April 15, 2007

Designer Hens Lay Anti-Cancer Eggs

Scientists at Scotland's Roslin Institute that produced Dolly the Sheep have genetically modified "designer" hens to lay eggs containing proteins that can fight human forms of cancer and other diseases. It is thought this will make a range of existing drugs easier and cheaper to produce.

The hens are producing proteins that have the potential to treat arthritis, multiple sclerosis, and malignant melanoma, or skin cancer.

The results of this research are to be published in today's issue of the Proceedings of the National Academy of Sciences.

The Roslin team genetically engineered the hens by inserting the gene for the desired proteins into the ovalbumin gene, a protein in egg white. They chose two proteins: human interferon b-1a, which is used to treat a range of tumours and virus infections, and miR24, a monclonal antibody used in the treatment of skin cancer.

They started by using a virus to insert the protein DNA into the DNA of chick embryos. The chicks were hatched and the researchers found that the male ones had DNA in their semen. These were bred with normal hens and the female chicks that carried the new genes then went on to produce the eggs containing the desired proteins. Some 500 genetically modified, or "transgenic" hens have now been created in this way.

The news was welcomed by the UK's leading cancer charity, Cancer Research UK, at the weekend. Herbie Newell, director of translational research at the charity said that anything that speeds up the number of new treatments available and reduces their cost "must be welcomed".

Dr Helen Sang of the Roslin Institute and lead scientist on the project has been working on this for 15 years. It could still be another 15 years before drugs become available because of the long development cycle of such innovative treatments. First the patent trials have to be completed, that takes about 5 years, and then the drug development and approval takes another 10 years.

The idea is to produce the protein-based drugs in flocks of birds reared as "biofactories" much in the same way as chickens are for normal eggs. The proteins are quite straightforward to harvest from the egg-white.

Using genetically modified organisms to create drugs for treating humans is not new. Insulin for treating diabetes is produced in genetically modified bacteria. Other more complex proteins have been produced in the milk of sheep, goats, cows and rabbits. However this is the first time that birds have been used and the researchers think this method could lead to cheaper and faster drug production because of the shorter life cycle of hens and eggs.

This latest Roslin work forms part of the Avian Transgenic Project, which includes the biotechnology firms Viragen and Oxford BioMedica.

Proceedings of the National Academy of Sciences of the United States of America.

Use of biotechnology in pharmaceutical manufacturing (wikipedia)

Written by: Catharine Paddock
Writer: Medical News Today

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