Will advances in stem-cell research mean the birth of the biological
April 21, 2009
The latest advances in stem-cell research mean someone could some day
become a biological single parent, the source of both the egg and the
sperm needed to make a baby.
"In theory, a single individual could be both mother and father to a
child. The individual does not even have to be living if there is a
stored sample of their cells," the University of Alberta's Tim
Caulfield and his colleagues write in a paper in the journal Cell Stem
Their paper, The Challenge of Regulating Rapidly Changing Science:
Stem Cell Legislation in Canada, documents how the speed and
unpredictability of scientific advances in the stem-cell field pose a
challenge to policy makers.
For example, scientists in a number of countries are now able to turn
adult skin cells into stem cells. Once they have been reprogrammed,
these cells regain the superhero-like powers of embryonic stem cells
and can be turned into many of the specialized cells that make up the
human body, including blood, brain or muscle cells.
But what if some of the reprogrammed stem cells originally taken from
an individual were coaxed into becoming sperm, while others were
transformed into eggs?
It hasn't happened yet, but research suggests it is possible, Dr.
Egg and sperm created from stem cells from one person could be used to
create an embryo, which could then be transferred to the womb of the
mom-pop, or in the case of a pop-mom, a surrogate mother.
The result could be something "very strange and dangerous," warns
Shinya Yamanaka, the Japanese stem-cell pioneer who discovered how to
reprogram adult skin cells to stem cells. His breakthrough made
headlines around the world in 2007.
Dr. Yamanaka's work, recognized this year with a prestigious Gairdner
award, offered an alternative to research involving stem cells from
aborted fetuses, which some people find repugnant on moral or
But it also raised other troubling possibilities about where stem-cell
science could be heading, questions that both scientists and ethicists
are now considering. Should biological single parenthood be allowed if
it proves possible? What are the risks to a child created in this way?
Could skin cells from one child be used to create another son or
daughter? Could someone steal a skin cell from someone famous and have
It is a hot topic, Dr. Caulfield says, and an example of how it is
difficult to design legislation that keeps up with the unpredictable
advances in fields such as stem-cell research.
It is unclear, he and his colleagues say, if Canadian legislation
governing reproductive technologies and embryonic stem-cell research
would prohibit making sperm and egg from skin cells.
Canada's legislation bans the genetic altering of sperm or eggs.
Until last month, researchers reprogramming adult cells into stem
cells did so by inserting a number of key genes that orchestrated the
transformation to an embryonic-like state. That's a genetic
But now, Canadian scientists have found ways to get rid of any trace
of those genes - which can cause cancer - once they have done their
work. Is that a genetic alteration? Would it be covered by legislation
if a stem cell derived from an adult skin cell was turned into sperm
or egg? It might circumvent the ban, Dr. Caulfield and his colleagues
"It really shows how the approach of rigid rules and rigid legislation
inevitably isn't going to work," Dr. Caulfield says.
Canada has one of the most restrictive laws governing stem cell-
research of any pluralistic society with a wide mix of religious
beliefs - and non-beliefs.
He argues that it is better to have a clearly articulated set of
principles that a regulatory body could interpret as research moves in
A child created with egg and sperm derived from one person wouldn't be
a clone - or genetically identical to the parent - because of the
mixing and matching in the chromosomes that takes place when egg and
sperm are formed.
Researchers have made substantial progress in coaxing stem cells to
become sperm or eggs, work that could provide new treatment for
infertility but that also opens the door to biological single
In mammals, the primordial cells that become egg and sperm appear to
be the same. But some researchers argue it would be easier to make an
egg from a man's skin cell then to make sperm from a female skin cell.
That's because cells from a female wouldn't have a Y chromosome, which
may carry genes involved in the production of sperm.
In 2006, researchers at the University of Newcastle upon Tyne in
Britain reported that they had transformed human stem cells into what
are called primordial germ cells, which give rise to sperm or eggs. In
mice, sperm derived from stem cells produced live pups.
In China, researchers recently reported that they had generated eggs
from stem cells taken from the ovaries of mice.