(March 22, 2009)
Stem Cell Research
Biological Pumps for All Sorts of Purposes:
Why There May Be No Difference Between
Stem Cell Therapies and Stem Cell Enhancements
For years, Dr. Clive Svendsen at the University of Wisconsin has sought
to use human stem cells as biological
pumps that can be implanted inside the human body where they will pump
out drugs to cure diseases. Svendsen is particularly interested in GDNF
– a neurotrophic chemical that may help prevent or slow the degeneration
of neurons – for dealing with diseases like Parkinson’s or ALS.
Now, Dr. Charles Murtaugh at the University of Utah has entered
the game. Just as Svendsen wants to insert stem cells into the brain
or muscle to produce GDNF, Murtaugh wants to insert stem cells into the
pancreas to produce insulin so diabetes sufferers will no longer have to
carry around mechanical pumps. The pumps will be inside, instead, using
the body’s resources to operate as little biological engines.
This would solve at least one of the challenges facing other approaches
to creating insulin producing cells. A team led by Dr. Lawrence Chan at
Baylor recently used genetic engineering techniques to
transform liver cells into insulin producers in mice. The problem: they
used gene therapy via a retrovirus to change the cells, a technique that
has occasionally resulted in death when tested in humans. Dr. Murtaugh’s
approach would get around the problem by genetically engineering the stem
cells outside the body and then re-implanting them.
The idea of biological pumps is one of the more exciting ideas floating
around in stem cell land, because you could potentially use them for just
about any drug that can be coded for by DNA. So long as you can insert the
gene for the protein in question into the stem cell, it will produce whatever
protein you want. But I want to use them here to raise a second point.
Stem-cell-based biological pumps are an excellent example of the argument
that there is very little difference in terms of skills and instrumentation
required for medical therapies and for other, non-medical purposes in the
realm of stem cells. Once Svendsen has developed a genetically modified
neural stem cell capable of producing GDNF after being successfully implanted
in the human brain, there is essentially no barrier to using the same technology
to permanently implant stem cells in the brain capable of generating other
DNA-derivable proteins that aren’t related to disease.
This raises a fundamental challenge to the logic under which stem cells
currently are being sold. Stem cell research, according to the arguments
put forward by researchers and the Obama Administration, is all about curing
diseases. On the other hand, if stem cell techniques can be used for purposes
other than medical therapies, then we enter into a much more complex moral,
ethical and policy terrain. The question then becomes: to what ends should
we put stem cells?
In recent decades, courts in various parts of the United States required
that recidivist criminals be implanted with Norplant, in certain cases,
in order to ensure they would have no more children. Prisons reportedly
use mental health drugs to maintain docile prison populations. What would
a state bent on ensuring social order do with the capacity to permanently
alter people’s internal body chemistry in ways that suited the state’s purposes?
What would a society bent on ensuring its own safety insist that the state
do? What might individuals seeking better athletic or cognitive performance
be willing to buy if it were sold? And if we can do it, how would we prevent
it from being sold, somewhere in the world?
I have not yet been convinced that this observation is sufficient to call
for halting all stem cell use. The medical benefits of stem cells may turn
out to be significant (if, as Michael Crow, ASU president, observes in the
Spring 2009 Issues
in Science and Technology, we can figure out how to better link
health research to health outcomes).
What I do suggest, however, is that we begin a public dialogue today about
the proper ends to which we put stem cells.
For additional Soapbox posts, click here!
