For the first time, scientists have created primates whose cells carry one of several sets of genetic instructions instead of one consistent assemblage of DNA. The three rhesus monkeys are chimeras, conglomerates of cells from up to six genetically different embryos.
Creating the monkey chimeras was much harder than achieving a similar result in mice, suggesting that embryonic stem cells from primates, probably including humans, are less flexible than their mouse counterparts. Those findings could have implications for regenerative medicine, which seeks to create replacement organs and cells from stem cells — efforts often first tested in mice.
Some people have worried that scientists working with embryonic stem cells, which have the potential to develop into any type of cell in the body, might inadvertently grow a human fetus in the lab. The new work shows that’s probably not going to happen, says developmental biologist Gerald Schatten of the University of Pittsburgh School of Medicine. It also means stem cells are less likely to run wild, creating tumors or growing into the wrong type of cell once implanted in a patient.