Male infertility may soon be a thing of the past according to mice. This week new research has been released that Japanese scientists have used laboratory-made sperm, using embryonic cells, to restore fertility in sterile mice. This may open up new avenues for researching and treating infertility in people. For example, men may be able to reprogram cells from the skin to act like sperm producing entities. Read on for details.

Historically, researchers have tried for years to make sperm and eggs in a dish, with limited success and some controversy. In 2003, several groups of scientists showed that it was possible to transform mouse embryonic stem cells into both sperm and eggs, but pregnancy failed.

In 2006 another team used lab-grown sperm to produce six mice, but the animals suffered genetic abnormalities and all died early and in 2009, researchers at Newcastle University made headlines by reporting the creation of human sperm in a test tube. Their paper was retracted weeks later on charges of plagiarism.

Now, the researchers added growth factors and other chemicals that are known to control activities such as cell proliferation and differentiation to mouse embryonic stem cells which had the effect of turning the embryonic cells into epiblast-like cells in a lab dish. These cell types are deposited early in embryogenesis in developing organs and persist in several organs into adulthood.

Next, by replicating the signaling process learned from the 2009 experiment, they coaxed the epiblast-like cells to become primordial germ cells. These primitive germ cells were transplanted into the testes of 7-day-old mice that were sterile and therefore couldn’t produce sperm naturally. But they now produced normal-looking sperm. Quite the breakthrough.

The lab-made sperm were used to fertilize eggs in a dish, creating 214 embryos, each comprising two cells. The embryos were transplanted into several female mice, which gave birth to a total of 65 healthy male and female pups.

Dr. Saitou, the research team leader stated:

“The mouse babies are just fine and they’ve had normal, fertile babies of their own. The pregnancy rate achieved in the mice was comparable to what’s typically seen using naturally produced sperm and artificial insemination.”

Now this exact process can’t be identically replicated in adult male humans, but it may be possible to reprogram a man’s mature cells into an embryonic-like state, and coax those cells to become healthy sperm in a dish.

The Japanese scientists did just that. They got reprogrammed mouse cells to turn into lab-made sperm, and then used the sperm to fertilize eggs and produce babies in the mice.

The ability to reprogram cells into an embryonic-like state is one of the most exciting advances in biology. But it is still an unreliable technique since it often requires the use of viruses that can trigger tumors. Not surprisingly, the Kyoto scientists found that 20% of the baby mice produced via reprogramming died prematurely, some from tumors.

George Daley, director of the stem-cell transplantation program at Children’s Hospital Boston commented:

“It’s a brilliant set of experiments. They restored fertility in the mice. It lays the groundwork for major insights into sperm development and fertility. It would be a monumental achievement since there’s currently no method for restoring female fertility.”

Written by Sy Kraft