A Brief History
Maternal Spindle Transfer is a technique similar to Pronuclear Transfer in its effort to prevent the transmission of mitochondrial disease. However, the main difference between these two techniques is that Maternal Spindle Transfer uses unfertilized eggs instead of the early embryos used in Pronuclear Transfer.
Researchers at the Oregon Science and Health University announced that they had successfully completed maternal spindle transfer in rhesus macaques in 2009. The results of the technique were, and continue to be, astonishing. Researchers reported that the macaques’ eggs were capable of supporting normal fertilization and they went on to have normal embryo development. Three healthy offspring were produced through the use of maternal spindle transfer. When born, no mutated mitochondria from the intending mother were detected. Their growth is monitored monthly and, at age two, they are currently no different from the experimental controls.
Currently, researchers at Newcastle University in the United Kingdom are collaborating with the Oregon researchers. The Newcastle group is testing the maternal spindle transfer technique on human embryos. No results have been published.
- Assisted reproductive technologies are used to extract the intending mother’s egg from her ovaries. The cytoplasm of the intending mother’s eggs contains the unhealthy mitochondria.
- Chromosomes, the nuclear DNA material, are found in the intending mother’s eggs are grouped together in a spindle-like formation. The chromosomes are removed for transfer to the donor egg. The chromosome-free egg, which contains the unhealthy mitochondria, is then discarded.
- Separately, a donated egg is also extracted from an unrelated woman who has healthy mitochondria. Similarly, the chromosomes of the donor’s egg are removed. However, these chromosomes are discarded, leaving behind the healthy mitochondria in the cytoplasm.
- The spindle-like chromosomes previously taken from the intended mother’s egg are inserted into the enucleated donor’s egg.
- The resulting reconstructed egg contains nuclear DNA from the mother and the healthy mitochondria from the donor.
- The resulting egg can now be fertilized with sperm from the intended father. The resulting embryo will be implanted into the intending mother and will develop unaffected by inherited mitochondrial disease.
Maternal Spindle Transfer, simplified