Stem Cells Coaxed to Make Precursors to Egg, Sperm

Oct. 29 -- WEDNESDAY, Oct. 28 (HealthDay News) -- In a step that might someday aid infertile couples, scientists have nudged stem cells to become human germ cells -- precursors to egg and sperm.

"For the first time we have a human genome-based system for how to make a germ cell or not," said lead researcher Renee Reijo Pera, director of the Center for Human Embryonic Stem Cell Research and Education at Stanford University School of Medicine. "I think it will play out to people's benefit because 10 to 15 percent of couples cannot have children."

The study, published online Oct. 28 in the journal Nature, provides both an experimental system for germ cell development as well as a method for coaxing germ cell production from embryonic stem cells (ESCs). It also identifies three molecules called RNA-binding proteins that are critical to the process, members of the so-called DAZ gene family.

Researchers can exploit the resulting system to study germ cell formation -- and in particular, ways it can go awry -- and to develop drugs that can manipulate the process, explained Reijo Pera.

More long-term, the system should ultimately aid infertile couples by providing a mechanism for generating sperm or eggs (gametes) in the laboratory, which can then be used for in vitro fertilization.

"This research basically tells us how to make a gamete," said Dr. Raymond Anchan, a fertility specialist and stem cell researcher at Brigham and Women's Hospital in Boston. "If we understand this, then we can think about making gametes from patient-specific stem cells," said Anchan, who was not involved in the study.

According to the National Women's Health Information Center, infertility affects approximately 10 percent of U.S. women -- some 6.1 million women aged 15 to 44. For many of those individuals, and also for many men, infertility stems from low or abnormal gamete production. Though researchers have had sporadic success turning human ESCs into germ cells, the process has been inefficient and difficult to study in the laboratory. Reijo Pera decided to try to change that.