Baby monkeys created by 'mixing' embryos

Posted by Emma Woollacott

Researchers have produced the first 'chimeric' monkeys, created from stem cells from two or more separate embryos.

The study shows that stem cell functions and abilities are different in primates and rodents, and the Oregon Health & Science University team says it will improve understanding of the differences between natural stem cells in early embryos and cultured embryonic stem cells.

"This is an important development - not because anyone would develop human chimeras - but because it points out a key distinction between species and between different kind of stem cells that will impact our understanding of stem cells and their future potential in regenerative medicine," says Shoukhrat Mitalipov of the Division of Reproductive and Developmental Sciences.

Scientists had previously been able to produce chimeric mice using pluripotent embryonic stem cells, derived from a later-stage embryo. However, the Oregon team's demonstrated that this doesn't work in higher animals, such as the rhesus macaques used in the study.

Instead, they found, it was necessary to use stem cells from an earlier stage of development - totipotent cells - which have the ability to divide and produce all of the differentiated cells in the placenta and the body of an organism.

By using totipotent cells, the team successfully produced three baby rhesus macaques named Roku, Hex and Chimero. The cells from the different embryos did not fuse to create the animals, but worked together to form tissues and organs.

Showing that pluipotent stem cells operate differently in mice and primates could have big implications for medicine.

"Stem cell therapies hold great promise for replacing damaged nerve cells in those who have been paralyzed due to a spinal cord injury or, for example, in replacing dopamine-producing cells in Parkinson's patients who lose these brain cells resulting in disease," says Mitalipov.

"As we move stem cell therapies from the lab to clinics and from the mouse to humans, we need to understand what these cells do and what they can't do, and also how cell function can differ in species."