3D printing technology can construct actual, working bridges on Earth, build elaborate decorative accessories for your home, produce prosthetics for amputees, and (unfortunately) manufacture working firearms. Although impressive, all these innovations have something in common: they are only producing inorganic, plastic-based material. What about organic materials, say, perhaps, human organs? Wouldn’t it be great if new organs could be printed out and used in surgical operations to save people’s lives? As it turns out, a group of Carnegie Mellon researchers have managed to do almost precisely this, producing models of a variety of human organs and body parts using a hacked 3D printer bought off the shop shelves. The new research, published in the journal Science Advances, demonstrates that it is possible to replicate the heart through 3D printing.

“3-D printing of various materials has been a common trend in tissue engineering in the last decade, but until now, no one had developed a method for assembling common tissue engineering gels like collagen or fibrin,” said TJ Hinton, a graduate student in biomedical engineering at Carnegie Mellon and lead author of the study, in a statement.

Biological materials are often soft and fragile in isolation, which proved a challenge for the scientists behind the study. Soft materials tend to collapse under their own weight when printed in air, meaning that the soft objects had to be printed inside a material that could support their structure. To this end, a “bath” of chemicals – a support gel akin to an exoskeleton – was used, one that held together the fragile soft printed structure as it formed. After the printing had concluded, the support gel could then be melted away by heating it to body temperature (37°C, or 99°F), leaving the soft material within intact.

These soft materials were not mere plastic copies of biological material: collagens, muscle fibers, miniature brain structures, and branching artery patterns made of biological matter have all been produced using the technique. Most impressively, using magnetic resonance imaging (MRI) scans of human coronary arteries and 3D images of embryonic human hearts, the team have managed to 3D print replicas of both. This type of “bioprinting” has been given the acronym of FRESH – Freeform Reversible Embedding of Suspended Hydrogels.

Printing a series of artery trees using this technique was perhaps the most substantial achievement by the team, who have produced complex biological structures with an unprecedented degree of precision. The team’s next step is to inject heart cells into these 3D printed biological tissue structures, essentially filling in the printed “scaffolding” with its biological “concrete”.

This research has obvious implications for medical science. Let’s just take one example: the heart. Human heart tissue has lost its ability to repair or regenerate itself once it is damaged. So if a heart needs to be operated on, it often requires new heart tissue. This isn’t always readily available, and the agonizing wait for a heart transplant from a donor often ends in tragedy. This waiting list could be significantly reduced by using 3D bioprinting: this FRESH technique could produce pieces of bespoke heart tissue for each specific case of heart damage.

3D bioprinters aren’t new: in this growing field of science, most of these printers cost over $100,000 (roughly £65,000) and require a specialist team of operators to use. Using a 3D printer bought by most consumers, and “hacking” it with open-source software and hardware, this research team have managed to replicate human organ structures for less than $1,000 (£650).