In a world-first, scientists from the University of Edinburgh, Scotland, led by Professor Clare Blackburn, have successfully created a fully functional organ.

Scientists were able to grow a fully functioning thymus gland, a vital regulator of the entire immune system, located near the heart, by reprogramming and then injecting cells into living mice.

The thymus gland serves a vital role in the training and development of T-lymphocytes or T cells, an extremely important type of white blood cell. T cells defend the body from potentially deadly pathogens such as bacteria, viruses and fungi.

Yet to be tested on humans, the technique involved scientists extracting fibroblast cells from a mouse embryo which were then reprogrammed into thymus cells, mixed with other cells and re-injected into the mice to develop into a functioning thymus.

To reprogram the cells, scientists forced the fibroblast cells to express only a single gene, not normally expressed by fibroblasts, which led to the production of a protein called FOXN1, triggering the fibroblasts to turn into thymus cells.

According to Prof Blackburn, if this technique could be tailored to humans, it could help treat transplant patients, specifically those with compromised immune systems.

“The ability to grow replacement organs from cells in the lab is one of the ‘holy grails’ in regenerative medicine. But the size and complexity of lab-grown organs has so far been limited.

“By directly reprogramming cells, we’ve managed to produce an artificial cell type that, when transplanted, can form a fully organised and functional organ,” Prof Blackburn said.

“This is an important first step towards the goal of generating a clinically useful artificial thymus in the lab.”

Prof Blackburn and her team advised it may take a  decade before this technology can be used in humans.