Bacteria triggers stem cell theory

Leprosy bacteria can force mature cells to function like potentially therapeutic stem cells, scientists have learned.

Other types of infectious bacteria may have the same ability, it is believed.

The discovery, reported in the journal Cell, could assist the development of new stem cell treatments, as well as help to combat infectious disease, say the researchers.

Scientists have only recently learned how to reprogramme adult cells by turning back their developmental clock. Induced pluripotent stem cells (iPS cells) made in this way behave like embryonic stem cells and have the potential to become any kind of living tissue.

IPS cells are said to show great potential for future regenerative therapies. But now it is clear that bacteria achieved the same result long before molecular scientists. In the case of the leprosy bugs, however, the aim is not to improve health but to spread a deadly infection.

Tests on mice showed that in the early stages of infection, the bacteria took cover from the body's immune defences by hiding in supporting cells within the nervous system. Once an infection was established, they reprogrammed the cells - known as Schwann cells - into stem cell-like cells.

Being pluripotent, the transformed cells were able to become other cell types, such as muscle cells, and migrate to different tissues. Carried with them, the bacteria were able to spread. The bacteria-generated iPS cells also secreted specialised proteins called chemokines that attract immune cells. These picked up the bugs and assisted in spreading the infection further.

Lead scientist Professor Anura Rambukkana, from the Medical Research Council Centre for Regenerative Medicine at the University of Edinburgh, said: "Bacterial infections can completely change a cell's make up, which could have a wide range of implications, including in stem cell research.

"This is very intriguing as it is the first time that we have seen that functional adult tissue cells can be reprogrammed into stem cells by natural bacterial infection, which also does not carry the risk of creating tumorous cells.

"Potentially you could use the bacteria to change the flexibility of cells, turning them into stem cells and then use the standard antibiotics to kill the bacteria completely so that the cells could then be transplanted safely to tissue that has been damaged by degenerative disease."

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Bacteria triggers stem cell theory