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Replacing missing teeth with new bioengineered teeth, grown from stem cells generated from a person's own gum cells, is a future method that could be superior to the currently used implant technology, but for now not all required pieces are in place.New research, published in the Journal of Dental Research and led by Professor Paul Sharpe, an expert in craniofacial development and stem cell biology at King's College London's Dental Institute, describes an important preliminary step towards the development of this method by sourcing the required cells from a patient's own gum.

Research towards producing bioengineered teeth, also called bioteeth, aims to grow new and natural teeth by employing stem cell technology which generates immature teeth (teeth primordia) that mimic those in the embryo. These can be transplanted as small cell pellets into the adult jaw to develop into functional teeth, given the right circumstances, programming and assembly -- all of that difficult to master and not even tested yet -- the researchers say.

Remarkably, despite the very different environments, embryonic teeth primordia were found to develop normally in the adult mouth. Embryonic tooth primordia cells can readily form immature teeth following dissociation into single cell populations and subsequent recombination, but until now the available sources of these cells were impractical to use in a general therapy.
"What is required is the identification of adult sources of human epithelial and mesenchymal [stem] cells that can be obtained in sufficient numbers to make biotooth formation a viable alternative to dental implants," said Sharpe.
This challenge was now solved by the researchers, who successfully isolated adult human gum (gingival) tissue from patients at the Dental Institute at King's College London and used this to get epithlial stem cells, also grewing more of it in the lab. These adult stem cells could then be combined with the embryonic stem cells of mice that form teeth -- called mesenchyme cells, and not yet available as human adult stem cells. By transplanting this combination of cells into mice, the researchers were able to grow hybrid human/mouse teeth containing dentine and enamel, as well as viable roots.
"Epithelial cells derived from adult human gum tissue are capable of responding to tooth inducing signals from embryonic tooth mesenchyme in an appropriate way to contribute to tooth crown and root formation and give rise to relevant differentiated cell types, following in vitro culture," explained Sharpe.
"These easily accessible epithelial cells are thus a realistic source for consideration in human biotooth formation. The next major challenge is to identify a way to culture adult human mesenchymal cells to be tooth-inducing, as at the moment we can only make embryonic mesenchymal cells do this."
Current implant-based methods of whole tooth replacement can occasionally cause problems as the natural root structure cannot be reproduced and as a consequence of the friction from eating and other jaw movement, loss of jaw bone can gradually occur around the implant.

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JOHANNESBURG (AP) -- Mozambique's rhinoceros population was wiped out more than a century ago by big game hunters. Reconstituted several years ago, it has again been driven to extinction, or to the brink of extinction, by poachers seeking their horns for sale in Asia.

A leading rhino expert told The Associated Press that the last rhino in the southern African nation has been killed. The warden in charge of the Great Limpopo Transfrontier Park — the only place where the horned behemoths lived in Mozambique — also says poachers have wiped out the last of the rhinos. Mozambique's conservation director believes a few may remain.

Elephants also could become extinct in Mozambique soon, the warden of the Great Limpopo Transfrontier Park, Antonio Abacar, told AP. He said game rangers have been aiding poachers, and 30 of the park's 100 rangers will appear in court soon.

"We caught some of them red-handed while directing poachers to a rhino area," Abacar said.

A game ranger arrested for helping poachers in Mozambique's northern Niassa Game Reserve said on Mozambican Television TVM last week that he was paid 2,500 meticais (about $80) to direct poachers to areas with elephants and rhinos. Game rangers are paid between 2,000 and 3,000 meticais ($64 to $96) a month.

While guilty rangers will lose their jobs, the courts serve as little deterrent to the poachers: killing wildlife and trading in illegal rhino horn and elephant tusks are only misdemeanors in Mozambique.

"Their legal system is far from adequate and an individual found guilty is given a slap on the wrist and then they say 'OK. Give me my horn back,'" said Michael H. Knight, chairman of the African Rhino Specialist Group of the International Union for the Conservation of Nature's Species Survival Commission.

A meeting of the group in February reported there might, possibly, be one white rhino left in Mozambique and no black rhinos at all, Knight said.

According to Abacar: "We have already announced the extinction of the rhino population in Limpopo National Park."

But Bartolomeu Soto, director of Mozambique's transfrontier conservation unit, told the AP "We believe we still have rhinos, though we don't know how many."

Mozambican news reports have said the last 15 rhinos in the park were slaughtered in the past month, but park officials said those reports were wrong. Soto said the misunderstanding had arisen over Abacar's statement to journalists that he had not seen a rhino in the three months since he was put in charge of the large park.

The only official figure available for rhino deaths is that 17 rhino carcasses were found in the park in 2010, Soto said. He said officials believe poaching must be taking place because rhino horn and elephant tusks carried by Asian smugglers are regularly seized at Mozambique's ports, although at least some of the contraband could be from animals killed by Mozambican poachers in neighboring South Africa. This week a person was arrested at the airport of the capital, Maputo, in possession of nine rhino horns, Soto said.

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