Stanford Researchers Create Germ Cells in the Lab

Building on previous research, scientists at Stanford University were able to make embryonic stem cells mature into reproductive germ cells, the cells responsible for forming sperm and eggs. 

Embryonic stem cells are the building blocks of life and can be manipulated into a variety of tissues types. Perhaps most remarkably, the Stanford researchers were able to coax these embryonic stem cells to “go all the way through the reductional process of meiosis so the cells contain just one copy of a chromosome, a critical step in sexual reproduction,” Lisa M. Krieger writes for the San Jose Mercury News.

Making a baby from these cells isn’t the point of the research; instead, the Stanford team plans to study the earliest stages of human development in order to examine infertility, genetic disease and birth defects.

“Human development is a very complex process, and we’ve never had a system before to study it in the lab, to see the things we can see now,” Renee Reijo Pera, the lead investigator who directs Stanford’s Center for Human Embryonic Stem Cell Research and Education Center, told the Mercury News.

In 2003, Carina Dennis reported in the journal Nature that “[s]ome pioneering biologists are trying to grow eggs and sperm in the lab,” and in the process “they’re entering a technical and ethical minefield.” Aside from dealing with the ethical issues, Dennis pointed out that researchers also face “formidable technical challenges.”

“One major hurdle is coaxing the cells to halve their number of chromosomes, which involves a form of cell division known as meiosis,” Dennis wrote. The Stanford researchers have done just that, bringing us one step closer to what Dennis calls “[s]ynthetic sex cells.”

Although the Stanford researchers have made progress in creating synthetic sperm and eggs, they aren’t quite there yet: Krieger reports for the San Jose Mercury News that they were able to make spermatids—immature sperm—from the germ cells, but have yet to produce oocytes, the eggs produced by women.

As Krieger explains, it isn’t “ethical or feasible” to create a baby from sperm or eggs produced in a lab, due to the fact that the germ cells created by the Stanford researchers contain transgenes, or foreign DNA.

“We don’t make children that carry foreign DNA,” Reijo Pera told the Mercury News. “It’s not ethical; we don’t know where the DNA could land” during the development process.

According to Reijo Pera, researchers are also “waiting for guidelines and regulations” on how to work with artificial germ cells.

In July, two independent studies in China found that mice can be produced using stem cells derived from adult connective tissue cells, raising hope that these cells could be an alternative to embryonic cells in stem cell research.

Learn more about stem cells, explore the stem cell debate and stay current on stem cell research with our Web Guide to Stem Cells.

Use the Fertility Problems Web Guide to find an overview of fertility issues, explanations of causes and treatments and resources for emotional support.