Chimera: scientists create a monkey with two sets of DNA - but it was euthanased 10 days later

Scientists in China have reported the first live birth of a “chimeric” monkey with stem cells taken from two embryos, which come from the same species of monkey – a crab-eating macaque – but are genetically distinct. The baby monkey was born with “a high proportion” of donor cells which had an average of 67% across the 26 different types of tissue, the scientists said.

The team in China, which has reported its work in the journal Cell, said its work has vast implications – from understanding more about devastating conditions such as motor neurone disease to finding ways to help conserve threatened species.

Senior author Zhen Liu, of the Chinese Academy of Sciences, said: “This is a long-sought goal in the field." Adding: “This work could help us to generate more precise monkey models for studying neurological diseases as well as for other biomedicine studies.”

Chimera animals which contain groups of cells from two or more organisms with distinct types of DNA and are important for studying embryonic development, but research has largely been restricted to mice.

While monkeys have previously been created in the lab using donor cells, the researchers said these creatures had a much lower contribution of cells from embryos “so you cannot really call them chimeric animals”.

Professor Mu-Ming Poo, scientific director of the Institute of Neuroscience at the Chinese Academy of Sciences, said: “Just having several cells (that) are partially distributed all over the monkey body with no real formation or clear structures – you cannot really say that is a chimera, strictly speaking.

“So the difference here is that now we have a very high level of contribution, with the donor cells forming a big part of the tissues (and) complex structures all over the monkey body.”

Stem cells are the body’s raw materials from which all other cells with specialised functions are generated, and for the study, the researchers used stem cell lines – a group of cells grown in a lab from a single stem cell – taken from a seven-day-old embryo.

These cells were then injected into embryos that were four to five days old these were then implanted into female macaques, resulting in 12 pregnancies and six live births. The cells were also infused with a green fluorescent protein so the researchers would be able to determine which tissues had grown out of the stem cells.

Of the six, one baby monkey was born alive and managed to survive for 10 days however, a vet euthanized it after 10 days due to respiratory failure and hypothermia.

Analysis showed this male newborn had donor stem cells in 26 different types of tissue, ranging from 21% to up to 92%.

Meanwhile, a foetus that was miscarried was also “substantially chimeric”, the researchers said, with stem cell-derived cells observed in the brain, heart, kidney, liver, and parts of the digestive system.

The researchers said that their work complied with the national ethical regulations in China and for their next steps, they want to explore “mechanisms that underlie the survival of the embryos in the host animals”.

Prof Poo said: “The health of the monkey is still a problem. If we want to produce a monkey model, we have to have a better chimera that can live longer.”