A chemical that causes bad breath can be used to convert dental stem cells into human liver cells, a finding which scientists say could help repair the key organ if damaged.

Researchers at the Nippon Dental University in Japan found that Hydrogen sulphide- the gas famed for generating the stench in stink bombs, flatulence and bad breath- can be harnessed to create liver cells which could prove a valuable treatment for patients. According to the scientists, small amounts of hydrogen sulphide are made by the body. It is also produced by bacteria and is toxic in large quantities.

The scientists found that the gas increased the purity and proportion of the stem cells.which were converted to liver cells when used alongside other chemicals.

"High purity means there are less 'wrong cells' that are being differentiated to other tissues, or remaining as stem cells," lead researcher Dr Ken Yaegaki said.

One of the concerns with dental pulp as a source of stem cells is the number that can be harvested. However, the study, which appeared in the Journal of Breath Research, did not say how many cells were actually produced.

Prof Chris Mason, a specialist in regenerative medicine at University College London, said, "It would be interesting to see how hydrogen sulphide works with other cells types."