An article has been recently published in scientific journal Nature (534; 383–386, 2016), describing the application of mitochondrial technique in viable human embryos. This experiment is considered as the first preclinical study in humans in this field.
Mitochondrial replacement technique
The technique used was pronuclear transfer, in which the authors had modified the application protocol to improve its efficacy. This technique had been previously tested on human embryos left over from in vitro fertilisation treatments, but for this reason, these experiments are not considered preclinical studies. Nevertheless, the investigators observed that the method used in the studies with abnormally fertilised human zygotes were not well tolerated by normally fertilised zygotes. They developed an alternative approach, bringing forward the time at which the pronuclei are transferred and modifying the transfer conditions.
In our opinion, both the previous experiments and the new study are ethically unacceptable, as they manipulate and destroy human embryos. While not surprising that this has not been taken into account in any of the studies. It is striking that further steps continue to be taken in a field whose permissibility not been agreed by the scientific community, on the grounds that it is a modification of the germ line and due to the safety concerns that it raises.