All the cool SF stories have autodocs that sniff out a severely wounded or recently deceased human, or whatever, and swot up replacement parts from the tattered remains of the carcass. If you have any piece of the original body, then you can manufacture needed components. We may be getting closer.

In a surprising advance that sidesteps the ethical debates surrounding stem cell biology, researchers have come much closer to a major goal of regenerative medicine, the conversion of a patient’s cells into specialized tissues that might replace those lost to disease.

The advance is an easy-to-use technique for reprogramming a skin cell of a mouse back to the embryonic state. Embryonic cells can be induced in the laboratory to develop into many of the body’s major tissues.

If the technique can be adapted to human cells, it would let scientists use a patient’s skin cell to generate new heart, liver or kidney cells that might be transplantable and would not be rejected by the patient’s immune system. . .

“From the point of view of moving biomedicine and regenerative medicine faster, this is about as big a deal as you could imagine,” said Irving Weissman, a leading stem cell biologist at Stanford University.

David Scadden, a stem cell biologist at the Harvard Medical School, said the finding that cells could be reprogrammed with simple biochemical techniques “is truly extraordinary and frankly something most assumed would take a decade to work out.”

I don't find this to be surprising. This has always seemed to me to be the only sensible approach. I wish that more researchers would get busy with this and speed up progress.

Last year Dr. Yamanaka and his colleague Kazutoshi Takahashi, both at Kyoto University, published a remarkable report relating how they had guessed at 24 genes that seemed responsible for maintaining pluripotency in mouse embryonic stem cells.

When they inserted all 24 genes into mouse skin cells, the cells showed signs of pluripotency. The Kyoto team then subtracted genes one by one until they had a set of four genes that were essential. The genes are inserted into viruses that infect the cell and become active as the virus replicates. The skin cell’s own copies of these genes are repressed since they would interfere with its function. “We were very surprised” that just four genes are sufficient to reprogram the skin cells, Dr. Yamanaka said.

OK, that's fair. Being surprised that so few genes are needed, and so the task is simpler than feared, makes sense.

An immediate issue is whether the technique can be reinvented for human cells. One problem is that the mice have to be interbred. Another is that the cells must be infected with the gene-carrying virus, which is not ideal for cells to be used in therapy. A third issue is that two of the genes in the recipe can cause cancer. Indeed 20 percent of Dr. Yamanaka’s mice died of the disease. Nonetheless, several biologists expressed confidence that all these difficulties will be sidestepped somehow.

“The technical problems seem approachable — I don’t see anyone running into a brick wall,” said Owen Witte, a stem cell biologist at the University of California, Los Angeles. In a Web cast about the research, Dr. Jaenisch predicted that the problems of adapting the technique to human cells will be solvable but he did not know when.

Faster, please.

I wonder where do the 4 genes come from that are needed to reprogram adult cells?

Update:

See this article about another paper on a related subject that had flawed data.

A University of Minnesota inquiry into the paper concluded earlier this year that the Nature figure was "significantly flawed," but there was no evidence that the mistakes were intentional. One outside adult stem cell researcher asked by the university to review the data believed the flawed data might weaken the conclusion of the paper somewhat, while another believed the findings were not affected.

Stem cell research has had a number of high profile scandals about data.

» Self Repair from University Update
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Tracked: June 6, 2007 04:16 PM