Researchers grew a fully functioning organ in a living animal from transplanted laboratory-created cells.

The University of Edinburgh research team created a thymus (an organ next to the heart that produces immune cells), they hope this breakthrough will lead to new treatments for people with weakened immune systems.

"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 the University of Edinburgh.

The team took cells called fibroblasts from a mouse embryo and turned them into thymus cells using a technique called reprograming. The reprogrammed cells changed shape to look like thymus cells, once mixed with other thymus cell types and implanted into a mouse the cells formed a replacement organ.

This is the first time researchers have made an entire living organ from cells that were created outside of the body and reprogrammed. In the past doctors have already shown patients with thymus disorders can be treated with infusions of extra immune cells or a thymus transplant soon after birth, but both are limited by a shortage in donors.

In the future researchers hope lab-grown cells could form the basis of a thymus implant to treat people with weakened immune systems. These treatments could benefit bone marrow transplant patients by helping them rebuild their immune systems; it could also help babies born with genetic conditions that prevent the thymus from developing properly or elderly people suffering from thymus deterioration.

"This is an exciting study but much more work will be needed before this process can be reproduced in a safe and tightly controlled way suitable for use in humans," said Dr. Rob Buckle, Head of Regenerative Medicine at the MRC.

The study is published today in the journal Nature Cell Biology.

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