They then removed the chromosomes, which contain the genes found in the cell nucleus, from the eggs of monkey B, and then transplanted the nuclear genes from the eggs of monkey A into the eggs of monkey B.

Then the eggs from monkey B, which now contained their own mitochondria but monkey A's nuclear genes, were fertilised. The fertilised eggs developed into embryos that were implanted in surrogate monkeys.

The initial implantation of two embryos resulted in the birth of healthy twin monkeys, nicknamed 'Mito' and 'Tracker' (in reference to the procedure used for imaging of mitochondria). These monkeys are the world's first animals derived by spindle transfer.

Follow-up testing showed that there was little to no trace of cross-animal mitochondrial transfer using this procedure. This demonstrates that the researchers were successful in isolating nuclear genetic material from mitochondrial genetic material during the transfer process.

'In theory, this research has demonstrated that it is possible to use this therapy in mothers carrying mitochondrial DNA diseases so that we can prevent those diseases from being passed on to their offspring,' added Mitalipov.

'We believe that with the proper governmental approvals, our work can rapidly be translated into clinical trials for humans, and, eventually, approved therapies,' he said, according to an OHSU release.

The research was published in the Wednesday advance online edition of Nature and is also scheduled for publication later.