 31, 2011
Summary:
Researchers at Johns Hopkins have found a better way to create induced pluripotent stem (iPS) cells -- adult cells reprogrammed with the properties of embryonic stem cells -- from a small blood sample. This new method, described last week in Cell Research, avoids creating DNA changes that could lead to tumor formation.
Johns Hopkins researchers created the safer iPS cells by transferring a circular piece of DNA into blood cells from anonymous donors to deliver the needed genetic components. The traditional way is to use viruses to carry DNA into a cell’s genome. Unlike the viral methods, the circular DNA the Hopkins team used is designed to stay separate from the host cell’s genome. After the iPS cells formed, the circular DNA delivered into the blood cells was gradually lost.
Using about a tablespoon of human adult blood or umbilical cord blood, the researchers grew the blood cells in the lab for eight to nine days. The researchers then transferred the circular DNA into the blood cells, where the introduced genes turned on to convert the blood cells to iPS cells within 14 days.
The research group verified conversion from mature blood cells to iPS cells by testing their ability to behave like stem cells and differentiate into other cell types, such as bone, muscle or neural cells. They also looked at the DNA from a dozen iPS cell lines to make sure there were no DNA rearrangements.
