Motherhood Gets An Egg-Stension

A Boston company said it is close to commercializing a method developed at Massachusetts General Hospital that would allow women to freeze their unfertilized eggs for possible later use.

The technique would be a major step forward in reproductive technology by allowing women to extend their fertility. Women who put off having children until later in life, or women whose ability to have children could be damaged by medical conditions, would still be capable of conceiving with their own eggs, or oocytes, officials for ViaCell Inc. told The Boston Globe on Tuesday.

"This is the most robust process for cryopreserving oocytes (not yet matured eggs) that's been demonstrated to date," said Marc Beer, chairman and chief executive of ViaCell, which is better known for freezing the umbilical cord blood of newborns to preserve stem cells. "It's ready for clinical trials. Hopefully this will work in clinical trials, and we'll be offering it to patients in 18 months."

ViaCell has contracted with Boston IVF to conduct clinical trials using eggs from volunteers.

MGH researchers said the technique has been successful in test tubes and in animal experiments.

ViaCell licensed the technique from North Kingstown, R.I.-based Gamete Technology Inc., a medical technology company that secured the rights from MGH doctors.

Doctors have long been able to freeze, then thaw, human sperm to fertilize eggs. But the human egg, because of its size and high water content, poses unique challenges. When frozen, the water in the egg can form crystals that destroy the egg or make it infertile.

MGH's technique involves injecting a sugar called trehalose into the eggs. Trehalose has been found to help frogs, salamanders and brine shrimp endure severe dehydration and freezing.

"The sugars are large molecules that can't pass through the cell membrane," said Mehmet Toner, a professor of biomedical engineering at MGH and Harvard Medical School, and one of the developers of the technique. "You get a little benefit having it outside the cell, but to get the full benefit of protection, you have to deliver the sugar into the egg."

A study published last year found that more than half of the eggs injected with trehalose survived freezing, while most of the eggs left untreated degenerated.

Fertility specialists say the technique does not mean that a safe and effective commercial service is near.

"This would really be a big deal," said Dr. Elizabeth Ginsburg, medical director of in vitro fertilization at Brigham and Women's Hospital. "But there's no literature to support that this is ready to be used clinically. We've got many years to prove safety before you could offer this to people."

Not every frozen egg is a potential embryo, said Dr. Michael Soules, director of the Division of Reproductive Endocrinology at the University of Washington Medical Center in Seattle. Some would be destroyed by freezing, some may fail to fertilize in the laboratory, and of those that are fertilized, only a few would mature enough to be implanted into a women's uterus, he said.