Laboratory grown Organs, a Thymus from scratch

Implanted Thymus (dark) and lighter kidney cells

Implanted Thymus (dark) and lighter kidney cells

Researchers from the MRC centre for regenerative medicine, at the university of Edinburgh have tweaked harvested cells to form Thymus cells in the laboratory. These cells then formed a fully functioning Thymus inside a living mouse after they were grafted onto it’s kidney.

The Thymus is an organ located in your chest cavity fairly close to the heart. It has a important function in your immunity. This function is to mature T-cells, a specialized type of cells in the immune system. T-cells attacks foreign substances(antigens) that it can identify through receptors on its surface. This ability is what is “learned” inside the Thymus. The T-cells runs a type of “gauntlet” in side the Thymus. The inside of the Thymus is lined with foreign proteins, if the T-cells do not react to those foreign proteins they are programmed for destruction, since an immunce cell that don’t attack foreign proteins are fairly useless. The T-cells then run a similar gauntlet but this time with the body’s own proteins, if they react to those they are also terminated. But now it’s thyme to get to the science news =).

Laboratory Grown Organs

The researchers took fibroblasts, a type of cells, from a mouse embryo and converted them into Thymus epithelial cells. Epithelial cells are a grouping of cells that line the surface of structures in the body. The conversion of the fibroblasts were accomplished by activating a gene in the fibroblasts DNA called FOXN1. This gene normally guides the development of the thymus in the embryonic state. After this activation the fibroblasts became a different type of cells called: induced thymus epithelial cells or iTECs. These cells were mixed with other cells associated with the Thymus and were grafted onto kidneys of laboratory mice. The mice was genetically identical to the harvested fibroblasts to avoid any rejection issues.

After four weeks the implanted cells had formed a fully functional Thymus with all the structures that exists in a normally developed organ.  The transplanted Thymus functioned normally. The researcher’s tests found that it efficiently matured the two most common types of T-cells; helper T-cells and Killer T-cells.

The implications of this is of course huge to regenerative medicine. To be able to grow organs  in the lab instead of relying on donations for transplantation could solve plenty of problems for the chronically ill. There is of course a long way to go to even get to human trials with the laboratory grown Thymus but it could potentially help people that either are born without a Thymus as is the case in a rare disease called DiGeorge syndrome or people with reduced immunity for any reason. Fragments of organs have been grown previously but this fully functioning organ is a big step forward towards being able to create body spare parts.

Content and Cover image credit: Medical Research Council/PA