Embryonic Stem Cells Reprogram Adult Cells
Scientists at Harvard University reported research yesterday in which they had succeeded in rejuvenating and reprogramming human adult skin cells by fusing them with embryonic stem cells. In a teleconference this morning, one of the researchers Kevin Eggan, an assistant professor of molecular and cellular biology at Harvard, told reporters that the research is aimed at helping scientists understand how adult cells can be reprogrammed, but that, "this research will not result in a functional entity useful for treatments."
One problem is that the cells contain both full sets of chromosomes from the embryonic and adult cells. These tetraploid cells do divide and exhibit all of the characteristics of embryonic stem cells. However, Eggan stressed the point that because they contain genetic material from two individuals, "they are useless for therapy." The really exciting aspect of the work is that these new tetraploid stem cell lines can be created using already abundant embryonic stem cell lines instead of rare human eggs, giving researchers far more lines in which to find and study the factors that can reprogram cells. Eggan explained that the eventual goal is to isolate the factors in eggs and embryonic stem cells that elicit reprogramming. Once these are known, they can be used to directly rejuvenate and transform adult cells without resorting to eggs or embryonic stem cells.
Why fuse the cells? Why not just isolate the cytoplasm from embryonic stem cells and inject it into adult cells to see if factors in the cytoplasm will reprogram adult cells? Eggan pointed out that trying to remove chromosomes from embryonic stem cells is technically extremely difficult. However, other teams are in fact pursuing this type of research. Eggan mentioned unpublished work being done by Yuri Verlinksy at the Reproductive Genetics Institute in Chicago in which genes are centrifuged from embryonic stem cells and their cytoplasm is used to dose adult cells and transform them into cells that act like embryonic stem cells.
Eggan acknowledged that main body of his team's research was done using a stem cell line that was derived using private funds in 2004. In August 2001, President George Bush limited federal research funding to only stem cell lines derived before that date. The Harvard team did later use a "presidentially approved" stem cell line to produce a new tetraploid stem cell line in a proof of concept experiment.
Eggan is well aware that his new study is falling right in the middle of the upcoming fight in Congress over whether or not to lift President Bush's restrictions on embryonic stem cell research. "Myself and my colleagues feel very very strongly that somatic cell nuclear transfer [cloning human embryonic stem cells] research and research using embryos left over from IVF treatments to produce stem cell lines should go forward," said Eggan. He stressed that his team's research is a complement to, not a substitute for, other promising types of stem cell research.