The “three parents” procedure - mitochondrial transplantation during in vitro fertilization - was successfully performed for the first time on healthy human embryos. The successful implementation of the operation makes it possible to use it in medicine at the end of 2017, according to the journal Nature.
The Three Parents Method involves transplanting mitochondrial DNA from a donor woman into the mother's egg, resulting in the baby receiving mitochondrial DNA from a third party. Scientists believe that this avoids the influence of mutations on the part of the mother, which can lead to diseases such as diabetes and deafness.
In 2010, Doug Turnbull of Newcastle University and his colleagues developed a new method that involves the fact that the harmful mitochondria in the egg are far from the nucleus (with DNA). So, you can first fertilize an egg, and then extract the nucleus from it and transplant it into a donor cell with healthy mitochondria.
Initially, the new method was tested only on defective embryos rejected during IVF procedures. At the same time, Turnbull found out that some of the dangerous mitochondrial DNA still gets into the embryo - due to liquid droplets adhering to the cell nucleus during transplantation.
In the new study, scientists transplanted nuclei 200 times using healthy donor eggs. Scientists have improved the procedure and dramatically reduced the number of harmful mitochondria.
As a result, 79 percent of the resulting embryos had less than 2 percent of harmful mtDNA, while 42 percent did not find it at all. The minimum indicator for healthy fetal development is 30 percent. In addition, the researchers raised the embryo survival rate from 40 to 90 percent, shifting the time of nuclear extraction: previously, this procedure was performed after 24 hours, now - after 8 hours.
The UK authorities must assess the safety of this method by the end of 2016 and decide whether it is possible to apply it to living patients.
