VATICAN CITY, April 23, 2013 ( – One of the top researchers in the field of stem cells has said that iPS (induced pluripotent) stem cells, the “embryo-like” cells hailed by many as the answer to the ethical problems presented by embryonic stem cells, are “probably” actually already embryos and have already, with the right conditions and treatment in the lab, developed into “complete animals” in experiments.

The revelation that some iPS cells are indistinguishable from single-cell embryos is likely to dismantle arguments supporting the cells as “ethical.”

In a surprise statement in his keynote address at the conference co-sponsored by the Vatican, Dr. John Gurdon, a pioneer in nuclear transfer cloning techniques, said that with iPS cells created from adult skin cells, “You can actually get a totally normal, reproducing, adult animal from a skin cell without the use of an egg.” 


He said it is possible to derive “a complete animal” from the cells. This is not theoretical, he added, but has already been done with mice.  

Speaking to after the lecture, Dr. Gurdon agreed that the possibility of creating whole organisms from a single skin cell “is quite remarkable.” Asked what the difference is between an iPS cell that has been reverted back to its pluripotent state and an embryo in its earliest, single-cell stage, Gurdon replied, “Probably none.”

“But it’s always difficult to prove,” he added. 

At the time of their discovery in 2007, iPS cells were hailed by both the research community and many in the pro-life world as a solution to the problem of obtaining pluripotent cells – those capable of producing all the tissue types of the body – without destroying human embryos. In 2012 Dr. Gurdon and Japanese scientist Shinya Yamanaka were jointly awarded the Nobel Prize in medicine for their work surrounding the development of iPS cells. 

Since their discovery, however, some ethicists have warned of various problems with iPS cells, including the fact that cells derived from embryos have been used in the process of creating the iPS cells. Some also warned that iPS cells could give rise to complete organisms and are, in fact, indistinguishable from embryonic cells that can be induced to begin replication as whole embryos. According to his own papers, Yamanaka said that some of the cells obtained through his process are “pluripotent,” while some are “totipotent,” which means they can spontaneously become embryos and start to develop into a mature organism. spoke with Dr. Dianne Irving, a former bench biochemist researcher with the National Institutes of Health in the US, who confirmed Dr. Gurdon’s assertion, saying, “Some iPS cell are potentially embryos.

Yamanaka himself stated in his research paper that in a test in the lab for signs of pluripotency, some of the iPS cells obtained “tested positive for embryonic antigens, not for pluripotent antigens,” explained Irving.

“Those were embryos,” she added. “So according to that assay some of the iPS cells are already embryos. Most of them are not, but have the potential to be reverted back.”

Some of the procedures used to create iPS cells, Irving continued, “take the DNA back too far, and end up with a new single cell embryo or a totipotent, rather than pluripotent cell, one that has the capacity to revert back to a new embryo”.

Irving described the process of “regulation,” a natural part of the embryo’s genetic systems, which automatically reacts to changes in an embryonic cell to correct genetic damage and reassert the direction of development to produce a whole embryo with the normal complement of 46 chromosomes. This process can also revert the DNA in a separated totipotent cell to what it needs to function as an embryo rather than just a “cell.”

“It may not be well known or understood in the public,” Irving said, “but in the scientific research community, it is well known that sometimes a pluripotent iPS cell could, through this process of regulation, spontaneously revert to being totipotent, which can then become an embryo.” 

“This has long been documented in the scientific literature. It’s not new,” she added.

In his lecture, Gurdon said, “You know from nuclear transfer that you can take the body [somatic] cell and it will be completely perfect. It makes a normal adult animal, and it will be completely reproductive, male and female and everything. So it can work perfectly. But it doesn’t all the time.”

“The more specialised the cell is, the harder it is to reverse it back. And we want to know why. But it’s definitely possible,” he added. 

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He said that theoretically it is possible to do this type of cloning with human materials. “That should be perfectly possible, if you’re allowed to do it.”

Irving noted that, looking at Yamanaka’s research papers, several of the procedures involved in creating iPS cells, as well as other adult stem cell techniques, should give pro-life people serious pause. Given the ability of cells to be reverted to the embryonic stage, she said, “any human cell can be used for reproductive purposes,” so pro-life people must start making very careful distinctions about what type of cell is being created and used and the methods used to obtain them. 

As well, she said, some tests for “full pluripotency” used in the process of iPS cell creation, called “tetraploid complementation” – called the TC Assay – require that at least two embryos be killed. Some of the materials used in creating or testing iPS cells, Irving said, “require bits and pieces of embryos for assay controls and culture media, and feeder cells that are usually fetal.” 

On iPS cells by themselves, Irving was adamant: “A totipotent cell can mean a stage one embryo, or it can also mean one of the [totipotent] cells from an eight cell embryo. The first is an embryo, the second is not one yet, but has the natural capacity to revert back to an embryo.” 

LSN also asked Dr. Gurdon if the advances of adult stem cells, which are becoming increasingly commonly used in human therapeutic applications, could have been possible without the preliminary work with embryonic stem cells. Gurdon replied, “It could have been, but it usually doesn’t work that way. Usually you have to get some idea that something is worth trying.” 

Embryo research, he said, “started a long time ahead” of adult stem cell research. “And that showed the fundamental principle of reversing everything [in the cell’s DNA] backwards does work. It was thought at the time it wouldn’t. 

“People felt that as cells become mature they would not go backwards and that was why that was important, because it [embryo research] showed, surprisingly, that you can make the cells go backwards. All the way back to the embryo.” 

These discoveries with embryos, he said, brought scientists to ask the question about what other types of cells could be reverted back to their pre-differentiated state.

Touching only briefly in his lecture on the subject of human cloning, Gurdon made another surprising statement, saying that human cloning by nuclear transfer has never worked, though he said that no one knows why. Gurdon himself has never experimented with human cloning, but he said in theory the technique should be the same as with frogs.

The process of injecting a fully formed nucleus, one with a full complement of genes, into an enucleated ovum, can be done successfully with frogs and many mammals, including monkeys, but not on humans. Simply implanting a nucleus into the cytoplasm of the ovum without any of the genetic material from the mother does not work, he said. 

Thus far, he said, “human nuclear transfer” experiments have failed to produce viable embryos. “It works very well for monkeys,” but on humans it “does not succeed without the participation of the egg chromosomes.” The embryo dies. “That’s always the outcome”.

Transfer cloning in humans requires the presence of the nucleus of the ovum as well as the second nucleus from another cell, “then the embryo is able to develop”. 

“What this means,” he said, “is that with the particular race of humans, you have to have the egg chromosomes present as well as an incoming nucleus from a somatic cell to get any normal development.” 

“That’s somewhat surprising,” he added, but said “it almost has to be a matter of time before someone discovers how to make that experiment work for humans, as it does for monkeys.” 

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