Animal eggs for human stem cell research

Why are embryonic stem cells needed?

Embryonic stem cells are basic cells that are not specialised into any specific cell type. Researchers investigating neurological diseases hope that they can learn how to trigger these embryonic stem cells to specialise into nerve cells in the laboratory, and in particular for MND research, motor nerve cells (neurones). If these experiments are successful, for the first time live human motor neurones can be used to further our understanding of MND and the search for effective treatments.

What does the new technique involve?

As the researchers specifically want to study human motor neurones, the embryonic stem cells need to be of human origin. The Human Fertilisation and Embryology Authority (HFEA) has licensed the use of human eggs for research, however, this is hampered by a lack of eggs. To get round this problem the researchers propose to use animal eggs, where the animal DNA has been replaced with human DNA. To date, either rabbit or cow eggs have been proposed.

DNA replacement

Within mammalian cells, 99%* of the DNA is stored in a compartment called the nucleus. The DNA within the nucleus of the animal egg will be removed, creating an ‘egg-shell’. The next step is to insert the nucleus of a human adult cell (usually a skin cell) into this animal ‘egg shell’. Human embryonic stem cells will form within this egg, as the genetic material controlling their development is 99% human.

*The remaining 1% of DNA in the cell is stored in another type of compartment called mitochondria. As each cell contains about 100-1000 mitochondria, depending on the function of the cell, the difficulty of extracting the remaining 1% of DNA becomes apparent!

Could people with MND contribute to this research?

Researchers may ultimately wish to use these human embryonic stem cells to create motor neurones that are actually affected by MND. To do this, they would need a skin cell donated by a person with the rare, inherited form of the disease. However, only those researchers granted a licence for this type of work would be able to use such skin cells. Any research that involves people is strictly regulated - in addition to obtaining their licence, the researchers would have to obtain approval from an ethics committee. Part of the application to this committee would include detailed proposals of how and where the participants would be approached.

How is the HFEA involved?

The Human Fertilisation and Embryology Authority (HFEA) regulate the Human Fertility and Embryology Act. The use of human eggs for research is only one part of this Act. It also regulates wider issues and concerns regarding fertility treatment and fertility research.

In order to reach a decision on whether to allow the creation of animal-human embryos, the HFEA carried out a public consulation to examine the issue. At the completion of this consultation, the HFEA made the decision to allow the use of animal-human embryos in scientific research.

Read our press release: New policy position on human/animal hybrid embryos welcomed