The researchers made a thymus by taking cells, identified as fibroblasts, from the embryo of a mouse and directly reprogrammed them into a totally unrelated kind of cell through an increased level of FOXN1 protein. This guides the embryo's development of the thymus.
Thymus is a butterfly-shaped gland which is a vital component of the immune system among humans. It is nestled beneath the breastbone in a person's upper chest. The thymus' role is to produce T-lymphocytes, or T-cells. The latter helps organize and lead the body's resistance against threats such as viruses, bacteria and even cancerous cells.
"By directly reprogramming cells, we've managed to produce an artificial cell type that, when transplanted, can form a fully organized and functional organ," says Prof Clare Blackburn, who led the team at the University of Edinburgh's Medical Research Council Centre for Regenerative Medicine. "This is an important first step towards the goal of generating a clinically useful artificial thymus in the lab."
The thymus cells, when mixed with other types of thymus cell and grafted in the kidneys of mice that are genetically identical, form a gland which has the identical structure, function, and complexity of a regular and healthy thymus. These can happen in a short span of four weeks.
Moreover, the lab-produced thymus has the capacity to produce T-cells by itself.
A disorder in the thymus can sometimes be treated by receiving extra immune cell infusions. Another solution is through the transplantation of thymus organ immediately after the baby's birth. However, these two solutions tend to be limited as there isn't enough supply of donors. The second issue deals with how successful it is to match the tissue with that of the recipient.
The researchers had aimed that the lab-grown cell can be used as the standard of performing thymus transplant procedure to patients with a weakened condition of the immune system. It could also pave the way for making patient-compatible T-cells which can be useful in cell-based therapies.
Other recipients that could benefit from the treatment include patients that needed to undergo a bone marrow transplant, babies that are born having genetic conditions, and older people since the thymus is believed to be the first among all human organs that deteriorate as one ages.
"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," says Dr. Rob Buckle, Head of Regenerative Medicine at the MRC.