In the quest for regenerative medicine, a Chinese research team has found a novel way of growing human teeth, from stem cells taken from urine.

Scientists around the world continue to investigate ways to regenerate teeth lost to aging and poor dental hygiene, hoping to soon find a technique to make the possible the plasticity of the human body — as Michelangelo sculpted David.

Stem cells from urine were used by researchers at the Guangzhou Institutes of Biomedicine and Health to grow a clump of cells forming a rudimentary tooth.

"The tooth-like structure contained dental pulp, dentin, enamel space and enamel organ," the researchers wrote in Cell Regeneration Journal. "In particular, these regenerative teeth contain enamel with ameloblast-like cells of human origin and possess physical properties found in the regular human tooth.

"Thus, human [stem cells] could be a candidate source of seed cells on human tooth tissue-engineering for further drug screening or regenerative therapies."

The findings demonstrated that stem cells from urine could potentially be used as a source of pluripotent stem cells, useful for developing many different parts of the human body. In 2011 research published the Journal of the American Society of Nephrology, a team from the South China Institute for Stem Cell Biology and Regenerative Medicine demonstrated a noninvasive method for generating induced pluripotent stem cells (iPSC) from urine.

The Chinese investigators found urine to be a potential wellspring for regenerative medicine. "There is no consensus regarding the preferred tissue from which to harvest donor cells for reprogramming into iPSCs, and some donor cell types may be more prone than others to accumulation of epigenetic imprints and somatic cell mutations," the researchers wrote, describing their use of renal tubular cells from urine.

"This procedure eliminates many problems associated with other protocols, and the resulting [stem cells] display an excellent ability to differentiate," they concluded. "These data suggest that urine may be a preferred source for generating" such cells.

However, others say urine is a poor choice from which to derive stem cells for regenerative medicine. "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," Chris Mason, a researcher at University College, London, told reporters. "You just wouldn't do it in this way."

Stem cells from urine presented a much higher risk of contamination through bacteria than with other sources, Mason said. "The big challenge here is the teeth have got a pulp with nerve and blood vessels which have to make sure they integrate to get permanent teeth."

Still, the Chinese researchers said they had intended the study as only a preliminary step for further study "toward the final dream of total regeneration of human teeth for clinical therapy".

The findings demonstrated the ability to use such stem cells to regenerate "patient-specific" dental tissues, or even teeth, as regenerative therapy.

Source: Cai J, Zhang Y, Liu P, Chen S, Wu X, Sun Y. Generation of tooth-like structures from integration-free human urine inducedpluripotent stem cells. Cell Regeneration. 2013.