LA JOLLA, Calif. — It was the salamanders.
Juan Carlos Izpisua Belmonte had spent years probing the inner workings of embryos, ferreting out the genes that give a body its shape or allow wings to form instead of legs. He’d tracked wafting chemical messengers that, like traffic police, guide streams of dividing cells either left or right. He’d even found a way to tweak animals to grow extra limbs. But one thing he never stopped thinking about was how salamanders could lose parts of their bodies and then regrow perfect replacements. Was it possible, he wondered, that humans might do the same?
The dogged pursuit of that question has pushed Izpisua Belmonte to the forefront of biology as he’s made one stunning discovery after another — many before the world is ready to deal with their far-reaching ethical implications.
Early this year, seeking a way to grow human organs for transplant, his group announced it had created pig-human chimeras — fetal pigs with human cells mixed in. His Salk Institute lab has discovered two new kinds of stem cells, including one considered the pinnacle of stem cells because, in addition to being able to create every type of cell in the body, it can also form tissues like the placenta and amniotic sac that embryos need to survive. Last December, they used a technique in mice that may help reverse aging by reprogramming adult cells back to their youth. (Click to Site)