Printing lungs
United says that it is now building a new, germ-proof pig facility, which will be ready in 2023 and support a clinical trial starting the following year. It’s not the fantastical commercial pig factory shown in Rothblatt’s architectural rendering, but it is a stepping-stone toward it. Eventually, Rothblatt believes, a single facility could supply organs for the whole country, delivering them via all-electric air ambulances. Over the summer, she claims, an aeronautics company she invested in, Beta Technologies, flew a vertical-lift electric plane from North Carolina to Arkansas, more than 1,000 nautical miles.
Ironically, pigs may never be a source of the lungs that Rothblatt’s daughter may need. That is because lungs are delicate and more susceptible to immune attack. By 2018, the results were becoming clear. Each time the company added a new gene edit to the pigs, hearts and kidneys transplanted into monkeys would last an extra few weeks or months. But the lungs weren’t improving. Time and again, after being transplanted into monkeys, the pig lungs would last two weeks and then suddenly fail.
“I actually believe there is no part of the body that cannot be 3D-printed.”
Martine Rothblatt
To create lungs, Rothblatt is betting on a different approach, establishing an “organ manufacturing” company that is trying to make lungs with 3D printers. That effort is now operating out of a former textile mill in Manchester, New Hampshire, where researchers print detailed models of lungs from biopolymers. The eventual idea is to seed these structures with human cells, including (in one version of the technology) cells grown from the tissue of specific patients. These would be perfect matches, without the risk of immune rejection.
This past spring, Rothblatt unveiled a set of printed “lungs” that she called “the most complex 3D-printed object of any sort, anywhere, ever.” According to United, the spongy structure, about the size of a football, includes 4,000 kilometers of capillary channels, detailed spaces mimicking lung sacs, and a total of 44 trillion “voxels,” or individual printed locations. The printing was performed with a method called digital light processing, which works by aiming a projector into a vat of polymer that solidifies wherever the light beams touch. It takes a while—three weeks—to print a structure this detailed, but the method permits the creation any shape, some no larger than a single cell. Rothblatt compared the precision of the printing process to driving across the US and never deviating more than the width of a human hair from the center line.
“I actually believe there is no part of the body that cannot be 3D-printed … including colons and brain tissue,” Rothblatt said while presenting the printed lung scaffolds in June at a meeting in California.
Some scientists say bioprinting remains a research project and question whether the lifeless polymers, no matter how detailed, should be compared to a real organ. “It’s a long way to go from that to a lung,” says Jennifer Lewis, who works with bioprinting at Harvard University. “I don’t want to rain on the parade, and there has been significant investment, so some smart minds see something there. But from my perspective, that has been pretty hyped. Again, it’s a scaffold. It’s a beautiful shape, but it’s not a lung.” Lewis and other researchers question how feasible it will be to breathe real life into the printed structures. Sticking human cells into a scaffold is no guarantee they will organize into working tissue with the complex functions of a lung.
Rothblatt is aware of the doubters and knows how difficult the technology is. She knows that other people think it won’t ever work. That isn’t stopping her. Instead, she sees it as her next chance to solve problems other people can’t. During an address to surgeons this year, Rothblatt rattled off the list of challenges ahead—including growing the trillions of cells that will be needed. “What I do know is that doing so does not violate any laws of physics,” she said, predicting that the first manufactured lungs would be placed in a person’s chest cavity this decade.
She closed her talk with a scene from 2001: A Space Odyssey, the one where an ape-man hurls a bone upward and it takes flight as a space station circling the Earth. Except Rothblatt substituted a photograph of herself piloting the zero-carbon electric plane she believes will someday deliver unlimited organs around the country.