Thanks to ideas formulated from childhood viewings of Jurassic Park, our conception of what scientists can accomplish is unlimited. Well, get this. Scientists are on the brink of something unimaginable, something that, until recently, was only possible in futuristic sci-fi movies: Bio technicians are working on making printable organs. Printable organs are produced like words on paper, but here, the “words” being used are stem cells.
Without getting into the controversy of stem cell research in and of itself, this is some really cool science. Generally, 3D printers work by crafting three-dimensional objects with a computer-aided design program, then forming them as instantly functional objects using a few basic raw materials. This technology has previously been used to make everything from jewelry and models of human faces to smartphone cases and battery-powered motors. All you need to do is to scan an existing physical object into a computer and a 3D printer can completely replicate it just a short while later, right down to the pins and screws, no assembly required.
Now let’s take this technology one step further, where “bio-ink,” as scientists refer to it, is used instead of our traditional ink. “Bio-ink” surpasses even the inkiest of pens. This concept is part of a process known as bio-fabrication: bringing together the critical cellular building blocks of organs using the mechanical precision of computer-driven, three-dimensional printing technology. For example, let’s say a patient needs a new trachea, an organ that scientists have successfully transplanted to a human with late-stage tracheal cancer using replicated stem cells. With a 3D printer and stem cell-saturated bio-ink, the trachea can be printed on demand using a technique that passes human embryonic stem cells (hESCs) through a printer without destroying them.
Early February, researchers from Scotland announced that they’d succeeded in acquiring an inkjet-style printer to craft an organic 3D object. They haven’t printed an organ just yet, but they have overcome a major obstacle; getting hESCs to survive the printing process. The solution involved adjusting the way the 3D printer operated, primarily the printing valve, which had to be fine-tuned to lightly deposit spots of hESCs in programmable patterns without risking the sustainability of the cells. The researchers worked out this kink by using two types of bio-inks and by manipulating the amount of cells in each droplet (less than five cells per droplet). The results were recently published in the 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, Scotland. Shu mentions that the printer is equivalent in size to a standard laser printer, and he also reports, “We found that the valve-based printing is gentle enough to maintain high stem cell viability, accurate enough to produce spheroids of uniform size, and most importantly, the printed hESCs maintained their pluripotency – the ability to differentiate into any other cell type.”
This scientific breakthrough is not completely unexpected, since printed cells and even printed DNA has been around for years already. Still, getting the hESCs effectively and precisely through a 3D printer without compromising their viability is no small feat. As Jason King, business development manager of stem cell biotech company Roslin Cellab, which took part in the research, said: “Normally laboratory grown cells grow in 2D but some cell types have been printed in 3D. However, up to now, human stem cell cultures have been too sensitive to manipulate in this way.” Although scientists predict that time remains before entire tracheas, and of course more complex organs containing networks of blood vessels are printed, a giant step in the right direction has been taken.
Moreover, the immediate benefits of this technology extend beyond human organ genesis. Shu and his team’s next project is to print liver tissue, which could essentially eliminate the use of animals in laboratory drug tests. This is beneficial primarily because current analysis of potential metabolite toxicity is conducted on experimental animals, which is not ideal, since animal models provide a less accurate representation of the metabolism and toxicity levels in humans. Also, it has been shown that cells growing in more physiological 3D cultures behave differently than cells grown in the 2D culture used in drug development. Additionally, when analyzing the potential toxic effects that drug metabolites may have on other cell types, it would be useful to have an in vitro system.
At the same time, the major benefit centers around organ production. As King mentions, “This is a scientific development which we hope and believe will have immensely valuable long-term implications… [such as] to provide organs for transplant on demand, without the need for donation and without the problems of immune suppression and potential organ rejection.”