In a first, living organ created from lab-grown cells

In a significant breakthrough, British scientists have grown a fully functional organ from transplanted laboratory-created cells in a living animal that can lead to new treatments for people with a weakened immune system.

They have created a thymus - an organ next to the heart that produces immune cells known as T cells that are vital for guarding against disease.

It is the first time that scientists have made an entire living organ from cells that were created outside of the body by reprogramming.

"Our research represents an important step towards the goal of generating a clinically useful artificial thymus in the lab," said professor Clare Blackburn from the MRC Centre for Regenerative Medicine at University of Edinburgh.

The team took cells called fibroblasts from a mouse embryo.

They turned the fibroblasts into a completely different type of cell called thymus cells, using a technique called reprogramming.

"The reprogrammed cells changed shape to look like thymus cells and were also capable of supporting development of T cells in the lab - a specialised function that only thymus cells can perform," Blackburn explained.

When the researchers mixed reprogrammed cells with other key thymus cell types and transplanted them into a mouse, the cells formed a replacement organ.

The new organ had the same structure, complexity and function as a healthy adult thymus.

With further refinement, researchers hope that their lab-grown cells could form the basis of a thymus transplant treatment for people with a weakened immune system.

The technique may also offer a way of making patient-matched T cells in the laboratory that could be used in cell therapies.

Such treatments could benefit bone marrow transplant patients and babies born with genetic conditions that prevent the thymus from developing properly.

The study appeared in the journal Nature Cell Biology.