A study published in the journal Nature Cell Biology, by scientists from the MRC Centre for Regenerative Medicine at the University of Edinburgh in the UK, reports that it was possible to create a fully functional thymus in mice.
The thymus plays a vital role in the immune system, by producing T cells. These cells are responsible for finding defective cells and infections to initiate an immune response. When a person does not have a fully operational thymus, does not generate sufficient T cells and therefore is vulnerable to infection and disease.
Although thymus disorders can sometimes be treated by infusions of additional immune cells, or thymus transplantation shortly after birth, researchers say both options are limited by the lack of donors and problems with tissues compatibility.
For this achievement, the researchers increased levels of FOXN1, a protein that guides normal thymus development in the embryo. The researchers used fibroblasts cells taken from mouse embryos and reprogramed them, through the FOXN1 protein increasing, to become thymic epithelial cells. These cells provide specialist functions of the thymus, enabling it to make T cells.
Then, the team combined the induced thymic epithelial cells (or iTEC) with other thymus and grafted onto the kidneys of genetically identical mice.
The researchers observed that after four weeks, the cells had produced well-formed organs with the same structure as a healthy thymus, with clearly defined regions – known as the cortex and medulla.
Dr Rob Buckle, Head of Regenerative Medicine at the MRC, said: “Growing ‘replacement parts’ for damaged tissue could remove the need to transplant whole organs from one person to another, which has many drawbacks – not least a critical lack of donors.”
However, he warned that more research is needed before this technique can be reproduced in the laboratory and suitable to use in humans
