Anger As Monkeys Created By Splicing Embryos

US researchers have unveiled the first three so-called "chimeric" monkeys - created by fusing cells from different rhesus monkey embryos.

The advance that led to the birth of Roku, Hex and Chimero could hold "great potential" for medical research in the future, but campaigners against experimenting on animals condemned it as "deeply disturbing".

Scientists effectively "glued" the cells from very early stage monkey embryos together before the "mixed" embryos were implanted into the wombs of mothers, according to research reported in an online edition of the journal Cell.

The monkeys have gene traits from all of the separate animals used to create them, meaning each represents up to six distinct genomes, or genetic codes.

Lead scientist Dr Shoukhrat Mitalipov, of the Oregon National Primate Centre, said: "The cells never fuse, but they stay together and work together to form tissues and organs.

"The possibilities for science are enormous."

But the British Union for the Abolition of Vivisection (BUAV) said using such animals in scientific research raised "enormous ethical concerns" and welfare concerns.

Dr Jarrod Bailey, the organisation's scientific consultant, said: "As few genetically modified animals show the 'desired' characteristics, many will be killed even before any research can take place, while others will die of severe and unrelated malformations caused by the genetic modifications.

"The monkeys who do exhibit characteristics of 'interest' are destined to suffer greatly by their very nature, and via the experiments to which they will be subjected."

Chimeric mice have already been used extensively in laboratories in order to study a host of ailments and remedies, including obesity, heart disease, anxiety, diabetes and Parkinson's disease.

However, the process used to create chimeric mice did not work with monkeys.

Rather than introducing embryonic stem cells that have been cultured in a lab dish into a mouse embryo, in monkeys they had to use the more potent early stage cells from a living embryo.

British stem cell expert Professor Robin Lovell-Badge, from the National Institute for Medical Research, said: "Chimeras have been and continue to be a very powerful experimental tool to help understand details of embryo development.

"However, almost all of these details have been determined using the mouse and it has only been an assumption that human and other mammals develop in similar ways."