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PLEASE don't think that this is some kind of end-all be-all wonderful cure-all, and PLEASE PLEASE don't let all the hype surrounding any use of the phrase "stem cell" in the media excite you. This is just some really fascinating research which has some interesting implications and potential uses.

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When I worked at NIH in a genetics laboratory this summer, we had weekly meetings where we read and discussed interesting genetics experiments that have been published. There was one we looked at, published in June, which details a FASCINATING and, I think, very important advance in the study of cell differentiation and "stem cells". I'll summarize it as best I can here because I find it incredibly surprising that almost no one else has heard of it.

This research built off of another experiment performed a year before. In this first experiment, scientists used a technique called microarray analysis to determine which genes were expressed more strongly in mouse embryonic stem cells than in mouse fibroblasts (connective tissue cells). They found a selection of several tens of genes which were expressed in the ES cells MUCH more strongly than in the fibroblasts. They then proceeded to take copies of these genes and insert them into retroviruses with promoters ensuring that the genes would be expressed no matter where they were inserted into the genome (retroviruses insert DNA randomly into the genome of cells they infect). After infecting the mouse fibroblasts with these custom retroviruses, they changed shape and behavior and began looking and behaving exactly like embryonic stem cells in culture. They also produced tumors when injected into adult mice - tumors of the type normally associated with injecting natural embryonic stem cells. The researchers removed genes one at a time from the retrovirus, and found a total of 4 genes that HAD to be present to completely reprogram the cells to behave like embryonic stem cells. They code for transcription factors - proteins that change the expression of other genes. The mouse cells eventually shut down the retrovirus DNA, but by the time they do the cells have been reprogrammed to express stem-cell genes.

The new research involved taking these reprogrammed cells and injecting them into very early mouse embryos. These cells had been infected with retroviruses containing the aforementioned 4 transformation genes AND a gene which causes any cell that contains it to glow green under the correct light (GFP). After letting the embryos gestate and be born, they found that the cells were incorporated into the mice and were present in all their tissues, showing that they really are nearly indistinguishable from embryonic stem cells. They mice even produced a few eggs and sperm descended from these embryonically transplanted cells.

I'm dead tired and will post a link tomorrow, along with an explanation of how this relates to humans. It is not as simple as you'd think to apply this process to humans - there are intrinsic problems, and genetics is a very complicated science... but I believe this is important and awesome research.

Again PLEASE don't overhype this. I've seen WAY too many people flip out or get way too excited because they let hype and unrealistic ideas overshadow thinking about the situation.