Two exciting advances

Wing regeneration:

Chop off a salamander's leg and a brand new one will sprout in no time. But most animals have lost the ability to replace missing limbs. Now, a research team at the Salk Institute for Biological Studies has been able to regenerate a wing in a chick embryo -- a species not known to be able to regrow limbs -- suggesting that the potential for such regeneration exists innately in all vertebrates, including humans.

Their study, published in the advance online edition of Genes and Development on Nov. 17, demonstrates that vertebrate regeneration is under the control of the powerful Wnt signaling system: Activating it overcomes the mysterious barrier to regeneration in animals like chicks that can't normally replace missing limbs while inactivating it in animals known to be able to regenerate their limbs (frogs, zebrafish, and salamanders) shuts down their ability to replace missing legs and tails.

"In this simple experiment, we removed part of the chick embryo's wing, activated Wnt signaling, and got the whole limb back - a beautiful and perfect wing," said the lead author, Juan Carlos Izpis�a Belmonte, Ph.D., a professor in the Gene Expression Laboratory.

Human heart valves from stem cells:

Scientists for the first time have grown human heart valves using stem cells from the fluid that cushions babies in the womb, offering an approach that may be used to repair defective hearts.

The idea is to create new valves in the laboratory while a pregnancy progresses and have them ready to implant in a baby with heart defects after it is born.

The Swiss experiment follows recent successes at growing bladders and blood vessels and suggests that people may one day be able to grow their own replacement heart parts, in some cases, even before they are born.