People may in future be able to have missing or diseased teeth replaced with ones grown from cells taken from their own mouth, scientists have predicted.
Hybrid teeth created by combining human
gum cells and stem cells from mouse teeth have been grown in laboratory
mice by researchers who hope the work could lead to dentures being
superseded by new teeth grown on a patient's jaw.
The mixture of
mouse and human cells was transplanted into adult mouse kidneys and grew
into recognisable tooth structures coated in enamel with viable
developing roots, according to a study published in the Journal Of Dental Research.
Two kinds of cell were used to make the bioengineered teeth.
Epithelial "surface lining" cells were taken from human gum tissue and
mesenchymal stem cells from the mouse embryos.
Mesenchymal cells can develop into a range of different tissues, including bone, cartilage and fat.
Professor Paul Sharpe, who led the research at King's College London's dental institute,
said: "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
"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."
Previous research has shown that embryonic teeth are capable of developing normally in the adult mouth.
is required is the identification of adult sources of human epithelial
and mesenchymal cells that can be obtained in sufficient numbers to make
biotooth formation a viable alternative to dental implants," said
Saturday, May 25, 2013
Saturday, May 18, 2013
The largest terrestrial animalBoth African elephants and Asian elephants need a lot of food and freedom to survive. They wander in small to large herds over sometimes incredibly large areas, while consuming up to several hundred kilograms of plant matter in a single day.
Elephants, in fact, place such great demands on their own environment that they frequently come into conflict with people who are competing for many of the same, often scarce, resources.
The Asian elephant has four hooves (occasionally five) on the hind foot and five on the forefoot, while the African elephant has three on the hind foot and five on the forefoot.
Although poaching of elephants for their ivory has declined since the 1989 worldwide ivory ban, it remains a widespread problem. Large quantities of African ivory, for example, are still finding their way to illegal markets in Africa and beyond. Elephants are also killed for their meat and hides.
Habitat loss also a concern
A more long-term threat is the reduction of habitat available to elephants in the face of expanding human populations. Habitat loss isolates many wild elephant populations, with ancient migratory routes cut off by human settlements.
Habitat loss and degradation also increases confrontations between elephants and people, often leading to deaths on both sides.