Human urine used as source of stem cells to grow teeth

Scientists in China report they've grown rudimentary teeth from stem cells taken from an unexpected source -- human urine. The technique of using stem cells that could be grown into tiny tooth-like structures could be developed into a way of replacing lost teeth, they said. Researchers in many countries looking for ways of growing new teeth to replace those lost with age and poor dental hygiene are increasingly focusing on stem cells. Scientists at the Guangzhou Institutes of Biomedicine and Health used urine as the starting point, harvesting cells passed from the body and modifying them into stem cells. The cells, when implanted into animals, began to resemble a tooth, the researchers said. "The tooth-like structure contained dental pulp, dentin, enamel space and enamel organ," they reported in the Cell Regeneration Journal. Some stem cell scientists have expressed doubts about using urine as a cell source. "It is probably one of the worst sources; there are very few cells in the first place and the efficiency of turning them into stem cells is very low," stem cell scientist Chris Mason of University College London told the BBC. "You just wouldn't do it in this way."