The technical obstacles will probably be overcome before
the legal ones. That’s because, Saitou’s misgivings notwithstanding, there is now a race on to perfect a laboratory method
for making human eggs. Saitou admitted he’s now in a “not
so enjoyable” competition with his old mentor, Azim Surani
of the University of Cambridge, to be the first to work out the
recipe. Hayashi, his former student, now at the University of
Kyushu, is also in the race. If any of them do perfect it, other
researchers might not be so hesitant to use it in an IVF clinic.
When I asked Hayashi, the younger of the two Japanese
scientists, how long it would take to master making human
gametes, he said 10 or 20 years. “How soon is the most di;cult
question, because I am doing the experiments and they are not
easy. I don’t want to be a liar and say five years,” he says. “Five
years later someone might blame me.”
Scientists can already coax iPS cells to form primitive
reproductive cells, like those made from B.D.’s tissue inside
a mouse. What’s still unsolved is how to take the final step of
turning those cells into functional sperm or eggs. In humans,
that process isn’t fully completed until puberty. With their
mice, Saitou and Hayashi tricked the iPS cells by placing
them inside a simulated ovary that they constructed out of tis-
sue harvested from fetal mice. Crafting such an incubator out
of human fetal cells isn’t practical because they are hard to
obtain. Instead, Saitou believes, he will need to manufacture
the supporting tissue from iPS cells as well. That additional
challenge could delay conclusion of the experiment.
If they do make human eggs or sperm, scientists would hit
another roadblock. That is because the only way to prove these
cells are the real thing would be to create a human o;spring.
Right now, that’s a step the Japanese scientists aren’t willing or
ready to consider.
Instead, to demonstrate this final step, Hayashi and Saitou
are also working with monkeys. Closely related to humans, the
animals will be a good model for demonstrating whether their
technology “is safe in a primate,” according to Hayashi. “What
we need to prove is that we can make nice, good-quality eggs.
For that we need to demonstrate o;spring,” he says.
Commercial interest is starting to swirl around the scientists. During my conversation with Hayashi, we were joined
by Hardy Kagimoto, the CEO of a Japanese biotech company called Healios that is seeking to turn iPS cells into a
treatment for blindness. Kagimoto also hopes to team with
Hayashi to explore lab-made human gametes. He said a
group of IVF doctors who operate a global network of clinics
was interested as well. “A big thing is happening, and soci-
“I don’t view something like in vitro
gametogenesis as something
scary. I see a group of people that