As more patients get lab-grown body parts, scientists face challenge of making complex organs

  • Article by: MALCOLM RITTER , AP Science Writer
  • Updated: June 17, 2013 - 2:35 PM

NEW YORK — By the time 10-year-old Sarah Murnaghan finally got a lung transplant last week, she'd been waiting for months, and her parents had sued to give her a better shot at surgery.

Her cystic fibrosis was threatening her life, and her case spurred a debate on how to allocate donor organs. Lungs and other organs for transplant are scarce.

But what if there were another way? What if you could grow a custom-made organ in a lab?

It sounds incredible. But just a three-hour drive from the Philadelphia hospital where Sarah got her transplant, another little girl is benefiting from just that sort of technology. Two years ago, Angela Irizarry of Lewisburg, Pa., needed a crucial blood vessel. Researchers built her one in a laboratory, using cells from her own bone marrow. Today the 5-year-old sings, dances and dreams of becoming a firefighter — and a doctor.

Growing lungs and other organs for transplant is still in the future, but scientists are working toward that goal. In North Carolina, a 3-D printer builds prototype kidneys. In several labs, scientists study how to build on the internal scaffolding of hearts, lungs, livers and kidneys of people and pigs to make custom-made implants.

Here's the dream scenario: A patient donates cells, either from a biopsy or maybe just a blood draw. A lab uses them, or cells made from them, to seed onto a scaffold that's shaped like the organ he needs. Then, says Dr. Harald Ott of Massachusetts General Hospital, "we can regenerate an organ that will not be rejected (and can be) grown on demand and transplanted surgically, similar to a donor organ."

That won't happen anytime soon for solid organs like lungs or livers. But as Angela Irizarry's case shows, simpler body parts are already being used as researchers explore the possibilities of the field.

Just a few weeks ago, a girl in Peoria, Ill., got an experimental windpipe that used a synthetic scaffold covered in stem cells from her own bone marrow. More than a dozen patients have had similar operations.

Dozens of people are thriving with experimental bladders made from their own cells, as are more than a dozen who have urethras made from their own bladder tissue. A Swedish girl who got a vein made with her marrow cells to bypass a liver vein blockage in 2011 is still doing well, her surgeon says.

In some cases the idea has even become standard practice. Surgeons can use a patient's own cells, processed in a lab, to repair cartilage in the knee. Burn victims are treated with lab-grown skin.

In 2011, it was Angela Irizarry's turn to wade into the field of tissue engineering.

Angela was born in 2007 with a heart that had only one functional pumping chamber, a potentially lethal condition that leaves the body short of oxygen. Standard treatment involves a series of operations, the last of which implants a blood vessel near the heart to connect a vein to an artery, which effectively rearranges the organ's plumbing.

Yale University surgeons told Angela's parents they could try to create that conduit with bone marrow cells. It had already worked for a series of patients in Japan, but Angela would be the first participant in an American study.

"There was a risk," recalled Angela's mother, Claudia Irizarry. But she and her husband liked the idea that the implant would grow along with Angela, so that it wouldn't have to be replaced later.

So, over 12 hours one day, doctors took bone marrow from Angela and extracted certain cells, seeded them onto a 5-inch-long biodegradable tube, incubated them for two hours, and then implanted the graft into Angela to grow into a blood vessel.

It's been almost two years and Angela is doing well, her mother says. Before the surgery she couldn't run or play without getting tired and turning blue from lack of oxygen, she said. Now, "she is able to have a normal play day."

This seed-and-scaffold approach to creating a body part is not as simple as seeding a lawn. In fact, the researchers in charge of Angela's study had been putting the lab-made blood vessels into people for nearly a decade in Japan before they realized that they were completely wrong in their understanding of what was happening inside the body.

"We'd always assumed we were making blood vessels from the cells we were seeding onto the graft," said Dr. Christopher Breuer, now at Nationwide Children's Hospital in Columbus, Ohio. But then studies in mice showed that in fact, the building blocks were cells that migrated in from other blood vessels. The seeded cells actually died off quickly. "We in essence found out we had done the right thing for the wrong reasons," Breuer said.

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