ShareThisA new film imagines lesbians conceiving with sperm derived from each other's stem cells -- and the science may not be far-fetched.
In the new Canadian film "The Baby Formula," two lesbians become pregnant using sperm derived from each other's stem cells.
The premise of the "mockumentary" may be fictional, but with the speed at which stem cell research is evolving, could same-sex human reproduction one day become reality? And should it?
Scientists already have taken the first baby steps toward realizing this brave new -- and controversial -- world of conception.
Stem cells are like the body's blueprint, giving rise to all the different cells that make up an organism, from skin to the brain, bone and blood. Harnessing them as factories to produce specialized cells to repair or regrow tissues is regenerative medicine's great hope.
In 2006, Karim Nayernia of Newcastle University generated sperm from male embryonic stem cells that fertilized female mice and produced offspring. A year later, the stem cell biologist and his team derived primitive sperm from stem cells taken from the bone marrow of human men.
Since then, Nayernia's group has been working to create sperm from women's bone marrow stem cells. It's expected to report its findings within weeks.
"We are now publishing a paper describing the producing of human sperm in the laboratory," says Nayernia, chair of the university's Stem Cell Biology Institute of Human Genetics. "It is male, but we have had some success with female."
Nayernia cites several reasons to pursue research on lab-based sperm: to help scientists better understand the genetics of these "germ" cells and to devise a safe means of testing how they are affected by environmental toxins and drugs.
Artificially derived sperm and eggs also could help researchers look for ways to protect the fertility of men and women undergoing cancer treatments, he says.
As for the idea of a woman's stem cells giving rise to sperm that could be used to fertilize another woman's egg, "scientifically, in principle, it is possible," Nayernia says.
But Toronto stem cell scientist Andras Nagy isn't so sure.
There would be several biological hurdles, Nagy says.
First, women's DNA contains two X chromosomes, but no Y (male) chromosome. "Without the Y chromosome, it's just simply not possible," Nagy says. "The other issue here is that ... the presence of two X chromosomes in a cell again (blocks) the sperm formation."
Germ cells must be able to undergo meiosis - the process of cell division that leads to sperm and eggs having just one set of 23 chromosomes, rather than pairs adding to 46, as found in all other cells. It's not clear whether sperm coaxed from female stem cells could do that.
"So ... as far as the biology is concerned, that film is based on fiction," Nagy says of "The Baby Formula."
Leaving aside the notion of same-sex reproduction, there are some "legitimate scientific reasons" why researchers would want to create both human sperm and eggs from stem cells, says Tim Caulfield, a University of Alberta professor of health science and law.
The technology would yield an unlimited supply of eggs and sperm for study, he says. At a practical level, it could allow infertile couples to produce offspring containing their own genetic material.
"They could use the technology to grow sperm and eggs, and then they could have kids," Caulfield says.
Being able to produce numerous eggs and sperm in the lab would also make it easier for couples at risk of passing on genetic mutations, such as those that cause Tay-Sachs or Huntington's disease, and to test embryos before implantation.
The ability to create eggs from stem cells also may allow a woman to conceive at a later age, when her natural supply has run out, he says.
What of the ethics of bypassing the usual means of making babies?
"The biggest hurdle, I think, is how are you going to test this technology?" Caulfield says. "At some point, you're actually going to have to start creating embryos."
Those embryos would have to be allowed to develop to a certain point to determine whether they were healthy and did not contain genetic abnormalities linked to mode of conception, he says.
In Canada, any discussion about spawning life with stem cell-generated sperm or eggs is moot. Current laws do not allow scientists to produce embryos by any means for research purposes.
Still, the mere idea of lesbian couples (or gay men using a surrogate mother) having a baby with their own genetic material is sure to horrify some people.
As the religious mother of one of the women in "The Baby Formula" says: "Who do you think you are, God?"
Nagy says "The Baby Formula" contains an important social message, even if the premise is fictional.
Stem cell research will push the boundaries of what is biologically possible, presenting society with a host of ethical challenges, he says. "It's a very, very rapidly changing world and we really have to be aware of that."
(Distributed by Scripps Howard News Service, www.scrippsnews.com.)
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