What If Your Ovaries Could Live Forever?S

The world, and especially our mother, never tires of telling us that our biological clocks are ticking. We'd better have those babies sooner rather than later because we're running out of eggs, they say relentlessly. And there's a pretty good reason: Unlike our male counterparts, who produce sperm until they're old and grey, a woman's fertility declines irreversibly with age, until it finally dies all together when we hit menopause. But some new research has found that our ovaries have stem cells that are capable of being harvested and turned into eggs in a lab. This amazing little discovery has the potential to change how we see the limits of women's fertility—and maybe shut our mothers up for at least a few years.

The promising research, led by Jonathan Tilly, a reproductive biologist at Massachusetts General Hospital in Boston, found that it was possible to isolate stem cells found in small quantities in women's ovaries and then turn them into normal egg cells, or oocytes. Tilly first started researching this subject a decade ago, when he began to think that mice had egg-producing stem cells in their ovaries. After Tilly's initial research, Chinese scientists were able to isolate these stem cells from adult mice in 2009. They cultured them in the lab and transplanted them into mice ovaries. Amazingly, they resulted in normal offspring. Tilly built on the technique the Chinese group was using and began trying to do the same thing with human ovarian stem cells.

As you might imagine, in the U.S. it's difficult to just start harvesting people's ovarian tissue. But he eventually got some from patients in Japan who were having sex-reassignment surgery and volunteered to donate theirs. From that tissue, he was able to isolate the stem cells, which were scattered on the outer part of the ovary mixed in with millions of other cells. He cultured them in the lab, and they turned into eggs, which appeared normal. It's like magic.

Ideally, Tilly's next move would be to attempt to turn the eggs into embryos by fertilizing them—though that brings with it a whole host of ethical and legal challenges. Nevertheless, even this discovery alters our ideas on the limits of female fertility. As Tilly told Nature Medicine, where he published his research, these stem cells change everything:

The discovery of oocyte precursor cells in adult human ovaries, coupled with the fact that these cells share the same characteristic features of their mouse counterparts that produce fully functional eggs, opens the door for development of unprecedented technologies to overcome infertility in women and perhaps even delay the timing of ovarian failure. … I think it opens up the chance that sometime in the future we might get to the point of having an unlimited source of human eggs.

That certainly sounds very sci-fi, though, of course, women already have one option for banking their eggs for future use. They can have them extracted and frozen, but that is a long, complicated, and painful process. Simply extracting and freezing a small piece of ovarian tissue with stem cells in it might be a lot more efficient and effective. Plus, because stem cells don't have as much water in them as eggs, they're less likely to be damaged by freezing and thawing.

While the ultimate goal is creating human embryos from ovarian stem cells, all of that is still a long way off. It will be difficult to even proceed with the next stages of research, given the ethical and legal hurdles that exist. Plus, eggs are already very finicky creatures and are prone to genetic errors, and it's possible that trying to create them from stem cells will only make them more problematic.

Still, this provides a new channel for fertility research and, if successful, could have a huge impact on the way infertility—which some 10 percent of women in the U.S. struggle with—is viewed and treated. Not only could make preserving ones fertility a lot easier, it could also single-handedly destroy the I-will-do-anything-to-get-pregnant-before-I-turn-40-no-matter-how-crazy-it-is genre of romantic comedies. What a blessing this might be on so many levels.

Stem Cells Turned Into Eggs [Wall St. Journal]
Unlimited human eggs 'potential' for fertility treatment [BBC]

Image via somersault18:24/Shutterstock.