Biologists at the New York Stem Cell Foundation's Research Institute have found that the "three parents" procedure, or mitochondrial transplant, which is used in in vitro fertilization, can be completely useless. The study is published in the journal Cell Stem Cell.
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. Therapy may be unsuccessful if a large number of unhealthy mitochondria remain in the mother's egg. However, if this number is less than one percent of the total number of mitochondria, then the effect will be insignificant.
In a new study, scientists have shown that even a small amount of unhealthy mitochondria can render therapy useless. To do this, they transplanted nuclei from eggs with healthy mitochondria into eggs with different numbers of damaged mitochondria, the proportion of which was less than 2.2 percent.
In most cases, mitochondrial transplants have been successful. However, in some cells, scientists observed how the proportion of unhealthy mitochondria increased from 1 percent to 100 percent. Such fluctuations in numbers occurred at random. According to scientists, in order for the procedure to make sense, it is necessary to correctly assess the risks of unsuccessful transplants.
In addition, it is necessary to improve the method of mitochondrial transplantation to reduce the likelihood of defective organelles entering. The method itself is still in clinical trials and has not been recognized as safe or effective in the United States. The method was approved in the UK, but no children have yet been born to three parents.