Last month I had the chance to hold a replica of the upper part of a human airway—the windpipe plus the first two bronchi. It had been made from collagen, the biological cement that holds our bodies together. It was slippery and hollow, with the consistency of undercooked pasta.
The structure had emerged from a refrigerator-size 3-D printer in Manchester, New Hampshire, at an outpost of United Therapeutics, a company that earns more than a billion dollars a year selling drugs to treat lung ailments.
One day, the company says, it plans to use a printer like this one to manufacture human lungs in “unlimited quantities” and overcome the severe shortage of donor organs.
Bioprinting tissue isn’t a new idea. 3-D printers can make human skin, even retinas. Yet the method, so far, has been limited to tissues that are very small or very thin and lack blood vessels.
United instead is developing a printer that it believes will be able, within a few years, to manufacture a solid, rubbery outline of a lung in exquisite detail, including all 23 descending branches of the airway, the gas-exchanging alveoli, and a delicate network of capillaries.
A lung made from collagen won’t help anyone: it’s to a real lung what a rubber chicken is to an actual hen. So United is also developing ways to impregnate the matrix with human cells so they’ll attach and burrow into it, bringing it alive.
“We are trying to build the little stick houses for cells to live in,” says Derek Morris, a project leader in United’s organ manufacturing group.
A time-lapse video shows the printing of a trachea and the first bronchial branches of a lung. The structure is made of collagen, the same connective material in our bodies.
ORGAN MANUFACTURING COMPANY
The 3-D-printing project is the latest in a series of high-wire engineering efforts launched by United’s CEO, Martine Rothblatt, a onetime aerospace entrepreneur (she was the founding CEO of Sirius Satellite Radio) who changed careers in the 1990s after her daughter developed a rare lung disease.
In creating United, Rothblatt parlayed an abandoned drug she picked up for $25,000 into a company that made her the highest-paid CEO in the biopharmaceutical industry last year—when she also set a speed record in an electric helicopter. Rothblatt says she expects electric drones to someday whisk organs from her factory to wherever they are needed.
United has already made some risky organ bets. One of its subsidiaries, Revivicor, supplies surgeons with hearts, kidneys, and lungs from genetically engineered pigs (these have been used in baboons, so far). Another, Lung Bioengineering, refurbishes lungs from human donors by pumping warm solution into them. About 250 people have already received lungs that would otherwise have been designated medical waste.
Don’t expect fully manufactured organs soon. United, in its company projections, predicts it won’t happen for another 12 years. Rothblatt acknowledges that the printed structure I saw is just a start. “It’s only two branches and no cells,” she says.
Even so, United’s effort to print entire organs, which got under way last year, may be the industry’s largest. It hired a South Carolina company, 3D Systems, to build the printer and is paying another company, 3Scan, to slice up lungs and create detailed maps of their interior. It has job ads out for roles such as “Mathematician—Human Organ Design.”
United’s organ manufacturing group is located in the same complex of former textile mills as BioFabUSA, an $80 million Defense Department tissue-printing initiative. Dean Kamen, the well-known inventor who leads BioFabUSA, says meetings with Rothblatt were what led him to apply to the government to host the institute. “I saw miracles she’s playing with and the frustration of the equipment she is using to do it,” he says. To Kamen, biologists are hindered by what he calls “19th-century technology” of flasks and beakers.
The collagen printer 3D Systems is using now operates according to a method called stereolithography. A UV laser flickers through a shallow pool of collagen doped with photosensitive molecules. Wherever the laser lingers, the collagen cures and becomes solid. Gradually, the object being printed is lowered and new layers are added.
United’s CEO, Martine Rothblatt
ANDRE CHUNG | WIKIMEDIA COMMONS
The printer can currently lay down collagen at a resolution of around 20 micrometers, according to United. Printing the anatomical details of a lung, however, will require features less than a micrometer in size.
“When you see the complexity of the lung, what nature does from conception to birth, there is no way to machine that or mold it. 3-D printing is the only way we have to create that geometry,” says Pedro Mendoza, director of bioprinting at 3DSystems.
Mendoza says 3D Systems plans to import techniques from the semiconductor industry—such as masks, mirrors, and more powerful lasers—to improve the printer’s resolution. Speed is also an issue. The structure I saw took 12 hours to print. A complete, detailed lung scaffold would take a year to build with the same printer.