By Hilary White

MARCH 11, 2009 ( – A new method of creating embryonic-like stem cells from ordinary skin cells is being lauded as the solution to the embryo research problem, but one prominent bioethicist has cautioned that there may still be unseen ethical problems and is urging caution.

Two teams of researchers, in Britain and Canada, have devised what they say is a safer technique for reprogramming adult cells so that they become “pluripotent” stem cells – those that can be changed into most of the tissue types of the human body. Published in the latest edition of the journal Nature, the work is described as the next phase of the discovery made in 2007 by Shinya Yamanaka of Kyoto University that created “embryonic-like” induced pluripotent stem (iPS) cells.

Dianne Irving, a former bench biochemist with the NIH and bioethics expert at Georgetown University, told that there must be caution among pro-life advocates in endorsing the work. “If it can be shown that the research is truly accurately performed and does not involve the use of embryo DNA or foetal material at any stage, then it should be at least given a chance,” Dr. Irving said.

But she warned, “The human studies reported so far have all used human embryos or human fetuses as sources of materials for cell culture, for genes that are transferred, and for assays, as well as for the original cells that are transformed.

“No test is reported to determine if totipotent cells (which could be newly formed human embryos) are inadvertently formed while producing iPS cells, and any damage to the original cell’s DNA or any left-over foreign DNA would surely cause serious immune rejection reactions in the patients.”

The first breakthrough procedure that created iPS cells used a virus to reprogram the DNA of the cell, but researchers were concerned that this method could have increased the risk of the cells becoming cancerous. The new method uses a DNA sequence, called a transposon, a mobile piece of DNA referred to as a “jumping gene,” that can extract the cell’s DNA and transform it into what the researchers have identified as a pluripotent stem cell. Tested successfully on mouse and human skin cells, the reprogrammed cell lines show they reproduced the behaviour of embryonic stem cells.

In November 2007, Dr. Shinya Yamanaka of Kyoto University and Dr. James Thomson at the University of Wisconsin published back-to-back studies that were widely hailed as moral alternatives to embryonic stem cell research.

A lead researcher in the work, Dr. Keisuke Kaji, of the MRC Centre for Regenerative Medicine at the University of Edinburgh, said, “I was very excited when I found stem cell-like cells in my culture dishes. Nobody, including me, thought it was really possible.”

Andras Nagy, Ph.D., of Mount Sinai Hospital in Toronto, said, “Using our method, it will be possible to remove not only the inserted genes, but all traces of our genetic modification from the human (pluripotent) cells, although we still need to improve the efficiency.”

The ethical problems, Irving said, could lie in the source of the genetic material being used to reprogram the adult cells to become iPS stem cells. She warned that the published research should be examined carefully before being endorsed as “ethical” by pro-life advocates.

In general, she said, the normal course of such research uses materials derived from aborted foetuses or from living embryos, which could not be endorsed by pro-life people. “Usually the procedure involved in creating iPS cells also requires the use of media or the use of culture cells that are also derived from human embryos and/or human fetuses.

“Often tests are performed on the resulting iPS cells using ‘DNA chips’, which contain human genes originally derived from human embryos and human foetuses. So it is important to analyze the ‘materials and methods’ section of the research study to determine if any human embryos or human fetuses were used and destroyed as the source of materials used.”

In addition, she cautioned that should the cells created be shown to be “totipotent” instead of “pluripotent”, it could mean that the process creates not embryo-like iPS cells, but entirely new, living and developing embryonic human individuals.

When Yamanaka and Thompson made the iPS breakthrough in 2007, much of the news media reported that it would mean an end of the use of embryos in stem cell research. But Dr. Thomson himself admitted that embryos had been instrumental to the advancement of his work.

He told MSNBC, “In our research, we actually used human embryonic stem cells as part of the screening process. So the research itself on human embryonic stem cells led to the next finding about pluripotent cells.”

“Just like Dolly was our inspiration to do the screening in the first place, we could not have successfully done the screening without the existence of human embryonic stem cells.”

“The Japanese group,” he said, “used four genetic factors in mice. They had tried the same [mouse] embryonic stem cell culture with human material and it didn’t work. Then they used human embryonic stem cell conditions that had been developed at my lab and other labs.”

Other stem cell researchers have admitted in their publications that such research often uses genes, those inserted into the adult cells, derived from human embryos or human foetuses.

Read related coverage:

New “Ethical” Embryonic Stem Cell Method Could Be Used to Create Humans