THURSDAY, Jan. 5 (HealthDay News) -- By gluing together cells from different genomes to form mixed embryos, researchers revealed they have created the world's first chimeric monkeys.

In the report published online and in the Jan. 20 issue of Cell, they said the monkeys, who are made up of as many as six different genomes, are normal and healthy.

By successfully implanting these genetically mixed rhesus monkey embryos into mothers, the scientists argued that doors have been opened for future studies since this type of research had previously been restricted to the production of mice carrying genetic mutations known as gene deletions.

"The cells never fuse, but they stay together and work together to form tissues and organs," said Shoukhrat Mitalipov of the Oregon National Primate Research Center at Oregon Health & Science University in a news release. "The possibilities for science are enormous."

In producing the chimeric monkeys, researchers said they mixed the cells from early-stage embryos because at that point the cells are totipotent -- or able to form a whole animal -- not just one specific type of tissue.

The researchers noted, however, that the use of cultured embryonic stem cells could have limitations. Mitalipov explained that the monkey embryos could prevent the cultured embryonic stem cells from combining as they do in mice. These stem cells may also not be as potent as those found in living embryos.

"We need to go back to basics. We need to study not just cultured embryonic stem cells but also stem cells in embryos. It's too soon to close the chapter on these cells," Mitalipov said. "We cannot model everything in the mouse. If we want to move stem cell therapies from the lab to clinics and from the mouse to humans, we need to understand what these primate cells can and can't do. We need to study them in humans, including human embryos."

Mitalipov pointed out there are no plans to produce human chimeras.

More information

The U.S. National Institutes of Health provides more information on stem cells.