File this under unexpectedly cool: organs you don't harvest, but instead print using an honest-to-goodness printer, just as you might words on paper, except in this case, the "words" are actual stem cells that could save someone's life.

MedicalRF.com / Getty Images A stem cell.

File this under unexpectedly cool: organs you don’t harvest, but instead print using an honest-to-goodness printer, just as you might words on paper, except in this case, the “words” are actual stem cells that could save someone’s life.

Let’s talk about 3D printers for a moment: high-tech contraptions that let you craft three-dimensional objects with a computer aided design program, then render them in the real world as instantly usable objects with, say, a little powder and some binding material. We’ve used such devices to make everything from jewelry and full-color models of human faces to smartphone cases and battery-powered motors. Scan an existing physical object like a crescent wrench into a computer and a 3D printer can completely replicate it just a short while later, no assembly required, right down to the adjustable jaws and cylindrical track.

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Now imagine a device that could print new organs on demand using cells in lieu of ink (call it “bio-ink,” because the scientists do). It’s part of a process known as biofabrication: assembling the essential cellular building blocks of organs using the mechanical exactness of computer-driven, three-dimensional printing technology.

Say you need a new trachea, a part of the body we’ve already managed to replicate using stem cells and successfully transplant to a human with late-stage tracheal cancer (I’m not making that up or exaggerating). With a 3D printer and a bunch of stem cell-saturated bio-ink, you might be able to just print that trachea on demand thanks to a new technique that lets you pass human embryonic stem cells (hESCs) through a printer nozzle without destroying them.

A team of researchers from Scotland announced Monday that they’d finally managed to get an inkjet-style printer to craft an organic 3D object. Not an actual organ (well, not yet), but these scientists claim they’ve been able to clear a crucial hurdle: getting hESCs, prized for their ability to become cells of any tissue type, to survive the printing process.

The solution involved rejiggering the way the inkjet-style 3D printer worked, specifically the printing valve, which had to be tweaked to ever-so-gently deposit blobs of hESCs in programmable patterns without compromising the viability and functionality of the cells themselves. The researchers figured out how to do this using two types of bio-inks as well as allow for independent control of the amount in each droplet (with considerable control granularity — down to less than five cells per droplet). The results of the experiment were just published in the bio-science print and online journal Biofabrication.

“We are able to print millions of cells within minutes,” said paper co-author Will Shu of the Heriot-Watt University in Edinburgh, reports Agence France-Presse. Shu adds that the printer is comparable in size to a garden variety desktop laser printer.

It’s not like we haven’t printed cells before — we’ve been able to print stuff as crazy-sounding as DNA for years. But getting hESCs through a 3D printer nozzle successfully using a method that allows how they emerge and in what amounts to be controlled precisely without compromising their viability and rendering them as 3D objects — that’s crazy-cool future science. And though it’ll be some time before we’re printing stuff like human tracheas, to say nothing of organs that require complex networks of blood vessels to sustain the tissue, we’re a momentous step closer after this breakthrough.

What’s more, the immediate benefits extend well beyond human organ genesis: Next up, Shu and team intend to print 3D liver tissue, which Shu hopes could eliminate the use of non-human animals in laboratory drug tests.

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