Wednesday, November 21, 2007

More on Stem Cell Developments

As I reported yesterday, there is a significant new development in stem cell research--the fact that skin cells can be used to creat stem cells. Much of the interest in this story is that it suggests that we need no longer research embryonic stems cells, and thus the bioethical problems are over. It is also offered as vindication of President Bush's policies on stem cell research.

Well, the science bloggers have had time to reflect on the developments. While they agree that this is a significant scientific development worthy of front page coverage, they also caution that it does not solve the bioethical issues. Why? As PZ Myers explains, one reason is that while this new tehcnique is great for stem cell research, it has severe limitations in therapeutic uses:

Another essential point is that scientists are excited about this work because it opens up avenues for basic research into development and differentiation. These cells are NOT useable for therapies…the immediate, practical applications that the electorate wants from stem cell research. They also cannot be used for reproductive cloning, although that won't trouble most people. These are cells with retroviral infections, potential unknown mutations, and that have genetic modifications that make them prone to collapse into cancers. We are not going to be able to grow new organs and tissues for human beings from a few skin cells using this particular technique. It's going to take more work on embryonic stem cells to figure out how to take any cell from your body, and cleanly and elegantly switch it to a stem cell state that can be molded into any organ you need. What this work says is that yes, we'll be able to do that, it isn't going to be that difficult, and that we ought to be supporting more stem cell research right now so we can work out the details.

Read it all here.

Mark Hoofnagle is a MD/PhD Candidate in the Department of Molecular Physiology and Biological Physics at the University of Virginia, elaborates on this issue:

So what are the remaining problems? The most critical is, of course, the use of retroviruses to transduce the cells. The problem is that previous attempts to use these vectors in humans, to treat severe-combined immunodeficiency (bubble boys), resulted in an unacceptable rate of oncogenic transformation of the treated cells causing the FDA to stop the trials. The kids got leukemias. This is terrible. The reason is that the retroviruses incorporate their genomes into ours. The advantage of this is that the genes are permanently expressed - long enough to transform the cells and maintain them until they are differentiated. The draw back is that the retroviruses prefer to insert themselves randomly in the genome in areas that are transcriptionally active. The result is that the transgenic promoters - powerful viral sequences that drive gene expression - may get stuck next to an oncogene, that can then cause cancer. Or cause epigenetic changes in the region of an oncogene that should be silenced. Or even interrupt a tumor-suppressor gene. All very bad outcomes that have been shown to cause cancer in humans using these vectors.

Mark also disputes the argument that this shows that embryonic stem cell research was unnecessary or that it can now be stoped:

Finally, as far as the anti-ESC types are concerned, they should not consider this a victory for their anti-science agenda or the policies of George Bush. First, these discoveries would not have been possible without ESC research. I also believe these cells would have been discovered in the same amount of time, with or without the political interference in science. Not only because somatic cell reprogramming was hotly studied long before this became a political issue but also because they represent an ideal stem cell - one that can be genetically matched to the donor, yet is still pluripotent. SCNT has been an incredibly difficult technology to make practical, as human eggs are difficult to obtain, and the process is very inefficient. We've also lost valuable years of study of pluripotent human stem cells in this idiotic debate, that would directly translate to our understanding of how to apply these cells in studies of disease and for clinical practice.

Read it all here.

PZ Myers agrees:

This discovery is probably going to become a political football in short order, with the far right politicians who have restricted American research into embryonic stem cells claiming vindication. However, let's point out some realities here. Americans did not make this discovery; Japanese researchers did. It required understanding of gene expression in embryonic stem cells, an understanding that was hampered in our country. It's going to require much more confirmation and comparison between the induced pluripotent stem cells and embryonic stem cells as part of the process of making this technique useful — science doesn't take just one result from a few labs and accept it as gospel truth. And we definitely need to figure out better ways of switching the four genes on. Figuring that out will require more research into how organisms switch cells into the ES state in situ &mdash we can't figure that out from these cells with inserted, artificial gene constructs.

And for those of you looking for some theology, at least one science blogger attempts to argue that this development argues against conception as the critical point for the development of the soul. Alex Palazzo,a postdoctoral fellow working in the Department of Cell Biology at Harvard Medical School argues:

One of the biggest implications of this research is this: the whole idea that a "soul" is created upon conception is not a tenable view anymore. Lets look at the facts - you can take any skin cell, turn on four genes and *presto* you get a cell that can potentially make a new organism, with its own brain, its own mind and its own "soul". Conception is not required to make a soul. This new person will be one of us and even if he or she has teratomas, he/she will feel, love, hate, cry and laugh just like any other member of our species. It is probable that one day the cells that we created by the activation of four genes will be indistinguishable from the cells from a blastocyst. So how can religious conservatives champion one line of research and not another? How can religious conservatives think that one clump of cells have a soul and the other doesn't? It just doesn't add up.

Let me rephrase this ... If we can create IPS cells then it means that a "soul" can be created without conception

Read it all here.

The bottomline? this is a very significant development, and it may indeed result in the development of stem cell technologies that do not require the use of human embryos. But, that development is still many years away. Perhaps more fundamentally, we need to think through the theological and ethical implications of all of this research and ask, like Alex does, whether one set of techniques really is ethically different than the other.

1 comment:

Peter Carey said...


In the small world department, Mark's sister in law was a classmate of mine at VTS...pretty funny,

Happy Thanksgiving!