Accessory genes

French says the advantage over the standard approach of creating mutant cell lines or transgenic animals with a particular type of defect to study a disorder, or to test new therapies, is that with SCNT, the mutation comes as just one component of the individual's complete genome - with any "accessory" genes that contribute to the disorder, and the individual subject's complete complement of micro-RNA regulatory elements.

"You get everything," he says. "So you can change anything in the cell to see what happens.

"For example, if someone is affected by Alzheimer's disease, you can make a representative ESC line and use it to screen thousands of molecules that might have a therapeutic benefit.

"You can also go into an ESC and repair a defective gene, and then implant it into the subject."

ESCs with "repaired" genes might be a better option than transgenic haemopoietic stem cells for treating blood disorders such as thalassaemia or sickle-cell anaemia, or immune-system defects, he says.

Haemopoietic stem cells are already partially differentiated, and while they can differentiate into any blood or immune-system cell, there is some evidence that they require the support of other, non-haemopoietic cell lineages to function efficiently. Cell communities in effect create their own niches with "friends" that supply the growth factors and signalling molecules needed to renew themselves.

ESC cells could also differentiate into non-haemopoietic lineages to recreate the full suite of cells and replace these cells, as well as all blood and immune system cells, he says.

Some people might also want to consider the possibility of preserving some of their own stem cell lines as an insurance policy against any future life-threatening disorders, such as heart disease.

French says Stemagen is already receiving inquiries for SCNT-derived embryonic cell lines for research, including from Australia and New Zealand.

Australian stem cell researches appear to be concentrating on downstream applications of SCNT, such as therapies for brain disorders like motor neuron disease, Alzheimer's disease and Parkinson's disease.

"We're at a stage in stem cell therapy equivalent to the penicillin era of antibiotics, and there are opportunities in Australasia to work with different groups, working with different genetics," he says.