Oct 25, 2015 | By Benedict

Ongoing research into the potential 3D printing of functioning human organs is one of today’s most exciting and potentially revolutionary areas of scientific study. However, whilst work is ongoing in all corners of the globe to develop bioprinting techniques which can successfully 3D print with organic materials, much progress needs to be made before scientists can realistically hope to hold a living, beating, 3D printed heart in their hands.

This week, researchers at Carnegie Mellon University took a few small steps along the road towards successful, potentially life-saving bioprinting. Although that ultimate goal remains distant, a group of scientists were able to print non-living replicas of coronary arteries and embryonic hearts in soft materials, using a specially modified 3D printer.

“We've been able to take MRI images of coronary arteries and 3D images of embryonic hearts and 3D bioprint them with unprecedented resolution and quality out of very soft materials like collagens, alginates and fibrins,” said Adam Feinberg, associate professor of Materials Science and Engineering and Biomedical Engineering at CMU.

Adam Feinberg

One of the biggest problems faced by scientists looking to use 3D printing technology for bioprinting is the non-rigid nature of the materials being used. 3D printing with plastics and metals is made possible by printing layer upon layer, with each layer hardening soon after it has left the nozzle of the 3D printer. The hardness of the 3D printed material allows more and more material to be stacked up vertically without the danger of it collapsing. When 3D printing with soft materials, this danger is a real problem. “The challenge with soft materials—think about something like Jello that we eat—is that they collapse under their own weight when 3D printed in air," explained Feinberg. "So we developed a method of printing these soft materials inside a support bath material. Essentially, we print one gel inside of another gel, which allows us to accurately position the soft material as it's being printed, layer-by-layer.”

CMU’s gel technique, which they have termed ‘FRESH’ (Freeform Reversible Embedding of Suspended Hydrogels), is not the first time that researchers have used a kind of gel to support fragile 3D printed structures made from soft materials. Last month, scientists at the University of Florida detailed their own innovative method for 3D printing objects out of human cells and other soft materials. Their method involved the use of a granular hydrogel named Carbopol EDT 2020, a product much like common hand sanitiser, to function as a kind of scaffold for the structures themselves—allowing them to be ‘suspended’ seemingly in mid-air.

So what’s new about CMU’s research? Although the use of gels to facilitate the 3D printing of soft structures has been seen before, the CMU team claim to be working with materials in entirely new ways. “3D 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. Furthermore, the team claim that the gel used in their FRESH procedure can be easily melted away and removed by heating to body temperature, avoiding potential damage to delicate biological molecules or living cells.

One big advantage of CMU’s 3D bioprinting technique is the low cost of their 3D printing hardware. While most 3D bioprinters cost over $100,000 and are often difficult to operate, Feinberg's group of CMU researchers have been conducting their research using only modified, consumer-level 3D printers such as those made by MakerBot. They have managed this feat by utilising open-source hardware and software; making modifications where necessary to suit their own needs.

"Not only is the cost low, but by using open-source software, we have access to fine-tune the print parameters, optimise what we're doing and maximize the quality of what we're printing," explained Feinberg. "It has really enabled us to accelerate development of new materials and innovate in this space. And we are also contributing back by releasing our 3D printer designs under an open-source license.”

The researchers’ full findings can be found in the latest issue of Science Advances.



Posted in 3D Printing Application



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