THE man who grew a human ear on the back of a mouse has made a breakthrough that brings the prospect of an artificial liver much closer. He believes he has solved the problem of growing the complex networks of blood vessels that artificial organs would need to sustain themselves within the body.
Until now, researchers trying to build replacement body parts have been limited to making relatively simple tissue, such as thin sections of cartilage and skin. That's because it has not been possible to grow the deep networks of blood vessels that organs need to stay alive. But now Jay Vacanti at Massachusetts General Hospital in Boston and Jeffrey Borenstein at the nearby Draper Lab have shown that it can be done.
Artificial organs would be a boon because organ donations cannot keep pace with demand. In the US, some 80,000 people are waiting for kidney, liver or heart transplants. And of the 23,000 Americans who need a liver, only 5000 got their wish last year. Artificial organs would slash these waiting lists and solve the big problem of organ rejection by growing them from the patient'scells.
Tissue engineers can already grow simple body tissues such as knee cartilage. They start with a shaped, porous scaffold made from a biodegradable plastic like polylactic glycolic acid (PLGA). The scaffold is "seeded" by plunging it into a solution of the patient's cells and then immersing it in a nutrient solution. As the cells multiply and clump together, the scaffold dissolves, leaving a piece of cartilage ready for transplant.
The new cartilage can survive because oxygen and nutrients from surrounding body fluids diffuse into the cells. But this doesn't work for the thicker tissues typical of livers and kidneys because nutrients can only diffuse across a few cell layers. Instead, they need an internal blood supply to deliver nutrients to cells deep inside the organ. "Without a blood supply, the tissue dies," says Borenstein, a micro-engineering exper
Contact: Claire Bowles