Hearts & Bones

Gordana Vunjak-Novakovic is at the forefront of regenerative medicine. Can her laboratory-grown body parts really work?

by Adam Piore Published Spring 2012
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“We’re now able to grow a full-size jawbone or cheekbone within three weeks. Doctors say the wait would be worth it, in many cases.” 
-Gordana Vunjak-Novakovic

“Why nature would create a tissue with no ability to repair itself is one of life’s mysteries,” she continues. “The same thing is true of brain, heart, and pancreatic tissue.”

The body parts that biomedical engineers were making progress on were those that, in addition to having some capacity for self-repair, have large surface areas relative to their mass. This was because a thin piece of tissue, once implanted, would be well exposed to the body’s veins and capillaries, increasing the likelihood that it would receive the blood and oxygen it needed. Skin was in this category, as were some tubular structures such as the urethra, trachea, and intestines, as well as the sack-like bladder, which is among the body’s simplest organs. (Today, biomedical engineers have succeeded in growing and implanting in people all of these tissue types, in addition to blood vessels.)

At Columbia, Vunjak-Novakovic continued working on cartilage but shifted her focus to one of the most daunting targets of all: the heart. The fibrous muscle tissues that compose the heart have little capacity for self-repair. Also, it would be difficult to get engineered heart tissue enough blood. “The walls of the heart are quite beefy, nearly a centimeter thick,” says Vunjak-Novakovic. “So any heart tissue we created would need to have its own vascular infrastructure ready to work efficiently as soon as it went into the body.”

But Vunjak-Novakovic decided that it would be worth the effort to create a tissue that could save lives. And she figured that by exploiting the knowledge of Columbia’s physicians, cell biologists, and other engineers, she might at least make some progress. “I decided that a key strength of our laboratory,” she says, “was going to be our openness to collaboration.”

Among the first Columbia physicians who showed interest in her work was the cardiologist Warren Sherman. In 2001, he was one of the first clinicians ever to inject stem cells into a person’s heart as a way of facilitating the organ’s recovery. He did this a few days after his patient had suffered a heart attack, aiming the stem cells straight into the region of the heart that had been deprived of blood and oxygen. His goal was to help the damaged muscle grow back. A large-scale clinical trial later showed that the treatment was beneficial, reducing the chances of subsequent cardiac episodes.

This procedure had shortcomings, however. “The stem cells you shoot in there don’t have good survival rates,” Sherman says. “If you inject two hundred million cells, you might get 5 percent of them to start growing as muscle.”

Sherman hoped that Vunjak-Novakovic might create new tissue in physically intact strips that could be applied, like living Band-Aids, to the damaged parts of the heart. He’d heard that a few years before showing up at Columbia, Vunjak-Novakovic had discovered that stem cells are more likely to turn into heart cells if they get zapped with electricity in the laboratory.

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