Reading some of the comments from Pharyngula's link to our stem cell discussion I keep on seeing the same lie repeated over and over again. That is that adult stem cells, usually referring to hematopoietic stem cells, are equivalent to ES cells, or have equal or better potential for therapeutic treatments.

One thing is true, if you can find something that adult stem cells do well the therapies are more rapidly attained. After all, if you can purify the cells from the patient, or a relative, no major obstacles prevent you from putting them back into the same patient. However, this is missing the point. No one is saying there aren't some things adult stem cells would be good for, the problem is the lie that they are equivalent to ES cells. They simply are not. It is a simple fact, adult stem cells can not be differentiated into all tisses. ES cells, by definition are totipotent. That means they have the ability to make every single cell in the body. Adult stem cells are great at making one or several types of cells. Hematopoietic cells, for instance, are good at making all types of blood cells. However, they can't be made to make all other cell types. Now some reports have shown some transdifferentiation capacity, that is making cells of another lineage that they ordinarily wouldn't make, but it has been at low frequency, and in many cases was simply fusion of two different cells together.

Two papers of interest came out in the last week demonstrating this issue. One is a JCI editorial about the failure of adult stem cells from the bone marrow to treat myocardial infarction. Basically, the cells either did nothing and were eliminated within 72 hours, or worse, created new pacemakers, altering the conduction of the heart. These trials were rushed into, and appear to now be a flop. The other paper of interest comes to us from Developmental Cell in which the authors showed ES cells could make sperm that were capable of then fertilizing ova and generating mice. Now, the therapeutic implications of this are probably pretty limited, and the attempts so far haven't generated perfectly healthy, fertile offspring every time, but there is no question that this shows how much more powerful ES cells are than adult stem cells. There is no way you'd get hematopoietic stem cells to do this, or at least, never so easily. The ES cells made the sperm cells without any special treatment, they automatically differentiate into all cell types when aggregated (they added retinoic acid to push things more towards this lineage). The researchers purified out the cells of interest using a transfected reporter gene. It's that simple. The ES cells make everything automatically, it's just a matter of purifying out what you want. Adult stem cells have no where near this level of plasticity. The new cells purified from spermatogonial stem cells might be nearly as powerful, but that has yet to be proven (and only come from men).

All scientists who study stem cells would love to have a cell as powerful as ES cells that don't piss off the right wingers, it would make our lives easier for sure. It just hasn't happened yet. Maybe if the spermatogonial stem cells come through, but there needs to be years more study and success in finding a female equivalent before we should direct funding away from ES cells. Until then, the whole world will be ahead of the US in this field, which not only means we lose the best researchers, valuable patents, and potential cures. But also the US won't play a role in defining the ethical use of these cells. The scientists in other countries who develop these treatments will decide how they're used, and an unintentional side effect of the right-wingers ES cell ban will be they will lose all control over the ethical use of the cells.

I also hear that Bush might use his first veto ever to block the new Senate ES-Cell funding bill. Want proof that it is a lie to say adult stem cells have more potential than ES cell research? Here's Karl Rove:

"We were all an embryo at one point, and we ought to as a society be very careful about being callous about the wanton destruction of embryos, of life," Rove said. Recent research, he said, shows that researchers "have far more promise from adult stem cells than from embryonic stem cells."

Proof positive, biggest. lie. ever.