Final Report (all chapters)

exclusively for the purpose it was developed for, an assumption obviously not supported by the
history of science and medicine.
A far more consequential research protocol involving the production of sperm was reported
from Japan in 2003. 73 In this experiment, the Japanese researchers cultivated embryonic stem
cells in a culture known to stimulate the growth of sperm. They then took these cells and
implanted them in mice testes, where apparently they fully developed into sperm. The
researchers retrieved the sperm and fertilized mice eggs, which began to divide.
According to the Japanese researcher, the study should improve our understanding of
embryonic development. The scientists were not secretive about what this generic statement may
mean. Their goal, according to one news story, was to enhance our ability to engineer sperm –
i.e., to produce artificial sperm based on specific genetic criteria. This could become possible
because, as the researchers pointed out, scientists already know how to insert genes into stem
cells.
Engineering sperm? Perhaps the Japanese scientist was simply naïve; or perhaps he
sincerely believed that engineering sperm is a research proposition as legitimate and
unproblematic as any other. Whatever the case may be, the view that human sperm could in the
not-too-distant future be genetically engineered to meet specific parental desires is qualitatively
different from the kind of rationales offered by scientists involved in potentially controversial
medical research. Whether there may be reasons good enough to justify engineering sperm
remains to be seen, but this question certainly cannot be decided by the scientific community
alone. 74
A more advanced version of the Japanese experiment was conducted by Harvard University
scientists in 2003. 75 In this case, the scientists were able to grow sperm cell precursors entirely in
a lab dish; implantation in testes was not necessary. They then injected these sperm-like cells
into a mouse egg cell. In some cases, the fertilized egg developed into an early-stage embryo, or
blastocyst. The scientists then tried to impregnate a mouse, without success. The Harvard group
is now replicating these results in human embryonic stem cells. The researchers were careful to
emphasize the scientific nature of their experiment and explicitly downplayed the possibility of
developing cures for male infertility. In essence, this method for producing sperm cell precursors
allows scientists to study imprinting, the process that regulates which genes are turned on or off
during embryo development, depending on whether they are inherited from the mother or the
73
74
75
Stem Cells Stimulated to Be Sperm (Associated Press, September 15, 2003 [cited August 2, 2005]); available
from http://www.wired.com/news/medtech/0,1286,60454,00.html; Rick Weiss, "Sperm Made from Stem Cells:
Development in Mice Raises Issues for Human Reproduction," Washington Post, September 16, 2003.
That this research was conducted at a privately funded university only underscores the need for public oversight.
Josh Chamot and Leslie Fink, Researchers Engineer Mouse Embryonic Stem Cells to Form Sperm Cell
Precursors (National Science Foundation, Office of Legislative and Public Affairs, December 10, 2003 [cited
August 3, 2005]); available from http://www.nsf.gov/od/lpa/news/03/pr03142.htm; Sylvia Pagàn Westphal,
"Stem Cells Can Become 'Normal Sperm'," New Scientist, May 7, 2003; Gretchen Vogel, "Embryonic Stem
Cells: Scientists Make Sperm in a Dish," Science 302, no. 5652 (2003).
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