Scientists in China say they have successfully grown a human tooth using stem cells taken from urine.
Researchers say the technique could one day be used as a way to replace teeth lost through aging and poor dental hygiene, with the added bonus that urine is deemed a less controversial source of stem cells than human embryos.
The team at the Guangzhou Institute of Biomedicine and Health extracted cells contained in the urine which would normally be passed from the body, such as those from the lining of the body's waterworks, and managed to coax them into becoming stem cells.
They then used these to implant the teeth-like structures in mice, and said the resulting bundle of cells eventually contained “dental pulp, dentin, enamel space and enamel organ,” researchers said.
The report, published in Cell Regeneration Journal, added that this could lead to further studies resulting in “the final dream of total regeneration of human teeth for clinical therapy”.
However the project has received has attracted criticism, and not just because it has only a 30 per cent success rate in its current form.
Prof Chris Mason, a stem cell scientist at University College London, told the BBC urine was “probably one of the worst sources” of stem cells.
He said: “There are very few cells in the first place and the efficiency of turning them into stem cells is very low. You just wouldn't do it in this way.“
He also said the risk of contamination was much higher than with other sources of cells, and that there was a long way to go before science overcame “the big challenge” of getting nerve and blood vessels to integrate in newly-formed permanent teeth.