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Mitochondrial DNA replacement therapy successfully tested in human eggs

29 October 2012
Appeared in BioNews 679

Scientists have successfully created human embryos containing donated mitochondrial DNA in an effort to stop children inheriting life-threatening diseases. The technique, known as spindle transfer, involves transferring the nucleus from the egg of a woman with potentially disease-causing mutations in her mitochondrial DNA, into a healthy donor egg which has had its nucleus removed.

'Using this process, we have shown that mutated DNA from the mitochondria can be replaced with healthy copies in human cells', said Dr Shoukhrat Mitalipov from Oregon Health and Science University in Portland, who led the research. 'This research shows that this gene therapy method may well be a viable alternative to preventing devastating diseases passed from mother to infant'.

Mutations in mitochondrial DNA, affecting approximately one in 200 babies, can lead to a range of problems including; muscle weakness, heart disease, learning disabilities and blindness. Spindle transfer was devised with the aim of allowing mothers to prevent the transmission of such mitochondrial disorders to their children and future generations, by replacing the mutant mitochondrial DNA with that from a healthy donor egg.

The researchers decided to test the technique on human cells after demonstrating that it can produce healthy offspring in monkeys. They showed that the process resulted in normal human embryos and moreover can be performed using frozen eggs. This is crucial if the method is to become a practical reality in the clinic. The next step - human clinical trials - is now under serious discussion. 'I would say that it's safe enough at this stage to proceed to clinical trials', said Dr Mitalipov.

The technique is not currently permitted for clinical use in the UK, as it falls within the status of germline gene therapy. This refers to any alterations to the DNA of sperm or eggs that are subsequently passed down to future generations.

The UK's Human Fertilisation and Embryology Authority (HFEA) are now overseeing a public consultation on whether this and other similar techniques, such as that carried out by UK researchers at Newcastle University (BioNews 554), should be made available to prevent the inheritance of mitochondrial diseases (Bionews 673).

Further research is needed into the viability of these techniques, as in the current study only half of the human eggs that underwent spindle transfer were successfully fertilised to produce embryos. Professor Peter Braude, a member of the HFEA expert committee, told the Independent that the research 'is exactly the sort of science that the HFEA committee recommended needed doing, and demonstrates further the feasibility of this technique. However it is still a long way off ready for human use'.

The study was published in the journal Nature.

Breakthrough: Scientists produce early-stage embryos by transferring genes between unfertilised human eggs, in bid to eliminate inherited mitochondrial diseases
Independent |  24 October 2012
DNA-swap technology almost ready for fertility clinic
Nature News |  24 October 2012
Eggs Trade Genes
The Scientist |  24 October 2012
OHSU researchers test new gene therapy method in human cells...and it works
Oregon Health & Science University (press release) |  24 October 2012
Towards germline gene therapy of inherited mitochondrial diseases
Nature |  24 October 2012
28 July 2014 - by Dr Rachel Montgomery 
The UK Government has announced that regulations around the use of mitochondrial replacement techniques will be presented to Parliament in the next few months...
14 October 2013 - by Dr Rosie Morley 
A group of European parliamentarians has criticised UK proposals to legislate for mitochondrial replacement therapy, calling it 'a eugenic practice'...
23 September 2013 - by Dr Rosie Morley 
A group of scientists has expressed concerns that it may be too soon to bring mitochondrial replacement techniques, which are still under development, to the clinic....
1 July 2013 - by Dr Rosie Morley 
The UK Government is to support the introduction of mitochondrial replacement therapy. The IVF-based procedure could allow women with mitochondrial disease the opportunity to have healthy children, by replacing their own, faulty, mitochondria with healthy mitochondria from a donor....
21 March 2013 - by Sandy Starr 
Mitochondrial replacement therapy, where a small amount of a mother's genetic material is swapped with material from a donor during IVF to avoid passing on heritable illnesses, enjoys the 'general support' of the public, the UK's fertility regulator says...
8 October 2012 - by Dr Sophie Pryor 
On 25 September 2012 the Progress Educational Trust held a debate on the issues surrounding new techniques to prevent the transmission of mitochondrial disease. The event was organised in partnership with City University London's science journalism course and was supported by the Wellcome Trust....
17 September 2012 - by Dr Sophie Pryor 
The UK's Human Fertilisation and Embryology Authority (HFEA) has launched a public consultation on the social and ethical impact of new methods that could prevent the transmission of some incurable mitochondrial diseases....
17 September 2012 - by Sarah Norcross 
Mitochondria don't normally get much press attention, they like to keep a low profile generating energy in the cells and leave nuclear DNA to grab the headlines...
25 June 2012 - by Dr Virginia Bolton 
Predictably, the publication of the Nuffield Council on Bioethics' report supporting further research into a technique to prevent inheritance of mitochondrial disease prompted a flurry of publicity. Equally predictably, nearly every newspaper - whether broadsheet or tabloid - went for the sensationalist angle and used the 'three-parent IVF' tag in their headline...
12 June 2012 - by Antony Starza-Allen 
The Nuffield Council on Bioethics has published a review of the ethical issues raised by proposed IVF techniques, which aim to prevent the transmission of faulty mtDNA from mother to child. The report concludes the techniques are ethically permissible, provided further research establishes their safety....
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