Japanese researchers have found a way to turn
mouse embryonic stem cells into sperm. A Kyoto University team coaxed mouse ESCs
into sperm precursors, called primordial germ cells (PGCs), and showed that these
cells can in turn give rise to healthy sperm.
When transplanted into mice that were unable to produce
sperm normally, the stem cell derived PGCs produced normal-looking sperm, which
were then used to successfully fertilize eggs. These fertilized eggs, when transplanted
into a recipient mother, produced healthy offspring that grew into fertile male
and female adult mice. The same procedure could produce fertile offspring from induced
pluripotent stem cells that are often derived from adult skin cells.
A number of research teams have created PGCs in the
past, but no healthy offspring have ever resulted.
Fertility expert Dr Allan
Pacey, of the University of Sheffield, told the London Telegraph: "This is quite a step forward in developing
a process by which sperm could be made for infertile men, perhaps by taking as a
starting point a cell from their skin or from something like bone marrow. Clearly
more work needs to be done to refine this process, but it's hugely exciting."
Already some research teams are trying to create sperm and eggs from induced
pluripotent stem cells. This would make it possible for gay couples to have children
who are genetically their own. Some progress has been made towards this headline-grabbing
goal. Last year scientists at M.D. Anderson Cancer Center in Houston produced male and female mice from two fathers using iPS cells.
The technique is too complicated to be practical but the potential for ethical controversy
is enormous. As ethicist Insoo Hyun, of Case Western Resrve University, noted some
time ago (Hastings Center Report, Jan-Feb 2008), “This fact could radically alter our commonsense
notions of human fertility and infertility.” ~ The Scientist, Aug 4; Science Daily, Aug 4