Scientists teach chickens to make human proteins inside their eggs

What if a chicken’s egg could do more than feed people? What if it could help grow medicines used in stem cell research and advanced therapies?

Scientists in Bengaluru are doing just that by working on chickens genetically designed to produce medically “important human proteins” directly inside their eggs, a method that could make complex biomedical research materials easier to produce and more widely available.

Researchers at the National Institute of Animal Nutrition and Physiology (NIANP) under the Indian Council of Agricultural Research (ICAR), Bengaluru, in collaboration with the ICAR–Indian Veterinary Research Institute (IVRI), have produced transgenic chickens carrying a human gene known as Leukemia Inhibitory Factor (LIF). The aim is to make the chickens produce this protein naturally inside their eggs, opening up a new way of producing important biomedical molecules. 

Therapeutic proteins such as LIF are widely used in laboratories, especially for growing stem cells, including embryonic and induced pluripotent stem cells, which are crucial for research into diseases, regenerative medicine and drug development. At present, such proteins are usually produced using microbes grown in specialised bioreactors, a process that is expensive and requires complex infrastructure.

Scientists across the world have been exploring whether animals or plants can be used instead as “living factories” to make these proteins. While plants such as leaves or seeds can be engineered to produce useful molecules, extracting pure proteins from them is difficult because plant cells are structurally complex. Animal systems, particularly chickens, offer several practical advantages.

Artabandhu Sahoo, Director, ICAR-NIANP, explained that chickens are considered especially suitable for this kind of genetic work because they reproduce quickly and lay eggs almost daily. A single egg can contain milligram quantities of therapeutic proteins, and a layer hen can produce around 520 eggs during her productive lifetime. This means large quantities of protein can potentially be produced using basic poultry-rearing facilities, without the need for costly industrial equipment. 

Eggs also offer other benefits. The protein environment inside an egg is relatively simple, making purification easier compared to plant sources. Studies have shown that proteins produced in eggs are stable for months at air-conditioned temperatures. Egg-derived therapeutic products have been found to be safe for human use by the U.S. Food and Drug Administration, he said.

The key scientific challenge in creating transgenic chickens was solved through the discovery of primordial germ cells (PGCs) more than a century ago. These are early cells that eventually give rise to sperm and eggs. Scientists learned that chickens can only be genetically modified by altering these cells. In practice, the PGCs are collected during a specific stage of embryo development, grown in laboratory culture, and genetically edited using modern genome-editing tools. The modified cells are then carefully tested and placed back into developing embryos, where they settle into the reproductive organs and pass the new gene to the next generation.

Using this approach, the Bengaluru-based research team has developed laboratory systems to culture chicken PGCs and successfully produced multiple male and female chickens carrying the human LIF gene. These birds have been tested to confirm the presence of the gene, and efforts are ongoing to express the protein in their eggs.

If successful at scale, this method could significantly reduce the cost of producing LIF and similar therapeutic proteins. Scientists say the same platform can also be adapted in the future to produce other important biomedical molecules at low cost.