No human embryos created or destroyed: Embryonic Stem Cells Created from Skin Cell
Dave Andrusko

The latest chapter in the stem cell saga comes from researchers Chad A. Cowan, Kevin Eggan, Douglas Melton, and Jocelyn Atienza at the Harvard Stem Cell Institute. They have created embryonic stem cells without using human ova or creating new embryos by fusing an adult skin cell with an existing line of embryonic stem cells. If proven to work, the technique would appear to circumvent lethally harvesting stem cells from human embryos.

However, while the research has received a great deal of attention, there are several important considerations.

First, there are other more promising sources, including, in particular, stem cells from umbilical cord blood. (See below.) These “adult” stem cells (meaning non-embryonic) already have proven therapeutic track records.

Second, the same team at Harvard suggested in a conference call with reporters that if they can figure out what coaxes adult stem cells to revert to embryonic stem cells, they might avert altogether the use of existing embryonic stem cell lines.

And, third, before such hybrid cells could be transplanted, the leftover DNA from the original “starter” embryonic stem cell needs to be removed. There is research in that area current being undertaken in a number of labs.

As reported in the journal Science, the Harvard Stem Cell Institute researchers fused ordinary skin cells with already existing embryonic stem cell colonies. Something (yet to be determined) in the stem cells “reprogrammed” the adult cell’s genes so thoroughly that the skin cell itself was turned into an embryonic stem cell. As Harvard News Service put it, the embryonic cells “reset the genetic clock of the adult cells, turning them back to their embryonic form.”

“Since the new stem cells in this technique are essentially rejuvenated versions of a person’s own skin cells, the DNA in those new stem cells matches the DNA of the person who provided the skin cells,” wrote the Washington Post’s Rick Weiss. “In theory at least, that means that any tissues grown from those newly minted stem cells could be transplanted into the person to treat a disease without much risk that they would be rejected, because they would constitute an exact genetic match.”

At this stage, any remedial properties these hybrid embryonic stem cells might provide remain strictly hypothetical. As Weiss observed, “Researchers caution, however, that like many other nascent therapies that initially seemed promising, stem cells may never live up to their promise.”

So where does this announcement fit into the larger discussion? The general idea offered by proponents is that stem cells from human embryos are like all-purpose repair kits that would replace injured or diseased body parts. This all too easily transitions into speculation that they could be a cure for Parkinson’s, diabetes, and a myriad of other diseases.

However, if the stem cells are, so to speak, off the rack (from so-called “spare embryos” from fertility clinics, or from an aborted baby), there are a number of problems—beginning with the recipient’s immune system which will attack foreign tissue. Thus, the push for “tailor made” stem cells, created by cloning an embryo and then harvesting the clone’s stem cells. Most newspaper accounts emphasized that the Harvard approach seems to sidestep this “controversial” practice.

There are considerable problems yet to be worked out. As mentioned, while the newly minted hybrid has all the characteristics of a new embryonic stem cell, it possesses two sets of DNA, or genes.

One is the DNA of the embryonic starter cell, and the other is the DNA of the person who donated the skin cell. To take the next step—to try to persuade these hybrid cells to grow into replacement components which would then be transplanted—the extra DNA from the original stem cell would need to be removed.

While the Harvard team describes this task as a “substantial technical barrier,” Weiss reported that “several teams, including ones in Illinois and Australia, have said in recent interviews that they are making progress removing stem cell DNA from such hybrid cells.”

In a conference call with reporters, Eggan offered this intriguing possibility: “If one could just simply understand how that process works, termed reprogramming, one might be able to directly turn adult cells into embryonic stem cells without an embryo or an egg.”

One other (among many) interesting considerations. Many critics complain that the cell lines which were in existence prior to August 2001—the only ones that can be used if federal dollars are to underwrite the research—are “old” and/or genetically flawed.

But if the Harvard research pans out, the newly created stem cells would possess the perfectly normal genetic makeup of the adult skin cell that was fused with the original embryonic stem cell.

To be sure, all this remains highly speculative. And, more to the point, the fascination with embryonic stem cells takes our eye off the ball—the extraordinary success to date using adult stem cells.

As Dr. David Prentice has written, “At least a dozen studies now show adult stem cells from bone marrow, umbilical cord blood, and placenta have the flexibility of embryonic stem cells, but without the scientific or ethical problems. And adult stem cells have already claimed success in treating at least 65 different human diseases.”

In fact, the potential to treat disease with stem cells from umbilical cord blood seems to grow almost monthly. Recently, a team discovered “primitive cells with clinical potential matching that of the far more controversial embryonic stem cells,” according to New Science. Dubbed “cord-blood-derived embryonic-like stem cells,” CBEs can be saved, banked, and multiplied without killing any human embryos.

“And with more and more ‘banks’ around the world for saving cord blood, the potential for finding tissue matches for every patient becomes more and more realistic,” according to New Science.

Meanwhile, there has been no success in humans using embryonic stem cells.