Mark Johnson

Milwaukee Journal Sentinel

Launched in 1978 with the birth of Louise Brown, the revolution of in vitro fertilization allowed a woman’s egg to be fertilized by a man’s sperm entirely in a lab, bringing hope to millions of couples plagued by infertility.

But what if the ingredients themselves — the sperm and the egg — were made in a lab, too?

Scientists have taken steps toward the concept known as in vitro gametogenesis, which could launch a second fertility revolution.

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A month ago, Japanese researchers announced in the journal Science that they had successfully grown reprogrammed human cells into an early developmental forerunner of an egg cell.

“I find in vitro gametogenesis research important for understanding the mechanisms of human development, genetic disorders and infertility,” said Shinya Yamanaka, who shared the 2012 Nobel Prize for Medicine and works for the Gladstone Institutes in San Francisco and Kyoto University.

“This research would also contribute to new treatment for related diseases. At the same time the research harbors ethical concerns questioning how far science and technology is allowed to intervene on life.”

He expressed the hope that scientists and others would work together to address these issues “so that we can find a good balance between the advancement of science and the avoidance of runaway technology.”

The method, which some scientists believe may one day replace in vitro fertilization, raises a host of new possibilities and also new ethical questions.

In theory, same-sex couples could conceive children containing full genetic contributions from each partner. In the case of a lesbian couple, scientists could fertilize one partner’s egg with cells from the other that have been reprogrammed into sperm.

“This could, of course, be of enormous value for those who are not in a position to make offspring by the normal process,” said John Gurdon, the British scientist who shared the Nobel Prize in Physiology or Medicine in 2012 with Yamanaka, in an email to the Milwaukee Journal Sentinel.

But the same technology raises a host of other possibilities. Theoretically, a child could be conceived with only one parent supplying the cells that are reprogrammed into both sperm and egg. A child could also be conceived with contributions from three parents; the third would contribute mitochondria, the parts of cells that convert food into energy.

Also, the new cut-and-paste gene-editing technique known as CRISPR-Cas9 means that if the baby is at risk of terrible disease or disability, it may someday be possible to edit out the genetic flaw causing the condition. Hand in hand with that power, however, would come the ability to engineer babies with special characteristics: speed, intelligence, strength.

Eli Adashi, former dean of medicine and biological sciences at Brown University, cautioned that “every scientific breakthrough of this magnitude generates mixed reaction and a societal unease that takes a while to sort out.”

Such unease greeted the advent of in vitro fertilization, Adashi said, adding, “I think in vitro gametogenesis will go through similar phases. It will clearly raise some eyebrows, and some will accept it.

“It will likely be your grandchildren and mine who will not think anything of it.”