UVA scientists have created a zebrafish embryo by instructing stem cells. Embryo wild-type (left), embryo constructed (right)

Several University of Virginia scientists have identified how to control the development of fish embryonic stem cells, marking a major breakthrough toward potentially growing human organs and tissues.

A vertebrate embryo is constructed by triggering two cell signals.

The research, published in the April 4 issue of the journal Science, is the first to show that a group of embryonic cells can be directed to grow in a particular way by stimulating only two signals that govern cell development. Researchers conducted their study using zebrafish embryonic stem cells to create a fish embryo.

Scientists Bernard and Christine Thisse of the School of Medicine and their research partners are already attempting to duplicate their findings in mouse cells. While the initial data is “encouraging,” Bernard Thisse says there are still challenges in adapting the technology up the evolutionary chain, where animals have longer gestation periods.

He says the ultimate goal for scientists in the field would be to manipulate human stem cells into various paths of development, potentially to reproduce organs or tissues.

The vertebrate embryo, built in vitro, developed a brain.

“It is definitely the next step, but to be fair, people should not expect [that technology] in the next two to three years,” Thisse says. “It’s a long-term goal. The move from knowing where to instruct cells to do the things you want them to do, to making human tissue may take a while.”

“When you look at what’s going on in stem cell research, there’s a lot that generally goes too fast from lab to medical application,” he says. “We have to be cautious.”