Human Exceptionalism

Beyond the Hype: Some Scientific Facts About Embryonic Stem Cells

Maureen Condic is a sterling scientist at the University of Utah, who advocates on behalf of ethical approaches to biotechnology. She bases her points in evidence and science, and in this piece in the current First Things, demolishes most of the perceived wisdom about the benefits of ESCR. It is a long article worth reading in full. Here is a preview of coming attractions in which Condic takes on the mantra “embryonic stem cells can become any cell in the body,” and points out that so far, researchers have been able to obtain little therapeutic benefit from ES cells even in mice:

“The assertion that embryonic stem cells in the laboratory can be induced to form all the cells comprising the mature human body has been repeated so often that it seems incontrovertibly true. What is missing from this assertion remains the simple fact that there is essentially no scientific evidence supporting it. Experiments have shown that embryonic stem cells are able to participate in normal embryonic development, an observation that is also true of cancerous embryonal carcinoma cells. When injected into early mouse embryos, both embryonic stem cells and embryonal carcinoma cells randomly contribute to every tissue of the developing body.

“Even more dramatically, when embryonic stem cells are injected into mouse embryos under specific experimental circumstances (a procedure known as tetraploid complementation), they can be induced to form all the cells of the postnatal body. These experiments prove that embryonic stem cells (and embryonal carcinoma cells) remain capable of responding appropriately to the developmental signals that regulate tissue formation in the embryo, and from these results we can conclude that if embryonic stem cells were intended to provide cell replacement therapies for embryos, they would represent a very promising therapeutic approach. The problem, of course, is that embryos are not the intended targets of stem cell therapies, and there is little reason to believe that the capabilities of embryonic stem cells in an embryonic environment are relevant to their therapeutic potential for non-embryonic patients.

When cells derived from embryonic stem cells are transplanted into adult animals, their most common fate is to die. Indeed, most such transplanted tissue does not survive beyond a few weeks in an adult environment (the only exception is blood cells, where small numbers of cells survive long term in mature animals). The rapid death of transplanted embryonic stem cell-derived cells stands in striking contrast to the robust survival of bona fide adult cells when transplanted to adult tissue. Typically, even the most promising experiments involving the transplant of embryonic stem cell derivatives have reported modest positive effects that persist for only a few weeks. In the few cases where tiny fractions of the transplanted cells survive for months (rather than weeks), this straggling band of survivors typically provides no therapeutic benefit.”

You won’t see any of that reported in the New York Times, which is why alternative media is so important.


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