Different types of hybrid embryo can be produced, but the most common type used in research is the cytoplasmic hybrid. This is created using a technique known as somatic cell nuclear transfer (SCNT).
In SCNT the nucleus from a human cell is placed into an an animal egg cell which has had its nucleus removed (denucleation). This hybrid cell is then artificially induced to divide by an electric shock and starts to multiply. After a few days stem cells can be harvested from this hybrid embryo and used in research.
Rejection free transplants
Until now, all patients receiving transplanted tissue from other people have had to deal with potentially fatal medical complications. Their immune system can reject the tissue as an 'invader'. This rejection has to be suppressed with powerful drugs which can have many side effects.
Stem cells created through the somatic cell nuclear transfer method offer the opportunity to create tissues and organs that would not be rejected. The hope is to grow these from stem cells created using the patient's own cell nuclei, which will be genetically the same as the patient's own tissue.
Modelling genetic diseases