BioWorld International Correspondent

LONDON - Two UK research teams have been given approval to create human/animal cloned embryos for use in embryonic stem cell research.

The one-year licenses will allow researchers to use enucleated animal oocytes as the vehicle for generating embryos from adult human cells, using the somatic cell nuclear transfer technique. The decision by the regulator, the Human Fertilization and Embryology Authority (HFEA), is a victory for the scientists concerned because the government had said previously that it would not allow the research.

The term "cybrids" has been adopted to describe the entities it is hoped to produce, to avoid mention of animal/human hybrids, or of chimeras.

One group, led by Lyle Armstrong, of Newcastle University's Stem Cell Institute, will use enucleated cattle oocytes to create embryos from adult cells, extract embryonic stem cells and then investigate how the cells differentiate into other types of tissue. Under UK law, any such embryos must be destroyed by day 14.

"Finding better ways to make human embryonic stem cells is the long-term objective of our work, and understanding reprogramming is central to this," Armstrong said.

"Cow eggs seem to be every bit as good at doing this job as human eggs, so it makes sense to use them since they are much more readily available," he added.

The research will start immediately. Armstrong's team has been practicing transferring adult cells from other animals into cattle oocytes to hone the technique, and the team hopes to make rapid progress using adult human cells.

The Newcastle application only received approval when the researchers dropped plans to use human nuclei supplied by the U.S. company Cambrex Corp., of East Rutherford, N.J., after the licensing committee considering the application said it was not satisfied the U.S. company's consent procedures met UK requirements. UK rules involve explicitly informing donors their cells will be fused with enucleated animal oocytes and obtaining the same level of consent as is required for gamete donation.

Instead, Armstrong's team will use cells obtained from a human embryonic stem cell line derived in Newcastle and dermal fibroblasts donated by patients.

The second license was granted to Stephen Minger, of the Stem Cell Biology Laboratory at King's College London, to generate embryos carrying disease genes. The project will involve isolating fibroblasts from patients with diseases including Parkinson's, Alzheimer's and spinal muscular atrophy. Any cell lines derived will be made freely available for research through the UK Stem Cell Bank.

Minger, who has expressed impatience with the length of the decision-making process, said he was pleased the HFEA "has finally after a year and a half" realized the importance of the proposed research.

He also thanked researchers, disease charities and patients' organizations for their support and said, "This shows that the scientific community can be involved in, and influence, government policy."

The UK took the lead in approving therapeutic cloning research, but until now researchers have used human eggs left over from in vitro fertilization treatments. As those are in short supply, scientists have lobbied to be able to use animal oocytes, both to practice cloning and stem cell extraction techniques, and to develop cell lines for use in drug discovery. No animal/human cybrid cell lines can be used in human therapies.

The applications for licenses were submitted 18 months ago, and the licensing committee took into consideration new developments in the reprogramming of adult somatic human cells into embryonic stem cells that have been reported since.

The committee said both projects remained valid because they would provide ways of learning more about cellular differentiation in the embryo.