NEW YORK – By the time 10-year-old Sarah Murnaghan finally underwent a lung transplant June 12, she’d been waiting for months, and her parents had sued to give her a better shot at surgery.
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 had 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 remains 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 those cells or others made from them to seed a scaffold that’s shaped like the organ he or she needs.
Then, “We can regenerate an organ that will not be rejected (and can be) grown on demand and transplanted surgically, similar to a donor organ,” said Dr. Harald Ott of Massachusetts General Hospital.
That won’t happen anytime soon for solid organs such as lungs or livers. But as Angela’s case shows, simpler body parts already are being put into patients as researchers explore the possibilities of the field.
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 one patient’s case 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.
Other kinds of implants also have shown that the seeded cells can act as beacons that summon cells from the recipient’s body, said Dr. William Wagner, director of the McGowan Institute for Regenerative Medicine at the University of Pittsburgh. Sometimes that works out fine, but other times it can lead to scarring or inflammation. Controlling what happens when an engineered implant interacts with the body is a key challenge.
So far, lab-grown parts implanted in people have involved fairly simple structures – basically sheets, tubes and hollow containers, said Dr. Anthony Atala, whose Wake Forest University lab also has made scaffolds for noses and ears. Solid internal organs such as livers, hearts and kidneys are far more complex to make.
His pioneering lab at Wake Forest is using a 3-D printer to make miniature prototype kidneys, some as small as a half-dollar, and other structures for research. Instead of depositing ink, the printer puts down a gel-like biodegradable scaffold plus a mixture of cells to build a kidney layer by layer. Atala expects it will take many years before printed organs find their way into patients.
Another organ-building strategy used by Atala and maybe half a dozen other labs starts with an organ, washes its cells off the inert scaffolding that holds cells together, and then plants that scaffolding with new cells.
“It’s almost like taking an apartment building, moving everybody out ... and then really trying to repopulate that apartment building with different cells,” said Dr. John LaMattina of the University of Maryland School of Medicine.
He’s using the approach to build livers. It’s the repopulating part that’s the most challenging, he said.
How long until doctors start testing solid organs in people? Ott said he hopes to see human studies on some lab-grown organ in five to 10 years. Wagner called that very optimistic and estimated 15 to 20 years is more realistic.
But LaMattina figures five to 10 years might be about right for human studies of his specialty, the liver.
“I’m an optimist,” he said. “You have to be an optimist in this job.”