Replacement Parts
To cope with a growing shortage of hearts, livers, and lungs suitable for transplant, some scientists are genetically engineering pigs, while others are growing organs in the lab.
For Joseph Vacanti, the quest to build new organs began after watching the death of yet another child. In 1983, the young surgeon was put in charge of a liver transplantation program at Boston Children’s Hospital in Massachusetts. His first operation was a success, but other patients died without ever being touched by a scalpel. “In the mid-80s, kids who were waiting for organs had to wait for a child of the same size to die,” says Vacanti. “Many patients became sicker and sicker before my eyes, and I couldn’t provide them with what they needed. We had the team, the expertise, and the intensive care units. We knew how to do it. But we had to wait.”
On the other side of the Atlantic, David Cooper was having the same problem. Having taken part in the first successful series of heart transplants in the United Kingdom, he had moved to South Africa to run a transplantation program at the University of Cape Town Medical School. At the time, people had a 50/50 chance of surviving such a procedure, but Cooper recalls that most of his patients were killed by a lengthy wait. “We just didn’t have enough donors,” he says.
Today, the organ shortage is an even bigger problem than it was in the 1980s. In the United States alone, more than 114,000 people are on transplant lists, waiting for an act of tragedy or charity. Meanwhile, just 14,000 deceased and living donors give up organs for transplants each year. The supply has stagnated despite well-funded attempts to encourage donations, and demand is growing, especially as the organs of a longer-lived population wear out.
Faced with this common problem, Vacanti and Cooper have championed very different solutions. Cooper thinks that the best hope of providing more organs lies in xenotransplantation—the act of replacing a human organ with an animal one. From his time in Cape Town to his current position at the University of Pittsburgh, he has been trying to solve the many problems that occur when pig organs enter human bodies, from immune rejection to blood clots. Vacanti, now at Massachusetts General Hospital, has instead been developing technology to create genetically tailored organs out of a patient’s own cells, abolishing compatibility issues. “I said to myself: why can’t we just make an organ?” he recalls.
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The ideal scaffold
While some scientists struggle to get human bodies to accept pig organs, others are attempting the more ambitious feat of engineering bespoke human organs from scratch. Such organs, grown from a patient’s own cells, should avoid the problems of immune rejection that plague the field of xenotransplantation. “Cartilage, skin, and bone are already on the market. Blood vessels are in clinical trials. The progress has been really gratifying,” says Laura Niklason of Yale University.
These tissues—either flat planes or hollow tubes—are relatively simple to produce, and consist of a small number of cell types. Solid organs, such as the lungs, heart, liver, and kidneys, pose a greater challenge. They are bigger, they contain dozens of cell types, and they have a complex architecture and an extensive network of the most essential component: blood vessels. “Every cell needs to eat and breathe, and each one needs to be close to a source of nutrition and oxygen,” says Vacanti. Still, he is optimistic that it should be possible to engineer even these complex organs. “People differ about whether it’ll be achieved in 5 or 100 years, but most people in the field believe that it’s a realistic goal,” he says.
Full article is long, but interesting:
http://www.the-scientist.com/?articl...acement-Parts/